Battery cell, battery device, electric device and separator

Abstract

Provided in the present application are a battery cell, a battery device, an electric device and a separator. The battery cell comprises a positive electrode sheet, a negative electrode sheet and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet; the separator comprises a porous base film and a coating arranged on at least one side of the porous base film; the coating comprises heat-resistant particles and first binder particles; the first binder particles are embedded in the heat-resistant particles and form protrusions on the surface of the coating; and the heat-resistant particles comprise organic compound particles having a spherical or near-spherical morphology. The technical solution of the present application is beneficial for improving the storage performance and cycle performance of the battery cell in a high-temperature environment.

Description

Battery cell, battery device, power consuming device, separator Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application No. 202411388765.7, filed on September 30, 2024, entitled “Silicon-containing Organic Resin Particles, Method for Producing Silicon-containing Organic Resin Particles, Silicon-containing Organic Resin Particle Dispersion, Separator, Secondary Battery Cell, Battery Device, and Power Consuming Device,” the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, and more particularly, to a battery cell, a battery device, a power consuming device, and a separator. BACKGROUND

[0003] In recent years, as the application range of batteries is becoming more and more extensive, batteries are widely used in energy storage power supply systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc.

[0004] The development of battery technology needs to consider many design factors, such as energy density, cycle life, storage performance, charge-discharge rate, reliability, etc. While battery cells have made great progress, higher requirements have also been placed on their various performance. Among them, the separator is an important component that supports the completion of the charge-discharge electrochemical process of the secondary battery cell. However, the adhesion performance in the separator is poor, which will affect the storage performance and cycle performance of the battery cell in a high temperature environment.

[0005] Therefore, how to improve the storage performance and cycle performance of the battery cell in a high temperature environment is a technical problem to be solved. SUMMARY

[0006] The present application is made in view of the above-mentioned problem, and provides a battery cell, a battery device, a power consuming device, and a separator, which is beneficial to improve the adhesion performance between the separator and the electrode tab, thereby improving the storage performance and cycle performance of the battery cell in a high temperature environment.

[0007] In a first aspect, a battery cell is provided, comprising: a positive electrode tab, a negative electrode tab, and a separator between the positive electrode tab and the negative electrode tab; the separator comprises a porous base film and a coating layer provided on at least one side of the porous base film; the coating layer comprises heat-resistant particles and first adhesive particles; the first adhesive particles are embedded in the heat-resistant particles, and form protrusions on the surface of the coating layer; the heat-resistant particles comprise organic compound particles, and the morphology of the organic compound particles is spherical or spheroidal.

[0008] In the embodiments of the present application, spherical or spherical-like organic heat-resistant particles with smooth surfaces are used to replace traditional irregular inorganic particles, and these binder particles can be effectively embedded between the spherical heat-resistant particles to form uniformly distributed micro-protrusions on the surface of the coating. On the one hand, the spherical organic particles have smooth surfaces and regular geometric shapes, and when they are physically mixed with the binder particles, there are fewer contact points between them and weaker forces, which can effectively reduce the coverage and shielding of the binder particles. This allows the binder particles to be more uniformly and fully dispersed in the coating and maximizes the exposure of their active surfaces during the preparation of the separator film, thereby exerting their inherent binding properties to enhance the adhesion between the separator film and the pole piece. On the other hand, these protrusions can generate strong local pressure when hot-pressed with the electrode pole piece, achieving deeper mechanical interlocking and physical anchoring, thereby enhancing the adhesion between the separator film and the pole piece. This not only effectively utilizes the binding properties of the binder itself, but also provides additional mechanical bonding force due to the protrusion structure, which allows the interface between the pole piece and the separator film to remain stable during long-term cycling, effectively reducing interface side reactions and pole piece peeling, thereby improving the cycle life of the battery. At the same time, the strong interface bonding can also reduce the risk of thermal runaway caused by interface separation at high temperatures, further enhancing the storage performance and cycle performance of the battery monomer in high-temperature environments.

[0009] In one possible implementation, the mass content of the organic compound particles in the coating is 50% to 80%.

[0010] In the embodiments of the present application, the mass content of the organic compound particles in the coating is set within the above range, which is beneficial to the separator film having appropriate initial adhesion and effectively isolating thermal shock and inhibiting dendrite penetration under high temperature conditions, thereby improving the overall thermal stability of the coating. At the same time, this is also beneficial to balancing the heat resistance of the separator film and allowing the first binder particles to have sufficient effective contact points. In this way, the adhesion between the separator film and the pole piece can be promoted, which is beneficial to interface contact, reduces internal resistance, and thus improves the cycle performance of the battery monomer.

[0011] In a possible implementation, the first binder particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, and t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

[0012] In the embodiments of the present application, the fluoropolymers in the first binder particles can provide electrochemical stability and electrolyte corrosion resistance, thereby facilitating the durability of the coating in long-term cycling; and the polar polymers in the first binder particles can enhance the chemical adsorption and physical anchoring between the first binder particles and the electrode plate through their strong polarity and functional groups, thereby improving the bonding strength of the interface. In the application scenario of the separator film, the type of the first binder particles can be selected according to the specific needs.

[0013] In a possible implementation, the average number average particle size of the first binder particles is 5 μm to 15 μm.

[0014] In the embodiments of the present application, the average number average particle size of the first binder particles meets the above range, which can reduce the phenomenon that smaller particles are prone to agglomeration, thereby facilitating ion and electron conduction. At the same time, this can also increase the effective bonding points to form close contact with the plate and improve the bonding strength. In addition, this is also conducive to improving the thermal stability of the coating, reducing the plugging of pores, thereby reducing the ion transmission resistance, causing battery polarization to intensify and capacity to decay.

[0015] In a possible implementation, the first binder particles are secondary particles.

[0016] In a possible implementation, the mass content of the first binder particles in the coating is 5% to 30%.

[0017] In the embodiments of the present application, the mass content of the first binder particles in the coating layer is set within the above range, which is beneficial to making the first binder particles have sufficient bonding points, thereby improving the cohesion and adhesion of the coating layer and reducing the powdering or peeling of the coating layer. Meanwhile, this will not cause excessive binder particles to coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0018] In a possible implementation, the coating layer further comprises second binder particles, and the second binder particles comprise at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, and t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

[0019] In the embodiments of the present application, the type of the second binder particles can be the same as or different from the type of the first binder particles, and the present application does not make any limitation in this aspect. For example, the first binder particles can be selected from fluoropolymers, and the second binder particles can be selected from non-fluoropolymers, so as to take into account the synergistic effect of the two types of polymer binder particles.

[0020] In a possible implementation, the average number average particle size of the second binder particles is 5 μm to 15 μm.

[0021] In the embodiments of the present application, the average number average particle size of the second binder particles satisfies the above range, which can reduce the phenomenon that smaller particles are prone to agglomeration, thereby facilitating the ion and electron conduction. Meanwhile, this can also increase the effective bonding points, so as to make the second binder particles form close contact with the pole piece and improve the bonding strength. In addition, this is also beneficial to improving the thermal stability of the coating layer and reducing the blocking of the pores, thereby reducing the ion transmission resistance and causing the battery polarization to intensify and the capacity to attenuate.

[0022] In a possible implementation, the second binder particles are secondary particles.

[0023] In a possible implementation, the mass content of the second binder particles in the coating layer is 5% to 30%.

[0024] In the embodiments of the present application, the mass content of the second binder particles in the coating is set within the above range, which is beneficial to making the second binder particles have sufficient bonding points, thereby improving the cohesion and adhesion of the coating and reducing the powdering or peeling of the coating. Meanwhile, this will not cause excessive binder particles to coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0025] In a possible implementation, the coating further comprises a third binder, and the third binder comprises at least one of polyimide, polyetherimide, polyacrylic acid, polyacrylate, ethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluororubber.

[0026] In the embodiments of the present application, the third binder is a water-based binder, which can wrap the solid particles in the slurry and form a continuous network structure after drying, thereby filling the gaps between the particles and enhancing the cohesion of the coating and reducing the powdering phenomenon. Meanwhile, the third binder can also wet the base film and the pole piece, thereby improving the interface compatibility. Therefore, the use of the third binder in the coating is beneficial to improving the structural stability and interface adhesion of the coating as a whole, thereby improving the cycle life of the battery.

[0027] In a possible implementation, the mass content of the third binder in the coating is 3% to 15%.

[0028] In the embodiments of the present application, the mass content of the third binder in the coating is set within the above range, which is beneficial to improving the binding force between the organic compound particles and reducing the cracking and peeling of the coating in high-temperature cycles, thereby improving the storage performance and cycle performance of the battery cell. In addition, this also causes the binder to appropriately fill the pores without affecting the ion conductivity, thereby reducing the polarization.

[0029] In a possible implementation, the organic compound particles Dn50 satisfy: 100 nm≤Dn50≤700 nm; wherein Dn50 refers to the particle size corresponding to the cumulative amount distribution of 50% in the particle size number distribution curve of the organic compound particles.

[0030] In the embodiments of the present application, for the organic compound particles, setting the Dn50 thereof in the above range can reduce local defects. In this way, it is beneficial to reduce the penetration of the electrolyte in a high temperature environment, reduce the occurrence of interface side reactions, reduce the storage gas production and the impedance in the cycle. At the same time, it can also reduce the case that the particles easily agglomerate and block the pores, promote the ionic conductivity, reduce the polarization in the high temperature cycle, and thus alleviate the capacity attenuation.

[0031] In a possible implementation, the organic compound particles include a cross-linked polymer, and a cross-linking degree of the cross-linked polymer is 70% to 98%.

[0032] In the embodiments of the present application, the cross-linking degree of the cross-linked polymer meets the above range, which is beneficial to make the organic compound particles have good structural stability at high temperature, so that the separator film remains stable under high temperature conditions, and thus the cycle stability of the battery cell is improved.

[0033] In a possible implementation, the cross-linked polymer includes a silicone polymer containing a siloxane structure.

[0034] In the embodiments of the present application, by using the silicone polymer containing a siloxane structure as the cross-linked polymer, it is beneficial to improve the storage performance and cycle performance of the battery cell under high temperature environment. Specifically, the stable Si-O bond has a high bond energy and is not easy to decompose under high temperature adjustment, which is beneficial to improve the stability of the material under high temperature environment. In addition, compared with inorganic particles, the density of the silicone polymer is lower, and the overall mass of the coating can be reduced under the same thickness, which is beneficial to improve the energy density of the battery cell.

[0035] In a possible implementation, the silicone polymer containing a siloxane structure includes a phenyl group, and the silicone polymer containing a siloxane structure includes a monomer and a cross-linking agent polymerized according to formula (I),

[0036]

[0037] wherein R1, R2 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, R3 includes C1-C4 alkyl or C4-C8 (meth) acryloyloxyalkyl, and R4 includes C2-C8 alkenyl or C4-C8 (meth) acryloyloxyalkyl; and the cross-linking agent includes divinylbenzene.

[0038] In the embodiments of the present application, the polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene is conducive to improving the storage performance and cycle performance of the battery monomer in a high-temperature environment. Specifically, in a high-temperature environment, the particle has a three-dimensional network skeleton formed by the phenyl structure and the monomer and the crosslinking agent, and the rigid silicon-oxygen skeleton can maintain structural integrity. This is conducive to improving the mechanical properties of the coating, thereby improving the storage performance and cycle performance of the battery monomer in a high-temperature environment.

[0039] In a possible implementation, the organosilicon polymer containing a silicon-oxygen structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing a silicon-oxygen structure is 75% to 95%; (2) the mass content of silicon elements in the organosilicon polymer containing a silicon-oxygen structure is 10% to 25%; and (3) the mass content of phenyl groups in the organosilicon polymer containing a silicon-oxygen structure is 2% to 12%.

[0040] In the embodiments of the present application, by limiting the crosslinking degree, the mass content of silicon elements, and the mass content of phenyl groups, the storage performance and cycle performance of the battery monomer in a high-temperature environment are improved.

[0041] In a possible implementation, the organosilicon polymer containing a silicon-oxygen structure includes a skeleton composed of a compound represented by formula (II),

[0042] R a [SiO 3 / 2 ] n formula (II),

[0043] wherein n is at least one of integers 4 to 12, and R a includes a cycloalkyl group, an aryl group, a C1-C3 alkyl group, a C1-C3 alkenyl group, and a C1-C3 alkynyl group. 12 includes a C1-C3 alkyl group. 12 includes a C1-C3 alkyl group. 12 includes a C1-C3 alkyl group. a includes a C1-C3 alkyl group.

