巴西专利BR112015004417B1 LITHIUM-ION BATTERY

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专利摘要:
LITHIUM-ION BATTERY. The present invention relates to the lithium-ion battery in combination with the fluorinated material effectively positioned for the reduction of combustion through said battery, the fluorinated material normally being non-gaseous and non-liquid and being itself effective to supply the reduction of combustion through said battery, such fluorinated material in such form as the material of construction of the battery box containing the battery, the film wrapped around said battery, and/or the semi-solid material at least in close proximity of the battery, such as by forming a coating on said battery or said film on said battery.
公开号:BR112015004417B1
申请号:R112015004417-4
申请日:2013-08-30
公开日:2021-08-10
发明作者:Dennis J. Kountz；George Martin Pruce；James Hoover
申请人:E.I. Du Pont De Nemours And Company；
IPC主号:

专利说明:

FIELD OF THE INVENTION
[001] The present invention relates to materials for use with lithium-ion batteries to reduce their combustion. BACKGROUND OF THE INVENTION
[002] A lithium ion battery (lithium ion battery) is a battery in which lithium ions travel between oppositely charged electrodes to generate electricity.
[003] Damage (malfunction) of a lithium-ion battery, such as by a short circuit inside the battery, is known to be able to produce a thermal leakage reaction that vaporizes the combustible components inside the battery, especially the electrolyte separating each anode from each battery cathode. Battery combustion involves ignition of flammable vapours, especially when reaching oxygen present in the air that comes in contact with flammable vapours, on the inside of the battery box in which the battery is housed or on the outside of the battery from that flammable vapors escape.
[004] In an effort to stop the flow of electricity to the compromised battery, the batteries were equipped with fusion which stops the flow of electricity above an excessive rise in temperature brought about by the leakage thermal reaction inside the battery.
[005] Since the electrical approach was not always effective in reducing combustion, several other techniques were tried.
[006] US patent 2011/0.177,366 describes the formation of the battery block case as a laminate of (i) a heat-conductive layer of metal or resin that has high heat conductivity, such as an industrial plastic and ( ii) a heat-absorbing layer of resin materials, ceramic materials or inorganic materials. Layer (i) forms the outside of the box and layer (ii) forms the inside of the box, so that the heat absorbed by layer (ii) is conducted outward from the inside of the battery block box through layer (i). Fluoro carbide resin is described as a possible material for layer (ii), and polytetrafluoroethylene (PTFE) is described as an example of a resin having superior heat resistance. The PTFE heat absorbing layer is described to contain from 20 to 70 parts by weight of the particulate material called material B dispersed therein, and PTFE is described to have excellent bonding properties. The function of particulate material B in layer (ii) is subjected to a thermal decomposition reaction, which absorbs heat and expands layer (ii) to form an insulating layer to protect the electronic devices on the outside of the block housing of the battery. Sodium hydrogen carbonate and aluminum hydroxide are described as examples of the material from B. As a clear compensation for the insulating effect of the insulating layer (ii) after heating, the battery block is also provided with a sinusoidal conduit ( 25) (Figure 2) to allow the escape of hot gases from the inside of the battery block box and the cooling air of this gas as it flows along the length of the conduit. The approach of the present invention is to try to avoid the emission of a high temperature flammable gas from the inside of the battery by limiting the temperature rise inside the battery and cooling the gas that escapes from the battery.
[007] Patent US 2009/0,176,148 describes the immersion of batteries for a container filled with a heat transfer fluid, and which contains a heat exchanger at least partially filled with the heat transfer fluid, in that the fluid is a liquid or a gas, such as water, glycols, perfluoro carbides, perfluoro polyethers, perfluoro amines, perfluoro ethers, silicone oils, petroleum hydrocarbons and the heat exchanger contributes to the removal of heat from immersed batteries. In another embodiment, the heat transfer fluid is a hydrofluoro ether that has a low boiling point temperature, for example, less than 80°C or even less than 50°C, vaporization of this liquid contributes to removal of heat from the submerged batteries. The disadvantage of this approach for improving battery safety, ie, reducing combustion, is the reliance on gas and/or liquid as the transfer fluid. Liquids or gases inside the battery block case are prone to escape after any openings being formed in the case, for example through subjecting the case to an impact.
[008] US patent 2010/0.047.673 describes filling the space between the battery block box and the batteries contained within the box with a non-flammable filling material, to exclude air from the inside of the box. In one embodiment, the liquid or gas is used as the fill material and is either contained within a polypropylene bag or absorbed into a high polymer to provide a gel-like material. Example 12 describes the preparation of a filler material for kneading 90% by weight magnesium hydrogen carbonate powder which releases carbon dioxide when superheated, with 10% by weight PTFE with a mortar binding effect, the resulting mixture then being molded into pellets, which then becomes the filler material on the inside of the battery box. A person skilled in the art knows that, for PTFE to have a binding effect, PTFE needs to be of the fine powder type, produced by polymerization in aqueous dispersion, followed by coagulation of the dispersed PTFE particles, the resulting clot being called the type of fine PTFE powder. This fine PTFE powder, before sintering, fibrillates when subjected to shear just as it does when mixed in a mortar. The fibrils that form the fibrillated PTFE act as a binding agent for the particulate material, such as the magnesium hydrogen carbonate used in Example 12. Of course, in this application, PTFE is used for its binding capacity, with magnesium hydrogen carbonate being the fire inhibitor in the filler material.
[009] There is still a need for an effective means to reduce combustion of a lithium-ion battery. BRIEF DESCRIPTION OF THE INVENTION
[010] The present invention refers to the material that is fluorinated, that is, neither gaseous nor liquid act to reduce combustion through a lithium ion battery. Therefore, one embodiment of the present invention is a lithium-ion battery which has the fluorinated material positioned effective for reducing combustion through said battery, said fluorinated material normally being non-gaseous and non-liquid and being effective to provide the reduction of said combustion through said battery. The positioning of the fluorinated material is in relation to the lithium-ion battery. The term "reduction of combustion" means that combustion never occurs even if the damage to the lithium-ion battery is such that an exothermic leakage reaction is expected, or combustion starts, its intensity is reduced, or the fire is very quickly extinct. The term “reduced intensity” means that when a plurality of lithium-ion batteries are present within the battery block case, combustion tends to be limited to just the damaged battery which is then easily extinguished. The term “non-gaseous and non-liquid” means under normal conditions, that is, at ambient temperature (from 15 to 25°C) and under a pressure of one atmosphere (1 MPa). The combination of these conditions and state of matter can also be expressed as normally non-gaseous and non-liquid. The term "being effective" means that no additional fluorinated material acts on (interacts with) the combustion for reduction, is essentially unnecessary. This does not preclude other independent combustion reduction measures, such as fusion.
[011] Another embodiment of the present invention is a battery pack comprising a box, at least one lithium-ion battery contained in said box, and the fluorinated material effectively positioned to reduce combustion through said battery, said fluorinated material normally being non-gaseous and non-liquid and being effective to provide reduction of said combustion through said battery. Preferably, the fluorinated material is the material of construction of the battery box or is positioned within the battery box or both.
[012] Each embodiment is applicable to one or more lithium batteries interconnected to supply electrical energy, that is, the positioning of the fluorinated material is applied to each of the batteries present, as well as being contained within a battery box.
