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    • 专利摘要:
    The field of this invention is ionically conductive materials that can be used in electrochemical generators. The object of this invention is to provide a new ionically conductive material which can be used in an electrochemical generator, for example in separators, solid polymer electrolytes or electrodes, having good mechanical properties and good ionic conductivity, and which be able to prevent dendritic growth in lithium batteries. This material comprises: 1. at least one polymer A, distinct from B, having an ionic conductivity of between 10-5 and 10-3 S / cm, 2. at least one polymer B having a mechanical strength characterized by a conservation module > 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa. 3. at least one reinforcing filler C. The subject of the invention is also films based on this type of material and processes for synthesizing these films. The invention also relates to a separator, a solid polymer electrolyte or an electrode based on this ionically conductive material and an electrochemical generator comprising such an ionically conductive material.
    公开号:FR3054078A1
    申请号:FR1656760
    申请日:2016-07-13
    公开日:2018-01-19
    发明作者:Jean-Yves Sanchez；Cristina Iojoiu；Yannick Molmeret；Claire Antonelli
    申请人:Centre National de la Recherche Scientifique CNRS；Institut Polytechnique de Grenoble；
    IPC主号:
    专利说明:

    Holder (s): POLYTECHNIC INSTITUTE OF GRENOBLE Public establishment, NATIONAL CENTER OF SCIENTIFIC RESEARCH -CNRS.
    Extension request (s)
    Agent (s): CABINET PLASSERAUD.
    FR 3 054 078 - A1 (54) ION CONDUCTIVE MATERIAL FOR ELECTROCHEMICAL GENERATOR AND METHODS OF MANUFACTURE.
    The field of this invention is that of mique materials comprising such an ionically conductive, ionically conductive material which can be used in electrochemical generators.
    The aim of this invention is to provide a new ion-conducting material which can be used in an electrochemical generator, for example in separators, solid polymer electrolytes or electrodes, having good mechanical properties and good ionic conductivity, and which be able to prevent dendritic growth in lithium batteries.
    This material includes:
    1. at least one polymer A, distinct from B, having an ionic conductivity of between 10 ' 5 and 10' * 1 2 3 S / cm,
    2. at least one polymer B having a mechanical strength characterized by a conservation modulus> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa.
    3. at least one reinforcing filler C.
    The invention also relates to films based on this type of material and methods of synthesis of these films. The invention also relates to a separator, a solid polymer electrolyte or an electrode based on this ionically conductive material and an electrochemical generator.
    i
    ION CONDUCTIVE MATERIAL FOR ELECTROCHEMICAL GENERATOR AND METHODS OF MANUFACTURE
    Field of the invention
    The field of this invention is that of ion-conducting materials which can be used in electrochemical generators, for example in separators, solid polymer electrolytes or electrodes.
    In particular, the present invention relates to an ionically conductive material comprising two polymers A and B, distinct from each other, and a reinforcing filler. The present invention also relates to films, in particular infiltrated films, based on this ion-conducting material and to methods of manufacturing these films.
    Technological background
    Electrochemical devices, like electrochemical cells and batteries, are all built according to the same model: a cathode (positive), an anode (negative), and, between the two, an electrolyte which allows the passage of ions but not the passage of electrons. Often, the electrolyte consists of salt (s) dissolved in a solvent or a mixture of polar aprotic solvents: these liquid electrolytes are commonly used in commercial batteries known as lithium-ion. Polar aprotic solvents can be partially or completely substituted by ionic liquids to reduce the flammability of electrolytes. Since the electrolyte is the most resistive constituent of the battery or more generally of the electrochemical generator, its thickness should be drastically reduced.
    Since the electrodes of the electrochemical cells are very close, a separator is added between the anode and the cathode in order to avoid any contact between the two electrodes and thus prevent short circuits. The separator is generally made of a porous material whose porosity is filled with the liquid electrolyte. The most used are macroporous films of polyolefins based on polyethylene such as Solupor®7P03A and Solupor®10P05A, or of polypropylene such as Celgard®2400. Other macroporous separators, which combine 3 porous polypropylene / polyethylene / polypropylene films, such as Celgard®2325, can also be used, but their filling with liquid electrolyte is much slower. One of the drawbacks of all these separators, and especially Celgard®2325, is that they greatly reduce the conductivity of the electrolyte (D. Djian, F. Alloin, S. Martinet, H. Ligner, J-Y. Sanchez,
    J. Power Sources 172 (2007) 416).
    In some cases, the same material can perform the function of separator and electrolyte: this is the case of solid polymer electrolytes where the polymer acts itself as a macromolecular solvent, dissolving the salts, and ensuring the mobility of the ions. It is then, for example, a film consisting of a polymer of the poly (oxyethylene) family (POE or PEO) in which a lithium salt has been dissolved (M. Gauthier, A. Bélanger, P Bouchard, B. Kapfer, S. Ricard, G. Vassort, M. Armand, JY. Sanchez, L. Krause, Large lithium polymer battery development The immobile solvent concept, J. Power Sources, 54 (1995) 163). These solid polymer electrolytes allow batteries to operate between 60 and more than 100 ° C but do not allow them to operate at ambient and sub-ambient temperatures and, therefore, meet the needs of portable electronics. They can however be impregnated with liquid solvents and / or ionic liquids to obtain a dense film swollen by the introduction of said solvents which is conductive at low temperature.
    In electrochemical cells, such as primary cells, batteries, supercapacitors or fuel cells, the separator filled with liquid electrolyte or the solid polymer electrolyte must be as thin as possible. This reduces its electrical resistance which is proportional to the thickness and improves the efficiency of the generator. However, it is also important that the separator or the solid polymer electrolyte is made of a material having good mechanical properties in order to prevent the risks of short circuit in an optimal manner.
    In particular, in lithium batteries, it is important to have a separator or a solid polymer electrolyte made of a material having good mechanical properties. Indeed, in these batteries, dendritic growth phenomena can occur. Dendritic growth appears when the battery is recharged, the lithium then forms balls or needles which can pass through the separator, which generates a short circuit. It is a particularly dangerous failure mechanism that can go as far as a fire. It is therefore crucial to prevent this phenomenon.
    In order to improve the mechanical properties of the materials used in the separators and the solid polymer electrolytes while allowing a reasonable thickness of the latter, it has been proposed to add reinforcing fillers in these materials.
    Patent application US2014 / 0227605 A1 discloses a polyolefin film comprising cellulose nanofibers. This reinforced film can be used as a separator.
    However, these materials used in separators or solid polymer electrolytes are not perfect and there is always a demand for new materials having good mechanical properties and which prevent dendritic growth.
    Goals
    In this context, the present invention aims to satisfy at least one of the following objectives.
    One of the essential objectives of the invention is to provide an ionically conductive material which can be used in an electrochemical generator, for example in separators, solid polymer electrolytes or electrodes.
    One of the essential objectives of the invention is to provide a material with ionic conduction having good mechanical properties.
    One of the essential objectives of the invention is to provide an ionically conductive material having good ionic conductivity.
    One of the essential objectives of the invention is to provide an ion-conducting material which prevents dendritic growth in lithium batteries.
    One of the essential objectives of the invention is to provide a material with mixed ionic / electronic conduction having good ionic and electronic conduction and also having good mechanical properties.
    One of the essential objectives of the invention is to provide a film based on an ion-conducting material having all or some of the above characteristics.
    One of the essential objectives of the invention is to provide a process for manufacturing a film based on an ion-conducting material having all or some of the above characteristics.
    One of the essential objectives of the invention is to provide a separator, a solid polymer electrolyte or an electrode based on an ionically conductive material having all or some of the above characteristics.
    One of the essential objectives of the invention is to provide an electrochemical generator comprising a separator, a solid polymer electrolyte or an electrode based on an ionically conductive material having all or some of the above characteristics.
    Brief description of the invention
    These objectives, among others, are achieved by the present invention which firstly relates to an ionically conductive material for an electrochemical generator, characterized in that it comprises:
    1. at least one polymer A, distinct from B, having an ionic conductivity of between 10 5 and 10 ′ 3 S / cm,
    2. at least one polymer B having a mechanical strength characterized by a conservation module> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa,
    3. at least one reinforcing filler C.
    Surprisingly, it has been discovered that such a material, that is to say comprising a mixture of two distinct polymers and at least one reinforcing filler, possesses both good mechanical properties and good ionic conductivity. . This type of material can therefore be used in electrochemical generators.
    The invention also relates to films based on this type of material. These can be fine and maintain good mechanical strength, so they can be used as a separator or solid polymer electrolyte in an electrochemical generator. In addition, surprisingly, it has been observed that these films prevent dendritic growth.
