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    • 专利摘要:
    An active material composition for a positive electrode of a lithium-ion electrochemical generator, comprising: - a lithiated oxide of formula Li1 + xMO2 in which: 0≤x≤0.15, M denotes NiaMnbCocM'd where a> 0; b> 0; c> 0; d≥0 and a + b + c + d = 1; M 'being selected from B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo or a mixture thereof; a lithium phosphate of formula LiMn1-yM "yPO4 where M" represents at least one element selected from the group consisting of Fe, Ni, Co, Mg and Zn; and 0 <y <0.5; the particle size distribution of the lithiated oxide being characterized by a first median volume diameter of the particles Dv501 ≥ 500 nm; the size distribution of the lithiated phosphate particles being characterized by a second median volume diameter of the particles Dv502 ≥ 500 nm; and Dv502 / Dv501 ≥1.5.
    公开号:FR3036538A1
    申请号:FR1554478
    申请日:2015-05-19
    公开日:2016-11-25
    发明作者:Erwan Dumont；Frederic Castaing；Cecile Tessier
    申请人:SAFT Societe des Accumulateurs Fixes et de Traction SA；
    IPC主号:
    专利说明:

    [0001] BACKGROUND ELECTRODE FOR LITHIUM ELECTROCHEMICAL GENERATOR TECHNICAL FIELD The technical field of the invention is that of the active materials intended to be used in the positive electrode (or cathode) of a rechargeable electrochemical generator (or accumulator) lithium.
    [0002] PRIOR ART In an electrochemical generator, an active material is a material that participates in electrochemical reactions to produce electrical energy when the electrochemical generator discharges. Lithiated oxides of transition metals are known as cathodic active material for use in electrochemical lithium generators. In the positive electrode, it is most often used as the active material lithium transition metal oxides of general formula LiMO2, where M represents at least one transition metal such as Mn, Ni, Co or a mixture thereof. These active ingredients make it possible to obtain high performances, particularly in terms of reversible cycling capacity and service life. For example, LiCoO2 and LiNiO2 respectively have a capacity of about 180 and 220 mAh / g. LiCoO2 however has two major drawbacks that are its toxicity and its high cost. It is also known to use a lithiated manganese oxide belonging to the family of spinels and having the formula LiMn 2 O 4. This compound has a low cost and an absence of toxicity, but has a reduced capacity (110 mAh / g) and a reduced lifetime that comes from the significant dissolution of the oxide in the electrolyte of the electrochemical generator . Other active materials of less cost than LiCoO2 and having good thermal stability and absence of toxicity have been studied, among which lithiated phosphates of at least one transition metal, such as LiFePO4 and LiMnPO4.
    [0003] The use of LiFePO4 and LiMnPO4 however faces their low electronic conductivity. It is generally necessary to add a large proportion of an electronically conductive material to the electrode in order to obtain an electrochemical generator having good discharge performance at a high current. In addition, LiFePO4 has a low specific energy due to the low electrochemical operating potential. LiMnPO4 has a higher operating potential, but on the other hand exhibits poor life when used as a positive electrode material against a negative graphite electrode in an electrochemical generator operating in cycling. In addition, it is difficult to reduce the porosity of an electrode made with one or the other of these materials, which leads to a low mass capacity of the generator containing these materials. An electrochemical generator has been sought which has a high mass capacity and a high cycle life. The document US 2013/0280610 describes an active material composition for a positive electrode of a lithium electrochemical generator, said composition comprising: a lithiated oxide of nickel, cobalt and manganese; a lithium phosphate of iron and manganese . This document teaches that using a lithiated oxide powder of nickel, cobalt and manganese whose particle size is different from that of lithium iron phosphate phosphate and manganese causes a decrease in the electrical conductivity of the electrode. To overcome this problem, it is described the use as starting material of a lithium iron phosphate and manganese powder whose size of the so-called "primary" particles is 5 to 200 nm. These particles are agglomerated into so-called "secondary" particles. To do this, a centrifugal spray drying technique is employed. The primary particles are mixed with water and the mixture is stirred. The primary particles agglomerate to secondary particles under the effect of centrifugal spray drying. The size of the secondary particles obtained can then be in the range from 5 to 20 μm. This document teaches that by forming secondary particles of lithiated phosphate of iron and manganese whose size is close to that of lithiated oxide particles of nickel, cobalt and manganese, the electronic conductivity of the active ingredient is increased and the capacity of the electrode. The process of manufacture described herein is complex because it requires the use of the centrifugal spray drying technique to create agglomerates. WO 2006/071972 discloses an active material composition for a positive electrode of a lithium electrochemical generator, said composition comprising: a lithiated oxide of cobalt or a lithiated oxide of nickel, a lithiated oxide of manganese type LiMn2O4 or a lithium phosphate which is either LiFePO4 or LiMnPO4. This document gives no information on the size of the lithium phosphate and lithiated oxide particles used.