[013] In each of these embodiments, the following preferences apply, individually and in any combination: (a) the non-fluorinated material is preferably a support material for a non-fluorinated material that has the function of reducing combustion . Therefore, the fluorinated material is essentially free of the binding function relative to the non-fluorinated material. The primary function of the fluorinated material is to reduce combustion. If the fluorinated material contains the non-fluorinated material, the amount of the non-fluorinated material contained by the fluorinated material preferably is not more than 15% by weight of the combined weight of the fluorinated material and non-fluorinated material, more preferably not more than 10% by weight, more preferably not more than 5% by weight, and for simplicity, even more preferably none. (b) the positioning of the fluorinated material is preferably at least in proximity to said drums. This proximity also applies to each lithium-ion battery in the electrical circuit. The term “at least in the vicinity of said battery” includes the fluorinated material being in contact with the lithium-ion battery, and when not in contact, therefore, being close to the lithium-ion battery or both. This proximity allows the fluorinated material to provide the effect of reducing combustion. While the term "is positioned effectively" provides this effect, this positioning is preferably without any intermediate metal structure between the battery and the fluorinated material, in which the fluorinated material is directly exposed to the combustion condition from the battery damaged, to provide combustion reduction. Therefore, for example, the fluorinated material is not a laminate with a metal layer facing the battery. The term “at least in proximity to the battery” includes fluorinated material positioned on the inside of the battery can and/or on the outside of the can. When positioned on the inside of the can, the fluorinated material and its location within the can is such that it does not interfere with battery performance compared to the fluorinated material not present inside the can, i.e., the fluorinated material does not have any significant detrimental effect on battery electrical performance.(c) the fluorinated material may comprise one or more fluorinated materials with different states and positions relative to the lithium battery. For example, when the lithium-ion battery is contained within a case to form a battery, the fluorinated material may include the fluoropolymer which forms at least the inner surface of said case as a liner of the case. Alternatively, the housing can be entirely produced from said fluoropolymer, i.e. the housing construction material is fluoropolymer. To serve as the housing material of construction, the fluoropolymer must be in a solid state and have the strength to withstand battery handling without breaking. Like a box liner, the fluorinated material can be in a semi-solid or solid state. The application of the fluorinated material such as a battery box or its coating is an example of positioning at least in close proximity to the fluorinated material in relation to the battery contained in the box. In this example, portions of the battery may be in contact with the inner surface of the case, while other portions of the battery will be out of contact, but close to its inner surface of the case. The fluorinated material is considered to be positioned within the box, even if the material is the material of construction of the box. Applications of the fluorinated material as a case liner and as described in paragraphs (e), (f) and (g) below are also examples, preferably for positioning the fluorinated material inside the battery case.(d) the fluorinated material may also include a fluoropolymer film, in contact with the lithium ion battery. This film, of course, is also solid and has sufficient strength to allow handling of the film without breaking it. A preferred method of establishing contact between the film and the lithium-ion battery is to wrap the film around the battery. Alternatively, instead of the film being in contact with the outside of the battery, the film/battery contact can be established by the film being on the inside of the battery, for example, positioned between the battery can and the battery electrodes .(e) in one embodiment, the fluorinated material may also include fluorinated material which comprises a fluoropolyether. In another embodiment, the fluorinated material can be a semi-solid. This semi-solid (state) is the normal state, that is, the state under the normal conditions of temperature and pressure mentioned above. The fluorinated material such as a semi-solid can be fluoropolyether. The semi-solid state facilitates the positioning of the fluorinated material such as fluoropolyether at least in proximity to the lithium ion battery, such as by forming a coating over at least a portion of the lithium ion battery, preferably as a coating on the battery surface where the “hot spot” is most likely to occur which leads to battery combustion, and most preferably over substantially the entire surface of the battery. Certain battery edges, where the surfaces on the external parts of the battery are together, present no danger of being the location of the hot spot resulting from battery damage, in which case, coating such edges by the fluorinated material may be unnecessary from a battery safety standpoint.(f) in another embodiment, the fluorinated material may be thermally destabilized fluoropolymer. This fluoropolymer is normally solid, but upon heating by damaging the lithium ion battery, this fluoropolymer decomposes to provide combustion reduction.(g) In another embodiment, the fluorinated material can also include a mixture of fluorinated composition and another material fluorinated. The other fluorinated material is preferably a solid and preferably a fluoropolymer and most preferably both. The preferred fluoropolymer is the thermally destabilized fluoropolymer mentioned in (f) above. The fluorinated composition preferably comprises a fluoropolyether. The mixture is preferably semi-solid. In yet another embodiment, the mixture is semi-solid and the fluorinated composition in the mixture comprises the fluoropolyether. Preferably, the fluorinated composition, such as that comprising the fluoropolyether, in the mixture is itself liquid, but the mixture with another fluorinated material, preferably the solid fluoropolymer, containing this liquid is non-liquid. The mixture is preferably semi-solid. In yet another embodiment, the semi-solid mixture comprises the solid fluorinated material and fluorinated composition as described above, has a sufficiently low molecular weight that, when mixed with the solid fluorinated material, the resulting mixture is semi-solid. Preferably, the other fluorinated material, such as comprising the fluoropolyether, is itself a liquid. The characterizations of liquid, non-liquid, solid, semi-solid (states), described above and later in this document, are the normal states, that is, the states under the normal condition of temperature and pressure mentioned above, unless otherwise indicated. other way. Therefore, these characterizations can be understood to be the same as normally liquid, normally non-liquid, normally solid and normally semi-solid. The mixture, preferably one that is semi-solid, can be positioned at least close to the lithium-ion battery, such as by a coating formed over the lithium-ion battery thereof, as described in the previous paragraph.(h) ) the fluorinated material can be a combination of fluorinated materials positioned separately from the lithium ion battery to provide a multiplicity of defenses against combustion by the lithium ion battery. In one embodiment, the fluoropolymer film described above can be used in combination with the fluoropolyether or blend described above. The mixture and fluoropolyether used in this embodiment are preferably semi-solids. In one aspect of this embodiment, the fluorinated material includes a fluoropolymer film, in contact with said battery and the fluorinated material which is (i) a mixture of the solid fluoropolymer and the fluorinated composition, or (ii) is in a semi-solid state, or ( iii) both. The preferred fluorinated composition comprises fluoropolyether. In another embodiment where the lithium battery is contained in a case to form a battery block, the fluorinated material may include the fluoropolymer which forms at least the inner part of the case or as the material of construction of the case as described above and said fluorinated material includes (a) fluoropolymer film in contact with said battery and/or (b) fluorinated material which is (i) a mixture of solid fluoropolymer and fluorinated composition as described above, or (ii) is in the semi-solid state as described above, or (iii) both. The application of the film and fluorinated material (i), (ii) and (iii) in relation to the lithium ion battery can be as described above. The preferred fluorinated composition below (i) and the fluorinated material above (ii) comprises the fluoropolyether.
[014] The term "semi-solid (state)" in all of these descriptions and embodiments thereof means that the fluorinated material, such as the fluoropolyether or the fluorinated composition in the mixture described above, is not a gas or a liquid under normal temperature conditions and pressure mentioned above. Preferably, this semi-solid state remains at the higher temperatures encountered in normal operation than the lithium-ion battery (and batteries), including recharging, when the battery is a rechargeable battery. Normal battery operation may include ambient temperature (from 15 to 25°C) and higher temperatures up to 40°C, sometimes up to 50°C and even higher, for example, at temperatures up to 60°C and even up to 80°C and for simplicity, under a pressure of one atm. The semi-solid state of the mixture differs from the liquid state in that it cannot flow under any of these temperature and pressure conditions. In contrast, the liquid state indicates the flowability, so as to take the shape of its container, while having a fixed volume. Instead of the flowability, the semi-solid state of the fluorinated material means it has the rigidity where it stays when it's positioned in the battery box. This positioning of the fluorinated material is facilitated by the semi-solid state characteristic of the mixture, that is, the mixture that can flow is sufficient under pressure to achieve intimate contact with the desired surfaces on the inside of the battery, for example, each battery and/or its connectors. The pressure applied can be just that of a trowel used to apply and spread the semi-solid on the inside of the battery box, when desired, such as on the battery and connectors to form a coating. Once applied and pressure is removed, the semi-solid state of the non-fluorinated material results in not flowing away from its applied position under normal operation of the lithium-ion battery and battery pack. Characteristic of being semi-solid, the fluorinated material in this state has the consistency of wax, bread dough, or putty, its rigidity can be controlled, for example, by the molecular weight of the fluorinated material or the fluorinated composition in the mixture and its proportion mixed with the other fluorinated material such as the solid fluoropolymer. When its fluorinated composition is used in the mixture to obtain the semi-solid state of the mixture it is itself a liquid at the temperatures mentioned above, this is indicative of a low molecular weight for the fluorinated composition such as fluoropolyether compared to the weight molecular structure of the solid fluorinated material such as the fluoropolymer in the mixture. Therefore, the liquid fluorinated composition has a boiling temperature (of one atm) greater than the particular maximum temperature among those mentioned above that can be encountered by the battery and battery block under normal operation. The relatively low molecular weight of the fluorinated composition confers high mobility under overheating which accompanies battery damage, therefore, facilitating access of the composition to the overheating area to reduce combustion.