[0044] In the embodiments of the present application, by introducing the structural unit represented by formula (II) into the organosilicon polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. The structure forms a uniform and stable rigid support frame through strong covalent bonds, thereby improving the storage and cycle performance of the battery in a high-temperature environment. Specifically, it can maintain structural integrity under high-temperature conditions, effectively reducing the shrinkage of the coating, thereby maintaining the stability of the three-dimensional polyhedral skeleton. By selecting the R1 substituent as a C1-C3 alkyl group, the thermal stability and chemical inertness of the polymer can be further enhanced, thereby improving the storage performance and cycle performance of the battery monomer in a high-temperature environment.

[0045] In a possible implementation, the organic silicon polymer containing a siloxane structure comprises one or more of monomers shown in formula (III) obtained by hydrolysis and polycondensation,

[0046]

[0047] wherein R'1 comprises an alkyl group with 1-3 carbon atoms.

[0048] In the embodiments of the present application, the organic silicon polymer with a cage structure can be obtained by hydrolysis and polycondensation of the monomers shown in formula (III). The polymer forms a three-dimensional network with uniform distribution and stable structure in the coating, which can effectively reduce the shrinkage of the coating under high temperature conditions, thereby improving the integrity and stability of the coating, which is conducive to improving the storage performance and cycle performance of the battery cell under high temperature environment. At the same time, the three-dimensional polyhedral skeleton structure formed by polymerization can also improve the high temperature wettability and retention capacity of the electrolyte, promote the uniform distribution of ions at the electrode interface, and reduce local lithium deposition and aggravation of side reactions. Therefore, the above-mentioned organic silicon polymer can improve the storage performance and cycle performance of the battery cell under high temperature environment.

[0049] In a possible implementation, the organic silicon polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organic silicon polymer containing a siloxane structure is 85%-97%; (2) the mass content of silicon in the organic silicon polymer containing a siloxane structure is 25%-45%; (3) the mass content of the skeleton composed of the compound shown in formula (II) in the organic silicon polymer containing a siloxane structure is 40%-60%.

[0050] In the embodiments of the present application, by controlling the crosslinking degree of the organic silicon polymer in the above range, the structural stability of the organic silicon polymer under high temperature environment can be enhanced, and the softening and deformation of the coating can be effectively reduced, thereby providing mechanical support for the battery cell.

[0051] In a possible implementation, the organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammogram of the organic compound particles in the first cycle has no oxidation peak in the voltage range of 0-4.4 V; (2) the organic compound particles have no glass transition temperature at 300°C; (3) the initial thermal weight loss temperature T 3d satisfies: T 3d ≥ 250°C; (4) the dissolution rate of the organic compound particles is less than or equal to 5% when the organic compound particles are soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days; and (5) the true density of the organic compound particles is 0.8 g / cm 3 -2.0 g / cm 3 .

[0052] In the embodiment of the present application, by limiting the oxidation peak of the cyclic voltammogram of the first cycle of the organic compound particle circulation, the glass transition temperature, the initial thermal weight loss temperature, the dissolution rate of the 60℃ constant temperature immersion for 7 days, and the true density, the overall performance of the battery monomer is improved.

[0053] In a possible implementation, the isolation film satisfies one or more of the following conditions: (1) the thickness of the coating layer is 0.5 μm to 10 μm; (2) the area density of the coating layer is 1.5 g / m 2 ~ 6 g / m 2 ; (3) the longitudinal thermal shrinkage rate of the isolation film is less than or equal to 5% when heated at 130℃ for 1h; (4) the transverse thermal shrinkage rate of the isolation film is less than or equal to 5% when heated at 130℃ for 1h; (5) the air permeability of the isolation film is 150 s / 100 mL to 500 s / 100 mL.

[0054] In the embodiment of the present application, by limiting the thickness, area density, longitudinal thermal shrinkage rate, transverse thermal shrinkage rate and air permeability of the coating layer, the overall performance of the isolation film is improved.

[0055] In a second aspect, a battery device is provided, including the battery monomer in the first aspect and any possible implementation.

[0056] In a third aspect, a power utilization device is provided, including the battery device in the second aspect.

[0057] In a fourth aspect, an isolation film is provided, including: a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer includes heat-resistant particles and first adhesive particles; the first adhesive particles are embedded in the heat-resistant particles, and form protrusions on the surface of the coating layer; the heat-resistant particles include organic compound particles, and the morphology of the organic compound particles is spherical or spherical-like.

[0058] In the embodiments of the present application, spherical or spherical-like organic heat-resistant particles with smooth surfaces are used to replace traditional irregular inorganic particles, and these binder particles can be effectively embedded between the spherical heat-resistant particles to form uniformly distributed micro-protrusions on the surface of the coating. On the one hand, the spherical organic particles have smooth surfaces and regular geometric shapes, and when they are physically mixed with the binder particles, there are fewer contact points between them and weaker forces, which can effectively reduce the coverage and shielding of the binder particles. This allows the binder particles to be more uniformly and fully dispersed in the coating and maximizes the exposure of their active surfaces during the preparation of the separator film, thereby exerting their inherent bonding properties to enhance the adhesion between the separator film and the pole piece. On the other hand, these protrusions can generate strong local pressure when hot-pressed with the electrode pole piece, achieving deeper mechanical interlocking and physical anchoring, thereby enhancing the adhesion between the separator film and the pole piece. This not only effectively utilizes the adhesive properties of the binder itself, but also provides additional mechanical bonding force due to the protrusion structure, which allows the interface between the pole piece and the separator film to remain stable during long-term cycling, effectively reducing interface side reactions and pole piece peeling, thereby improving the cycle life of the battery. At the same time, the strong interface bonding can also reduce the risk of thermal runaway caused by interface separation at high temperatures, further enhancing the storage performance and cycle performance of the battery monomer in high-temperature environments.

[0059] In one possible implementation, the mass content of the organic compound particles in the coating is 50% to 80%.

[0060] In the embodiments of the present application, the mass content of the organic compound particles in the coating is set within the above range, which is beneficial to the separator film having appropriate initial adhesion and effectively isolating thermal shock and inhibiting dendrite penetration under high temperature conditions, thereby improving the overall thermal stability of the coating. At the same time, this is also beneficial to balancing the heat resistance of the separator film and allowing the first binder particles to have sufficient effective contact points. In this way, the adhesion between the separator film and the pole piece can be promoted, which is beneficial to interface contact, reduces internal resistance, and thus improves the cycle performance of the battery monomer.

[0061] In a possible implementation, the first binder particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, and t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

[0062] In the embodiments of the present application, the fluoropolymers in the first binder particles can provide electrochemical stability and electrolyte corrosion resistance, thereby facilitating the durability of the coating in long-term cycling; and the polar polymers in the first binder particles can enhance the chemical adsorption and physical anchoring between the first binder particles and the electrode plate through their strong polarity and functional groups, thereby improving the bonding strength of the interface. In the application scenario of the separator film, the type of the first binder particles can be selected according to the specific needs.

[0063] In a possible implementation, the average number average particle size of the first binder particles is 5 μm to 15 μm.

[0064] In the embodiments of the present application, the average number average particle size of the first binder particles meets the above range, which can reduce the phenomenon that smaller particles are prone to agglomeration, thereby facilitating ion and electron conduction. At the same time, this can also increase the effective bonding points, so that the first binder particles form close contact with the electrode plate, thereby improving the bonding strength. In addition, this is also conducive to improving the thermal stability of the coating, reducing the plugging of pores, thereby reducing the ion transmission resistance, causing battery polarization to intensify and capacity to decay.

[0065] In a possible implementation, the first binder particles are secondary particles.

[0066] In a possible implementation, the mass content of the first binder particles in the coating is 5% to 30%.

[0067] In the embodiments of the present application, the mass content of the first binder particles in the coating layer is set within the above range, which is beneficial to making the first binder particles have sufficient bonding points, thereby improving the cohesion and adhesion of the coating layer and reducing the powdering or peeling of the coating layer. Meanwhile, this will not cause excessive binder particles to coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0068] In a possible implementation, the coating layer further comprises second binder particles, and the second binder particles comprise at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, and t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

[0069] In the embodiments of the present application, the type of the second binder particles can be the same as or different from the type of the first binder particles, and the present application does not make any limitation in this aspect. For example, the first binder particles can be selected from fluoropolymers, and the second binder particles can be selected from non-fluoropolymers, so as to take into account the synergistic effect of the two types of polymer binder particles.

[0070] In a possible implementation, the average number average particle size of the second binder particles is 5 μm to 15 μm.

[0071] In the embodiments of the present application, the average number average particle size of the second binder particles satisfies the above range, which can reduce the phenomenon that smaller particles are prone to agglomeration, thereby facilitating the ion and electron conduction. Meanwhile, this can also increase the effective bonding points, so as to make the second binder particles form close contact with the pole piece and improve the bonding strength. In addition, this is also beneficial to improving the thermal stability of the coating layer and reducing the blocking of the pores, thereby reducing the ion transmission resistance and causing the battery polarization to intensify and the capacity to attenuate.

[0072] In a possible implementation, the second binder particles are secondary particles.

[0073] In a possible implementation, the mass content of the second binder particles in the coating layer is 5% to 30%.

[0074] In the embodiments of the present application, the mass content of the second binder particles in the coating is set within the above range, which is beneficial to making the second binder particles have sufficient bonding points, thereby improving the cohesion and adhesion of the coating and reducing the powdering or peeling of the coating. Meanwhile, this will not cause excessive binder particles to coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0075] In a possible implementation, the coating further comprises a third binder, and the third binder comprises at least one of polyimide, polyetherimide, polyacrylic acid, polyacrylate, ethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluororubber.

[0076] In the embodiments of the present application, the third binder is a water-based binder, which can wrap the solid particles in the slurry and form a continuous network structure after drying, thereby filling the gaps between the particles and enhancing the cohesion of the coating and reducing the powdering phenomenon. Meanwhile, the third binder can also wet the base film and the electrode sheet, thereby improving the interface compatibility. Therefore, the use of the third binder in the coating is beneficial to improving the structural stability and interface adhesion of the coating as a whole, thereby improving the cycle life of the battery.

[0077] In a possible implementation, the mass content of the third binder in the coating is 3% to 15%.

[0078] In the embodiments of the present application, the mass content of the third binder in the coating is set within the above range, which is beneficial to improving the binding force between the organic compound particles and reducing the cracking and peeling of the coating in high-temperature cycles, thereby improving the storage performance and cycle performance of the battery cell. In addition, this also causes the binder to appropriately fill the pores without affecting the ion conductivity, thereby reducing the polarization. BRIEF DESCRIPTION OF DRAWINGS

[0079] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0080] FIG. 1 is a structural schematic diagram of a positive electrode sheet according to an embodiment of the present application;

[0081] Figure 2 is a schematic diagram of the structure of a single battery cell according to an embodiment of this application;

[0082] Figure 3 is a schematic diagram of the structure of a battery cell according to another embodiment of this application;

[0083] Figure 4 is a schematic diagram of a battery device according to an embodiment of this application;

[0084] Figure 5 is a schematic diagram of the structure of a battery device according to an embodiment of this application;

[0085] Figure 6 is a schematic diagram of the structure of an electrical device according to an embodiment of this application;

[0086] Figure 7 is a pyrolysis spectrum of the organic compound powder of Example 1 of this application;

[0087] Figure 8 is a SEM image of the organic compound particles in Example 1 of this application;

[0088] Figure 9 is a SEM image of the inorganic particles in Comparative Example 1 of this application.

[0089] Figure label:

[0090] 1-Vehicle; 11-Housing shell; 12-Electrode assembly; 121-Positive electrode sheet; 1211-Positive current collector; 1212-Positive electrode film; 13-Cover plate; 100-Battery cell; 400-Battery assembly; 401-Upper casing; 402-Lower casing; 500-Motor; 600-Controller.