    [0004] US 2014/0138591 discloses an active material composition for a positive electrode of a lithium electrochemical generator, said composition comprising: - a lithium iron and manganese phosphate, - a lithium oxide of nickel, manganese and of cobalt. It is said that the use of this composition makes it possible to manufacture a generator having a high mass capacity, as well as an increased safety of use in case of an increase in temperature. Lithium iron phosphate and manganese is preferably in the form of a powder whose particle size is less than 100 nm. According to this document, using this range of particle sizes would promote the transport of lithium and increase the electronic conductivity of lithium phosphate of iron and manganese. Nevertheless, the Applicant has found that the use of such a range of particle sizes makes it difficult to make an electrode. This difficulty results in either: - a too high porosity, - or a poor adhesion of the active material to the current collector, electrode support, during the calendering step of the electrode. Calendering is one of the manufacturing steps of the electrode during which the current collector of the electrode, coated on at least one of its faces of active material, passes between two cylinders in rotation. Both cylinders exert pressure on the electrode. The adjustment of the spacing between the two cylinders makes it possible to adjust the thickness of the electrode and its porosity to the desired values. US 2014/0045069 discloses an active material composition for a positive electrode of a lithium electrochemical generator, said composition comprising: - a compound of LiNii_bZb02 type where Z represents one or more elements selected from Co, Mn, Al, Mg and V; and b is from 0 to 0.4. a compound of LiMni_aXaPO4 type where X represents Mg and / or Fe and is from 0 to 0.3.
    [0005] It is said that this composition makes it possible to reduce the elution of manganese in the electrolyte and to increase the life of the generator during cycling. To manufacture this active ingredient composition, for each of these two compounds, powders whose particle size is preferably between 1 and 40 nm are used. According to this document, the use of such a range of sizes would make it possible to reduce the dissolution of the active material in the electrolyte, to facilitate the insertion of lithium ions into the active material and to reduce the electrical resistance of the active substance. electrode. Nevertheless, the Applicant has found that, as in document US 2014/0138591 commented on above, the use of such a range of particle sizes made it difficult to produce an electrode. WO 2014/102071 discloses a positive electrode of a lithium electrochemical generator comprising a current collector on which at least two layers of electrochemically active material are deposited. The first layer in contact with the current collector may be a mixture of lithium iron phosphate and manganese phosphate with a lithium transition metal oxide. The second layer contains a lithium phosphate of iron. This document gives no information on the size of the lithium phosphate and lithiated oxide particles used. A positive electrode for a lithium-ion type electrochemical generator is sought which has both a low porosity, that is to say a porosity of less than about 50%, preferably of between 30 and 40%, and whose active material composition has good adhesion to the current collector. Preferably, it is sought that this electrode has a high mass capacity. More preferably, it is sought to have a long life when used under cycling conditions. SUMMARY OF THE INVENTION The subject of the invention is an active material composition for a positive electrode of a lithium-ion type electrochemical generator, comprising: a lithiated oxide of transition metals of formula Lii-p'M02 in which : 0 <x <0.15, M denotes NiaMnbCocM'd where a> 0; b> 0; c> 0; d> 0 and a + b + c + d = 1; M 'being selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo or a mixture thereof; a lithium transition metal phosphate of the formula LiMnO- yM "yPO4 where M" represents at least one element selected from the group consisting of Fe, Ni, Co, Mg and Zn; and 0 <y <0.5; the lithiated oxide and the lithiated phosphate being in the form of particles; the particle size distribution of the lithiated oxide being characterized by a first median volume diameter of the particles Dv501> 500 nm; the size distribution of the lithiated phosphate particles being characterized by a second median volume diameter of the particles Dv502> 500 nm; and Dv502 / Dv50 '> 1.5. According to one embodiment, the lithium phosphate of transition metals is coated with a carbon layer. According to one embodiment, the composition comprises from 30 to 80% by mass of lithiated oxide, and from 70 to 20% by weight of lithium phosphate. According to one embodiment, the composition comprises from 20 to 50% by weight of lithiated oxide, and from 80 to 50% by weight of lithium phosphate. According to one embodiment, 0.60> a> 0.45; 0.35> b> 0.25; 0.25> c> 0.14. According to one embodiment, Dv502> 1 μm and Dv50 '> 1 μm.