[015] The solid state of the fluoropolymer used as the material of construction of the battery box, the battery box liner, and the film and fluoropolymer component of the mixture described above differs from the semi-solid state through the display of stiffness, but not of the flowability under the pressure mentioned above. Therefore, the solid fluoropolymer does not have the consistency of wax, dough, or putty. Mixing together the fluorinated composition of the solid and liquid fluoropolymer provides the preferred semi-solid state of the resulting mixture. In one embodiment, the fluoropolymer in each of its applications as a fluorinated material described above resists deformation as indicated by its tensile strength exposure of at least 1 MPa (ASTM D638 standard at 23°C), preferably, at least 5 MPa. The semi-solid state can be characterized by exposure to a tensile strength of zero, usually due to the inability to form tensile test specimens that have sufficient integrity to be tested for tensile strength.
[016] The fluorinated material in each of the applications described above, in relation to the present invention provides combustion reduction. Using a combination of fluorinated materials as described above and which combination to use will depend on the Li-ion battery pack and the special pack battery pack containing the Li-ion battery (batteries) under consideration for combustion reduction. While the fluorinated material in the applications mentioned above is stable at temperatures that can be encountered through a Li-ion battery and battery pack in normal operation, as mentioned above, the much higher temperatures reached when the battery is damaged by such an event abnormality such as a short circuit, improper charging, or other malfunction results in the battery's combustion-reducing fluorinated material. BRIEF DESCRIPTION OF THE FIGURES
[017] Figure 1 is a schematic plan view of a set of four lithium-ion batteries, including their electrical interconnection, showing an implementation of the semi-solid mixture application of the present invention;
[018] Figure 2 is a schematic side view of the battery block in Figure 1:
[019] Figure 3 is a schematic plan view of a battery block, the cover removed, which contains a set of sixteen lithium batteries and their electrical interconnection, showing another embodiment of the application of the semi-solid mixture of the present invention;
[020] Figure 4 is a cross-sectional view of the battery block of Figure 3, the cover in place, along line 4-4 of Figure 3:
[021] Figure 5a is an isometric view of a lithium-ion battery placed on a fluoropolymer film;
[022] Figure 5b is the battery of Figure 5a showing the film partially wrapped around the battery;
[023] Figure 5c is the battery of Figure 5b showing the film completely wrapped around the battery to form a seam; and
[024] Figure 6 is a schematic isometric view of the layers of materials present in a prismatic battery cell and containing the layers of fluorinated material for combustion reduction. DETAILED DESCRIPTION OF THE INVENTION
[025]The batteries in Figure 1 are the jelly-roll type of lithium-ion batteries 2, 4, 6 and 8, in which the layers of anode, electrolyte and cathode are rolled to form a cylindrical shape housed inside a can cylindrical. The electrolyte that does not act as a physical separator between the anode and cathode, will include a separator, in which the electrolyte is absorbed. The anode and cathode can also include the energy scavengers. The anodes of batteries 2 and 4 are electrically connected in parallel through the bus (14) and the anodes of batteries 6 and 8 are electrically connected in parallel through the bus (16). The bus (18) electrically interconnects the busbars (14) and (16) in series to form the positive terminal of the battery pack as shown by the + symbol in Figure 1. The busbars (20) and (22) electrically connect the cathodes of batteries 2 and 4 and 6 and 8 respectively. The bus (24) electrically interconnects the buses (20) and (22) to form the negative terminal for the battery pack as indicated by the symbol - in Figure 1.
[026] The semi-solid fluorinated material with one of the identities described above is present as a coating (26) on the busbars (14), (16), (20), and (22) and their underlying anodes and cathodes, as shown in Figure 1. The coating is formed by applying the semi-solid material to the upper parts (anode) and lower parts (cathodes) of batteries 2, 4, 6 and 8 and pressing the material into intimate contact with the current-carrying elements in the part. external part of each of the batteries. In fact, the coating is formed at both ends of the anode and cathode ends of the batteries and their associated busbars, as shown in Figure 2. If desired, the semi-solid fluorinated material can also be applied to form a coating over the uncoated lengths of the busbars (18) and (24) shown in Figure 1. Since the current is concentrated at the ends of the anode of the batteries and the busbars that carry this current to the positive terminal, preferably at least these busbars (electrical connectors) are coated by semi-solid fluorinated material. Anodes, cathodes and busbars are all electrical connectors for each battery and battery pack.
[027] The fluorinated material applied to the connectors as present for the coating (26) in Figure 1 must be electrically non-conductive, so as not to cause short circuits.
[028]Li-ion battery can be any type, including prismatic lithium-ion battery, in which the anode / electrolyte separator / cathode layers are stacked on top of each other, and the resulting assembly of many layers anode / electrolyte separator / cathodes are housed in a foil barrier layer that forms the battery can. This foil barrier, preventing electrolyte leakage and isolating from the atmosphere, is often referred to as a bag. A positive and a negative electrode extend from the outside of the bag, forming the electrical interconnection between the layers of anodes and cathodes, respectively, inside the bag. The prismatic lithium-ion battery cannot be used in combination with a box, in that situation, the application of the fluorinated material in relation to the prismatic battery will be compatible with the absence of the box.
[029] In another embodiment of the present invention, the fluorinated semi-solid material is positioned as a coating on the outside of the pouch, at least around the electrodes and on the electrode itself after its interconnection with the device to be fed by the battery. The liner on the bag can then be wrapped with the fluoropolymer film as a second fluorinated material to reduce prismatic battery combustion.
[030]The Li-ion battery can be either a primary battery or a secondary battery. The recharging feature of the secondary battery makes this a preferred battery for the application of the present invention.
[031] Figure 3 shows a set of sixteen lithium-ion batteries 32, 34, 36 and 38, like the batteries of Figure 1, but contained within a box (28) to form a battery pack (30). The anodes of the batteries (32) are electrically connected through the busbar (40) of the batteries (34) through the busbar (42), the batteries (36), through the busbar (44), and the batteries (38) through the busbar (46). Busbars (40), (42), (44), and (46) are electrically interconnected through busbar (48) to provide the positive battery terminal. The cathodes of the batteries (32) are electrically connected through the bus (50), the batteries (34) through the bus (52), the batteries (36) through the bus (54), and the batteries (38) through the bus (56). Busbars (50), (52), (54) and (56) are electrically interconnected via bus (58) to provide the negative battery terminal. A coating (60) of the fluorinated semi-solid material is formed over all surfaces of the batteries and their busbars, as shown in Figure 3.
[032] Figure 4 shows that the battery block box (28) consisting of a bottom receptacle (64), inside which the battery block of Figure 3 is positioned, and the cover (62) in position of closure forming the box (28). The fluorinated semi-solid material is deep enough to allow the material to form a coating (60) over all surfaces of the battery and its bars on the inside of the case (28). One embodiment of achieving the formation of this coating is to first form a bed of the semi-solid fluorinated material on the inside of the lower receptacle (64). Then the electrically interconnected battery pack can be pressed into this bed. The material that is forced upwards by this pressure can then be spread to form a coating over any uncoated upward facing surface (the batteries and the busbars), therefore encapsulating the battery pack and its busbars within. of the semi-solid mixture. If the amount of fluorinated semi-solid material in the bed is insufficient to coat the upturned surfaces, then additional material can be added and distributed over the entire uncoated battery/busbar surface. The housing (28) can then be closed by adding the lid (62) to the bottom of the receptacle (64). Li-ion prismatic batteries can be replaced with the jelly-roll batteries in Figures 1 through 4. The semi-solid fluorinated material does not have to fill all the space inside the case as shown in Figure 4; some empty space may exist. Alternatively, most of the entire space inside the box can be filled with the fluorinated semi-solid material, thereby encapsulating the battery pack.
[033] As is apparent from the above description of the positioning of the mixture, in relation to batteries and connectors, preferably, the semi-solid fluorinated material allows for intimacy of contact to be achieved, especially on irregularly shaped surfaces or surfaces that they are not readily accessible. Instead of the fluorinated material forming a direct coating on one or more of these elements, the coating can also be indirect. For example, the battery may have a fluoropolymer film wrap, and the mixture is formed as a coating on top of the film wrap.