[0091] The accompanying drawings are not drawn to scale. Detailed Implementation

[0092] The following detailed description of embodiments of the battery cell, battery device, and power-consuming device of this application, with appropriate reference to the accompanying drawings, may omit unnecessary details. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0093] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges are also intended to include any and all sub-ranges of the same, wherein each sub-range is inclusive of the end values. For example, if a range is from 1 to 10, then the range includes any and all sub-ranges between (and including) the minimum of 1 and the maximum of 10, that is, any and all sub-ranges having a minimum of equal to or greater than 1 and a maximum of equal to or less than 10, e.g., 5-10. In other words, the range of "1 to 10" is intended to include the range of "5 to 10" as well as other ranges. Also, the terms "first", "second", and the like, do not denote any order, quantity, or importance, but rather are used to identify one element from another, and the terms "left", "right", "front", "back", "top", "bottom", "over", "under", and the like in the description and in the claims are used for descriptive purposes and not necessarily for describing permanent positional relationships. Terms concerning attachments, e.g., secured to, coupled to, and the like, are intended to encompass the attachment mechanisms of means-plus-function claims, and include attachments by way of interlocking, adhesive, welding, brazing, soldering, and the like.

[0094] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the description and claims of the application as well as the above information provided herein are intended to cover all alternatives, modifications, and equivalents. The terms "comprising", "having", "including", and "containing" used herein are meant to be open-ended terms that specifically allow for the inclusion of unknown analogs, as well as intended equivalents.

[0095] Unless otherwise specified, all embodiments and optional embodiments of the application can be combined with each other to form new technical solutions.

[0096] Unless otherwise specified, all technical features and optional technical features of the application can be combined with each other to form new technical solutions.

[0097] If not otherwise specified, all steps of the present application can be carried out in sequence or randomly, preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any sequence, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0098] The development of battery technology needs to consider various design factors, such as energy density, cycle life, discharge capacity, charge-discharge rate, reliability, etc. Among them, the separator film is an important component to support the charge-discharge electrochemical process of the secondary battery cell. The commonly used separator film is usually made of polyolefin material. However, the heat resistance of polyolefin material is poor, and it is easy to soften or melt at high temperature, thereby causing internal short circuit of the secondary battery cell. In order to improve the heat resistance of the separator film and maintain its adhesion performance, a heat-resistant coating and an adhesive layer are usually coated on the separator film. However, the content of the adhesive in the separator film with this structure is limited, which makes the adhesion performance of the separator film poor, which will affect the storage performance and cycle performance of the battery cell in high temperature environment.

[0099] In order to solve the above problems, the related technology usually composites heat-resistant particles with irregular shape such as alumina and boehmite with adhesive particles to prepare a composite coating. Thus, the coating can have both heat resistance and adhesion performance. However, these heat-resistant particles usually have rough surfaces and irregular shapes. This makes it easy for the heat-resistant particles to cover and wrap the surface of the adhesive particles during the preparation of the coating, and induces the agglomeration of the particles, thereby hindering the effective contact and adhesion between the adhesive particles and the electrode plate, and further reducing the adhesion performance.

[0100] Therefore, the embodiments of the present application provide a battery cell, comprising: a positive electrode plate, a negative electrode plate and a separator film, the separator film being located between the positive electrode plate and the negative electrode plate; the separator film comprises a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer comprises heat-resistant particles and first adhesive particles; the first adhesive particles are embedded in the heat-resistant particles, and form protrusions on the surface of the coating layer; the heat-resistant particles comprise organic compound particles, and the morphology of the organic compound particles is spherical or spherical-like.

[0101] In the technical solution, the spherical or spherical-like organic heat-resistant particles with smooth surfaces are used to replace the traditional irregular inorganic particles, and the particles can be effectively embedded between the spherical heat-resistant particles to form uniformly distributed micro-protrusions on the surface of the coating. On the one hand, the spherical organic particles have smooth surfaces and regular geometric shapes, and when they are physically mixed with the binder particles, the contact points between them are fewer and the force is weaker, which can effectively reduce the coverage and shielding of the binder particles. This allows the binder particles to be more uniformly and fully dispersed in the coating and maximizes the exposure of their active surfaces during the preparation of the separator film, thereby exerting their inherent binding properties to enhance the adhesion between the separator film and the electrode plate. On the other hand, these protrusions can generate strong local pressure when they are hot-pressed with the electrode plate, achieving a deeper mechanical interlocking and physical anchoring effect, thereby enhancing the adhesion between the separator film and the electrode plate. This not only effectively utilizes the binding properties of the binder itself, but also provides additional mechanical bonding force due to the protrusion structure, which helps to maintain the stability of the interface between the electrode plate and the separator film during long-term cycling, effectively reducing the interface side reactions and electrode plate peeling, thereby improving the cycle life of the battery. At the same time, the strong interface bonding can also reduce the risk of thermal runaway caused by interface separation at high temperatures, further enhancing the storage performance and cycle performance of the battery cell in high-temperature environments.

[0102] The battery cell, battery device, power utilization device, and separator of the present application will be described below with reference to the accompanying drawings.

[0103] [Battery cell]

[0104] The present application provides a battery cell. Generally, the battery cell includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During the charging and discharging process of the battery cell, active ions are embedded and extracted between the positive electrode plate and the negative electrode plate. The electrolyte serves as a conductor for the active ions between the positive electrode plate and the negative electrode plate. The separator is arranged between the positive electrode plate and the negative electrode plate, mainly serving to prevent short circuiting between the positive and negative electrodes, while allowing the active ions to pass through. In some embodiments, the above-mentioned battery cell is also referred to as a secondary battery, and the battery cell can be the smallest battery unit.

[0105] The technical solution of the present application can be applied to various battery cells, such as lithium-ion batteries, lithium metal batteries, sodium-ion batteries, potassium-ion batteries, etc., and the present application does not limit this. For the sake of convenience, the following description will take a lithium-ion battery as an example.

[0106] During the charging process of the lithium-ion battery, lithium ions are extracted from the positive active material, move and embed into the negative material; during the discharging process, lithium ions are extracted from the negative material, move and embed into the positive active material.

[0107] It should be understood that the "intercalation" process described in the present application refers to the process in which lithium ions are intercalated into the positive active material and the negative material due to electrochemical reactions, and the "deintercalation" process described in the present application refers to the process in which lithium ions are deintercalated from the positive active material and the negative material due to electrochemical reactions.

[0108] Next, the separator film, the positive electrode sheet, the negative electrode sheet and the electrolyte of the battery cell of the present application will be described with appropriate reference to the accompanying drawings.

[0109] In some embodiments, the separator film is located between the positive electrode sheet and the negative electrode sheet; the separator film comprises a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer comprises heat-resistant particles and first binder particles; the first binder particles are embedded in the heat-resistant particles, and protrusions are formed on the surface of the coating layer; the heat-resistant particles comprise organic compound particles, and the morphology of the organic compound particles is spherical or spheroidal.

[0110] In the embodiments of the present application, the porous base film refers to a thin film material having a micrometer and / or nanometer level pore structure. The porous base film can be a single-layer thin film or a multi-layer composite thin film. When the porous base film is a multi-layer composite thin film, the materials of the layers can be the same or different.

[0111] In some embodiments, the porous base film can comprise a film or non-woven web selected from any one or at least two of the following: polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyether sulfone, polyphenylene ether, cyclic olefin copolymer, polyphenylene sulfide, polyvinyl naphthalene.

[0112] In some embodiments, the thickness of the porous base film can be 4 μm to 15 μm, and optionally 4 μm to 9 μm.

[0113] In some embodiments, the porosity of the porous base film can be 25% to 60%, and optionally 28% to 50%.

[0114] In some embodiments, the average pore size of the porous base film can be 25 nm to 82 nm.

[0115] The average pore size of the porous base film can be tested by using a capillary porosimetry tester (bubble point method). An exemplary testing method is as follows: a circular sample with a diameter of 25 mm is taken, 3-5 drops of wetting liquid are dropped on it, and after the sample is completely wetted, it is placed in a mold, then an inert gas (such as nitrogen) is used to extrude the wetting liquid in the pore channels of the sample to be tested, the extrusion gas pressure and flow rate are inversely proportional to the pore size, and by software sampling and pressure and pore size conversion analysis, the average pore size of the sample to be tested is obtained. The testing instrument can be a CFP 1500 pore size analyzer from PMI company, and the testing pressure can be 100 psi to 350 psi.

[0116] In the embodiments of the present application, the heat-resistant particles refer to particles that have certain thermal stability, can maintain their physical properties and chemical properties in a high-temperature environment, and are not prone to cracking, melting or softening.

[0117] In the embodiments of the present application, the "organic compound" refers to a carbon-containing compound, which generally includes hydrogen, oxygen, nitrogen, sulfur and other elements in addition to simple compounds such as carbon oxides, carbonic acid, carbonates and the like.

[0118] In the embodiments of the present application, the "organic compound particles" refer to solid particles composed of molecules mainly composed of carbon (C), hydrogen (H), oxygen (O), nitrogen (N) and the like connected by covalent bonds. For the separator film, the heat resistance of the separator film can be increased by disposing organic compound particles in the coating layer thereof. The organic compound particles are the main component of the coating layer. These organic compound particles are micron or nanometer level solid particles with high melting point, high thermal stability and high chemical inertness, which can be uniformly dispersed in the coating layer, thereby realizing the heat resistance of the separator film.

[0119] In the embodiments of the present application, the "morphology of the particles is spherical or spheroidal" refers to the particles being close to a sphere or being in an approximately spherical state as a whole in geometric shape.

[0120] As an example, the morphology of the particles being spherical or spheroidal can be tested by using instruments and methods known in the art. Specifically, as an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film in a regular and clear area is selected. Then, the micro-morphology of the coating layer on the separator film is measured by using a scanning electron microscope (SEM) and referring to the standard JY / T010 1996. Then, the two-dimensional projection profile, edge curvature, surface morphology and contrast change of the particles in the coating layer are observed. If the particle edge is smooth, the curvature is consistent, the surface is uniform, the contrast transition is natural, and the particle projection is circular, it is determined that the particle morphology is spherical. If the particle profile is close to circular, the edge is slightly irregular, and the surface may have slight undulations, it is determined that the particle morphology is spheroidal.

[0121] For the separator film, the heat resistance of the separator film can be increased by disposing heat-resistant particles in the coating layer thereof. The heat-resistant particles are the main component of the coating layer. These heat-resistant particles are micron or nanometer level solid particles with high melting point, high thermal stability and high chemical inertness, which can be uniformly dispersed in the coating layer, thereby realizing the heat resistance of the separator film.

[0122] Meanwhile, by using the heat-resistant particles and the first binder particles in the isolation film, the adhesion between the isolation film and the pole piece can be improved, so that the storage performance and the cycle performance of the battery cell in a high-temperature environment can be improved.

[0123] In some embodiments, the mass content of the organic compound particles in the coating layer is 50% to 80%. For example, the mass content of the organic compound particles in the coating layer is 50%, 53%, 55%, 58%, 60%, 63%, 66%, 70%, 75%, 80% or any value within the above range. By setting the mass content of the organic compound particles in the coating layer within the above range, the isolation film has appropriate initial adhesion and can effectively isolate heat shock and inhibit dendrite penetration in a high-temperature environment, thereby improving the overall thermal stability of the coating layer. At the same time, this also helps to balance the heat resistance of the isolation film and enables the first binder particles to have sufficient effective contact points. In this way, the adhesion between the isolation film and the pole piece can be promoted, thereby facilitating interface contact, reducing internal resistance, and further improving the cycle performance of the battery cell.

[0124] In some embodiments, the first binder particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-hydroxymethyl acrylamide copolymer, lauryl methacrylate-N-hydroxymethyl methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-hydroxymethyl methacrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-hydroxymethyl acrylamide-acrylonitrile copolymer. Among them, the fluoropolymer in the above first binder particles can provide electrochemical stability and resistance to electrolyte corrosion, thereby promoting the durability of the coating layer in long-term cycling; and the polar polymer in the first binder particles can enhance the chemical adsorption and physical anchoring between the electrode pole piece through its strong polarity and functional groups, thereby improving the adhesion strength of the interface. In the application scenario of the isolation film, the type of the first binder particles can be selected according to the specific needs.

[0125] In some embodiments, the first binder particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene).

[0126] The first binder particles have strong polar C-F bonds, which can effectively adsorb and enrich lithium ions in the electrolyte, forming a high-concentration ion region at the interface, thereby promoting the transmission of active ions. At the same time, the high dielectric constant of the first binder particles helps the dissociation of lithium salts, reduces the ion migration resistance, and thus improves the kinetic performance of the battery cell.