    The invention also relates to an infiltrated film based on this type of material and three methods of synthesis of these films.
    The invention also relates to a separator, a solid polymer electrolyte or an electrode based on this ionically conductive material.
    The invention also relates to an electrochemical generator, such as a battery, a battery, a supercapacitor or an electrochromic glazing comprising such an ionically conductive material.
    Brief description of the figures
    FIGS. 1A and 1B represent images with a scanning electron microscope, SEM, of a film obtained according to example 1.
    FIGS. 2A and 2B represent SEM images of a film according to the invention obtained according to example 2.
    FIGS. 3A and 3B represent SEM images of a film according to the invention obtained according to example 3.
    FIGS. 4A and 4B represent SEM images of a film according to the invention obtained according to example 4.
    FIG. 5 represents the mechanical characterization curves by DMA of the films according to Examples 1 to 4.
    FIG. 6 represents the curves obtained during the characterization by tensile test of the films 2 to 4.
    FIG. 7 represents the curves obtained during the thermal characterization, by thermogravimetric analysis (ATG), of the films according to Examples 6 to 9 with the curve M1 representing Example 7, the curve M2 Example 6, the curve M3 l Example 8 and the curve M4 Example 9.
    FIG. 8A represents the SEM image of a film obtained according to the example
    7. FIG. 8B represents the SEM image of a film obtained according to Example 6. FIG. 8C represents the SEM image of a film obtained according to Example 8. FIG. 8D represents the SEM image of a film obtained according to Example 9.
    FIG. 9 represents the mechanical characterization curves in elongation of the films according to examples 6 to 9 with the curve M1 representing example 7, the curve M2 example 6, the curve M3 example 8 and the curve M4 1 example 9.
    FIG. 10 represents the conductivity measurements of the films according to examples 6 to 9 with the curve M1 representing example 7, the curve M2 example 6, the curve M3 example 8 and the curve M4 example 9.
    FIG. 11 represents the mechanical characterization curves by DMA of the films according to Examples 14 to 16.
    FIG. 12 represents the conductivity measurements of the films according to Examples 14, 17 and 18.
    FIG. 13 represents the conductivity measurements of the films according to Examples 17, 20 and 21.
    FIG. 14 represents the mechanical characterization curves by DMA of the films according to Examples 22 and 23.
    FIG. 15 represents the mechanical characterization curves in elongation of the films according to Examples 22 and 23.
    FIG. 16 represents a particular embodiment of a film produced from three films according to the invention.
    Detailed description of the invention
    ION CONDUCTIVE MATERIAL
    The preferred characteristics of the ionically conductive material 1 -2 3 according to the invention are detailed below.
    Polymer A is a polymer having an ionic conductivity of between 10 ' 5 and 10' 3 S / cm. This conductivity is measured by electrochemical impedance spectrometry at room temperature.
    For example, polymer A is chosen from polymers comprising an oxyalkylene chain in the main chain or in a pendant chain.
    Ί
    According to one embodiment of the invention, the polymer A is a solvating polymer. The term "solvating agent" is intended to mean, for example, capable of dissolving one or more alkali or alkaline-earth metal salts, for example salts of lithium, sodium, magnesium or calcium. For this, the polymer A contains heteroatoms (N, O, S) and for example bonds of ether and / or amine type.
    A solvating polymer is a polymer which comprises solvating units containing at least one heteroatom chosen from sulfur, oxygen, nitrogen and phosphorus.
    According to one embodiment of the invention, the polymer A is chosen from crosslinked or non-crosslinked solvating polymers, which optionally carry grafted ionic groups.
    Examples of solvating polymers that may be mentioned include:
    polyether homopolymers chosen from poly (oxyethylene), poly (oxypropylene), poly (oxytrimethylene) and poly (oxytetramethylene), said homopolymers having a linear structure, a comb structure, a star structure or a structure in dendrimers;
    block copolymers or graft copolymers of the polyether type, whether or not forming a network. Among these block copolymers, mention may be made of those in which certain blocks carry functions which have redox properties and / or certain blocks have crosslinkable groups and / or certain blocks have ionic functions; random, random or alternating copolymers containing repeating oxyalkylene units, whether or not forming a network. Among the oxyalkylene units, mention may be made of the oxyethylene unit, the oxypropylene unit, the 2-chloromethyloxyethylene unit, and the oxyethyleneoxymethylene unit, which respectively come from the opening of the ethylene oxide ring, propylene oxide, epichlorohydrin and dioxolane and which are particularly preferred. Mention may also be made of the oxyalkenylene units which originate from the ring opening of epoxyhexene, vinyl glycidyl ether, allyl glycidyl ether, glycidyl acrylate or glycidyl methacrylate;
    polyphosphazenes, polysiloxanes, polyacrylates, polymethacrylates, polyacrylamides and polystyrenes carrying oligoether branches;
    linear polycondensates prepared for example by Williamson reaction between polyethylene glycol and dichloromethane. Such polycondensates are described in particular by J.R. Craven et al MaKromol. Chem. Rapid Comm., 1986, 7, 81;
    polyethylene glycol networks crosslinked by isocyanates or the networks obtained, prepared from polycondensates carrying crosslinkable groups, such as double or triple bonds, for example by a Williamson reaction with an unsaturated dihalide as described by F. Alloin, et al., J. of Electrochem. Soc. 141, 7, 1915 (1994);
    networks prepared by reaction of polyethylene glycol modified with terminal amine functions, such as the commercial products Jeffamine @, and isocyanates, linear or branched polyethyleneimines as well as Nalkylpolyethyleneimines and their mixtures.
    For example, polymer A is chosen from poly (oxyethylene) and poly (meth) acrylates having oligo (oxyalkylene) chains.
    Polymer B is a polymer with good mechanical strength, it is characterized by a conservation modulus> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa. This conservation module is measured by Dynamic Mechanical Analysis (DMA) at 30 ° C.
    Polymer B can, for example, be chosen from semi-crystalline polymers whose amorphous phase has a low glass transition temperature (for example less than or equal to 20 ° C.) and a high melting temperature (for example greater than or equal at 110 ° C) such as PVdF (polyvinylidene fluoride) and its copolymers with hexafluoropropene (HFP) or chlorotrifluoroethylene (CTFE).
    Polymer B can, for example, be chosen from semi-interpenetrating networks based on poly (oxyalkylene) (POE), whose glass transition temperature, Tg, is less than or equal to -50 ° C (Tg <223 K ) and the melting point of which is greater than or equal to + 65 ° C.
    Polymer B can be chosen from ionic semi-crystalline polymers such as carboxymethylcellulose (CMC) often used often as a binder for electrodes.
    Polymer B can also be chosen from amorphous polymers having a glass transition temperature greater than or equal to 110 ° C. As examples of such polymers, mention may be made of polyvinyl pyridine, polyindene, polycoumarone, polyacrylonitrile, polymethacrylonitrile, poly-a-methylstyrene, polycarbonates or P VP (polyvinyl-pyrrolidone).
    Polymer B can also be chosen from so-called high performance polymers, such as polyphenylene oxides, phenylene polysulfides, polysulfones, polyethersulfones, polyamide-imides, in neutral or ionic form.
    Polymer B can be a polymer with a perfluorinated backbone carrying ionic groups such as the Nafion® ionomers produced by Dupont de Nemours or Aquivion® produced by Solvay in the form of their salts.
    According to one embodiment of the invention, the polymer B is chosen from semi-crystalline polymers having an amorphous phase between a low glass transition temperature (for example less than or equal to 20 ° C) and a high melting temperature (for example greater than or equal to 110 ° C);
    semi-crystalline ionic polymers;
    amorphous polymers having a glass transition temperature greater than or equal to 110 ° C;
    so-called high performance polymers, in neutral or ionic form; and their mixtures.
    According to one embodiment of the invention, the polymer B is chosen from fluoropolymers such as homopolymers and / or copolymers of vinylidene fluoride (PVDF), hexafluoropropylene (HFP), tetrafluoroethylene (TFE) or chlorotrifluoroethylene ( CTFE), said fluoropolymers possibly comprising ionic groups, such as sulfonates, sulfonamides or sulfonyl imides, ammonium or phosphonium groups;
    ίο semi-crystalline polymers based on POE, whose glass transition temperature is less than or equal to -50 ° C (Tg <223 K) and whose melting temperature is greater than or equal to + 65 ° C;
    polysulfones (PSu), comprising ionic groups or not; polyethersulfones (PES), comprising ionic groups or not; polyarylretherketones such as polyetheretherketone (PEEK), comprising ionic groups or not;
    polyimides (PI), fluorinated or not, comprising ionic groups or not;
    polyamide-imides, comprising ionic groups or not; phenylene polysulfides, comprising ionic groups or not; polyarylethers such as polyphenylene oxide, comprising ionic groups or not;
    polyolefins such as homopolymers and / or copolymers of ethylene, propylene, styrene, N-vinyl-pyrrolidone, vinyl pyridine, indene, coumarone;
    homopolymers and copolymers of acrylonitriles (PAN);
    homopolymers and copolymers of methacrylonitriles, such as polymethacrylonitrile;
    polycarbonates, such as polyethylene carbonate; and their mixtures.