[034] Figure 5a shows a lithium-ion battery (2), the same as shown in Figure 1, which has an anode connector (66) that extends from one end of the battery. Battery 2 is in a fluoropolymer film (68). If in Figure 5b, the film (68) is partially wrapped around the side surface of the battery 2. In Figure 5c, the film (68) is fully wrapped around the side surface of the battery 2 so as to form a seam (70 ). The seam is kept closed by conventional means (not shown) to maintain the fluoropolymer film overlap without using the flammable material. Wrapped film can be used on any Li-Ion battery in any arrangement within a battery box. For example, battery 2 of Figure 5c may be replaced with batteries 32, 34, 36, and 38 in Figure 3, prior to application of the fluorinated material to form a coating (60) on top of the film (68).
[035] Figure 6 shows another embodiment of the present invention in which the fluorinated material is positioned on the inside of the battery, rather than outside the battery, that is, inside the battery can, instead of outside the battery can as in the embodiments of Figures 1-5a, b, and c. In Figure 6, the battery is the prismatic battery (72) which consists of a stack of layers of materials, as follows: - sheet metal (74) forming the upper and lower layers of the battery (72), - layer of material fluorinated (76) adjacent to each sheet metal layer, - anode current collecting layer (78) adjacent to one of the layers (76), - ionically active layer (80) adjacent to the anode current collecting layer (78) , - cathode current collecting layer (82) adjacent to another layer of fluorinated material (76), - ionically active layer (84) adjacent to cathode current collecting layer (82), and a porous separating layer (86) positioned between layers (80) and (84).
[036] For simplicity, the sheet metal layers are not shown wrapping the sides of the other layers to form the battery can (pocket) (72), and the anode and cathode current collector tabs are not shown if extending through the pouch for electrical connection.
[037] Sheet metal layers (74) are preferably aluminum and are preferably coated (not shown) on both surfaces (top and bottom) with the polymer for electrical insulation purposes. Other sheet metal layer references include preference for these polymer coatings present on the sheet metal of the sheet metal layer. The polymer coating on the surface of the sheet metal layer (74) facing the outside of the battery is preferably polyamide and the polymer coating of the surface of the sheet metal layer facing the inside of the battery , preferably, is polypropylene. The layers of fluorinated material (76) preferably are a fluoropolymer film forming each such layer. The anode current collecting layer (78) is preferably copper, and the cathode current collecting layer (82) is preferably aluminum. The layers of fluorinated material (76) such as in film form may be in contact with respective current collecting layers (78) and (82). The layers of fluorinated material (76), such as in film form may also be in contact with respective layers of sheet metal (74). The fluorinated material, preferably in film form, can be separated from, i.e., unbonded, to the adjacent sheet metal layer and/or to the adjacent current-collecting layer. The ionically active layers (80) and (82) are preferably the coatings on the respective current-collecting layers (78) and (82). An example of layer (80) is graphite and lithiated binder, and an example of layer (82) is metal oxide and lithiated binder. The combination of layers (78) with (80) and (82) with (84) form the battery electrodes. The porous separating layer (86) is a porous material that contains electrolytes, the pores that allow the passage of lithium ions during discharge. The porous material separator may be polymeric, in which the polymer itself is hydrophilic or has a hydrophilic coating on the surfaces of the separator, including its pores,
[038] The fluorinated material used for the reduction of combustion in the present invention are themselves non-flammable under the combustion conditions found in damage to the lithium-ion battery.
[039] Regarding the use of fluoropolymer as the fluorinated material in applications such as the battery box, the lining of the internal surface of the box, the material of construction of the box, the film, and the solid fluoropolymer, being the solid component of the blending with the fluorinated composition or as filling the solid as particles around the lithium ion battery inside a battery box, the identity of the fluoropolymer will vary according to the particular application. In general, for all these applications, the fluoropolymer, including the thermally destabilized fluoropolymer, preferably comprises a carbon atom backbone as the polymer chain, -CCC-CC-CCCCC-CX-, where x is the number of additional carbon atoms present which together with the substituents in the polymer chain provide the desired molecular weight for the fluoropolymer, and making the fluoropolymer solid. Fluoropolymers having molecular weights of at least 50,000 (Mn) are commercially available, making it convenient to use these fluoropolymers. The fluoropolymer preferably is also solid at least at the temperatures encountered during normal operation of the lithium battery and battery pack as mentioned above. At the higher temperatures found when the Li-ion battery is damaged, the fluoropolymer may melt. Preferably, however, the melting temperature of the fluoropolymer is at least 200°C. Alternatively, the fluoropolymer can be one that softens on heating, rather than having a distinct melting temperature. In both cases, the fluoropolymer is preferably melt flowable. However, the fluoropolymer remains solid under normal lithium-ion battery operation as mentioned above.
[040] Preferably, it fluoropolymer contains at least 50% by weight of fluorine, preferably at least 60% by weight, and more preferably at least 70% by weight of fluorine, based on weight total fluoropolymer (excludes end groups). In one embodiment of the present invention, if hydrogen is present in the repeating units that make up the polymer chain, preferably the hydrogen is only mono-substituted on any of the carbon atoms that make up the polymer chain or on any secondary group attached to the polymer chain, since the presence of -CH2 - can impair the non-flammable capacity of the fluoropolymer. Preferably, the hydrogen content, if any, is not more than 2% by weight, more preferably not more than 1% by weight and most preferably not more than 0.5% by weight, based on the total weight of the fluoropolymer. A small amount of hydrogen along the polymer chain may have a beneficial effect in thermally destabilizing the fluoropolymer, therefore aiding its combustion reduction effect, as will be discussed below. In another embodiment of the present invention, the fluoropolymer is a perfluoro polymer. The term perfluoropolymer means that the monovalent substituents on the carbon atoms forming the polymer chain of the polymer are all fluorine atoms, with the possible exception of end groups.
[041] The preferred fluoropolymers in each of the applications mentioned above are those that are melt-processable tetrafluoroethylene copolymers, for example, comprising at least 40 to 99% by mol of repeating units derived from tetrafluoroethylene (TFE). ) (by polymerization) and from 1 to 60% by mol of units derived from at least one other comonomer, with a total of 100% by mol. Preferred comonomers with TFE to form perfluoropolymers are perfluoro ophelines containing 3 to 8 carbon atoms, such as hexafluoropropylene (HFP), and/or perfluoro(ethyl vinyl ether) (PAVE) where the alkyl group is linear or branched contains 1 to 5 carbon atoms. The preferred PAVE monomers in these TFE copolymers and those described below are those in which the alkyl group contains 1, 2, or 3 carbon atoms, and the copolymer can be produced using a variety of PAVE monomers. Preferred TFE copolymers include FEP (TFE / HFP copolymer and TFE / HFP / PAVE copolymer) and PFA (TFE / PAVE copolymer), where PAVE is the most preferred perfluoro(ethyl vinyl ether) (PEVE) or perfluoro(propyl vinyl ether) (PPVE), or the combination of perfluoro(methyl vinyl ether) (PMVE) and PPVE, that is, the copolymer of TFE / PMVE / PPVE, sometimes referred to as MFA. Less preferably, it is a fluoropolymer having -CH2- units of the polymer chain, such as THV (TFE/HFP/VF2 copolymer). The FEP preferably contains from 5 to 17% by weight of HFP, the remainder being TFE, with the PAVE content, if present, being from 0.2 to 2% by weight based on the total weight of FEP. The PFA preferably contains at least 2% by weight of PAVE, the remainder being TFE, based on the total weight of PFA.
[042] Regarding the application, in which the fluoropolymer is a solid component of the mixture with the fluorinated composition, in one embodiment such solid fluoropolymer is thermally destabilized. The destabilization of the fluoropolymer when exposed to heat (temperature) that precedes or accompanies combustion through the lithium ion battery provides a combustion reduction effect. The destabilization of the fluoropolymer results in its decomposition. Fluoropolymers are known for their thermal stability, especially resulting from the strong chemical bond between the carbon and fluorine atoms predominating in the fluoropolymer. It is common, however, for the fluoropolymer as polymerized to have thermally labile moieties, especially labile end groups, resulting from the ingredients that provide the free radicals in the aqueous polymerization medium during the polymerization reaction. As much as or a total of greater than 300 labile end groups and more often at least 400 such end groups, -COOH, -COF, and/or -CONH2, per 106 carbon atoms may be present in the fluoropolymer as polymerized. For example, the common persulfate polymerization initiator in the aqueous polymerization medium results in the formation of carboxyl end groups, -COOH, at the end of the polymer chain. These groups decompose at elevated temperatures, which indicates the thermal instability of the fluoropolymer. Decomposition involves the scission of the carboxyl end groups, leaving behind the reactive group of CF2-, which can lead to the formation of a new unstable end group, perfluoro vinyl, -CF = CF2, extending down the polymer chain. Before such destabilized fluoropolymers are available from the manufacturer for commercial use, the fluoropolymer undergoes a stabilization process that replaces the unstable end groups with stable end groups. This allows the fluoropolymer to be made by melting such as by melt extrusion, without the formation of bubbles in the extrusion product resulting from the decomposition of the fluoropolymer end groups. For an example of stabilization, FEP is subjected to a wet heat treatment at elevated temperatures to replace the unstable end groups with the stable end group -CF2H. FEP and PFA undergo fluorination treatment to replace the unstable end groups with the stable end group -CF3.