[0127] In some embodiments, the average number average particle size of the first binder particles is 5 pm to 15 pm. For example, the average number average particle size of the first binder particles is 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 11 pm, 12 pm, 13 pm, 14 pm, 15 pm, or any value within the above range. Specifically, the average number average particle size of the first binder particles satisfies the above range, which can reduce the phenomenon that smaller particles are prone to agglomeration, thereby promoting ion and electron conduction. At the same time, this can also increase the effective bonding points, allowing them to form a close contact with the pole piece and improve the bonding strength. In addition, this is also conducive to improving the thermal stability of the coating, reducing the blocking of the pores, thereby reducing the ion transmission resistance, causing battery polarization to intensify and capacity to decay.

[0128] As an example, the average number average particle size of the first binder particles can be tested using devices and methods known in the art. For example, a scanning electron microscope (e.g., ZEISS Sigma300) is used to obtain a scanning electron microscope (SEM) image of the separator film according to JY / T010-1996. Specifically, after the battery cell is disassembled, the separator film is peeled off, and the separator film in a regular and clear area is selected. As an example, the following method can be used for testing: a test sample with a length x width = 50 mm x 100 mm is randomly selected on the separator film, a plurality of test areas (e.g., 5) are randomly selected in the test sample, and the particle size of the first binder particles in each test area is read under a certain magnification (e.g., 500x or 1000x when measuring the first binder particles), that is, the distance between the two farthest points on the first binder particle is taken as the particle size of the first binder particle. The number of first binder particles and the particle size values in each test area are counted, and the arithmetic mean of the first binder particles in each test area is taken as the number average particle size of the first binder particles in the test sample. To ensure the accuracy of the test results, a plurality of test samples (e.g., 10) can be repeatedly tested according to the above method, and the average value of each test sample is taken as the final test result.

[0129] In some embodiments, the first binder particles are secondary particles.

[0130] It should be noted that, for the particles, primary particles and secondary particles have the meanings known in the art. The primary particles refer to particles that are not in an agglomerated state; the secondary particles refer to particles that are in an agglomerated state formed by the aggregation of two or more primary particles.

[0131] As an example, the morphology of the binder particles (e.g., the morphology of the primary particles or the morphology of the secondary particles) can be tested using devices and methods known in the art. For example, the testing can be performed by using a scanning electron microscope (e.g., ZEISS Sigma 300). Specifically, as an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film in a regular and clear area is selected. Subsequently, the scanning electron microscope (SEM) is used, and the micro-morphology of the coating on the separator film is measured according to the standard JY / T010 1996. In this way, the morphology of the binder particles can be obtained by observing the micro-morphology of the coating surface in the SEM image.

[0132] In some embodiments, the mass content of the first binder particles in the coating is 5% to 30%. For example, the mass content of the first binder particles in the coating is 5%, 7%, 10%, 13%, 15%, 18%, 20%, 23%, 26%, 28%, 30%, or any value within the above range. By setting the mass content of the first binder particles in the coating within the above range, it is beneficial to have enough bonding points for the first binder particles, thereby improving the cohesion and adhesion of the coating and reducing the occurrence of powdering or peeling of the coating. At the same time, it will not cause excessive binder particles to coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0133] In some embodiments, the coating further comprises second binder particles, the second binder particles comprising at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol methacrylamide-acrylonitrile copolymer. The second binder particles can be the same type as the first binder particles or a different type, which is not limited in the present application. For example, the first binder particles can be fluorine-containing polymers, and the second binder particles can be non-fluorine polymers, so as to take advantage of the synergistic effect of the two types of binder particles.

[0134] In some embodiments, the second binder particles have an average number average particle size of 5 μm to 15 μm. For example, the second binder particles have an average number average particle size of 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any value within the above range. The average number average particle size of the second binder particles within the above range can reduce the agglomeration of small particles, thereby facilitating ion and electron conduction. At the same time, this can also increase the effective bonding points, so as to form a close contact with the electrode sheet and improve the bonding strength. In addition, this can also improve the thermal stability of the coating, reduce the plugging of the pores, thereby reducing the ion transport resistance, causing the battery polarization to intensify and the capacity to decay.

[0135] As an example, the average number average particle size of the second binder particles can be tested using equipment and methods known in the art. For example, using a scanning electron microscope (e.g., ZEISS Sigma300), reference JY / T010-1996, a scanning electron microscope (SEM) picture of the separator film is obtained. Specifically, after the battery cell is disassembled, the separator film is peeled off, and a regular and clear area of the separator film is selected. As an example, the following method can be used for testing: a test sample of 50 mm x 100 mm is randomly selected on the separator film, a plurality of test areas (e.g., 5) are randomly selected in the test sample, and the particle size of the second binder particles in each test area is read (i.e., the distance between the two farthest points on the second binder particle is taken as the particle size of the second binder particle) under a certain magnification (e.g., 500x or 1000x when measuring the second binder particles), the number and particle size values of the second binder particles in each test area are counted, and the arithmetic mean of the second binder particles in each test area is taken as the number average particle size of the second binder particles in the test sample. To ensure the accuracy of the test results, a plurality of test samples (e.g., 10) can be repeatedly tested according to the above method, and the average value of each test sample is taken as the final test result.

[0136] In some embodiments, the second binder particles include at least one of methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

[0137] The second binder particles described above contain polar groups (such as carboxyl, amide, hydroxymethyl) that can form hydrogen bonds and chemical bonds with the substrate; at the same time, the side chain alkyl structure provides flexibility and wettability, enhancing interface contact and adhesion. Therefore, the use of these binder particles can improve the bonding performance of the separator film.

[0138] In some embodiments, the second binder particles are secondary particles.

[0139] In some embodiments, the mass content of the second binder particles in the coating layer is 5-30%. For example, the mass content of the second binder particles in the coating layer is 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25%, 28%, 30% or any value within the above range. Setting the mass content of the second binder particles in the coating layer within the above range is beneficial to have enough bonding points for the second binder particles, thereby improving the cohesion and adhesion of the coating layer and reducing the powdering or peeling of the coating layer. At the same time, it will not cause excessive binder particles to coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0140] In the embodiments of the present application, the mass content of the second binder particles can be lower than that of the first binder particles. For example, the mass content of the second binder is less than that of the first binder particles, which is beneficial to form a basic bonding network for the first binder particles, and the second binder particles with less content can further strengthen the bonding effect as high-strength anchor points. Wherein, setting a lower content will not affect the ion conductivity of the battery cell due to the excessive content of the binder particles.

[0141] In some embodiments, the coating layer further comprises a third binder, and the third binder comprises at least one of polyimide, polyetherimide, polyacrylic acid, polyacrylate, ethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluorine rubber.

[0142] In the above technical solution, the third binder is an aqueous binder which can wrap the solid particles in the slurry and form a continuous network structure after drying to fill the gaps between the particles, thereby enhancing the cohesion of the coating layer and reducing the powdering phenomenon. At the same time, it can also wet the base film and the pole piece, thereby improving the interfacial compatibility. Therefore, using the third binder in the coating layer is beneficial to improve the overall structural stability and interfacial adhesion of the coating layer, thereby improving the cycle life of the battery.

[0143] As an example, the substance type of the first binder particles, the second binder particles, and the third binder can be tested using devices and methods known in the art. For example, the infrared spectrum of the material can be tested to determine the characteristic peaks it contains, thereby determining the substance type. Specifically, the organic particles can be subjected to infrared spectrum analysis using instruments and methods known in the art, such as an infrared spectrometer, for example, a Fourier transform infrared spectrometer of IS10 type from Nicolet, USA, according to GB / T 6040-2002 General Test Method for Infrared Spectrum Analysis.

[0144] In some embodiments, the mass content of the third binder in the coating layer is 3% to 15%. For example, the mass content of the third binder in the coating layer is 3%, 5%, 7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value within the above range. Setting the mass content of the third binder in the coating layer within the above range is advantageous to improve the binding force between the organic compound particles, reduce the cracking and falling of the coating layer in high-temperature cycles, thereby improving the storage performance and cycle performance of the battery cell. In addition, this also makes the binder appropriately fill the pores without affecting its ionic conductivity, thereby reducing the polarization.

[0145] In some embodiments, the organic compound particles Dn50 satisfies: 100 nm≤Dn50≤700 nm; wherein Dn50 refers to the particle size corresponding to the cumulative amount distribution of 50% in the particle size number distribution curve of the organic compound particles. For example, the organic compound particle Dn50 is 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 350 nm, 380 nm, 400 nm, 500 nm, 600 nm, 700 nm, or any value within the above range. For the organic compound particles, setting their Dn50 within the above range can reduce local defects. In this way, it is advantageous to reduce the penetration of the electrolyte in a high-temperature environment, reduce the occurrence of interface side reactions, reduce the storage gas production and impedance in the cycle. At the same time, this can also reduce the situation that the particles easily agglomerate and block the pores, promote the ionic conductivity, reduce the polarization in high-temperature cycles, and thereby alleviate the capacity decay.

[0146] After the battery monomer is discharged to 0% SOC at 0.33C, the battery monomer is disassembled to obtain a separator film, and the Dn50 of the organic compound particles is a meaning known in the art and can be tested by instruments and methods known in the art. For example, a scanning electron microscope (for example, ZEISS Sigma 300) is used to obtain a scanning electron microscope (SEM) picture of the separator film with reference to JY / T010-1996. As an example, the following method can be used for testing: an arbitrary test sample with a length x width = 50 mm x 100 mm is selected on the separator film, a plurality of test regions (for example, 5) are randomly selected in the test sample, and the particle size of the organic compound particles in each test region is obtained under a certain magnification (for example, 500x or 1000x when measuring the organic compound particles) by Image J software (i.e., the distance between the two farthest points on the organic compound particle is taken as the particle size of the organic compound particle), and the number and particle size values of the organic compound particles in each test region are counted, so as to obtain the particle size number distribution curve of the organic compound particles. The Dn50 result is obtained by software analysis. In the particle size number distribution curve of the organic compound particles, the Dn50 refers to the particle size of the organic compound particles corresponding to the cumulative particle size concentration reaching 50%.

[0147] In some embodiments, the organic compound particles include a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%. For example, the cross-linking degree of the cross-linked polymer is 70%, 75%, 78%, 80%, 83%, 85%, 87%, 89%, 90%, 92%, 94%, 96%, 97%, 98%, or any value within the above range.

[0148] The "cross-linked polymer" in the embodiments of the present application refers to a polymer material in which the molecular chains are cross-linked by chemical bonds to form a three-dimensional network structure. The structure is usually formed by cross-linking a plurality of reactive functional groups during polymerization or post-processing, so that the whole polymer forms a stable spatial structure. The cross-linking degree refers to the degree of cross-linking between the molecular chains of the cross-linked polymer by chemical bonds. The higher the cross-linking degree, the more cross-linking points between the molecular chains, and the more stable the structure of the polymer, thereby improving the stability of the separator film in a high temperature environment. The cross-linking degree in the embodiments of the present application refers to the proportion of the molecular chain segments bound by the cross-linked network in the total chain segments of the cross-linked polymer obtained by nuclear magnetic resonance (NMR) at a specific temperature and a specific test frequency; by testing the polymer by nuclear magnetic resonance, different components in the polymer backbone have different relaxation kinetics, for example, the monomer or solvent part has strong fluidity and decays the slowest; the non-cross-linked segment has certain molecular motion characteristics and decays relatively slowly; and the cross-linked segment is highly constrained and has small molecular motion characteristics and decays quickly; therefore, by collecting the entire polymer signal and calculating the proportion of the cross-linked signal, the cross-linking degree of the polymer backbone can be obtained.

[0149] In the embodiments of the present application, the crosslinking degree of the crosslinked polymer can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21 MHz, 0.5 g of the cleaned and dried sample (the organic compound particles described above) is taken, is loaded into a clean sample tube and is inserted into a probe to a specified depth, the probe coil diameter is 13 mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the crosslinking degree of the crosslinked polymer is obtained by collecting the entire polymer signal, calculating the proportion of the crosslinking signal by fitting software, and selecting the "crosslinking degree" or "T2 relaxation" test mode in the software, and the PQ001 nuclear magnetic resonance analyzer automatically obtains the relaxation decay curve. During data processing, the software decomposes the relaxation components by exponential fitting, calculates and outputs the crosslinking degree result according to the degree of restriction of molecular chain movement.

[0150] The crosslinking degree of the crosslinked polymer meets the above range, which is beneficial to make the organic compound particles have good structural stability at high temperature, so that the isolation film remains stable under high temperature conditions, thereby improving the cycle stability of the battery cell.

[0151] In some embodiments, the crosslinked polymer includes a silicone polymer containing a siloxane structure.