    Preferably, polymer B is chosen from fluoropolymers, in particular polyvinylidene fluoride (PVDF) and its copolymers, polysulfones (PSu), polyethersulfones (PES), polyetheretherketones (PEEK), polyimides (PI), and their mixtures.
    According to one embodiment of the invention, the polymer A / polymer B ratio is between 95/5 and 5/95. For example, this ratio can be 95/5, 80/20, 75/25, 50/50, 25/75, 20/80 or 95/5.
    The reinforcing filler C comprises a cellulosic material. Preferably, the reinforcing filler C comprises at least one nanocellulose. For example, the reinforcing filler comprises at least one nanocellulose and a material chosen from chitin, chitosan, gelatin, sericin and their mixtures.
    The reinforcing filler improves the mechanical properties of the ionically conductive material and therefore reduces the thickness of the film and improves safety.
    Nanocellulose is a cellulose having a nanostructure, that is to say having a structure of which at least one dimension is between a few nanometers and 15-20 nanometers. There are three types of nanocellulose:
    nanocrystalline cellulose, also called cellulose nanowhiskers or crystalline nanocellulose, which is found in the form of crystalline and rigid nanoparticles. This type of nanocellulose is obtained by acid hydrolysis of cellulose.
    cellulose microfibrils, or cellulose nanofibrils, which are fibers of several micrometers in length and having a width of between 5 and 20 nanometers. These fibers are isolated from cellulose by mechanical action.
    bacterial nanocellulose, produced by bacteria.
    According to one embodiment of the invention, the reinforcing filler is chosen from nanocrystalline cellulose and cellulose microfibrils.
    According to one embodiment of the invention, the reinforcing filler is a mixture of two nanocelluloses, for example a mixture of nanocrystalline cellulose and cellulose microfibrils.
    According to one embodiment of the invention, the reinforcing filler is a mixture of nanocelluloses and chitosan.
    According to one embodiment of the invention, the reinforcing filler is contained in the ionically conductive material at a concentration of between 0.5 and 30% by weight, preferably between 2 and 20% and even more preferably between 5 and 15%.
    According to one embodiment of the invention, the ionically conductive material also comprises one or more conventional additives, for example mineral or organic fillers such as battery grade silica.
    According to one embodiment of the invention, the ionically conductive material also comprises at least one salt which makes it possible to ensure better ionic conductivity, for example an alkali or alkaline earth metal salt. In a particularly preferred manner, it is a lithium salt, preferably chosen from LiTFSI, LiPF 6 , LiBF 4 , LiAsF 6j LiCICU, L1CF3SO3 and their mixtures. It can also be a salt of another alkali metal, such as sodium or a salt of alkaline earth metal such as calcium or magnesium. Particularly preferably, the salt is LiTFSI. The salt is contained in the ion-conducting material in an amount such that the O / M ratio (M = metal) is between 6 and 40, preferably between 16 and 30. The O / M ratio is the ratio between the concentration depending on ether of the material and the salt concentration. The ionically conductive material comprising a salt as described above can be used as a solid polymer electrolyte.
    According to one embodiment of the invention, the ion-conducting material also comprises at least one solvent, preferably polar aprotic or an ionic liquid which makes it possible to increase the ionic conductivity at low temperature. The organic solvent is chosen from the solvents typically used in lithium batteries. These are, for example, fluorinated carbonates or not, such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, or other solvents such as 2-methyl THF or methyl acetamide. The ionic liquid is typically a tetraalkylammonium salt such as 1-butyl-lmethylpyrrolidiniun bis (trifluoromcthanc sulfonylimide).
    According to an embodiment of the invention, the ionically conductive material further comprises at least one filler having an electronic conductivity. In this case, the material has a mixed ion / electronic conduction. The filler having an electronic conductivity can be chosen from carbon fibers or powder, graphene, carbon nanotubes, acetylene black, graphite or a graphitic material, and mixtures thereof.
    MOVIE
    The invention also relates to a film based on the ionically conductive material described above. The film is a thin layer of material comprising polymers A and B and the reinforcing filler C. It can be a simple mixture of the polymers and the reinforcing filler, an infiltrated film comprising the reinforcing filler or an assembly of several layers of films according to the invention.
    The present invention also relates to the use of this film to prevent dendritic growth in batteries, in particular lithium or sodium batteries.
    The film can have a thickness of between 10 and 300 μm, preferably between 20 and 250 μm and better still between 10 and 220 μm. Films having a thickness between 10 and 20 μιη can also be obtained. This relatively small thickness, the good mechanical properties of the material and its ionic conductivity make it a good solid polymer electrolyte for an electrochemical generator, in particular for lithium polymer batteries operating above 25 ° C. When this film additionally contains at least one solvent and / or an ionic liquid, its conductivities at low temperature allow it to be used in portable electronics applications.
    INFILTER FILM OBTAINED BY INFILTRATION OF A POROUS POLYMER
    The present invention also relates to a film based on the ionically conductive material described above, characterized in that it is an infiltrated film and in that the polymer A is infiltrated into the polymer B. This film is obtained by infiltration of a porous polymer. In this case, the polymer B is a porous polymer whose polymer A fills the pores. It is also possible that the polymer A, in addition to filling the pores of the polymer B, forms a layer completely covering the layer of porous polymer B.
    The reinforcing filler C can be included in the porous polymer layer B and / or in the polymer layer A. When the reinforcing filler C is contained in the polymer layer A, this makes it possible to increase its mechanical strength and maintain this polymer in the pores of the porous polymer layer B. When the mechanical strength of A is deemed sufficient, the polymer B can be mixed with the reinforcing filler resulting in a reinforcement which persists after the melting temperature of B, if the latter is semi-crystalline, or after the glass transition temperature of B if the latter is an amorphous polymer. We can also include the reinforcing filler C in both B and A, which substantially consolidates the whole. The polymer layer A can also comprise at least one salt as described above. This gives the whole a good ionic conductivity. It is also possible to add to this infiltrated film at least one solvent, preferably polar aprotic and / or an ionic liquid.
    Polymer B is a porous polymer, it can be chosen from the polymer polymers B above.
    In particular, polymer B and chosen from semi-crystalline polymers such as: polyethylene, polypropylene, copolymers of ethylene and propylene, polyvinylidene fluoride homopolymer, PVdF, and its copolymers such as copolymers incorporating hexafluoropropene (HFP) and / or chloro trifluoroethylene, CTFE, isotactic or syndiotactic polystyrene, poly-ether-ketone, PEK, and poly-ether-ether-ketone, such as Victrex®PEEK, phenylene polysulphide, PPS, and their mixtures;
    or from amorphous polymers with a high glass transition temperature, whether or not carrying ionic functions, such as:
    polyamide-imides, polyimides, PI, fluorinated or not, polysulfones, PSU, polyethersulfones, PES, polyarylethers such as polyphenylene oxide, PPO and their mixtures.
    According to one embodiment of the invention, when the polymer A, in addition to filling the pores of the polymer B, forms a layer completely covering the layer of polymer B, the layer of polymer B can also comprise at least one filler having electronic conductivity. The filler having electronic conductivity can be carbon fibers or powder, graphene, carbon nanotubes, acetylene black, graphite or a graphitic material, or mixtures thereof.
    FILM COMPRISING MULTIPLE LAYERS
    It is possible to superimpose different films according to the invention according to the desired application.
    For example, a film with exclusively ionic conductivity can be superimposed on a film with mixed ionic / electronic conduction as described above. This type of overlay can be used in batteries. In this case the ionically conductive film must be in direct contact with either the anode or the cathode. The exclusively ionic conduction film then interrupts the electronic conduction circuit, avoiding accelerated self-discharge and short-circuiting of the battery. This type of structure makes it possible to increase the thickness between the electrodes without practically increasing the internal resistance, due to the electronic conductivity.
    It is also possible to have a superposition of 3 layers of films, for example an exclusively ionic conduction film can be interposed between 2 films with mixed electronic / ionic conduction. In the case of use in a battery, each of the 2 films with mixed electronic / ionic conduction is in contact with the negative (anode) or positive (cathode) electrode. An exemplary embodiment is described in FIG. 16.