[043] The destabilized solid fluoropolymer used in the present invention is not subjected to any stabilization treatment, such as end-group stabilization, but instead is used in its thermally destabilized form, i.e., the thermally unstable portions, such as the labile end groups present in the fluoropolymer. Heating through the lithium ion battery caused by such damage such as improper charging or short circuit or other malfunction results in heating of the solid fluoropolymer to cause decomposition of the fluoropolymer and unstable portions. Therefore, the term “thermally destabilized” means that the fluoropolymer decomposes when exposed to heat generated by damage to the lithium ion battery. This decomposition results in non-combustible volatiles being emitted from the fluoropolymer. These volatiles reduce combustion, or prevent it from occurring, confine it if it does, or instantly eliminate any fire that does occur.
[044] A preferred destabilized fluoropolymer is the FEP mentioned above, but with end groups not being stabilized, so as to possess the unstable end groups mentioned above.
[045] Another realization of thermally destabilized fluoropolymer is the fluoropolymer that contains the thermally destabilized groups, such as the -CH2-CH2- or -CH2- of the polymer chain in the small amount that provides the thermal decomposition of the fluoropolymer without imparting the ability to not be flammable to the fluoropolymer. Such thermally unstable groups can be present in combination with thermally unstable end groups such as those described above. A preferred thermally destabilized fluoropolymer that contains at least the thermal instability of the polymer (main) chain is the copolymer of TFE, HFP and ethylene, with the amount of ethylene in the copolymer being small to satisfy the preferred maximum hydrogen contents mentioned above . The TFE and HFP contents of the ethylene / HFP / TFE copolymer can be the same as for the FEP dipolymer mentioned above.
[046] The destabilized fluoropolymer, preferably, is one that becomes fluid under the heating provided by the damaged lithium-ion battery. The thermally destabilized fluoropolymers mentioned above, in general and specifically, are melt fluid. In the case of fluoropolymers having a melting temperature, such heating exceeds the melting temperature. The fluoropolymer softens sufficiently on this heating that it becomes molten and fluid or melts to become molten fluid. The heat provided by the damaged battery changes the fluoropolymer from solid state to liquid state. This thermally destabilized or non-thermally destabilized flux of the fluoropolymer contributes to the exclusion of oxygen from combustion vapors resulting from the superheated electrolyte, and/or firestop. The fusion flow may be sufficient to seal the opening in the battery block box from which combustion vapors escape from the battery box.
[047] The thermally destabilized fluoropolymer can be used by itself as the fluorinated material for reducing the combustion of the lithium ion battery, that is, not mixed with the fluorinated composition. One form of this fluoropolymer and the other fluoropolymers described above is used by itself as the particulate filler material on the inside of the battery box, filling the space between the batteries, the box and the inside of the box. Another form of fluoropolymer is a fabricated form such as a film, as long as the fabrication does not decompose the fluoropolymer. A film of this fluoropolymer can be produced by depositing an aqueous emulsion of particles of the fluoropolymer onto a surface, followed by drying to obtain the film. The thermally destabilized fluoropolymer film, for example, can be used as a wrap for the lithium-ion battery, ie, outside the battery can, or inside the battery can, as shown in Figure 6. In any location, the film thickness is preferably 0.5 to 20 mils (12.5 to 500 micrometers), more preferably 2 to 15 mils (50 to 375 micrometers). Inside, the application of the can, preferably the fluorinated material such as in film form is not in the path of the lithium ions passing between the anode and cathode. Current collector layers such as layers (78) and (82) of Figure 6 provide separation and shielding of layers (76) (Figure 6) of the fluorinated material from ionically active layers such as layers (80) and (84) (Figure 6).
[048] In relation to the application of fluoropolymer, as the material of construction of the battery block box, such as the box (28) in Figures 3 and 4, or an inner lining thereof, the material of construction of the battery box. Battery block can be any material that is non-flammable and provides the strength necessary for the integrity of the case when subjected to expected conditions of use. Fluoropolymer, however, is the preferred material of housing and/or liner construction because of its contribution to reduced combustion. It is also preferred that the fluoropolymer as the battery box construction material has a melting temperature of at least 240°C, preferably at least 280°C. Preferred fluoropolymers for this application are PFA and FEP, as described above. The fluoropolymer, when it is PFA, can be thermally destabilized or have thermally stable end groups and can be used as the material of construction of the box, or as a liner, such as a metal box. When the fluoropolymer is not PFA as the material of construction of the battery box, preferably such a fluoropolymer, for example FEP, is not thermally destabilized when used as the material of construction of the battery box, as it is destabilizing could occur in the fabrication of fluoropolymer housing fusion. Both materials are also preferred materials for the case lining. The box can then be produced from a non-fluoropolymer, such as metal. The liner can be the thermally stabilized or unstabilized (destabilized) fluoropolymer having the melting temperatures mentioned above.
[049] Regarding the application of the fluoropolymer as a film to provide a winding for the lithium ion battery, this fluoropolymer can be the same as described above. The film can be the thermally destabilized fluoropolymer or the non-thermally destabilized fluoropolymer such as FEP with the labile end groups replaced by the stable end groups as described above. The FEP film is preferred for this application, and when the film is FEP, it is preferably non-thermally destabilized, i.e. the FEP of the film is stabilized such as through the stabilization of the end group mentioned above. The film thickness can be any thickness that provides the burn-reducing effect. For example, the film thickness can be from 2 to 15 mils (50 to 375 micrometers).
[050] When the fluoropolymer used for the construction or lining of the battery box and for the battery winding is not thermally destabilized, such fluoropolymer, however, provides combustion reduction or through decomposition under intense heating resulting from the damaged battery either through the fusion flow excluding oxygen from the combustion source or through both effects. The difference between the fluoropolymer that is (i) thermally destabilized versus (ii) is not thermally destabilized is that chemical groups, such as the thermally unstable end groups and/or the thermally unstable chemical bonds, such as the CH bond, compared with the CF bond are present in the fluoropolymer (i) but not the fluoropolymer (ii).
[051] In another embodiment, the fluoropolymer film can also be produced from polytetrafluoroethylene (PTFE), which is well known for not being melt fluid, that is, this polymer does not flow in the molten state. PTFE refers to (a) polymerized tetrafluoroethylene by itself without any significant comonomer present, ie, the homopolymer, and (b) modified PTFE, which is a copolymer of TFE with these small concentrations of comonomer at the point of melting of the resulting polymer is not substantially reduced below that of PTFE. Modified PTFE contains a small amount of the modifier comonomer that reduces crystallinity to improve processing, but without melting. Examples of such monomers include perfluoro opheline, i.e. hexafluoropropylene (HFP) or perfluoro(alkyl vinyl ether) (PAVE), wherein the alkyl group contains 1 to 5 carbon atoms, with perfluoro(ethyl vinyl ether) ) (PEVE) and perfluoro(propyl vinyl ether) (PPVE) with chlorotrifluoroethylene (CTFE), perfluorobutyl ethylene (PFBE), or another monomer that introduces bulky secondary groups into the molecule being preferred. The concentration of such comonomers preferably is less than 1% by weight, more preferably less than 0.5% by weight, based on the total weight of TFE and comonomer present in the PTFE. A minimum amount of at least 0.05% by weight is preferably used to show a significant effect. PTFE, including modified PTFE, can also be characterized by its high melting temperature of at least 330°C, typically at least 331°C and more often at least 332°C (all first-heat ). The high melt viscosity of PTFE including modified PTFE results from its extremely high molecular weight (Mn), for example at least 106 and generally well in excess, for example the Mn of at least 2 x 106. The non-melting fluidity of PTFE resulting from this high molecular weight manifests as a melt flow rate (TFF) of 0 when measured according to ASTM D 1.238 at 372°C and using a weight of 5 kg. A good indicator of unmelt meltability is that PTFE including modified PTFE has a melt flow viscosity of at least 1 x 106 Pa • s and preferably at least 1 x 108 Pa • s. The measurement of creep melt viscosity is described in column 4 of US patent 7,763,680. PTFE as the fluoropolymer wound film for the lithium ion battery does not flow in the molten state, however, it undergoes decomposition under intense heating through damage to the battery. The mass of PTFE present in the film and in close proximity provides contact with the battery, however, it provides the effect of reducing combustion. When PTFE as the fluorinated material is in film form, the film is preferably non-porous and exhibits the hydrophobic character of PTFE (and other fluoropolymers such as FEP and PFA).