    [0006] According to one embodiment, Dv502> 15 μm and Dv501> 5 μm. According to one embodiment, Dv50 2 / Dv50 '> 2, preferably Dv502 / Dv50'> 3.
    [0007] According to one embodiment, M "is Fe. According to one embodiment, α <0.50. The invention also relates to an electrode comprising the active material composition described above.
    [0008] According to one embodiment, the electrode comprises only lithiated transition metal oxide and lithiated transition metal phosphate as electrochemically active materials. Finally, the subject of the invention is also a lithium electrochemical generator comprising: at least one positive electrode which is an electrode as described above; at least one negative electrode comprising a material capable of inserting and disinserting lithium into its structure. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 shows the variation of the porosity of an active material composition comprising lithiated oxide in increasing proportions. FIG. 2 represents the variation of the mass capacity of an active material composition comprising lithiated oxide in increasing proportions. Figure 3 shows the variation of the internal resistance of an active ingredient composition comprising lithiated oxide in increasing proportions. Of course, the present invention is not limited to the examples and embodiments described and shown, but it is capable of numerous variants accessible to those skilled in the art.
    [0009] DESCRIPTION OF EMBODIMENTS The lithiated transition metal oxide used in the invention has the formula Li 1 + 1 in which: 0 <x <0.15, M denotes NiaMnbCocM'd where a> 0; b> 0; c> 0; d> 0 and a + b + c + d = 1; and M 'is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo or a mixture thereof. According to one embodiment, a <0.60. According to one embodiment, a <0.60. According to one embodiment, a <0.50.
    [0010] According to one embodiment, 0.55> a> 0.45. According to one embodiment, 0.40> b> 0.15; preferably 0.35> b> 0.20. According to one embodiment, 0.30> c> 0.10; preferably 0.25> c> 0.15.
    [0011] According to one embodiment, x <0.10; preferably 0.01 <x <0.06. Examples of lithiated oxide are: LiNi 3 Mn 3 ClO / 302; Li1 + Ni0.5Mn0.3Co0.202 with 0.01 <x <0.10, preferably 0.01 <x <0.06; Li1 + Ni0.6Mn0.2Co0.202 with 0.01 <x <0.10, preferably 0.01 <x <0.06. In one embodiment, Ni, Mn and Co are partially substituted by aluminum, such as the compound of the formula LiNi0.3Mn0.5Coo, i5Alo, o502. The lithium transition metal phosphate used in the invention has the formula LiMnO 3 yPO 4 where M "represents at least one member selected from the group consisting of Fe, Ni, Co, Mg and Zn; and 0 <y <0.5. Preferably M "is Fe in one embodiment y> 0.10, preferably y> 0.20, more preferably y> 0.30 Examples of lithium phosphate are LiFe0.2Mn0.8PO4; LiFe0 , 33Mn0.67PO4 According to the invention, the lithiated oxide and the lithiated phosphate used are each in the form of a powder The size distribution of the lithiated oxide particles is characterized by a first median diameter by volume Dv50 'greater than or equal to 500 nm The distribution of the size of the lithium phosphate particles is characterized by a second median diameter in volume Dv502 greater than or equal to 500 nm The equivalent diameter of a particle denotes the diameter of a sphere having the same volume as this particle.The median term means that 50% of the volume of the lithiated oxide particles (or lithium phosphate) consists of particles having an equivalent diameter of less than 500 nm and 50% of the particle volume of p Lithium oxide (or lithiated phosphate) articules consists of particles having an equivalent diameter greater than 500 nm.