    PREPARA TION PROCESSES
    The present invention also relates to three methods of preparing a film as described above: two methods of preparing a film based on a simple mixture of polymers and a method of preparing an infiltrated film obtained by infiltration of a porous polymer.
    In all three processes, it is possible to increase the conductivity of the system by adding at least one solvent as described above to the film obtained. This increases the conductivity at low temperatures.
    Track 1:
    The infiltrated film is prepared according to route 1.
    This process includes the following steps:
    implementation of a porous polymer layer B, optionally comprising a reinforcing filler C and / or a filler having an electronic conductivity;
    infiltration of polymer A, or of the macromonomer capable of forming, after polymerization, polymer A, with optionally a reinforcing filler C and / or a salt and / or a polymerization initiator, in the pores of polymer B;
    optionally, polymerization of the macromonomer capable of forming polymer A after polymerization.
    The reinforcing filler can be included in the layer of porous polymer B and / or be introduced with the polymer A.
    The porous polymer layer B forms a porous film B. The porous polymer layer B can be a commercial porous film such as Solupor®. This layer of porous polymer B can also be prepared by techniques known to those skilled in the art such as electrospinning or phase inversion (Non-solvent Induced Phase Separation) as described in the publication by Witte et al, Journal of membrane science 117, (1996), 1-31.
    The infiltration step can be repeated several times depending on the desired pore filling rate.
    When the infiltration of polymer A is such that a layer of polymer A completely covers the porous film B, the latter may comprise a filler having an electronic conductivity as described above. Polymer A completely covering polymer B, electronic insulation is maintained and the resulting infiltrated film can still be used as a separator.
    According to a first variant, the infiltration of the polymer A into the pores of the porous film B can be carried out by passing a solution containing the polymer A through the porous film, the solution possibly optionally containing a salt as described above or a reinforcing filler C as described above.
    According to a second variant, the infiltration of the polymer A into the pores of the porous film B is carried out by infiltrating, into the pores of the porous film B, at least one macromonomer capable of forming, after polymerization, the polymer A, then inducing the polymerization of these macromonomers in order to obtain the polymer A. Preferably, the macromonomer is liquid and not very viscous, which makes it possible to infiltrate the macromonomers without using a solvent. A polymerization initiator is also infiltrated into the pores of the porous film, dissolving it in the macromonomers. Among the polymerization initiators, mention may be made of photoinitiators or initiators with thermal decomposition, such as ΓΑΙΒΝ (Azo-bis isobutyronitrile) or PBO (benzoyl peroxide).
    Preferably the macromonomer capable of forming, after polymerization, the polymer A, is a (meth) acrylate with at least one oligo (oxyalkylene) chain.
    Track 2:
    The film comprising a simple mixture of the polymers can be prepared according to route 2.
    The process then includes the following steps:
    - Preparation of a mixture of polymer A, of polymer B, of reinforcing filler C, and optionally of salt, in a solvent; pouring this mixture onto a support such as a glass, metal or polymer plate, or even an electrode;
    drying for example in an oven or an oven, possibly under a gas flow.
    possibly crosslinking.
    Cross-linking makes it possible to form an insoluble three-dimensional network, which improves the mechanical strength of the membrane. It can in particular be carried out by UV irradiation.
    Pouring the mixture directly onto the electrode makes it possible not to remove the membrane from the support on which it was poured.
    The drying speed can be controlled in order to avoid cracks and residual stresses due to too rapid drying.
    According to one embodiment, the mixture of polymer A, of polymer B and of reinforcing filler C can comprise a salt as described above. In this case, the reinforcing filler C is introduced as late as possible in order to avoid its aggregation upon contact with the salt.
    Track 3:
    The film comprising a simple mixture of the polymers can be prepared according to route 3.
    The process then includes the following steps:
    - Preparation of a mixture of polymer A, of polymer B, of reinforcing filler C, and optionally of salt, in a solvent;
    lyophilization of the mixture obtained;
    - hot pressing to obtain a film.
    Hot pressing produces a semi-penetrated network film and initiates cross-linking if necessary.
    According to one embodiment, the mixture of polymer A, of polymer B and of reinforcing filler C can comprise a salt as described above. In this case, the reinforcing filler C is introduced as late as possible in order to avoid its aggregation upon contact with the salt.
    SEPARATOR
    The present invention also relates to a separator comprising an ionically conductive material as described above. For example, the separator is a film based on the ionically conductive material as described above. It may be a film based on a simple mixture of the polymers and the reinforcing filler or an infiltrated film comprising a reinforcing filler.
    For example, the separator is a film comprising:
    at least one polymer A, distinct from B, having an ionic conductivity of between 10 5 and 10 ′ 3 S / cm, at least one polymer B having a mechanical strength characterized by a conservation modulus> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa, at least one reinforcing filler C, comprising at least one nanocellulose, at least one solvent, as described above.
    Typically, the separator has a thickness advantageously between 10 and 200 μm.
    SOLID POLYMER ELECTROLYTE
    The present invention also relates to a solid polymer electrolyte comprising an ionically conductive material as described above and at least one salt which makes it possible to ensure better ionic conductivity. For example, the solid polymer electrolyte is a film based on the ionically conductive material as described above. It can be a film comprising a simple mixture of polymers A & B and the reinforcing filler C or an infiltrated film.
    For example, the solid polymer electrolyte is a film comprising:
    at least one polymer A, distinct from B, having an ionic conductivity of between 10 ' 5 and 10' 3 S / cm, at least one polymer B having a mechanical strength characterized by a conservation modulus> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa at least one reinforcing filler C, comprising at least one nanocellulose, at least one salt, as described above, which makes it possible to ensure better ionic conductivity.
    Typically, the solid polymer electrolyte has a thickness of between 10 and 200 µm.
    The salt which ensures better ionic conductivity is for example an alkali or alkaline earth metal salt. In a particularly preferred manner, the salt is a lithium salt, preferably chosen from LiTFSI, LiPF 6 , LiBF 4 , LiAsF fi L1CIO4 and their mixtures. It can also be a salt of another alkali metal, such as sodium, or a calcium or magnesium salt. Particularly preferably, the salt is LiTFSI.
    ELECTRODE
    The present invention also relates to an electrode, for example a cathode, comprising the ionically conductive material as described above.
    For example, the ionically conductive material is used as an electrode binder.
    According to one embodiment, the electrode comprises:
    at least one polymer A, distinct from B, having an ionic conductivity of between 10 ' 5 and 10' 3 S / cm, at least one polymer B having a mechanical strength characterized by a conservation modulus> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa, at least one reinforcing filler C comprising at least one nanocellulose, at least one filler having electronic conductivity, for example chosen from carbon fibers or powder, graphene, nanotubes carbon, acetylene black, graphite or a graphitic material, and mixtures thereof, at least one active material such as, for example, LFP (Lithium Iron Phosphate) or Li x CoO2 (lithiated cobalt oxide) .
    This type of electrode is particularly suitable for batteries with solid polymer electrolyte.
    ELECTROCHEMICAL GENERATOR
    The present invention also relates to an electrochemical generator comprising an ionically conductive material as described above. According to one embodiment of the invention, the electrochemical generator is a cell or a battery, for example a lithium battery, a supercapacitor or an electrochromic glazing.
    For example, the electrochemical generator comprises a separator, a solid polymer electrolyte or an electrode as described above.
    EXAMPLES:
    Material:
    The films are prepared using polyvinylidene fluoride (PVDF) having a molar mass of approximately 650,000 g.mol ' 1 , poly (ethylene glycol) methyl ether methacrylate (mono-PEGMA) having a molar mass of approximately 500 g .mol ' 1 , poly (ethylene glycol) dimethacrylate (di-PEGMA) having a molar mass of approximately 550 g.mol' 1 , of linear poly (oxyethylene) (POE) having a molar mass of approximately 300000 g. mol ' 1 , and crosslinkable polycondensate of POE, synthesized from polyethylene glycol.
    The reinforcing filler used is nanocrystalline cellulose (NCC) or a mixture of NCC and chitosan. Unless otherwise indicated, the reinforcing filler percentages are expressed by mass relative to the total mass of polymer used.
    The films are subjected to a Dynamic Mechanical Analysis (DMA) in order to measure their mechanical properties. These measurements are carried out on a Q800 device of the TA brand.