[052] With respect to the fluorinated material when comprising the fluoropolyether, this is a preferred fluorinated composition for use as the fluorinated material. Preferred polyethers are fluoropolyethers (FPE), preferably perfluoropolyethers (PFPE), the two may have any chain structure, in which the oxygen atoms in the backbone of the molecule are separated by the saturated fluoro carbon groups containing de 1 to 3 carbon atoms, preferably the perfluoro carbon groups. More than one type of fluoro carbon group can be present on the fluorinated composition molecule. The expression FPE is inclusive of PFPE. Representative FPE structures are- (-CFCF3-CF2-O-)n (I)- (CF2-CF2-CF2-O-)n (II)- (CF2-CF2-O-)n-(-CF2- O-)m (III)- (-CF2-CFCF3-O-)n-(-CF2-O-)m (IV)
[053] These structures are discussed by Kasai in J. Appl. Polymer Sci. 57, 797 (1995) and are commercially available as certain Krytox® and Fomblin® products. Preferably, the FPE has a carboxyl group at one or both ends of the FPE chain backbone. For FPE monocarboxyl, the other end of the molecule is usually perfluorinated, but it may contain a hydrogen atom. FPE having a carboxyl group at one or both ends, which can be used in the present invention, contains at least two ether oxygen atoms, more preferably at least 4 ether oxygen atoms, and most preferably further preferably at least 6 oxygen atoms of ethers, i.e., n in the above Formulas is at least 2, 4, or 6 and in the above Formulas is at least 1, 2 or 3. Preferably at least minus one of the fluoro carbon groups separating the ethers oxygens, and more preferably at least two such fluoro carbon groups contain 2 or 3 carbon atoms. Most preferably, at least 50% of the fluoro carbon groups separating the ethers from oxygens contain 2 or 3 carbon atoms. Furthermore, preferably, the EPF contains a total of at least 9 carbon atoms. The maximum value of n and m in the Formulas above determines the physical state of the FPE. When EPF is used alone for the fluorinated material, i.e. it is not mixed with any other material, the sum of n and m is preferably sufficient for the FPE to be at least semi-solid. Although more than one FPE can be used as the fluorinated material, preferably only one FPE is used. The EPF is considered a composition since, as commercially available, FPEs are generally a mixture of FPEs where the value of n or m determined is the average number of groups of n and m present in the FPE.
[054] FPEs and especially PFPEs have a high thermal stability, even when carboxyl groups are present at one or both ends of the chain structure. The heat provided by the damaged lithium-ion battery, however, causes the FPE to decompose, including its similarity to the decomposition of the fluoropolymer which has the thermally unstable portions, such as the carboxyl end groups. The decomposition products of FPE are non-flammable volatiles that reduce combustion similar to the effect of fluoropolymers, including the destabilized fluoropolymers described above.
[055] Regarding when the fluorinated material is a mixture of the fluorinated composition and another fluorinated material, the preferred fluorinated composition is the FPE described above, except that the sum of the values of nor is sufficient for the EPF not to be a gas, under normal conditions of temperature and pressure mentioned above and is preferably not a gas under the normal operating temperatures of the lithium-ion battery mentioned above. Preferably, the mixture is a semi-solid as described above under each of these conditions. In one embodiment, the semi-solid state of the mixture is obtained through the other fluorinated material of the mixture being solid and the liquid composition being fluorinated. These blend components are blended in proportions that produce the blend being semi-solid. Therefore, the molecular weight of the fluorinated composition is low enough that, when mixed with the solid fluoropolymer, a semi-solid mixture is formed. According to this embodiment, when the fluorinated composition is FPE, the sum of the value of n and m in the above Formulas of FPE is preferably such that the EPF is liquid. These liquid and solid states are in relation to the components of the mixture per se and these states and the semi-solid state are in relation to normal conditions and preferably under the conditions found in the normal operation of the lithium-ion battery, as mentioned above . The preferred liquid state for the fluorinated composition means the fluorinated composition wherein the mixture has a boiling temperature higher than these temperatures and preferably has a boiling temperature of at least 100°C at a pressure of atm.
[056] In one embodiment, the other fluorinated material in the mixture is the solid fluoropolymer which is preferably thermally destabilized as described above. Also preferably, this solid fluoropolymer is melt flowable.
[057] In another embodiment regarding the fluorinated composition being a mixture, the other fluorinated material can be the solid fluoropolymer which is low molecular weight PTFE, which is commonly known as the micronized PTFE powder, in order to distinguish the from the PTFE described above. While the molecular weight of the micronized PTFE powder is relatively low for PTFE, that is, the molecular weight (Mn) of the micronized powder is generally in the range of 104 to 105 to provide a solid polymer. The result of this lower molecular weight of the micronized PTFE powder is that it has melt flowability, i.e. melt flowability, in contrast to PTFE which is not melt flowable. The melt fluidity of the micronized PTFE powder can be characterized by a melt flow rate (MFR) of at least 0.01 g / 10 min, preferably at least 0.1 g / 10 min and, more preferably at least 5 g / 10 min, and even more preferably at least 10 g / 10 min, measured in accordance with ASTM D 1238, at 372°C, using a weight of 5 kg in the molten polymer. The fluoropolymers described above, including thermally destabilized fluoropolymers but excluding PTFE, are preferably also characterized by these melt flow rates. While the low molecular weight of the micronized PTFE powder imparts melt flowability to the polymer, the micronized PTFE powder itself is not melt fabricated, i.e. an article molded from the melt of the micronized PTFE powder is useless , due to extreme fragility. Due to its low molecular weight (compared to melt-free PTFE), it has no strength. An extruded filament of micronized PTFE powder is so brittle that it breaks after bending. In general, compression molded plates cannot be produced for tensile or bending tests of micronized PTFE powder due to the inability to form tensile strength test specimens that have sufficient integrity to be tensile strength tested . In which neither the traction nor the MIT Vida Flex property can be tested. In fact, this polymer lacks (0) the tensile strength and a zero cycle MIT Vida Flex. In contrast, PTFE is flexible rather than brittle, for example, as indicated by an MIT Vida Flex (ASTM D-2176 standard, using 0.21 mm (8 mil) thick compression-molded film) of, at least 1000 cycles, preferably at least 2000 cycles. Melt-flow fluoropolymers, with the exception of micronized PTFE powder, also preferably have this Flex Life, making them melt-fabricated as well as being melt-fluid.
[058] Mixing the fluorinated composition and other fluorinated material and their preferred identities, as described above, can be produced by mixing together the fluorinated composition, preferably as a liquid, with the other fluorinated material, in the form of particles. The particles of the other fluorinated material can be those that result from the polymerization process to make the material, such as the solid fluoropolymer. For example, polymerization in aqueous dispersion typically results in the formation of fluoropolymer particles that have an average particle size of no more than 0.5 micrometers, as measured by laser light scattering. The recovery of the fluoropolymer particles from the aqueous polymerization medium results in the agglomeration of the primary particles from the polymerization process to form the secondary particles of the agglomerated primary particles, the secondary particles that have an average particle size of 200 to 800 micrometers, depending on measured by laser light scattering (ASTM D 4464 standard). Micronized PTFE powder generally has a smaller particle size for secondary fluoropolymer particles. Such lower particle size is from 4 to 50 micrometers average particle size as measured by laser light scattering. Therefore, the overall average particle size of the other fluorinated material is preferably from 4 to 800 micrometers. The thermally destabilized fluoropolymer when used alone as a filler material can have this same particle size. This use as a filler material would replace the semi-solid coating (60) of Figure 3 and would substantially fill the entire space between the batteries (32), (34), (36) and (38) and the case (28).
[059] The mixing process can be carried out at room temperature (from 15 to 25° C) for convenience. Mixing can be carried out manually or by mechanical means. The components are added to the mixing vessel and subjected to mixing. Since a solid being mixed is preferably a liquid, mixing is complete when no concentration of one of the components is visible. Instead, a mixture that appears homogeneous, which is preferably semi-solid, is obtained. The fluoropolymer particles, in general, will have a white color, and the fluorinated composition, in general, will be a colorless liquid, with the result being a mixture that has a uniform white appearance.