    [0012] In a preferred embodiment, Dv50 'and Dv502 are greater than or equal to 1 μm. In a preferred embodiment, Dv50 'is greater than or equal to 5 μm and / or Dv502 is greater than or equal to 15 μm. In a preferred embodiment, 90% of the volume of the lithiated oxide (or lithiated phosphate) particles consists of particles having an equivalent diameter greater than 500 nm and 10% of the volume of the lithiated oxide particles (or Lithium phosphate) consists of particles having an equivalent diameter of less than 500 nm. The invention therefore excludes the use of lithiated oxide powder or lithiated phosphate nanometer, that is to say whose equivalent diameter is less than about 100 nm. Particle size measurement can be performed by the laser granulometry technique.
    [0013] According to the invention, the Dv502 / Dv501 ratio is greater than or equal to 1.5. In a preferred embodiment, Dv502 / Dv50 'is greater than or equal to 2, or even greater than or equal to 3. This has the effect of reducing the porosity of the active material, and therefore of increasing its compactness. The increase in compactness allows an increase in the energy density of the electrode. As explained above, it is known that a lithium phosphate is a poor electronic conductor while a lithiated oxide is a good electronic conductor and therefore it is preferable to use lithiated oxide particles having a median diameter of volume greater than that of lithium phosphate particles. However, it has been discovered that it is possible to manufacture an electrode having a satisfactory mass capacity, even using lithiated phosphate particles having a volume median diameter greater than that of the lithiated oxide particles. The lithiated oxide and lithiated phosphate powders can be obtained by grinding particles larger than the desired size, followed by sieving to retain only the particles of desired size. The lithiated oxide and lithiated phosphate powders can also be obtained from particles of a size smaller than that desired. The particles are agglomerated to form a cluster, called the "secondary" particle as opposed to the non-agglomerated particles called "primary" particles. The secondary particles may for example be obtained using the centrifugal vapor drying technique. This technique is further described in US 2013/0280610 commented above. The person skilled in the art possesses the necessary knowledge enabling him to determine the operating conditions for grinding and sieving the particles or agglomerating them to obtain secondary particles. According to one embodiment, a lithiated phosphate powder consisting essentially of primary particles whose volume median diameter Dv502 is greater than or equal to 500 nm is used, and not of secondary particles. Lithium transition metal oxide and lithiated phosphate are mixed to form an active ingredient composition. The lithiated oxide and lithiated phosphate may be mixed using conventional mixing techniques, for example a planetary mixer, to obtain the active ingredient composition according to the invention. According to one embodiment, the active material composition does not comprise active material other than lithiated oxide and lithium phosphate. In one embodiment, the lithium phosphate is coated with a carbon layer prior to mixing with the lithiated oxide. In the mixture obtained, the lithiated oxide may represent from 20 to 80% by weight of the composition and the lithium phosphate may represent from 80 to 20% by weight of the composition.
    [0014] In a preferred embodiment, the lithiated oxide represents from 30 to 80% by weight of the composition and the lithiated phosphate represents from 70 to 20% by weight of the composition. It has indeed been found that it is in the range of 30 to 80% of lithiated oxide that the porosity of the electrode was optimal. Figure 1 shows the variation of the porosity of an active material composition comprising lithiated oxide in increasing proportions. It shows different parts: - when the active ingredient composition consists essentially of only lithium phosphate, that is to say that it contains less than 5% by mass of lithiated oxide, its porosity is high. It is greater than 50%. An electrode whose electrochemically active material consists essentially of lithiated phosphate can hardly be compacted. This difficulty in decreasing the porosity of the electrode causes problems of electronic conductivity of the electrode and therefore problems of chargeability and dischargeability. when the active ingredient composition comprises from 30 to 80% of lithiated oxide, the porosity is between 30 and 40%, which is desired. The choice of the percentage range of 30 to 80% thus makes it possible to reduce the porosity of the electrode and to solve the problems of poor electronic conductivity of the electrode. when the active ingredient composition comprises more than 80% of lithiated oxide, the porosity of the mixture increases, which is undesirable.