    Preparation of infiltrated films based on mono and / or di-PEGMA (polymer A),
    PVDF (polymer B) and NCC (reinforcing filler C) according to channel 1
    Example 1 (comparative example): Synthesis of a PVDF film containing 7% by mass of NCC
    2.3 g of PVDF are weighed in a 40 ml bottle and 14 ml of N, NDimethylformamide (DMF) are added. The mixture is stirred at 50 ° C until completely dissolved. A dispersion of 4% NCC in DMF is prepared by mixing 6 g of NCC in 150 mL of DMF using a high power ultra turrax homogenizer. 4.4 mL of this dispersion (ie 0.18 g of NCC) are then added to the PVDF solution and the mixture is stirred vigorously. The mixture is then poured onto a glass plate using a machine type ‘coating’‘doctor blade’® to obtain a thickness of 0.8 mm. The whole is then immersed in ethanol for 15 min in order to create the porosity by Non-solvent Induced Phase Separation (NIPS, Witte et al, Journal of membrane science 117, (1996), 1-31). The whole “glass plate + film” is then removed from the ethanol bath and taken to the oven. The film is dried under vacuum at 60 ° C for at least 50 hours and then easily peeled off using forceps and a spatula before being stored. The macroporous film obtained at a thickness of approximately 90 microns.
    Example 2: Synthesis of a PVDF film containing 7% by mass of NCC infiltrated with mono-PEGMA
    1.0 g of mono-PEGMA and 50 mg of benzoyl peroxide are weighed in a 20 mL bottle.
    A 6 × 6 cm square of a macroporous film of PVDF and containing 7% by mass of NCC prepared according to example 1 is cut out and deposited on a sintered glass. The mono-PEGMA preparation is then poured dropwise using a Pasteur pipette over the entire surface of the film and infiltrated through the porosity of the film thanks to a vacuum obtained by a water pump. The infiltrated film is then brought to 80 ° C. for 24 hours in an oven. A post crosslinking at 110 ° C for 2 hours and at 130 ° C for 2 hours is then carried out.
    Example 3 Synthesis of a PVDF Film Containing 7% by Mass of NCC Infiltrated with Di-PEGMA
    A PVDF film containing 7% by mass of NCC and infiltrated with di-PEGMA was obtained according to the procedure described in Example 2 using 1.0 g of di-PEGMA in place of the mono-PEGMA.
    Example 4: Synthesis of a PVDF film containing 7% by mass of NCC infiltrated with a mixture of mono and di-PEGMA
    A PVDF film containing 7% by mass of NCC infiltrated with a mixture of mono and di-PEGMA was obtained according to the procedure described in Example 2 using 0.5 g of mono-PEGMA and 0.5 g of di-PEGMA instead of 1.0 g of mono-PEGMA.
    Characterization of the infiltration process
    The films prepared according to Examples 2 to 4 were weighed before and after infiltration in order to quantify the gain in mass of the films. Table 1 summarizes the results obtained. These data show that there is indeed an infiltration of polymers of the PEGMA type into the PVDF film containing 7% by mass of NCC.
    Table 1: Mass gain of films
    PVDF NCC m initial m final m infiltrated Gainmass Example 2 0.5589 g 0.6841 g 0.1252 g 22% Example 3 0.4993 g 0.6041 g 0.1048 g 21% Example 4 0.5193 g 0.6095 g 0.0902 g 17%
    Characterization of the morphology of the infiltrated films
    The morphology of the various films prepared according to Examples 1 to 4 was characterized by scanning electron microscopy (SEM, Philips XL-30). A sample of each film (0.5 x 0.5 mm) is fixed on a support with a conductive carbon adhesive and the surface of the sample is then metallized with gold. A voltage of 15 kV is applied and the images are obtained at different magnifications. The two sides of each film were observed without noting any notable differences.
    Figures 1 to 4 show the images obtained for the different films. These images show that the films infiltrated by di-PEGMA and the mixture of mono and di-PEGMA have a porosity lower than that of the film infiltrated by mono-PEGMA. All of the infiltrated films are less porous than the original macroporous PVDF film reinforced with 7% NCC. This shows that the infiltration process is effective.
    Mechanical characterization by DMA
    The films prepared according to Examples 1 to 4 are characterized between -100 ° C and + 180 ° C. The samples are rectangular films having the dimensions close to 14 mm x 6.5 mm x 0.1 mm (L x 1 x e). The samples are cooled to -100 ° C and then the films are heated at a rate of 2 ° C / min to 180 ° C undergoing a deformation of 0.05% at a frequency of 1 Hz.
    FIG. 5 represents the variation of the value of the preservation module as a function of the temperature for these four films.
    These curves show that at low temperature, the infiltration of the films by the various PEGMAs contributes to increasing the value of the preservation module (Storage Modulus): + 50% at -100 ° C for the film infiltrated with mono-PEGMA according to Example 2 and for the film infiltrated with a mixture of mono and di-PEGMA according to Example 4. As regards the film infiltrated with di-PEGMA according to Example 3, the preservation module is almost tripled at -100 ° vs.
    The zoom shows that beyond 120 to 130 ° C. the mechanical strength of the films infiltrated according to examples 2 to 4 is considerably improved compared to the film not infiltrated according to example 1. This is a guarantee of safety in the event of strongly exothermic malfunction of the battery.
    Mechanical characterization by tensile test
    The films according to Examples 2 to 4 were then characterized by carrying out tensile tests at 30 ° C. with a drawing speed of 0.1 N / min. The samples are rectangular films having the dimensions close to 12 mm x 6 mm x 0.1 mm.
    FIG. 6 represents the curves obtained. The results are comparable to those obtained with non-infiltrated NCC-reinforced PVDF films as described in Example 1.
    Conductivity measurements
    The measurements are carried out with a Solartron 1287-1260 impedance meter, coupled to a computer for data processing, in the frequency range 0.1 Hz-10 MHz, the amplitude of the sinusoidal signal is fixed at +/- 100mV.
    The samples of infiltrated films according to Examples 2 to 4 are immersed for 25 min in a solution of Lithium hexafluorophosphate (LP 30 from Sigma Aldrich, mixture of ethylene carbonate and dimethyl carbonate- EC / DMC = 50/50 (v / v ) - with 1.0 M LiPF6) and then mounted in Swagelok cells.
    Each measurement was carried out twice to ensure the reproducibility of the determined conductivities. The conductivity values obtained at 25 ° C are summarized in Table 2.
    Table 2: conductivity measurements
    σ (mS / cm) Example 2 6.7 Example 3 2.9 Example 4 3.4
    Typically, a macroporous film of PVDF reinforced with 6% of NCC has a conductivity of 2.5 mS / cm at 25 ° C after being submerged in LP30. These results show that the infiltrated films have better conductivity.
    Preparation of reinforced films according to channel 2
    The films contain an amount of LiTFSI salt ((CF 3 SO2) 2NLi) such that the O / Li ratio is 25.
    Preparation of reinforced films based on POE (polymer A), PVDF (polymer B) and NCC (reinforcing filler C).
    Example 5: synthesis of a POE / PVDF film (50/50) with 7% NCC
    1.0 g of POE, 1.0 g of PVDF and 0.26 g of LiTFSI are weighed in a 60 ml flask and 20 ml of DMF are added. The mixture is stirred at 60 ° C until completely dissolved. A dispersion of 4% NCC in DMF is prepared by mixing 6 g of NCC in 150 ml of DMF using a high power homogenizer of the ultra turrax type. 3.77 mL of this dispersion (i.e. 0.15 g of NCC) are then added to the polymer solution and the mixture is vigorously stirred at 70 ° C. using a mechanical stirrer for ten minutes then degassed , to avoid the formation of bubbles, using a pump.
    The mixture is then poured with a coating machine and a doctor blade to reach a thickness of 1.5 mm on a glass plate. The whole "glass plate + film" is then brought to the oven. The films are dried under vacuum at 60 ° C for at least 50 hours and then delicately peeled off using forceps and a spatula before being stored. Control of the total elimination of DMF is carried out by infrared spectroscopy. The film obtained has a thickness of approximately 200 μm. This thickness allows reliable mechanical measurements.
    Example 6: synthesis of a POE / PVDF film (80/20) containing 7% of NCC
    An 80/20 POE / PVDF film was obtained according to the procedure described in Example 5 using 1.6 g of POE, 0.4 g of PVDF, 0.42 g of LiTFSI and 21 ml of DMF.
    Example 7: synthesis of a POE / PVDF film (90/10) containing 7% of NCC
    A POE / PVDF 90/10 film was obtained according to the procedure described in the example using 1.8 g of POE, 0.2 g of PVDF, 0.47 g of LiTFSI and 22 ml of DMF.