[0152] In the embodiments of the present application, the siloxane structure refers to a Si-O-Si bond skeleton formed by alternating connection of silicon atoms and oxygen atoms. The silicone polymer can refer to a high molecular polymer containing a silicon-oxygen bond (Si-O-Si) and / or a silicon-carbon bond (Si-C) in the main chain or side chain.

[0153] As an example, the chemical structure and type of the silicone polymer are well known in the art, and can be tested by using instruments and methods known in the art. Specifically, as an example, after the battery cell is disassembled, the isolation film is peeled off, and the isolation film in a regular and clear area is selected. Then, the isolation film is soaked in N,N-dimethylformamide, and after centrifugal separation, the supernatant is taken, and then the supernatant is coated on a potassium bromide wafer. After drying the potassium bromide wafer, the silicone polymer is obtained, or the silicone polymer powder is directly taken. The silicone polymer is placed into an infrared spectrum analyzer (for example, model: Thermo Nicolet iS5 Fourier infrared spectrometer) for analysis, and the test is performed according to GB / T6040-2002, and it is analyzed according to the measurement result that the silicone polymer contains a Si-O stretching vibration peak.

[0154] By using the organosilicon polymer containing siloxane structure as the crosslinked polymer, the storage performance and cycle performance of the battery cell in a high temperature environment can be improved. Specifically, the stable Si-O bond has a high bond energy and is not easy to decompose under high temperature adjustment, which can help to improve the stability of the material in a high temperature environment. In addition, compared with inorganic particles, the density of the organosilicon polymer is lower, and the overall mass of the coating can be reduced under the same thickness, which is beneficial to improve the energy density of the battery cell.

[0155] In some embodiments, the organosilicon polymer containing siloxane structure includes a phenyl group, the organosilicon polymer containing siloxane structure is polymerized from a monomer and a crosslinking agent represented by formula (I),

[0156]

[0157] wherein R1, R2 each independently includes C1-C4 alkyl, C2-C4 alkenyl, R3 includes C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, and R4 includes C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; the crosslinking agent includes divinylbenzene.

[0158] In the embodiments of the present application, R1 and R2 each independently includes at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, ethenyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, and 2-methyl-1-propenyl.

[0159] R3 includes at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, (meth)acryloyloxy methyl, 2-((meth)acryloyloxy) ethyl, 3-((meth)acryloyloxy) propyl, or 4-((meth)acryloyloxy) butyl.

[0160] In some embodiments, R3 is methyl or (meth)acryloxyalkyl, which is beneficial to the stability of the main chain of the crosslinked polymer when R3 is methyl, and R3 is acryloyloxypropyl, which can further participate in crosslinking to improve the crosslinking degree of the crosslinked polymer; R4 is alkenyl or acryloxyalkyl, which can realize efficient crosslinking through a free radical polymerization reaction, and further help to improve the crosslinking degree of the crosslinked polymer, thereby improving the high temperature stability of the crosslinked polymer.

[0161] R4 includes at least one of ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, (meth)acryloyloxymethyl, 2-((meth)acryloyloxy) ethyl, 3-((meth)acryloyloxy) propyl, or 4-((meth)acryloyloxy) butyl.

[0162] Acryloxyalkyl refers to an alkyl chain structure functional group containing an acryloxy end group, (Meth)acryloxyalkyl refers to a (meth)acryloxy group substituted with a hydrogen atom on a carbon atom directly connected to a carbonyl group (C=O), providing a reaction site through the acrylate double bond (C=C) at the end of the molecular chain, which can further undergo a free radical polymerization reaction with a crosslinking agent, which is conducive to improving the crosslinking degree of the silicone polymer.

[0163] In the embodiments of the present application, the crosslinking agent refers to a compound containing two or more functional groups capable of reacting with the functional groups on the polymer chain in the molecule, thereby forming covalent bridges between the polymer molecular chains and constructing a three-dimensional network structure. For example, the divinylbenzene in the embodiments of the present application can undergo crosslinking reaction with alkenyl or acryloyl groups to form covalent bonds between molecular chains with ethylene bridge and benzene ring as connecting points, forming a three-dimensional network structure of the phenyl-containing silicone polymer, thereby improving the structural stability of the phenyl-containing silicone polymer.

[0164] Through the polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene, the storage performance and cycle performance of the battery monomer under high temperature environment are improved. Specifically, under high temperature environment, the particle has a three-dimensional network skeleton formed by the phenyl structure and the monomer and the crosslinking agent, and the rigid silicon-oxygen skeleton can maintain structural integrity. This is conducive to improving the mechanical properties of the coating, thereby improving the storage performance and cycle performance of the battery monomer under high temperature environment.

[0165] In some embodiments, the method for preparing the phenyl-containing silicone polymer comprises the following steps: providing a pre-emulsion containing monomers, crosslinking agents, emulsifiers, initiators, and water, and performing emulsion polymerization under the conditions of heating, inert gas protection, and stirring to obtain silicone resin particles. The monomers include silane coupling agents containing alkenyl and / or acryloxy groups, and the mass fraction of the crosslinking agent is 2%-30% based on the total mass of the monomers and the crosslinking agent.

[0166] The monomers include silane coupling agents containing alkenyl and / or acryloxy groups, so free radicals are generated between the monomers, crosslinking reactions occur, and the monomers also undergo crosslinking reactions with the crosslinking agent. Therefore, the phenyl-containing silicone polymer with a three-dimensional network structure can be formed using the monomers and the crosslinking agent of the present disclosure, which is not easy to soften or deform at high temperatures and has high heat resistance and electrochemical stability.

[0167] The crosslinking agent can have a mass fraction of 2-30%, for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, or a range defined by any of the foregoing values, based on the total mass of the monomer and the crosslinking agent being 100%.

[0168] The crosslinking agent can have a mass fraction in the above range, and the silicon-containing organic resin particles can have high electrochemical stability and good heat resistance.

[0169] Alternatively, the crosslinking agent can have a mass fraction of 8-14%, 8-13%, 8-12%, 9-14%, 9-13%, 9-12%.

[0170] In some embodiments, the monomer can include an acryloyloxy silane coupling agent.

[0171] Alternatively, the monomer of formula (I) can include one or more of γ-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloyloxypropyltriethoxysilane, γ-methacryloxypropyl triisopropoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-methacryloxypropyl tri(methoxyethoxy)silane, 3-methacryloxypropyl methyl dimethoxysilane, 3-acryloxypropyl methyl dimethoxysilane, methacryloxypropyl dimethyl methoxysilane, (3-acryloyloxy)dimethyl methoxysilane, 3-methacryloxypropyl dimethylethoxysilane, 3-(methacryloxy)propyl methyl diethoxysilane.

[0172] In some embodiments, the monomer of formula (I) can include a first monomer and a second monomer.

[0173] The first monomer can include one or more of γ-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloyloxypropyltriethoxysilane, γ-methacryloxypropyl triisopropoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3-methacryloxypropyl tri(methoxyethoxy)silane.

[0174] The second monomer can include one or more of 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0175] The first monomer and the second monomer are different in activity, and by combining the two and reacting with the crosslinking agent, a siloxane structure-containing silicone polymer can be obtained.

[0176] In some embodiments, the emulsifier can include, but is not limited to, one or more of alkyl sulfate, alkyl sulfonate, Tween emulsifier, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, cetyl stearyl alcohol polyether, oleyl ether. Alternatively, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, Tween 20, Tween 40, laureth-7, laureth-9, laureth-10, oleyl ether-10.

[0177] In some embodiments of the present application, the amount of emulsifier added can be 0.1 g to 3.0 g. For example, the amount of emulsifier added can be 0.2 g, 0.4 g, 0.6 g, 0.8 g, 1.0 g, 1.2 g, 1.4 g, 1.6 g, 1.8 g, 2.0 g, 2.2 g, 2.4 g, 2.6 g, 2.8 g, 3.0 g, or any value within the above range. The amount of emulsifier determines the number of micelles in the pre-emulsion, and micelles are the main nucleation site for polymer particles. The more micelles, the smaller the particle size of the siloxane structure-containing silicone polymer obtained, and the more the number of particles. The less micelles, the larger the particle size of the siloxane structure-containing silicone polymer obtained, and the less the number of particles. Therefore, by adjusting the amount of emulsifier added, a siloxane structure-containing silicone polymer with a Dn50 of 100 nm to 700 nm can be obtained.

[0178] In some embodiments, the initiator can include, but is not limited to, one or more of sodium persulfate, potassium persulfate, ammonium persulfate, sodium sulfite, sodium bisulfite, azobisisobutyronitrile, azobisisobutyramidine hydrochloride, azobisisobutylimidazole hydrochloride, azobisisopropylimidazole.

[0179] In some embodiments, the heating temperature of the maturation stage of the emulsion polymerization reaction can be 75°C to 95°C, for example, it can be 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 88°C, 90°C, 93°C, 95°C, or a range consisting of any of the above values.

[0180] In some embodiments, the heating time of the maturation stage of the emulsion polymerization reaction can be 1 h-4 h, for example, can be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, or a range consisting of any of the above values.

[0181] In some embodiments, the emulsion polymerization reaction can comprise the following steps: under the conditions of a first heating temperature, inert gas protection and stirring, the pre-emulsion is added dropwise into a reactor containing water, after a reaction time, the temperature is raised to the heating temperature of the maturation stage to carry out the maturation reaction, and the silicon-containing organic resin particles are obtained.

[0182] Optionally, the first heating temperature can be 55℃-95℃.

[0183] Optionally, the first time can be 3h-8h.

[0184] In some embodiments, the pre-emulsion can further comprise a PH adjuster. Optionally, the PH adjuster can include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia, etc. By adding the PH adjuster, the PH value of the pre-emulsion can be adjusted.

[0185] In some embodiments, the method for preparing the silicon-oxygen structure-containing organic silicon polymer further comprises the step of magnetic removal after the emulsion polymerization reaction is completed.

[0186] In some embodiments, the silicon-oxygen structure-containing organic silicon polymer satisfies one or more of the following conditions: (1) the crosslinking degree of the silicon-oxygen structure-containing organic silicon polymer is 75%-95%; (2) the mass content of silicon element in the silicon-oxygen structure-containing organic silicon polymer is 10%-25%; (3) the mass content of phenyl in the silicon-oxygen structure-containing organic silicon polymer is 2%-12%.

[0187] For example, the crosslinking degree of the silicon-oxygen structure-containing organic silicon polymer is 75%, 77%, 79%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 95%, or any value within the above range; the mass content of silicon element in the silicon-oxygen structure-containing organic silicon polymer is 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25%, or any value within the above range; the mass content of phenyl in the silicon-oxygen structure-containing organic silicon polymer is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 7%, 9%, 10%, 11%, 12%, or any value within the above range.

[0188] In the embodiments of the present application, the crosslinking degree of the organosilicon polymer containing siloxane structure can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21 MHz, 0.5 g of the cleaned and dried sample (the above-mentioned organosilicon compound particles) to be tested is taken, is loaded into a clean sample tube and is inserted into a probe at a specified depth, the probe coil diameter is 13 mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the crosslinking degree of the crosslinked polymer is obtained by calculating the proportion of the crosslinking signal from the fitting software by collecting the entire polymer signal; the "crosslinking degree" or "T2 relaxation" test mode is selected in the software, and the PQ001 nuclear magnetic resonance analyzer automatically obtains the relaxation decay curve. During data processing, the software decomposes the relaxation components by exponential fitting, and calculates and outputs the crosslinking degree result according to the degree of restriction of molecular chain movement.

[0189] In the above embodiments, the crosslinking degree of the organosilicon polymer containing siloxane structure is set within the above range, which is beneficial to promote the chain segment movement. This can reduce the case that the coating is prone to micro-cracks, thereby improving the cycle performance; at the same time, this can also promote ion transmission and alleviate the polarization phenomenon at high temperature. In addition, this is also beneficial to maintain the mechanical strength of the coating, thereby promoting the cycle performance of the battery cell.