    [0015] It has also been found that the mass capacity of the active ingredient composition reaches its maximum value when the lithiated oxide represents from 20 to 30% by weight of the composition. Figure 2 shows the variation of the mass capacity of an active material composition comprising lithiated oxide in increasing proportions. Surprisingly, it shows that the mass capacity of the electrode does not follow a linear law and finds an optimum for a mixture comprising from 20 to 30% by mass of lithiated oxide. It has also surprisingly been found that the internal strength of the bulk active material composition of the composition does not vary linearly with the amount of lithiated oxide. FIG. 3 represents the variation of the internal resistance of an active material composition comprising lithium oxide in increasing proportions. It shows that the internal resistance goes through a minimum when the composition comprises 20 to 70%, preferably 25 to 50% by weight of lithiated oxide. Preferably, the lithiated oxide represents from 30 to 45% by weight of the composition. More preferably, the lithiated oxide represents from 35 to 40% by weight of the composition.
    [0016] The method of depositing the active material composition on a current collector will now be described. Deposition can be done by a coating process. In this process, a paste is prepared by mixing the active material composition with generally a binder, an electronically conductive compound and a solvent which can be organic or aqueous. In the case of an organic solvent, it may be N-methyl-2-pyrrolidone (NMP). The paste is deposited on a metal strip serving as a current collector. The deposition of the paste can be done either on one of the faces of the current collector only, or simultaneously on both sides of the current collector. An electrode is then obtained which is dried to evaporate the solvent. The electrode can then be compressed during a calendering step. The calendering step makes it possible to adjust the thickness of the deposited layer. The deposited layer has a thickness after calendering generally between 251.1m and 300p.m. The amount of paste deposited on the current collector generally ranges from 15 mg / cm 2 to 50 mg / cm 2, which makes it possible to make a generator suitable for applications requiring high energy or applications requiring high power. Since the lithiated oxide and the lithium phosphate are mixed before deposition on the current collector, the invention excludes the situation in which the lithiated oxide and the lithium phosphate would be in the form of two superposed distinct layers.
    [0017] The active ingredient composition is generally from 80 to 98% by weight of the weight of the dough. The binder and the electronically conductive compound each generally represent from 1 to 10% by weight of the weight of the dough. The current collector is preferably a two-dimensional conductive support, such as a solid or perforated strip, based on carbon or metal, for example nickel, steel, stainless steel or aluminum. Generally, the current collector of the positive electrode is aluminum and its thickness is between 6 iam and 35 min. The binder has the function of reinforcing the cohesion between the particles of active material as well as improving the adhesion of the paste to the current collector. The binder may contain one or more of the following components: polyvinylidene fluoride (PVdF) and its copolymers, polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polymethyl methacrylate or butyl, polyvinyl chloride (PVC) polyvinylformal, polyesters and polyether amide blocks, polymers of acrylic acid, methacrylic acid, acrylamide, itaconic acid, sulfonic acid, elastomers and cellulosic compounds. Among the elastomers that may be used, mention may be made of ethylene / propylene / diene terpolymers (EPDM), styrene / butadiene copolymers (SBR), acrylonitrile / butadiene copolymers (NBR), styrene / butadiene / styrene block copolymers (SBS) or styrene / acrylonitrile / styrene (SIS), styrene / ethylene / butylene / styrene copolymers (SEBS), styrene / butadiene / vinylpyridine terpolymers (SBVR), polyurethanes (PU), neoprenes, polyisobutylenes (PIB), butyl rubbers, and mixtures thereof. The cellulosic compound may be carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), hydroxypropylcellulose (HPC) or hydroxyethylcellulose (HEC). The electronically conductive additive is generally selected from graphite, carbon black, acetylene black, soot or a mixture thereof. The present invention also relates to a lithium electrochemical generator comprising a positive electrode as described above. The electrochemical generator according to the invention further comprises at least one negative electrode, at least one electrolyte and at least one separator and which will now be described.
    [0018] The negative electrode is prepared in a conventional manner. The active ingredient may be lithium metal or a lithium metal alloy. It may also consist of a conductive support serving as a current collector which is coated with a layer containing the active material and further comprising a binder and a conductive material. The active ingredient is able to insert lithium into its structure. It may be selected from lithium compounds, a carbonaceous material capable of inserting lithium into its structure such as graphite, coke, carbon black and vitreous carbon. It may also contain tin, silicon, carbon and silicon based compounds, carbon and tin compounds and carbon, tin and silicon based compounds and a silicon oxide. titanium such as Li4Ti5012. It may comprise silicon whose surface is grafted with an organic group as described in document EP-A-2 242 129. It may comprise a SiC nanocomposite material as described in document FR-A-2 885 734. The anodes used may also consist of oxides, nitrides or phosphide of transition metals. The current collector of the negative electrode may be copper.