    Example 8 (comparative example): synthesis of a POE / PVDF film (80/20) containing 0% of NCC
    A POE / PVDF 80/20 film was obtained according to the procedure described in the example, not using NCC.
    Example 9 (comparative example): synthesis of a POE / PVDF film (90/10) containing 0% of NCC
    A POE / PVDF 90/10 film was obtained according to the procedure described in Example 7, not using NCC.
    Thermal characterization
    The thermal degradation of the films according to Examples 6 to 9 was measured by thermogravimetric analysis with a Perkin Elmer Pyris 1 TGA under an oxidizing atmosphere (air). The mass loss of a 10 mg sample was recorded from room temperature to 450 ° C with a heating rate of 10 ° C / min.
    FIG. 7 represents the results obtained. These results show that:
    films containing 20% PVDF (M2 and M3) initiate a first mass loss around 200 ° C which is very slightly less pronounced in the presence of cellulose (M2). For these films a second mass loss is observed around 400 ° C;
    films containing 10% PVDF (Ml and M4) initiate an abrupt and strong loss of mass around 400 ° C;
    from 400 ° C the films containing 20% PVDF (M2 and M3) experience a less significant and more gradual loss of mass than the membranes containing 10% PVDF (Ml and M4).
    The films according to Examples 6 to 9 have a thermal stability up to 200 ° C, which is much higher than the maximum temperature in the batteries (about 100 ° C).
    Calorimetric characterization
    The calorimetric analysis of the films according to Examples 6 to 9 was carried out with a Mettler Toledo 822 DSC under a nitrogen atmosphere. The heat flow of a 10 mg sample was recorded during a cooling and heating ramp at the speed of 10 ° c / min between -70 ° C and 200 ° C.
    The calorimetric parameters are summarized in Table 3.
    Table 3: calorimetric measurements
    cooling heater POE crystallization Tmax (-C) / ÛHc (J / g) PVDF crystallization Tg (^ C) POE fusion PVDF Tmax (-C) / ÛHf (J / g) fusion Tmax (-C) / ÛHc (J / g) Tmax (-C) / ÛHf (J / g) NCC-POE / PVDF (90/10) 26 / 59.9 102 / 4.3 -33.9 56 / 62.9 147-155 / 1.2 NCC-POE / PVDF (80/20) 21 / 50.8 114 / 8.1 -33.8 55 / 55.2 152 / 4.9 POE / PVDF (80/20) 26 / 53.9 111-119 / 8.1 -35.7 51 / 57.7 150 / 3.9 POE / PVDF (90/10) 24 / 63.5 105 / 3.4 -35.5 53 / 67.6 149-156 / 1.6
    From this analysis we can observe:
    The addition of NCC results in a very slight decrease in Tg regardless of the percentage of PVDF, which is within the measurement uncertainty range, the addition of NCC slightly modifies the crystallization and fusion of PVDF and POE although no trend can be discerned between the different samples.
    Characterization of the morphology of the films obtained
    The morphology of the films according to Examples 6 to 9 was characterized by scanning electron microscopy (SEM, Philips XL-30). A sample of each film (0.5 x 0.5 mm) is fixed on a support with a conductive carbon adhesive and the surface of the sample is then metallized with gold. A voltage of 15 or 5 kV is applied and the images are obtained at different magnifications. The two faces of each membrane were observed without noting any notable differences.
    Figure 8 shows the photos obtained. We can visually observe that all the films have a “grainy” morphology. The PVDF nodules within the POE attest to the phase separation between the PVDF and the POE. The two phases are continuous, they constitute two three-dimensional structures nested one in the other. The membranes containing 20% PVDF (M2 and M3) have much more defined PVDF domains. It is not possible to establish significant morphological differences when incorporating NCC.
    Mechanical characterization by tensile tests
    The films were characterized with DMA TA Q800 by performing tensile tests at 30 ° C with a drawing speed of 0.1 N / min. The samples are rectangular films having the dimensions close to 12 * 6 * 0.1 mm.
    FIG. 9 represents the results obtained. From this analysis it can be observed that the addition of NCC contributes to modifying the mechanical properties. Regardless of the percentage of PVDF, the NCC causes an increase in the Young's modulus and a decrease in the strain at break. A higher percentage of PVDF improves the mechanical strength.
    Conductivity measurements
    The films according to Examples 6 to 9 were synthesized by adding a lithium salt (LiTFSI). Fa molar concentration of lithium salt, expressed in number of oxygen atoms (O) of the POE polymer relative to the number of lithium cation (Li + ) of the lithium salt, is O / Li = 25 in the four cases . This concentration is usual in the literature because it makes it possible to obtain good performance in operation. The films thus obtained were characterized in symmetrical cells, that is to say between two identical electrodes of metallic lithium. The cells were assembled in a glove box under an argon atmosphere (humidity less than 5 ppm, oxygen less than 5 ppm) so as not to degrade the lithium and not to rewet the films. The assemblies are then sealed in plasticized aluminum pouches to remain airtight, and installed in a thermostatically controlled enclosure to conduct conductivity measurements at different temperatures.
    The conductivity measurement is carried out by electrochemical impedance spectroscopy, on a VMP-300 potentiostat from the BioLogic brand. The measurements are made during the temperature drop (between 84 ° C, or 1000 / T = 2.8; and 21 ° C, or 1000 / T = 3.4). If the cell no longer conducts below a certain temperature, no measurement is taken.
    Electrochemical impedance spectroscopy is performed after stabilization of the temperature and the electrolyte resistance value of the membrane. A frequency sweep between 1 MHz and 1 Hz with a potential amplitude adapted to the sample (between 30 and 100 mV) is carried out. The representation of the current value on a Nyquist graph makes it possible to determine the value of the electrolyte resistance (the electrolyte being in our case the film), which then makes it possible to calculate the conductivity of the sample with the formula next :
    e fixS
    With σ the conductivity of the cell expressed in S.cm ' 1 , e the thickness of the electrolyte (in cm), R the resistance of the electrolyte (measured by electrochemical impedance spectroscopy, expressed in Ohm), and S the surface of the sample in cm 2
    FIG. 10 represents the results obtained.
    We can observe that in the case of the films according to Examples 6 and 8, each containing 20% of PVDF, the conductivity values measured are lower than those of the films according to Examples 7 and 9 which contain only 10% of PVDF.
    In addition, for membranes containing 20% PVDF, the addition of 7% NCC causes a drop in conductivity values, by a factor of 3 at 85 ° C.
    On the other hand, for the films according to Examples 7 and 9 containing 10% of PVDF, the addition of 7% of NCC (film according to Example 7) does not cause a significant reduction in the conductivity. The film is therefore reinforced without affecting the conductivity with a PVdF rate of 10%;
    The conductivity values decrease slightly to 1000 / T = 3.1 or T = 50 ° C, the value at which the POE of the membrane crystallizes. This value is between the values measured in DSC in heating and cooling because here we allow the POE time to crystallize, while the DSC was performed in a dynamic regime (10 ° C / min).
    Below 50 ° C, the conductivity values drop more quickly because the electrolyte is then solid.
    Preparation of reinforced films based on crosslinkable polycondensate of POE (PC) (polymer A), POE (polymer B) and NCC (reinforcing filler C).
    Example 10 Synthesis of the Crosslinkable Polycondensate of POE (PC 1000)
    In a reactor, 30 g (30 mmol) of polyethylene glycol 1000 (PEG1000) are mixed with 4.9 g (120 mmol) of NaOH. The mixture is stirred using a mechanical stirrer for 3 hours at 65 ° C. The temperature is lowered to 50 ° C. and then 3.48 mL (29.4 mmol) of 3-chloro-2-chloroprop-1-ene are added dropwise. Stirring is continued for 24 hours at 50 ° C and a paste is obtained.
    Water is added to dissolve the polymer, then the solution is transferred to an Erlenmeyer flask and diluted with water to 600 ml. Acetic acid is added gradually until the solution has a pH of 7 (control with pH paper). The product is purified by ultrafiltration with a cutoff threshold of 3000 g.mol 1 in order to remove the oligomers, the CH 3 COONa salt formed and the excess of NaOH. When the conductivity of the filtrate is close to that of deionized water (10 pS.cm ' 1 ) the ultrafiltration is finished.
    The solid is lyophilized and the product is obtained in the form of a white solid.