[060] Solid fluoropolymer is known for its non-stick characteristic, making it useful for non-stick cookware surfaces. Accompanying this feature is its incompatibility with other materials. Mixing together the fluoropolymer particles with an incompatible liquid will not produce a homogeneous mixture. Instead, the incompatible liquid will simply drain from the fluoropolymer particles. Most organic solvents are incompatible with the fluoropolymer, ie the particles do not dissolve in such solvents. The fluorinated composition in liquid form is sufficiently compatible with the solid fluoropolymer in particulate form to form a homogeneous composition, preferably the semi-solid mixture, i.e. the liquid fluorinated composition does not drain from the mixture. The particle size of the solid fluoropolymer is preferably that which is effective for producing a homogeneous semi-solid mixture with the fluorinated composition.
[061] The proportions of each component in the mixture are adjusted to obtain the deformation capacity of the mixture at the desired time, the mixture is positioned in relation to the lithium-ion battery, such as by forming a coating on the battery of lithium ions (batteries) and their connectors. For determining fluoropolymer particles, the proportion of the fluorinated composition will vary depending on the molecular weight of the composition just as the molecular weight affects the viscosity of the liquid. While the coating of the semi-solid mixture on the lithium-ion battery (or connectors) can harden when the battery is used at extremely low temperatures, i.e., the deformation capacity desired for the application process for the battery and connectors such as formation of a coating of the semi-solid mixture on the lithium-ion battery (batteries) or film wrapped around the battery, and on the connectors that is necessary in establishing the recipe for the mixture, especially to obtain the preferred semi-solid state for the mixture. For convenience, the application process of the semi-solid mixture, such as in a coating process, can be conducted at room temperature (from 15° to 25°C).
[062] Preferably, the mixture, more preferably, semi-solid, comprises from 4 to 96% by weight of each fluorinated composition and other fluorinated material components, based on the combined weight of these components to total 100% by weight. On the same basis, the additionally preferred proportions are from 5 to 95% by weight of the fluorinated composition and from 95 to 5% by weight of the other fluorinated material, from 10 to 90% by weight of the fluorinated composition and from 90 to 10% by weight of the other fluorinated material, 50 to 90% by weight of the fluorinated composition and 90 to 50% by weight of the other fluorinated material, 50 to 85% by weight of the fluorinated composition and 15 to 50% by weight of the other fluorinated material, all based on the combined weight of these blend components to total 100% by weight. The fluorinated composition and other fluorinated material components of the mixture, in each of these ratios, can have any of the identities described above. With respect to each of these ratios, the preferred mixture is semi-solid, the preferred fluorinated composition is preferably a liquid, which is preferably fluoropolyether, including PFPE, and the other preferred fluorinated material comprises a solid material which preferably it is the fluoropolymer, more preferably the thermally destabilized fluoropolymer. Micronized PTFE powder is also an example of the preferred solid fluoropolymer materials in the blend.
[063] The coating thickness of the semi-solid mixture formed in the lithium-ion battery is preferably at least 25 micrometers (one mil). In the realization of Figures 3 and 4, a much thicker coating is formed.
[064] The combination of fluorinated materials, such as (i) a film and a layer of semi-solid fluorinated material on the film, or (ii) such as a box or coating, in combination with the film or coating of (i), or (iii) such as a mixture of the fluorinated composition with another fluorinated material in combination with (ii) or the film of (i) provides multiple defenses against combustion through the battery, such defenses preferably also result from different identities of fluorinated materials providing different contributions to the reduction of this combustion. The same is true of the placement of the fluorinated material, either inside or outside the battery can. The fluorinated material outside the battery can be in forms such as the box, box liner, rolled film and/or mixture of the fluorinated composition individually or in combination, in further combination with the fluorinated material, such as in the form of a film, positioned with the battery can, as interposed between the can, for example, the sheet metal layers (74) and the current-collecting layer, such as the layers (78) and (82) (Figure 6), i.e. between the can and the battery electrodes. EXAMPLES EXAMPLE 1
[065] In this Example, the lithium batteries in the set shown in Figure 3 are 4.8V each, providing a voltage of 19.2 for the battery pack in a box. The fluorinated material is a semi-solid mixture comprising tetrafluoroethylene/hexafluoropropylene (FEP) copolymer which has a melt flow rate (MFR) of 30 g/10 min and a hexafluoropropylene content of 10% by weight. The copolymer has a molecular weight (Mn) greater than 50,000 and has a melting temperature of 255°C. The mixture has the consistency of putty. The copolymer is in the form of secondary particles that have an average particle size of about 300 micrometers. The copolymer is a solid copolymer exhibiting a tensile strength greater than 5 MPa, and is thermally destabilized as indicated by its end group population being greater than 500 unstable end groups / 106 carbon atoms, at least 90% of which are the -COOH and the remainder comprising -CONH2. The mixture also comprises - CF3CF2CF2-O-(-CFCF3-CF2-O-)n-COOH-CFCF3,- where n is an average of 14, giving a molecular weight of about 2,500, as the fluorinated composition, which it is liquid at room temperature and has a boiling temperature greater than 100°C. These components are mixed together in a 50:50 weight ratio at room temperature and applied by a hand trowel for the batteries and connectors ( bars) on the inside of the battery block box to reach the coverage shown in Figures 3 and 4. The battery block is equipped with thermocouples to monitor the internal temperature at specific locations within the battery block box. A nail is driven through the battery box to impale one of the Li-ion batteries to short circuit. An impaled battery is one that is located adjacent to a thermocouple. The thermocouple reveals that short circuit of the battery across the nail is achieved when the temperature measured by the thermocouple reveals a rapid rise in temperature. The steam coming out of the box is visible. The vapor ignites and is instantly plunged through the coating of the semi-solid mixture.EXAMPLE 2
[066] The experiment of Example 1 is repeated with the exception that the mixture is replaced by the FEP film which has a thickness of 6 mils (150 micrometers) wrapped around each battery, and the result of the reduction in combustion is similar to from Example 1.EXAMPLE 3
[067] The experiment of Example 1 is repeated with the exception that the mixture is replaced by the PTFE film which has a thickness of 6 mils (150 micrometers) wrapped around each battery, and the result of the reduction in combustion is similar to from Example 1.EXAMPLE 4
[068]The experiment from Example 1 is repeated, with the exception that each battery is first wound with the FEP film from Example 2 and then the mixture is applied to the batteries on top of the film winding. The result of the combustion reduction is similar to that of Example 1.EXAMPLE 5
[069] The experiment of Example 1 is repeated, with the exception that the TFE / HFP copolymer is replaced by the micronized PTFE powder which has an average particle size of 7 microns, and the proportion of the micronized powder is 25% in weight based on the combined weight of the micronized powder and the FPE. The result of the combustion reduction is similar to that of Example 1.EXAMPLE 6
[070] The battery block of Example 1 is used and tested as in Example 1, without the presence of the semi-solid mixture, but the battery block box is produced from PFA as the material of construction of the box. The result of the combustion reduction is similar to that of Example 1.EXAMPLE 7
[071] The experiments of Examples 4 and 6 are repeated, and the result of combustion reduction using the combination of the FEP film winding and the PFA box is similar to that of Example 1.EXAMPLE 8
[072] The experiment of Example 1 is repeated, with the exception that the fluoropolyether of molecular weight of 2,500 is replaced by the fluoropolyether which has the same molecular structure, but with a greater number of n groups to give a molecular weight of about 7,500 . The resulting semi-solid mixture provides similar combustion reduction results as in Example 1.EXAMPLE 9
[073] The experiment from Example 8 is repeated with the exception that FEP is replaced by the micronized PTFE powder from Example 5, and similar combustion reduction results are obtained.EXAMPLE 10
[074] The experiment of Example 2 is repeated with the exception that the 5 mil thick tetrafluoroethylene / hexafluoropropylene / ethylene copolymer film, where the HFP content is 7.6% by weight and the weight of hydrogen supplied per copolymerized ethylene units is 0.13% by weight. The copolymer also has a lower amount of hydrogen present (0.006% by weight) as end groups -C2H5 derived from using ethane as the chain transfer agent in the polymerization to produce the copolymer. The copolymer has a molecular weight (Mn) greater than 50,000 and an MFR of 30 g / 10 sec. The film is produced by compression molding at a temperature just above the 285°C melting temperature of the copolymer. The combustion result is similar to Example 1.EXAMPLE 11
[075] The experiment from Example 10 is repeated, with the exception that the TFE / HFP / ethylene copolymer film is positioned on the inside of the can, between it and the battery electrodes, and the combustion result is similar to that of the Example 1. The results of Examples 2 to 11 are shown as similar to that of Example 1, since the result of the reduction in combustion is so fast that it is difficult to see any difference in the result.