    [0019] The electrolyte is chosen from a non-aqueous liquid electrolyte comprising a lithium salt dissolved in a solvent and a solid electrolyte polymer conductive ion ion lithium ions, such as polyethylene oxide (PEO). The lithium salt is chosen from lithium perchlorate LiC1O4, lithium hexafluorophosphate LiPF6, lithium tetrafluoroborate LiBF4, lithium trifluoromethanesulfonate LiCF3SO3, lithium bis (fluorosulfonyl) imide Li (FSO2) 2N (LiFSI), lithium trifluoromethanesulfonimide LiN (CF3SO2) 2 (LiTFSI), lithium trifluoromethanesulfonemethide LiC (CF3SO2) 3 (LiTF SM), lithium bisperfluoroethylsulfonimide LiN (C2F5SO2) 2 (LiBETI), 4,5-dicyano-2 lithium (trifluoromethyl) imidazolide (LiTDI), lithium bis (oxalatoborate) (LiBOB), lithium tris (pentafluoroethyl) trifluorophosphate LiPF3 (CF2CF3) 3 (LiFAP) and mixtures of the foregoing.
    [0020] Preferably, the solvent is a solvent or a mixture of solvents chosen from common organic solvents, in particular saturated cyclic carbonates, unsaturated cyclic carbonates, non-cyclic carbonates, alkyl esters, such as formates, acetates, propionates or butyrates, ethers, lactones such as gammabutyrolactone, tetrahydrothiofene dioxide, nitrile solvents, and mixtures thereof. Examples of saturated cyclic carbonates include ethylene carbonate (EC), fluoroethylene carbonate (FEC), propylene carbonate (PC), butylene carbonate (BC), and mixtures thereof. this. Unsaturated cyclic carbonates include, for example, vinylene carbonate (VC), its derivatives and mixtures thereof. Non-cyclic carbonates include, for example, dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), dipropyl carbonate (DPC) and mixtures thereof. this. Among the alkyl esters, mention may be made, for example, of methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, butyrate and the like. ethyl, propyl butyrate and mixtures thereof. Among the ethers, there may be mentioned, for example, dimethyl ether (DME) or diethyl ether (DEE), and mixtures thereof. The separator may consist of a layer of polypropylene (PP), polyethylene (PE), polytetrafluoroethylene (PTFE), polyacrylonitrile (PAN), polyethylene terephthalate (PET) or a mixture of layers of different types. . The polymers mentioned can be coated with a ceramic layer.
    [0021] EXAMPLES In the examples below, the positive electrode comprises a current collector which is an aluminum strip. There is deposited thereon by coating a layer consisting of a paste comprising after evaporation of the solvent: 30 - 89% by weight of a composition of active material according to the invention. The chemical formula of the lithiated oxide and lithiated phosphate entering into the active ingredient composition, as well as their respective proportions are given in Table 1 below; - 6% by weight of a mixture of carbon black and graphite, serving as electronic conductive agent; 35 - 5% by weight of polyvinylidene fluoride (PVDF) serving as binder. The electrode thus produced is then calendered. The negative electrode comprises lithium metal as the active material.
    [0022] The separator used comprises polypropylene and polyethylene. The electrolyte is a lithium salt dissolved in a solvent based on alkyl carbonates. Electrochemical generators have been manufactured. They differ in the composition of the active ingredient used in the positive electrode. These different electrodes are nevertheless calendered identically. The negative electrodes, the separators and the electrolyte are identical. These electrochemical generators have undergone a lifetime cycling test at 60 ° C. The discharge current is C / 5, where C is the rated capacity of the generator. The charge is at a current of C / 5 up to a voltage of 4.4 V without maintenance charge (without "floating"). For each electrochemical generator manufactured, the following parameters were qualitatively evaluated. - Feasibility of the electrode, that is to say measurement of the adhesion of the active material composition to the current collector and measurement of the porosity of the electrode - Initial capacity of the electrochemical generator 15 - Retention of capacity after 50 cycles at 60 ° C. The porosity of the electrode is calculated after the calendering step by the difference between the geometric volume calculated from the dimensions of the electrode and the theoretical volume calculated from the densities of the various components of the electrode divided by the volume. theoretical.