[0190] As an example, the mass content of silicon element in the organosilicon polymer is the meaning known in the art, which can be tested by using the instruments and methods known in the art. Specifically, as an example, in the embodiments of the present application, a powder sample (usually a few milligrams) of the organosilicon polymer containing siloxane structure is taken, is cleaned with anhydrous ethanol or deionized water for 1-2 minutes to remove surface impurities; then is placed in an oven and dried at 60-80°C for 1-2 hours to completely remove water (to avoid the influence of sample volatilization on the vacuum environment during testing). The dried powder is evenly spread on conductive glue (to ensure that the powder does not accumulate and does not fall off); then a layer of 5-10 nm thick gold is sprayed on the surface thereof by using an ion sputtering instrument; or after the battery cell is disassembled, the separator film is peeled off, and a regular and clear area of the separator film is selected. Then, the separator film sample is fixed on a sample stage and is subjected to gold spraying or carbon spraying treatment to make the surface conductive; the sample stage containing the sample to be tested is placed in the SEM sample chamber, the cabin door is closed, the vacuum system is started, and the instrument is pumped to the required high vacuum state (usually 10 -3 -10 -5Pa). After the vacuum is up to the standard, the electron gun voltage (usually 5-20 kV) and working distance (usually 5-15 mm) are adjusted, the sample stage is moved by the control software, and the target observation area is found. The focus and magnification (from low magnification 100x positioning to high magnification for observing details) are gradually adjusted to obtain clear SEM morphology images, and the feature points or areas that need to be analyzed by EDS are marked. In the SEM software, the EDS detector is started, the marked analysis area (single-point analysis, line scanning or area scanning can be selected) is selected, and the collection time (usually 10-30 seconds, the longer the time, the more accurate the element signal) is set. The energy-dispersive x-ray spectroscopy (EDS) provided with the ZEISS sigma300 is used to analyze the elements on the surface of the silicone polymer containing siloxane structure to detect the content of silicon elements in the silicone polymer containing siloxane structure. According to the data results of the instrument, the distribution of each element can be obtained, and thus the mass percentage of silicon elements can be obtained.

[0191] Setting the mass content of silicon elements in the silicone polymer containing siloxane structure within the above range helps to improve the proportion of inorganic siloxane skeleton in the silicone polymer. In this way, the siloxane skeleton including silicon elements provides higher thermal decomposition temperature and oxidation resistance, so that the separator film has structural stability in a high-temperature environment.

[0192] As an example, the mass content of phenyl groups in the silicone polymer has a meaning known in the art, which can be tested by using instruments and methods known in the art. As an example, after the battery monomer is disassembled, the separator film is peeled off. Then, the organic compound particle powder of the coating in the separator film is scraped off as a sample to be tested, dried to remove adsorbed water, and then placed in a desiccator for cooling standby. Specifically, a pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) can be used to test the mass content of phenyl groups in the silicone polymer. Specifically, 0.5-1 mg of the above silicone polymer is weighed as a test sample, loaded into a quartz cracking tube of a pyrolysis instrument, cracked at 550°C for 1.2 s, and tested in an inert gas (such as helium) to crack the sample into volatile small molecules, which are then introduced into a gas chromatograph-mass spectrometer. The HP-5ms (30m x 0.25mm x 0.25μm) chromatographic column is selected, the temperature is set to 30°C for 5 min, the temperature is increased at 10°C / min to 250°C, and the temperature is maintained at 250°C for 5 min. The carrier gas is high-purity helium with a flow rate of 1.0 mL / min. The mass spectrometry uses electrochemical ionization, the ion source temperature is 230°C, and the fragment scan range is m / z 25-200. By comparing with the EVA standard cracking spectrum in the NIST library, the characteristic ions corresponding to the phenyl groups are detected, and it can be inferred that the silicone polymer includes phenyl structures. The internal standard method is used to calculate the mass content of the phenyl groups in the silicone polymer based on the above fragment peak area corresponding to the characteristic phenyl groups.

[0193] Since the phenyl-containing organosilicon polymer contains Si-O bonds, the bond energy is high. By setting the mass content of phenyl in the organosilicon polymer containing a siloxane structure in the above range, it is not easy to decompose at high temperature, which is beneficial to further improve the stability of the battery cell at high temperature.

[0194] Therefore, by limiting the crosslinking degree, the mass content of silicon elements and the mass content of phenyl as described above, it is beneficial to improve the storage performance and cycle performance of the battery cell in a high temperature environment.

[0195] In some embodiments, the organosilicon polymer containing a siloxane structure includes a skeleton composed of a compound shown in formula (II),

[0196] R a [SiO 3 / 2 ] n formula (II),

[0197] wherein n is at least one of integers 4 to 12, R a including cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; optionally, n is 8, R a includes C1-C3 alkyl.

[0198] In the embodiments of the present application, n can be 4, 5, 6, 7, 8, 9, 10, 11, 12, or any value within the range obtained by combining two numerical values from 4 to 12.

[0199] R a may include one or more of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, phenyl, naphthyl, anthryl, phenanthryl, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, ethenyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butenyl, and pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, ethynyl, 1-propynyl, 2-propynyl (propargyl), 1-butynyl, 3-butynyl, 1-pentynyl, 3-pentynyl, and hexynyl, heptynyl, octynyl, nonynyl, decynyl, undecynyl, dodecynyl.

[0200] Optionally, n is 8, R a includes at least one of methyl, ethyl, n-propyl, isopropyl.

[0201] By introducing the structural unit shown in formula (II) into the silicone polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. The structure forms a uniform and stable rigid support frame through strong covalent bonds, thereby improving the storage and cycle performance of the battery under high temperature environment. Specifically, it can maintain structural integrity under high temperature conditions, effectively reduce coating shrinkage, thereby maintaining the stability of the three-dimensional polyhedral skeleton. By selecting the R1 substituent group as C1-C3 alkyl, the thermal stability and chemical inertness of the polymer can be further enhanced, thereby improving the storage performance and cycle performance of the battery cell under high temperature environment.

[0202] In some embodiments, the silicone polymer containing siloxane structure comprises one or more of the monomers shown in formula (III) obtained by hydrolysis and polycondensation,

[0203]

[0204] wherein R'1 includes C1-C3 alkyl. For example, R'1 is methyl, ethyl or propyl.

[0205] In the embodiments of the present application, the silicone polymer containing siloxane structure is prepared by hydrolyzing the monomer shown in formula (III), then adding a catalyst, and performing polycondensation under heating conditions to obtain the silicone polymer containing siloxane structure.

[0206] Thus, the silicone polymer containing siloxane structure is obtained by hydrolysis and polycondensation reaction.

[0207] In some embodiments of the present application, the temperature for hydrolysis of the monomer shown in formula (III) is 10-40°C, for example, the temperature for hydrolysis can be 20-29°C, 21-28°C, 22-27°C, 23-26°C, 24-25°C, etc.

[0208] In some embodiments of the present application, the temperature for heating is 30-100°C, for example, the temperature for heating can be 30-99°C, 35-95°C, 40-90°C, 45-85°C, 50-80°C, 55-75°C, 60-70°C, etc.

[0209] In some embodiments of the present application, the heating time is 2-48h, for example, the heating time can be 2h, 3h, 8h, 10h, 15h, 20h, 24h, 36h, 48h, etc.

[0210] Specifically, the monomer of formula (III) is first hydrolyzed to generate silanol, while releasing alcohol to form a mixed solution, and the alcohol increases the solubility of the organosiloxane monomer in the solution; then, under the action of a catalyst, the silanol begins to condense, and Si-O-Si bonds are formed between silanols, further forming a network structure, and nucleation begins. Finally, these nuclei continuously absorb silanol from the solution and continue to grow until the organosilicon polymer containing a cage-like polysilsesquioxane skeleton is formed. The nucleation process and the nucleus growth process are competitive, and the reaction temperature affects the two processes. When the nucleation process dominates, more nuclei are generated, and the particle size of the final organosilicon polymer is smaller; when the nucleus growth dominates, the particle size of the final microspheres is larger. The increase in temperature accelerates the reaction, so that more nuclei are generated in the initial stage of the reaction, more silanol is consumed, and the growth of the nucleus in the later stage is limited, so that the particle size of the final organosilicon polymer is smaller. Controlling the heating temperature in the range of 30-100°C can promote the uniform particle size of the organosilicon polymer and improve the cycle performance of the secondary battery.

[0211] In some embodiments, the organic compound particles and the first binder particles are mixed in a certain mass ratio, stirred and mixed uniformly in deionized water to obtain a separator slurry. Then, the slurry is uniformly coated on both surfaces of the substrate, and the solvent is removed by drying to obtain a coating. Through the above preparation method, the first binder particles can be effectively embedded between the spherical organic compound particles to form uniformly distributed microconvexities on the surface of the coating, which is beneficial to improve the storage performance and cycle performance of the battery monomer in a high temperature environment.

[0212] In some embodiments of the present application, the catalyst includes at least one of ammonia water, triethylamine, sodium hydroxide, magnesium hydroxide, or ammonium hydroxide.

[0213] By adopting the hydrolysis-polycondensation reaction of the monomer of formula (III), an organosilicon polymer with a cage structure can be obtained. The polymer forms a uniformly distributed and stable three-dimensional network in the coating, which can effectively reduce the shrinkage of the coating under high temperature conditions, thereby improving the integrity and stability of the coating, which is beneficial to improve the storage performance and cycle performance of the battery monomer in a high temperature environment. At the same time, the three-dimensional polyhedral skeleton structure formed by polymerization can also improve the high temperature wettability and retention capacity of the electrolyte, promote the uniform distribution of ions at the electrode interface, and reduce local lithium deposition and aggravation of side reactions. Therefore, the above-mentioned organosilicon polymer can improve the storage performance and cycle performance of the battery monomer in a high temperature environment.

[0214] Optionally, R'1 is methyl. In this way, it is beneficial to further improve the storage performance and cycle performance of the battery monomer in a high temperature environment.

[0215] In some embodiments, the siloxane structure-containing organosilicon polymer satisfies one or more of the following conditions: (1) the crosslinking degree of the siloxane structure-containing organosilicon polymer is 85% to 97%; (2) the mass content of silicon elements in the siloxane structure-containing organosilicon polymer is 25% to 45%; and (3) the mass content of the skeleton composed of the compound represented by formula (II) in the siloxane structure-containing organosilicon polymer is 40% to 60%.

[0216] For example, the crosslinking degree of the siloxane structure-containing organosilicon polymer is 85%, 87%, 89%, 90%, 91%, 93%, 95%, 96%, 97% or any value within the above range; the mass content of silicon elements in the siloxane structure-containing organosilicon polymer is 25%, 27%, 29%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 45% or any value within the above range; and the mass content of phenyl groups in the siloxane structure-containing organosilicon polymer is 40%, 41%, 43%, 45%, 48%, 50%, 53%, 56%, 58%, 60% or any value within the above range.

[0217] In the embodiments of the present application, the crosslinking degree of the siloxane structure-containing organosilicon polymer can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21 MHz, 0.5 g of the cleaned and dried sample (the above-mentioned organosilicon compound particles) to be tested is taken, is loaded into a clean sample tube and is inserted into a probe to a specified depth, the probe coil diameter is 13 mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the crosslinking degree of the crosslinked polymer is obtained by collecting the entire polymer signal, calculating the proportion of the crosslinked signal by fitting software, and selecting the "crosslinking degree" or "T2 relaxation" test mode in the software, and the PQ001 nuclear magnetic resonance analyzer automatically obtains the relaxation decay curve. During data processing, the software decomposes the relaxation components by exponential fitting, calculates and outputs the crosslinking degree result according to the degree of restriction of molecular chain movement.

[0218] By controlling the crosslinking degree of the organosilicon polymer within the above range, the structural stability of the organosilicon polymer in a high-temperature environment can be enhanced, and the softening and deformation of the coating can be effectively reduced, thereby providing mechanical support for the battery cell.

[0219] As an example, in the embodiments of the present application, a powder sample (usually a few milligrams) of an organosilicon polymer containing a siloxane structure is ultrasonically cleaned with anhydrous ethanol or deionized water for 1-2 minutes to remove surface impurities; then it is placed in an oven and dried at 60-80°C for 1-2 hours to completely remove moisture (to avoid sample volatilization affecting the vacuum environment during testing). The dried powder is evenly spread on conductive glue (ensuring that the powder does not accumulate or scatter); then a layer of 5-10 nm thick gold is sprayed on its surface using an ion sputtering instrument; or after disassembling the battery monomer, the separator film is peeled off, and a regular and clear area of the separator film is selected. Then, the separator film sample is fixed on the sample stage and subjected to gold spraying or carbon spraying treatment to make its surface conductive; the sample stage containing the sample to be tested is placed in the SEM sample chamber, and after closing the hatch, the vacuum system is started to achieve the required high vacuum state (usually 10 -3 -10 -5 Pa) of the instrument. After the vacuum is met, the electron gun voltage (usually 5-20 kV) and working distance (usually 5-15 mm) are adjusted, the sample stage is moved by the control software to find the target observation area. The focus and magnification (from low magnification 100 times positioning to high magnification for observing details) are gradually adjusted to obtain clear SEM morphology images, and the characteristic points or areas that need to be analyzed by EDS are marked. In the SEM software, the EDS detector is started, the marked analysis area (single-point analysis, line scanning or area scanning can be performed) is selected, and the collection time (usually 10-30 seconds, the longer the time, the more accurate the element signal) is set. Using the Energy-Dispersive X-ray Spectroscopy (EDS) provided with the ZEISS sigma300, the surface of the organosilicon polymer containing a siloxane structure is analyzed to detect the content of silicon elements in the organosilicon polymer containing a siloxane structure. According to the data results of the instrument, the distribution of each element can be obtained, and thus the mass percentage of silicon elements can be obtained.