    Example 11: synthesis of a POE / NPC1000 film (50/50) containing 10% of NCC
    0.20 g of POE, 0.11 g of LiTFSI and 0.20 g of PC1000 obtained according to Example 10 are dissolved in 10 ml of distilled water in 10 ml of distilled water. Then 0.0040 g are added. Irgacure 2959 photoinitiator and finally lmL of 4% NCC dispersion in water. The mixture is stirred for 12 hours. The air bubbles are removed using a pump and the solution is poured into a 9 cm diameter petri dish. When the solvent is evaporated the film is crosslinked under UV by exposing it under the lamp for one minute (2 x 30 seconds) with a minute of waiting between the first and the second UV exposure. At the end of the cross-linking PC 1000, a three-dimensional network NPC 1000 is transformed and forms with the homopolymer POE a semi-interpenetrated network POE / NPC1000. In the following examples from 12 to 21 inclusive, these semi-interpenetrating networks are formed after UV crosslinking.
    The films are dried under vacuum at 70 ° C for at least 72 hours and stored in the glove box.
    Example 12: synthesis of a POE / NPC1000 film (75/25) containing 10% of NCC
    A POE / NPC1000 film (75/25) containing 10% of NCC was obtained according to the procedure described in Example 11 using 0.30 g of POE, 0.10 g of PC 1000 and 0.0020 g of Iragcure 2959.
    Example 13: synthesis of a POE / NPC1000 film (25/75) containing 10% of NCC
    A POE / NPC1000 film (25/75) containing 10% of NCC was obtained according to the procedure described in Example 11 using 0.10 g of POE, 0.30 g of PC 1000 and 0.0060 g of Iragcure 2959.
    Example 14: Synthesis of a PQE / NPC1000 (75/25) film containing 6% of NCC
    A POE / NPCIOOO film (75/25) containing 6% of NCC is obtained according to the procedure described in Example 12 using 6 ml of 4% NCC dispersion, ie 0.024 g of NCC.
    Example 15: synthesis of a POE / NPCIOOO film (75/25) containing 12% of NCC
    A POE / NPCIOOO film (75/25) containing 12% of NCC is obtained according to the procedure described in Example 12 using 0.048 g of NCC.
    Example 16 (comparative example): synthesis of a POE / NPCIOOO film (75/25) with 0% NCC
    A POE / NPCIOOO film (75/25) without NCC is obtained according to the procedure described in Example 12 by not using NCC.
    Example 17: synthesis of a POE / NPCIOOO film (50/50) containing 6% NCC
    A POE / NPCIOOO film (50/50) containing 6% NCC is obtained according to the procedure described in Example 11 using 0.024 g of NCC.
    Example 18: synthesis of a POE / NPCIOOO film (25/75) containing 6% NCC
    A POE / NPCIOOO film (25/75) containing 6% NCC is obtained according to the procedure described in Example 13 using 0.024 g of NCC.
    Example 19: synthesis of a POE / NPCIOOO film (25/75) containing 12% NCC
    A POE / NPCIOOO film (25/75) containing 12% NCC is obtained according to the procedure described in Example 13 using 0.048 g of NCC.
    Example 20 (comparative example): synthesis of a POE / NPCIOOO film (50/50) with 0%
    NCC
    A POE / NPCIOOO film (50/50) without NCC is obtained according to the procedure described in Example 11 using no NCC.
    Example 21: synthesis of a POE / NPCIOOO film (50/50) containing 12% NCC
    A POE / PCIOOO film (50/50) containing 12% NCC is obtained according to the procedure described in Example 11 using 0.048 g of NCC.
    Mechanical characterization by DMA
    The films according to Examples 14, 15 and 16 are characterized between -100 ° C and + 100 ° C. The samples are rectangular films having the dimensions close to 15 mm x 6 mm x 0.150 mm (L x 1 x e). The samples are cooled to -100 ° C and then the films are heated at a rate of 3 ° C / minute to 100 ° C undergoing a deformation of 0.05% at a frequency of 1Hz.
    The results obtained are presented in FIG. 11. These results show that the films have a conservation modulus E ′ value of 6000 MPa at -100 ° C. At the glass transition temperature, all the films see their conservation modulus drop: up to 100 MPa for the unreinforced film according to example 16, and up to 300 MPa for the two reinforced films. It should be noted that at this stage, where the polymers have not yet melted, few differences are noted between the sample containing 6% (film according to example 14) and that containing 12% of NCC (film according to l 'example 15). At the POE melting temperature, i.e. 43 ° C, the conservation modules drop again: Up to 1 MPa for the unreinforced film, and 8 Mpa for the film reinforced with 6% NCC, and 70 MPa for the film containing 12% NCC.
    The reinforcement provided by the NCCs is therefore respectively 8 times for the 6% film (film according to Example 14) and 70 times for the 12% film (film according to Example 15).
    Conductivity measurements.
    The conductivity measurements are carried out with a Hewlett Packard 4192A impedance meter, coupled to a computer for data processing, in the frequency range 5 Hz-13 MHz, the amplitude of the sinusoidal signal is fixed at +/- 10 mV. The samples are mounted in a glove box under argon in Swagelok cells.
    Conductivity measurements were carried out on films according to Examples 14, 17 and 18 in order to study the effect of the polymer A / polymer B ratio on the conductivity. Measurements are taken up and down in temperature from 20 ° C to 90 ° C. The measurement is carried out every 10 ° C. after stabilization in temperature for 1 hour. The conductivities were taken at the time of the temperature drop. Each measurement was carried out twice to ensure the reproducibility of the determined conductivities.
    Figure 12 shows the results obtained. The conductivity measurements are similar at high temperatures for the three samples, with a conductivity at 90 ° C (1000 / T = 2.75) between 5 and 7 mS / cm.
    The conductivity at a temperature below the melting point of POE (43 ° C) drops for the samples containing the highest proportion of POE, but remains at a higher level for the sample containing only 25% by mass of POE . This is mainly due to NPC1000 which prevents the formation of POE crystallites.
    Conductivity measurements were also carried out on films according to Examples 17, 20 and 21 in order to study the effect of the amount of NCC on the conductivity. Figure 13 shows the results obtained. These results show that the introduction of reinforcing fillers results in a decrease in the conductivity of the samples. For example, at 1000 / T = 2.75 or T = 90 ° C, which is representative of the temperature of use of solid electrolytes, the unreinforced film according to Example 20 has a conductivity of 1.10 ' 3 mS / cm , that containing 6% by mass of NCC (example 17) has a conductivity of 7.10 ' 4 mS / cm and that containing 12% by mass of NCC (example 21) has a conductivity of 4.5.10 -4 mS / cm. There is therefore a decrease in performance by a factor of 1.5 for the 6% sample and by a factor of 2 for the sample containing 12% NCC. However, these losses of electrochemical performance remain limited in comparison with the mechanical reinforcement gained by the reinforced films.
    Dendritic growth measurements
    The dendritic growth measurements are carried out with a VMP300 potentiostat of the BioLogic brand, coupled to a computer for data processing.
    A piece of film is assembled between two lithium metal electrodes, by hot rolling. A low intensity direct current (2mA) is imposed on the terminals of the sample in order to cause the migration of lithium ions from one electrode to the other. The voltage value is measured continuously. It must remain stable in the absence of dendrite because it then corresponds to the potential difference between the two electrodes. When a dendrite pierces the film, voltage peaks are observed, resulting from the short circuit caused by the contact of the two electrodes by the dendrite.
    In the case of an unreinforced film according to Example 21, the first dendrites are observed after 5 hours of operation.
    The same experiment is carried out on films reinforced according to the invention until the exhaustion of the positive lithium electrode, which is entirely emptied in the negative electrode. The results are presented in Table 4.
    Table 3: Dendritic growth measurements on the reinforced films according to the invention
    Sample Time before emptying the positive electrode Appearance ofdendrites Example 14 25h No Example 15 8 p.m. No Example 17 10 p.m. No Example 18 7 p.m. No Example 19 7 p.m. No
    The time until the positive electrode is completely consumed varies because the films are not all the same thickness, slowing the transport of lithium. However, these results show that all the films according to the invention prevent dendritic growth, even after almost 20 hours of use.
    Preparation of reinforced films based on crosslinkable polycondensate of POE (PC) (polymer A), POE (polymer B) and NCC or NCC / chitosan (reinforcing filler C) according to route 3
    Example 22: Synthesis of a POE / NPC1000 film (80/20) containing 10% of NCC and
    1.33% chitosan.
    1.20 g of POE and 0.3 g of PC1000 according to Example 10 are dissolved in 43.8 ml of distilled water in a 60 ml bottle, then 0.39 g of LiTFSI and 0.02 g of chitosan are added. A dispersion of 2.3% NCC in distilled water is prepared by mixing 2.56 g of NCC in 110 ml of distilled water using a high power ultra turrax homogenizer. 6.9 mL of this dispersion (ie 0.16 g of NCC) are then added and the mixture is vigorously stirred. Then, 0.15 mg of 4,4'azobis (4-cyanovaleric acid), a polymerization initiator, are added and the preparation is poured into a cylindrical tube and frozen with liquid nitrogen and finally the water is eliminated. by lyophilization. The samples are then hot pressed (between 80 and 90 ° C) to trigger crosslinking by the radical route and to obtain semi-interpenetrating network films (~ 300 μm thick).