    [0023] The results are summarized in Table 1 below: Ex. Ratio Dv502 Dv501 Composition Composition Feasibility Capacity LFMP retention * / (LFMP) mec) of the NMC of the initial LFMP of capacity NMC ** (am) (am) 1 electrode after 50 (% /%) cycles at 60 ° C 1 100/0 18 LiFe0.331 4110.67PO4 - + ++ 2 90/10 18 6 Li1.06Ni0.51 4110.3C00202 LiFe0.331 4110, 67PO4 + + ++ 3 80/20 18 6 Li1.06Ni0.51 4110.3C00.202 LiFe0.331 4110.67PO4 + + ++ 4 70/30 18 6 Li1.06Ni0.51 41103C00202 LiFe0.331 4110.67PO4 ++ ++ ++ 5 20/80 18 6 Li1.06Ni0.51 4110.3C00.202 LiFe0, 31 4110 7r) 04 ++ ++ + 6 0/100 6 Li1.06Ni0.51 4110.3C00,202 ++ ++ - 7 70/30 0.2 6 Li1.06Ni0.51 4110.3C00.202 LiFe0 3M110.67PO4 - 8 70/30 0.26 Li1.06Ni0.51 LiFe0.2Mn0.8PO4 - 9 70/30 18 6 Li1.01Ni0.61 4110.2C00,202 LiFe0.331 4110.67PO4 ++ ++ ++ Table 1 3036538 13 * The abbreviation NMC means lithiated oxide of transition metals. ** The abbreviation LFMP refers to the lithium phosphate transition metal. -: very insufficient -: insufficient 5 +: satisfactory ++: very satisfactory Examples 7 and 8 show that the use of a lithiated phosphate powder whose median particle diameter Dv502 diameter is 0.2 .im does not It is not possible to obtain a satisfactory feasibility: either the active substance does not adhere to the current collector after the calendering step, or its porosity is too high. Examples 2-6 and 9 show that when the lithiated phosphate particles are characterized by a Dv502 value of 18 μm, a satisfactory feasibility of the electrode (indicated by the symbols "+" and "++") is obtained) .
    [0024] The electrode of Example 6 exhibits poor capacity retention due to the absence of lithiated phosphate. Among the compositions in which the lithiated phosphate particles have a Dv502 of 18 μm, the following results are observed: The composition of Example 1 has a porosity that is too high (approximately 52%), due to the fact that absence of lithiated oxide. - The feasibility of the electrodes of Examples 4, 5 and 9 is very satisfactory (indicated by the symbol "++"). The active material composition of these electrodes contains between 30% and 80% of lithiated oxide. In these examples, the porosity is less than or equal to about 40%, which is very satisfactory. The compositions of Examples 4 and 9 which contain 30% NMC provide both feasibility, initial capacity and satisfactory capacity retention. The electrodes of Examples 2 and 3 have a higher porosity than that of Examples 4 and 5, and therefore less satisfactory, because of a lower percentage of lithiated oxide (10%, 20% for Examples 2 and 3 at instead of 30 and 80% for Examples 4 and 5).
    权利要求:
    Claims (13)
    [0001]
    REVENDICATIONS1. Active material composition for a positive electrode of a lithium-ion type electrochemical generator, comprising: a lithiated transition metal oxide of the formula Li 1 + 1 in which: 0 <x <0.15, M denotes NiaMnbCocM ' where a> 0; b> 0; c> 0; d> 0 and a + b + c + d = 1; M 'being selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo or a mixture thereof; a lithiated transition metal phosphate of formula LiMn-M "yPO4 where M" represents at least one element selected from the group consisting of Fe, Ni, Co, Mg and Zn; and 0 <y <0.5; the lithiated oxide and the lithiated phosphate being in the form of particles; the particle size distribution of the lithiated oxide being characterized by a first median volume diameter of the particles Dv501> 500 nm; the size distribution of the lithiated phosphate particles being characterized by a second median volume diameter of the particles Dv502> 500 nm; and Dv502 / Dv501> 1.5.
    [0002]
    The composition of claim 1, wherein the lithium transition metal phosphate is coated with a carbon layer.