[0220] The above-mentioned range of silicon element mass content can maintain the material with high thermal stability, thereby improving the storage performance and cycle performance of the battery monomer in a high temperature environment.

[0221] As an example, the mass content of the skeleton of the compound represented by formula (II) in the organosilicon polymer can be tested using instruments and methods known in the art. As an example, after the battery cell is disassembled, the separator film is peeled off. Then, the organic compound particle powder of the coating in the separator film is scraped off as a sample to be tested, dried to remove adsorbed water, and then placed in a desiccator to cool for standby. Specifically, a pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) instrument can be used to test the mass content of the phenyl group in the organosilicon polymer. Specifically, 0.5-1 mg of the organosilicon polymer described above is weighed as a test sample, loaded into a quartz cracking tube of a pyrolysis instrument, cracked at 550°C for 1.2 s, and tested in an inert gas (such as helium) to crack the sample into volatile small molecules, which are then introduced into a gas chromatograph-mass spectrometer. The chromatographic column is selected to be HP-5ms (30 m x 0.25 mm x 0.25 μm), the temperature is set to 30°C for 5 min, the temperature is increased at 10°C / min to 250°C, and the temperature is maintained at 250°C for 5 min. The carrier gas is high-purity helium with a flow rate of 1.0 mL / min. The mass spectrometer uses electrochemical ionization, the ion source temperature is 230°C, and the fragment scan range is m / z 25-200. By comparing with the EVA standard cracking spectrum in the NIST library, the characteristic ions corresponding to the skeleton of the compound represented by formula (II) are detected, and it can be inferred that the organosilicon polymer includes the skeleton of the compound represented by formula (II). The internal standard method is used to calculate the mass content of the skeleton of the compound represented by formula (II) in the organosilicon polymer based on the area of the above-mentioned fragment peak corresponding to the skeleton of the compound represented by formula (II).

[0222] The organosilicon polymer containing the skeleton of the compound represented by formula (II) has a cage skeleton bond and a three-dimensional structure, and the spatial structure is stable. The mass content of the skeleton of the compound represented by formula (II) in the organosilicon polymer containing the siloxane structure is limited within the above-mentioned range, which can prevent the decomposition of the organosilicon polymer at high temperatures, and is beneficial to further improve the stability of the battery cell at high temperatures.

[0223] Therefore, by limiting the crosslinking degree, the mass fraction of silicon elements, and the mass content of the phenyl group, the storage performance and the cycle performance of the battery cell under high temperature conditions can be improved.

[0224] In some embodiments, the organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammetry curve of the organic compound particles in the first cycle does not have an oxidation peak in the voltage range of 0 to 4.4 V; (2) the organic compound particles do not have a glass transition temperature at 300°C; (3) the initial thermal weight loss temperature T 3d satisfies: T 3d≥ 250℃; (4) the dissolution rate of the organic compound particles in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 is less than or equal to 5% after immersion at 60℃ for 7 days; (5) the true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 .

[0225] For example, the glass transition temperature Tg of the organic compound particles is 200℃, 220℃, 240℃, 280℃, 300℃, 350℃, 400℃, 500℃, or any value within the above range; the initial thermal weight loss temperature T 3d of the organic compound particles is 320℃, 350℃, 370℃, 400℃, 500℃, or any value within the above range; the dissolution rate of the organic compound particles in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 is less than or equal to 5% after immersion at 60℃ for 7 days, and is 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 4.5%, 5%, or any value within the above range; the true density of the organic compound particles is 0.8 g / cm 3 , 1.0 g / cm 3 , 1.2 g / cm 3 , 1.4 g / cm 3 , 1.6 g / cm 3 , 1.8 g / cm 3 , 1.9 g / cm 3 , 2.0 g / cm 3 , or any value within the above range.

[0226] As an example, the oxidation peak potential of the cyclic voltammetry curve of the organic compound particles can be tested as follows: the organic compound particles, the binder polyacrylate, and the conductive agent conductive carbon black are dissolved in water in a solid content mass ratio of 64:7:29 to prepare a slurry, the slurry is coated on an aluminum foil as a positive electrode, a lithium foil is used as a negative electrode, and a button cell is assembled; the button cell is subjected to cyclic voltammetry (CV) test, the scanning rate is 0.10 mV / s, the voltage range is 2.50V-5.00V, and the cycle is 3 cycles, and the voltage corresponding to the peak point of the first cycle cyclic voltammetry curve is taken as the oxidation peak potential. The electrolyte salt of the electrolyte used for testing is LiPF6, and the concentration is 1 mol / L. The solvent of the electrolyte is obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0227] The cyclic voltammogram of the organic compound particle in the first cycle in the embodiment of the present application has no oxidation peak in the voltage range of 0V to 4.40V, indicating that the organic compound particle is stable in the voltage range of 0V to 4.40V and has good electrochemical stability. The electrochemical stability of the conventional organic particles is generally poor and is prone to decomposition under high voltage. Therefore, the organic compound particle in the embodiment of the present application can be applied to a high-voltage battery cell, so that the battery cell has good capacity performance under high voltage, and the working voltage and energy density of the battery cell are improved.

[0228] The glass transition temperature Tg refers to the transition temperature of a material from a glass state to a high-elasticity state, which shows a step change on a DSC curve.

[0229] As an example, the glass transition temperature T g The test can be performed as follows: take an appropriate amount of sample (for example, 5mg-15mg) and place it in a differential scanning calorimeter (DSC) crucible, shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60mL / min, protective gas 20mL / min; program settings: temperature increase from 25℃ to 200℃ at a rate of 10℃ / min, hold for 5min to eliminate thermal history, temperature decrease from 200℃ to -40℃ at a rate of 10℃ / min, and temperature increase from -40℃ to 300℃ at a rate of 10℃ / min. The glass transition temperature T g .

[0230] The glass transition temperature of the organic compound particle is greater than or equal to 200℃, which means that the DSC curve of the organic compound particle remains in a solid state below 200℃ and does not undergo molecular chain segment movement or softening, thereby improving the thermal stability of the isolation film. In this way, the isolation film can maintain its structural integrity and mechanical properties at high temperatures, thereby facilitating the improvement of the storage performance and cycle performance of the battery cell in a high-temperature environment.

[0231] The initial thermal weight loss temperature T 3d of the organic compound particle is greater than or equal to 250℃, indicating that the weight of the organic compound particle does not change significantly at high temperatures, and thus the organic compound particle has high heat resistance and thermal stability and is not prone to thermal decomposition during the use of the battery cell.

[0232] As an example, the initial thermal weight loss temperature T 3d of the organic compound particle refers to the temperature corresponding to a 3% loss in the mass of the sample tested by thermogravimetric analysis relative to the initial mass. The initial thermal weight loss temperature T 3dThe test can be performed as follows: take an appropriate amount of sample (for example, 5 mg-15 mg) and place it in an alumina crucible of a thermal gravimetric analyzer (TGA), shake it flat, and cover it with a crucible cover; parameter settings: nitrogen atmosphere, purge gas 60 mL / min, protective gas 20 mL / min; temperature rising program: temperature rising rate 10 ℃ / min, temperature range 35 ℃-600 ℃; obtain the temperature corresponding to a 3% loss in sample mass relative to the initial mass (i.e., 97% of the initial mass) from the test curve, which is the initial thermal weight loss temperature T 3d .

[0233] The organic compound particles are used in the separator film, and the organic compound particles can better generate a force resisting shrinkage of the separator film. In this way, the separator film can maintain a stable pore structure at high temperatures, thereby reducing the phenomenon of short circuiting of the electrodes. At the same time, this can also reduce the oxidative decomposition of the electrolyte, thereby improving the high-temperature storage performance and cycle life.

[0234] The dissolution rate can refer to the proportion of the particles dissolved or decomposed in the electrolyte.

[0235] As an example, the swelling degree of the organic compound particles in the embodiments of the present application can be tested as follows: take an appropriate amount of sample (for example, about 1 g), and record the mass as m1, and place it in a semi-permeable membrane sample bag, seal it, and the sample bag can permeate the solvent but cannot permeate the sample; immerse the sample bag in an appropriate amount of solvent (for example, about 50 g) and immerse it at 60 ℃ for 7 days, then take out the sample bag, take out the sample from the sample bag, wipe off the excess solvent, and weigh the mass of the sample again m2; swelling degree = (m2-m1) / m1x100%. The solvent is a mixed solvent obtained by mixing ethylene carbonate (EC) and methyl ethyl carbonate (EMC) in a volume ratio of 3:7.

[0236] The organic compound particles have a dissolution of less than 5% after being immersed in the electrolyte at 60 ℃ for 7 days, and are not easy to precipitate or dissolve in the electrolyte environment, reducing the occurrence of electrolyte contamination or side reactions between the organic compound particles and the electrolyte during the cycle process of the battery cell, and the separator film has good structural stability, which is beneficial to the cycle performance and reliability of the battery cell. The true density refers to the mass per unit actual volume (excluding internal voids, i.e., not including open pores and closed pores and inter-particle voids) of the material in an absolutely dense state.

[0237] As an example, the true density can be tested by the following method. As an example, take the organic compound particles with a mass of M, place the carbon base in a true density tester (AccuPyc II 1340 analyzer) at room temperature (15-25°C), close the test system, and introduce helium gas according to the program. By detecting the gas pressure in the sample chamber and the expansion chamber, and then calculating the gas volume in the sample chamber and the expansion chamber according to the ideal gas state equation respectively, the gas volume displaced by the carbon base under certain temperature and pressure conditions is obtained, that is, the true volume V of the organic compound particles. The true density of the organic compound particles is the mass M of the organic compound particles / the true volume V of the organic compound particles, and the unit of the true density is g / cm3. 3 .

[0238] The true density refers to the mass per unit actual volume (excluding internal voids, i.e., not including open pores and closed pores and inter-particle voids) of a material in an absolutely dense state.

[0239] As an example, the true density can be tested by the following method. As an example, take the organic compound particles with a mass of M, place the carbon base in a true density tester (AccuPyc II 1340 analyzer) at room temperature (15-25°C), close the test system, and introduce helium gas according to the program. By detecting the gas pressure in the sample chamber and the expansion chamber, and then calculating the gas volume in the sample chamber and the expansion chamber according to the ideal gas state equation respectively, the gas volume displaced by the carbon base under certain temperature and pressure conditions is obtained, that is, the true volume V of the organic compound particles. The true density of the organic compound particles is the mass M of the organic compound particles / the true volume V of the organic compound particles, and the unit of the true density is g / cm3. 3 .

[0240] Compared with inorganic particles with a larger density, such as boehmite and alumina, the true density of the organic compound particles is smaller, and the energy density of the battery cell can be improved without increasing the thickness of the coating.

[0241] Therefore, by limiting the oxidation peak of the cyclic voltammetry curve of the organic compound particles after one cycle, the glass transition temperature, the initial thermal weight loss temperature, the elution rate after constant temperature immersion at 60°C for 7 days, and the true density, the overall performance of the battery cell can be improved.

[0242] In some embodiments, the coating does not include inorganic particles.

[0243] In some embodiments, the coating includes inorganic particles, and the mass fraction of the inorganic particles is 0.1%-50% based on the total mass of the coating.

[0244] In other embodiments, the coating includes inorganic particles, and the mass fraction of the inorganic particles is 50%-92% based on the total mass of the coating.

[0245] In one example, the inorganic particles include at least one of SrTi03, Sn02, Ce02, MgO, NiO, CaO, ZnO, Zr02, Y203, AI203, boehmite (AIO(OH)), AI(OH)3, Ti02, SiC, which have a large dielectric constant and are advantageous for improving ion transport efficiency in the coating.