    Example 23 Synthesis of a POE / NPC 1000 Film (80/20) Containing 10% of NCC
    In a 60 ml bottle, 1.23 g of POE and 0.3 g of PC1000 according to Example 10 are dissolved in 44.1 ml of distilled water and then 0.40 g of LiTFSI are added. A dispersion of 2.3% NCC in distilled water is prepared by mixing 2.56 g of NCC in 110 ml of distilled water using a high power ultra turrax homogenizer. 7.4 mL of this dispersion (i.e. 0.17 g of NCC) are then added and the mixture is stirred vigorously. Then 0.15 mg of 4,4'-azobis (4-cyanovaleric acid), a polymerization initiator, are added and the preparation is poured into a cylindrical tube and frozen with liquid nitrogen and finally the water is removed by lyophilization. The samples are then hot pressed (between 80 and 90 ° C) to trigger crosslinking by the radical route and to obtain semi-interpenetrating network films (~ 300 μm thick).
    Mechanical characterization by DMA
    The membranes are characterized between -100 ° C and + 180 ° C using a DMA TA Q800. The samples are rectangular films having the dimensions close to 10 * 5.0 * 0.3 (L * w * e in mm). The samples are cooled to -100 ° C and then the films are heated at a rate of 2 ° C / min to 180 ° C undergoing a deformation of 0.05% at a frequency of 1Hz.
    Figure 14 shows the results obtained. The addition of chitosan leads to an increase in the modulus of conservation at low temperature of approximately 1000 MPa but does not delay the temperature at which the first fall of modulus takes place. The addition of chitosan also makes it possible to maintain a conservation modulus of more than 500 MPa over more than 50 ° C.
    Characterization by tensile tests
    The membranes were characterized with DMA TA Q800 by performing tensile tests at 30 ° C with a drawing speed of 0.1 N / min. The samples are rectangular films having the dimensions close to 10 * 5.0 * 0.3 mm.
    The addition of chitosan causes a slight increase in the deformation at break. The Young's modulus is not modified but the plastic deformation seems greater (significantly greater slope).
    权利要求:
    Claims (15)
    [1" id="c-fr-0001]
    1. Ionically conducting material for an electrochemical generator, characterized in that it comprises:
    1. at least one polymer A, distinct from B, having an ionic conductivity of between 10 5 and 10 3 S / cm,
    [2" id="c-fr-0002]
    2. at least one polymer B having a mechanical strength characterized by a conservation module> 200 MPa, for example between 200 and 5000 MPa or between 350 and 1500 MPa
    [3" id="c-fr-0003]
    3. at least one reinforcing filler C.
    2. Ionically conducting material according to claim 1 characterized in that the polymer B is chosen from the following polymers:
    semi-crystalline polymers having an amorphous phase between a low glass transition temperature (for example less than or equal to 20 ° C) and a high melting temperature (for example greater than or equal to 110 ° C);
    semi-crystalline ionic polymers;
    amorphous polymers having a glass transition temperature greater than or equal to 110 ° C;
    so-called high performance polymers, in neutral or ionic form; and their mixtures.
    3. Ionically conductive material according to one of claims 1 or 2 characterized in that the polymer A is chosen from polymers comprising an oxyalkylene chain in the main chain or in a pendant chain.
    [4" id="c-fr-0004]
    4. ion-conducting material according to any one of the preceding claims, characterized in that the reinforcing filler C comprises at least one nanocellulose, for example, the reinforcing filler C comprises at least one nanocellulose and a material chosen from chitin, chitosan, gelatin, sericin and their mixtures.
    [5" id="c-fr-0005]
    5. Ionically conductive material according to any one of the preceding claims, characterized in that it also comprises at least one alkali or alkaline earth metal salt, preferably a lithium salt, even more preferably a chosen lithium salt. among LiTFSI, LiPFg, L1BF4, LîAsFô and L1CIO4, L1CF3SO3 and their mixtures.
    [6" id="c-fr-0006]
    6. Film characterized in that it comprises an ionically conductive material according to any one of the preceding claims.
    [7" id="c-fr-0007]
    7. Film according to claim 6 characterized in that it is an infiltrated film and in that the polymer A is infiltrated into the polymer B.
    [8" id="c-fr-0008]
    8. Separator for electrochemical generator characterized in that it comprises an ionically conductive material according to one of claims 1 to 5.
    [9" id="c-fr-0009]
    9. Polymer electrolyte for an electrochemical generator characterized in that it comprises an ionically conductive material according to one of claims 1 to 5.
    [10" id="c-fr-0010]
    10. Electrode for electrochemical generator characterized in that it comprises an ionically conductive material according to one of claims 1 to 5.
    [11" id="c-fr-0011]
    11. An electrochemical generator characterized in that it comprises an ionically conductive material according to one of claims 1 to 5.
    [12" id="c-fr-0012]
    12. Use of a film according to one of claims 6 or 7 to prevent dendritic growth in lithium batteries.
    [13" id="c-fr-0013]
    13. A method of manufacturing a film according to claim 6 characterized in that it comprises the following steps:
    - Preparation of a mixture of polymer A, of polymer B, of reinforcing filler C, and optionally of salt, in a solvent;
    pouring this mixture onto a support such as a glass, metal or polymer plate, or even an electrode;
    drying for example in an oven or an oven, possibly under a gas flow.
    possibly crosslinking.
    [14" id="c-fr-0014]
    14. A method of manufacturing a film according to claim 6 characterized in that it comprises the following steps:
    - Preparation of a mixture of polymer A, of polymer B, of reinforcing filler C, and optionally of salt, in a solvent;
    lyophilization of the mixture obtained;
    - hot pressing to obtain a film.
    [15" id="c-fr-0015]
    15. Method for manufacturing an infiltrated film according to claim 7, characterized in that it comprises the following steps:
    implementation of a porous polymer layer B, optionally comprising a reinforcing filler C and / or a filler having a
    5 electronic conductivity;
    infiltration of polymer A or of the macromonomer capable of forming polymer A after polymerization, with optionally a reinforcing filler C and / or a salt and / or a polymerization initiator, in the pores of polymer B;
    10 - optionally, polymerization of the macromonomer capable of forming polymer A after polymerization.
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    同族专利:
    公开号 | 公开日
    WO2018011521A1|2018-01-18|
    US20190229315A1|2019-07-25|
    EP3485525A1|2019-05-22|
    JP2019530128A|2019-10-17|
    KR20190039949A|2019-04-16|
    US11069940B2|2021-07-20|
    FR3054078B1|2018-09-07|
    CN109716556A|2019-05-03|
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    法律状态:
    2017-06-28| PLFP| Fee payment|Year of fee payment: 2 |
    2018-01-19| PLSC| Publication of the preliminary search report|Effective date: 20180119 |
    2018-07-30| PLFP| Fee payment|Year of fee payment: 3 |
    2019-07-30| PLFP| Fee payment|Year of fee payment: 4 |
    2020-07-30| PLFP| Fee payment|Year of fee payment: 5 |
    2021-07-29| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1656760|2016-07-13|
    FR1656760A|FR3054078B1|2016-07-13|2016-07-13|ION CONDUCTION MATERIAL FOR ELECTROCHEMICAL GENERATOR AND METHODS OF MAKING|FR1656760A| FR3054078B1|2016-07-13|2016-07-13|ION CONDUCTION MATERIAL FOR ELECTROCHEMICAL GENERATOR AND METHODS OF MAKING|
    US16/317,488| US11069940B2|2016-07-13|2017-07-12|Ionically conductive material for electrochemical generator and production methods|
    CN201780057254.9A| CN109716556A|2016-07-13|2017-07-12|Ionic conductivity material and preparation method for electrochemical generator|
    PCT/FR2017/051914| WO2018011521A1|2016-07-13|2017-07-12|Ionically conductive material for electrochemical generator and production methods|
    EP17751438.7A| EP3485525A1|2016-07-13|2017-07-12|Ionically conductive material for electrochemical generator and production methods|
    JP2019501654A| JP2019530128A|2016-07-13|2017-07-12|Ion conductive material for electrochemical power generation apparatus and manufacturing method|
    KR1020197004303A| KR20190039949A|2016-07-13|2017-07-12|Ion-conductive materials for electrochemical generators and methods for their manufacture|
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