权利要求:
Claims (9)
[0001]
1. LITHIUM-ION BATTERY (2, 4, 6, 8), characterized by having a fluorinated material (26) comprising a solid fluoropolymer positioned effective for reducing combustion through said battery, said fluorinated material (26) being non-gaseous and non-liquid under normal conditions and itself being effective to provide reduction of said combustion through said battery (2, 4, 6, 8), wherein said fluorinated material (26) further comprises a liquid fluoropolyether and said effective positioning form a coating of said fluorinated material (26) on at least a portion of said lithium-ion battery (2, 4, 6, 8).
[0002]
BATTERY (2, 4, 6, 8) according to claim 1, characterized in that said fluorinated material (26) is free of non-fluorinated material or contains 15% or less by weight of non-fluorinated material.
[0003]
BATTERY (32, 34, 36, 38) according to claim 1, characterized in that it additionally has a battery box (28) in which said battery (32, 34, 36, 38) is contained, said fluorinated material (60) including fluoropolymer forming at least the inner surface of said battery box (28).
[0004]
BATTERY according to claim 1, characterized in that said battery includes a can (72) forming the casing of said battery, and said fluorinated material (26) is positioned inside and outside said can (72).
[0005]
BATTERY according to claim 1, characterized in that it additionally includes a fluoropolymer film (68) in contact with said battery.
[0006]
BATTERY according to claim 1, characterized in that said solid fluoropolymer is a thermally destabilized fluoropolymer having at least 300 unstable end groups chosen from -COOH, -COF, and/or -CONH2 per 106 carbon atoms .
[0007]
BATTERY according to claim 5, characterized in that the fluorinated material (26) forms a coating on said film (68).
[0008]
BATTERY (32, 34, 36, 38) according to claim 1, characterized in that it additionally has a housing (28) in which said battery is contained, said housing (28) having at least one surface internal fluoropolymer, and additionally include a fluoropolymer film (68) in contact with said battery.
[0009]
BATTERY according to claim 1, characterized in that said fluoropolyether is liquid under normal conditions, but is present as a non-liquid mixture with said solid fluoropolymer.

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法律状态:
2018-11-21| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

2020-06-23| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

2021-07-06| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

2021-08-10| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 30/08/2013, OBSERVADAS AS CONDICOES LEGAIS. |

2021-08-24| B16C| Correction of notification of the grant [chapter 16.3 patent gazette]|Free format text: REF. RPI 2640 DE 10/08/2021 QUANTO AO INVENTOR. |

优先权:

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US201261694891P| true| 2012-08-30|2012-08-30|

US61/694,891|2012-08-30|

US201261703942P| true| 2012-09-21|2012-09-21|

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PCT/US2013/057436|WO2014036352A1|2012-08-30|2013-08-30|Li-ion battery having improved safety against combustion|

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