    [0003]
    3. Composition according to claim 1 or 2, wherein the composition comprises - from 30 to 80% by weight of lithiated oxide - from 70 to 20% by weight of lithium phosphate.
    [0004]
    4. Composition according to claim 1 or 2, wherein the composition comprises: - from 20 to 50% by mass of lithiated oxide - from 80 to 50% by weight of lithium phosphate.
    [0005]
    5. Composition according to one of the preceding claims, wherein: 0.60> a> 0.45; 0.35> b> 0.25; 0.25> c> 0.14.
    [0006]
    6. Composition according to one of the preceding claims, wherein: Dv502> 1 pm and Dv501> 1 pm.
    [0007]
    The composition of claim 6 wherein Dv502> 15μm and Dv50 '> 5μm. 3036538 15
    [0008]
    8. Composition according to one of the preceding claims wherein Dv502 / Dv50> 2, preferably Dy502 / Dy501> 3.
    [0009]
    9. Composition according to one of the preceding claims, wherein M "is Fe.
    [0010]
    10. Composition according to one of the preceding claims, wherein a <0.50.
    [0011]
    11. Electrode comprising the active material composition according to one of the preceding claims.
    [0012]
    12. Electrode according to the preceding claim comprising only the lithiated oxide of transition metals and lithium phosphate transition metals as electrochemically active materials. 15
    [0013]
    13. Electrochemical lithium generator comprising: - at least one positive electrode which is an electrode according to one of claims 11 and 12; at least one negative electrode comprising a material capable of inserting and disinserting lithium into its structure. 20 5 10
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    同族专利:
    公开号 | 公开日
    EP3298644A1|2018-03-28|
    EP3298644B1|2019-10-30|
    US20180145314A1|2018-05-24|
    KR20180011145A|2018-01-31|
    WO2016184896A1|2016-11-24|
    CN107660316A|2018-02-02|
    US10862108B2|2020-12-08|
    FR3036538B1|2017-05-19|
    CN107660316B|2021-06-18|
    引用文献:
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    US20110223482A1|2008-11-06|2011-09-15|Gs Yuasa International Ltd.|Positive electrode for lithium secondary battery and lithium secondary battery|
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    WO2015040005A1|2013-09-20|2015-03-26|Basf Se|Electrode materials for lithium ion batteries|FR3112030A1|2020-06-26|2021-12-31|Saft|Use of lithium secondary electrochemical elements containing a mixture of a lithiated nickel oxide and a lithiated manganese iron phosphate for automotive applications|CN103268936B|2004-12-28|2016-08-31|波士顿电力公司|Lithium rechargeable battery|
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    ES2798309T3|2013-07-09|2020-12-10|Dow Global Technologies Llc|Mixed positive active material comprising lithium metal oxide and lithium metal phosphate|FR3091623A1|2019-01-03|2020-07-10|Commissariat A L'energie Atomique Et Aux Energies Alternatives|ELECTROCHEMICAL CELL FOR LITHIUM BATTERY COMPRISING A SPECIFIC NEGATIVE ELECTRODE IN METAL LITHIUM AND A POSITIVE ELECTRODE ON AN ALUMINUM MANIFOLD|
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    DE102019135048A1|2019-12-19|2021-06-24|Bayerische Motoren Werke Aktiengesellschaft|Lithium ion battery and method of making a lithium ion battery|
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1554478A|FR3036538B1|2015-05-19|2015-05-19|POSITIVE ELECTRODE FOR LITHIUM ELECTROCHEMICAL GENERATOR|FR1554478A| FR3036538B1|2015-05-19|2015-05-19|POSITIVE ELECTRODE FOR LITHIUM ELECTROCHEMICAL GENERATOR|
    PCT/EP2016/061113| WO2016184896A1|2015-05-19|2016-05-18|Positive electrode for a lithium electrochemical generator|
    US15/571,872| US10862108B2|2015-05-19|2016-05-18|Positive electrode for a lithium electrochemical cell|
    KR1020177035902A| KR20180011145A|2015-05-19|2016-05-18|Anode for lithium electrochemical cell|
    CN201680028522.XA| CN107660316B|2015-05-19|2016-05-18|Positive electrode of lithium electrochemical power generation device|
    EP16723131.5A| EP3298644B1|2015-05-19|2016-05-18|Positive electrode for a lithium electrochemical generator|
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