[0246] In some embodiments, the separation film satisfies one or more of the following conditions: (1) the thickness of the coating is 0.5 μm to 10 μm; (2) the areal density of the coating is 1.5 g / m 2 ~ 6 g / m 2 ; (3) the longitudinal thermal shrinkage of the separation film is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage of the separation film is less than or equal to 5% when heated at 130°C for 1 h; and (5) the air permeability of the separation film is 150 s / 100 mL to 500 s / 100 mL.

[0247] For example, the thickness of the coating can be 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value within the above ranges; the areal density of the coating can be 1.5 g / m 2 , 1.8 g / m 2 , 2 g / m 2 , 2.2 g / m 2 , 2.4 g / m 2 , 2.6 g / m 2 , 2.8 g / m 2 , 3 g / m 2 , 3.2 g / m 2 , 3.5 g / m 2 , 3.8 g / m 2 , 4 g / m 2 , 4.5 g / m 2 , 5 g / m 2 , 5.3 g / m 2 , 5.7 g / m 2 , 6 g / m 2or any value within the above range; the longitudinal heat shrinkage of the separator film after constant temperature heating at 130℃ for 1h can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range; the transverse heat shrinkage of the separator film after constant temperature heating at 130℃ for 1h can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range; the air permeability of the separator film can be 150s / 100mL, 200s / 100mL, 250s / 100mL, 300s / 100mL, 350s / 100mL, 400s / 100mL, 450s / 100mL, 500s / 100mL or any value within the above range.

[0248] The thickness of the coating refers to the thickness of the coating on one side of the porous base film. Setting the thickness of the coating in the above range can form a uniform and dense thermal insulation layer, thereby balancing the energy density and cycle performance of the battery cell.

[0249] As an example, the areal density of the coating can be tested by the following method: first, stack the single separator film containing the coating in the embodiments of the present application and the single separator film substrate without the coating independently to 6 layers, and apply pressure to make each layer tightly adhere and without bubbles. Then, cut the two groups of stacks according to the cutting template, respectively, to obtain 6 samples. Then measure the total mass M1 of the 6 samples of the coated group and the total mass M2 of the 6 samples of the uncoated substrate group, and calculate the average mass of the coating on the single separator film by the formula M=(M1-M2) / 6. Then, measure the area S of a single sample, and the areal density of the coating can be obtained according to the formula "coating areal density=M / S".

[0250] Setting the areal density of the coating in the above range is beneficial to balancing the stability and high pressure resistance of the separator film, while not increasing the weight of the separator film, thereby being beneficial to the energy density and reliability of the battery cell.

[0251] Heat shrinkage refers to the percentage of size change of the separator film at high temperature, which is an important indicator for measuring the thermal stability of the separator film.

[0252] As an example, the release film is punched into a sample with a width of 50 mm and a length of 100 mm by a punch press, 5 parallel samples are placed on an A4 paper, and then the A4 paper with the samples is placed on the corrugated paper with a thickness of 1 mm to 5 mm. The temperature of the air oven is set to 130°C, and after the temperature reaches the set temperature and stabilizes for 60 min, the A4 paper placed on the corrugated paper is placed in the air oven, and the timing starts. After reaching the set time (1 h in the present disclosure), the length and width of the release film are measured, and the values are marked as a and b, respectively. The longitudinal (MD) heat shrinkage rate = [(100-a) / 100] x 100%, and the transverse (TD) heat shrinkage rate = [(50-b) / 50] x 100%. The average value of 3 parallel samples is taken as the test result.

[0253] The release film is heated at 130°C for 1 h, and the longitudinal and transverse heat shrinkage rates meet the above range, which is beneficial to maintaining the stability of the release film in a high temperature environment and improving its mechanical integrity. In this way, the short circuit caused by the exposure of the pole piece can be reduced, thereby reducing the probability of thermal runaway and improving the cycle performance of the battery cell.

[0254] The air permeability (Gurley value) of the release film refers to the time required for 100 mL of air to pass through the release film, which characterizes the resistance of the pore structure of the release film to gas / liquid transmission.

[0255] As an example, the air permeability value of the release film can be tested according to GB / T 36363-2018. Specifically, the release film is cut into a square of 5 cm in size, and a gas permeameter is used to test the time required for 100 ml of air to pass through 6.45 cm 2 of the release film under a pressure of 1.21 kPa, as the air permeability value of the release film, in s / 100 ml. The average value of 3 parallel samples is taken as the test result.

[0256] By setting the air permeability of the release film within the above range, it is beneficial to promote the uniform wetting of the electrolyte and maintain the rapid transmission of ions, and to reduce the electrochemical polarization caused by too low air permeability of the release film, thereby reducing the cycle performance of the battery cell.

[0257] Therefore, by limiting the thickness, areal density, longitudinal heat shrinkage rate, transverse heat shrinkage rate, and air permeability of the coating, the overall performance of the release film can be improved.

[0258] In some embodiments, the peeling force between the coating layer of the isolation film and the porous base film can be greater than or equal to 28 N / m. For example, the peeling force between the coating layer of the isolation film and the porous base film can be 28 N / m, 30 N / m, 32 N / m, 34 N / m, 36 N / m, 38 N / m, or any value within the above range. In this way, the coating layer can reduce the occurrence of delamination or peeling during the expansion and contraction of the pole piece, thereby maintaining the integrity of the pore structure and promoting uniform ion transmission. At the same time, this can also reduce the direct contact of the electrolyte with the base film caused by local peeling of the coating layer, and reduce the interface side reaction and impedance growth.

[0259] As an example, the peeling force between the coating layer of the isolation film and the porous base film can be tested as follows: cut the isolation film into 3 pieces of 2.5 cm x 15 cm, paste the pieces on a test steel plate, use a test tape with a width of 2 cm to paste on the side of the isolation film to be tested, use a tensile testing machine, clamp the steel plate on one side and the tape on the other side for 180° peeling test, take the average value of the peeling force of the 3 pieces as the peeling force between the coating layer of the isolation film and the porous base film. The tensile rate is 50 mm / min.

[0260] It should be noted that the coating parameters of the above-mentioned isolation film are the coating parameters of one side of the porous base film. When the coating is arranged on both sides of the porous base film, the coating parameters of any one side meet the present disclosure, which is considered to fall within the protection scope of the present disclosure.

[0261] In some embodiments, the isolation film can be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation film is a multi-layer composite film, the materials of the layers can be the same or different, without particular limitation.

[0262] The isolation film can be prepared according to methods known in the art.

[0263] [Isolation film]

[0264] The present application provides an isolation film.

[0265] In some embodiments, the isolation film is located between the positive pole piece and the negative pole piece; the isolation film comprises a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer comprises heat-resistant particles and first binder particles; the first binder particles are embedded in the heat-resistant particles, and form protrusions on the surface of the coating layer; the heat-resistant particles comprise organic compound particles, and the morphology of the organic compound particles is spherical or spherical-like.

[0266] By using the above-mentioned heat-resistant particles and first binder particles in the isolation film, the adhesion between the isolation film and the pole piece can be improved, thereby improving the storage performance and cycle performance of the battery monomer in a high-temperature environment.

[0267] In some embodiments, the mass content of the organic compound particles in the coating layer is 50% to 80%. For example, the mass content of the organic compound particles in the coating layer is 50%, 53%, 55%, 58%, 60%, 63%, 66%, 70%, 75%, 80% or any value within the above range. Setting the mass content of the organic compound particles in the coating layer within the above range is conducive to making the isolation film have appropriate initial adhesion and effectively insulate against thermal shock and inhibit dendrite penetration under high temperature conditions, thereby improving the thermal stability of the coating layer as a whole. At the same time, this is also conducive to balancing the heat resistance of the isolation film and making the first binder particles have sufficient effective contact points. In this way, the adhesion between the isolation film and the pole piece can be promoted, thereby facilitating interface contact, reducing internal resistance, and thereby improving the cycle performance of the battery cell.

[0268] In some embodiments, the first binder particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer. Among them, the fluoropolymer in the above first binder particles can provide electrochemical stability and electrolyte corrosion resistance, thereby promoting the durability of the coating in long-term cycling; and the polar polymer in the first binder particles can enhance the chemical adsorption and physical anchoring between the electrode pole piece through its strong polarity and functional groups, thereby improving the bonding strength of the interface. In the application scenario of the isolation film, the type of the first binder particles can be selected according to the specific needs.

[0269] In some embodiments, the first binder particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene).

[0270] The first binder particles have strong polar C-F bonds, which can effectively adsorb and enrich lithium ions in the electrolyte, forming a high-concentration ion region at the interface, thereby promoting the transmission of active ions. At the same time, the high dielectric constant helps the dissociation of lithium salt, reduces the ion migration resistance, and thus improves the kinetic performance of the battery cell.

[0271] In some embodiments, the average number average particle size of the first binder particles is 5 μm to 15 μm. For example, the average number average particle size of the first binder particles is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, or any value within the above range. Specifically, the average number average particle size of the first binder particles meets the above range, which can reduce the phenomenon that smaller particles are prone to agglomeration, thereby promoting ion and electron conduction. At the same time, this can also increase the effective bonding points, making them form a close contact with the pole piece, and improve the bonding strength. In addition, this is also conducive to improving the thermal stability of the coating, reducing the blocking of the pores, thereby reducing the ion transmission resistance, causing battery polarization to intensify and capacity to decay.

[0272] In some embodiments, the first binder particles are secondary particles.

[0273] It should be noted that, for particles, primary particles and secondary particles have meanings known in the art. The primary particles refer to particles that are not in an agglomerated state; the secondary particles refer to agglomerated particles formed by two or more primary particles.

[0274] In some embodiments, the mass content of the first binder particles in the coating is 5% to 30%. For example, the mass content of the first binder particles in the coating is 5%, 7%, 10%, 13%, 15%, 18%, 20%, 23%, 26%, 28%, 30%, or any value within the above range. Setting the mass content of the first binder particles in the coating within the above range is conducive to having enough bonding points for the first binder particles, thereby improving the cohesion and adhesion of the coating, reducing the powdering or peeling of the coating. At the same time, this will not cause excessive binder particles to be coated on the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0275] In some embodiments, the coating further comprises second binder particles, the second binder particles comprising at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol methacrylamide-acrylonitrile copolymer. The type of the second binder particles can be the same as or different from the type of the first binder particles, which is not limited in the present application. For example, the first binder particles can be selected from fluoropolymers, and the second binder particles can be selected from non-fluoropolymers, so as to take into account the synergistic effect of the two types of polymer binder particles.

[0276] In some embodiments, the average number average particle size of the second binder particles is 5 μm to 15 μm. For example, the average number average particle size of the second binder particles is 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm or any value within the above range. In this way, the adhesion effect of the second binder particles and the overall performance of the battery cell can be taken into account. When the average number average particle size of the second binder particles satisfies the above range, the phenomenon that smaller particles are prone to agglomeration can be reduced, so as to facilitate ion and electron conduction. At the same time, this can also increase the effective adhesion points, so as to form close contact with the pole piece and improve the adhesion strength. In addition, this is also beneficial to improve the thermal stability of the coating, reduce the plugging of the pores, so as to reduce the ion transmission resistance, cause the battery polarization to be intensified and the capacity to be attenuated.

[0277] In some embodiments, the second binder particles comprise at least one of methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-N-methylol methacrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol methacrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol methacrylamide-acrylonitrile copolymer.

[0278] The second binder particles contain polar groups (such as carboxyl, amide, hydroxymethyl) that can form hydrogen bonds and chemical bonds with the substrate; at the same time, the side chain alkyl structure provides flexibility and wettability, enhancing interface contact and adhesion. Therefore, the use of these binder particles can improve the bonding performance of the separator film.

[0279] In some embodiments, the second binder particles are secondary particles.

[0280] In some embodiments, the mass content of the second binder particles in the coating layer is 5% to 30%. For example, the mass content of the second binder particles in the coating layer is 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25%, 28%, 30% or any value within the above range. Setting the mass content of the second binder particles in the coating layer within the above range is beneficial to having enough bonding points for the second binder particles, thereby improving the cohesion and adhesion of the coating layer and reducing the occurrence of powdering or peeling of the coating layer. At the same time, it also does not make excessive binder particles coat the surface of the heat-resistant particles, thereby blocking the ion transmission channel and causing the ion conductivity to decrease.

[0281] In the embodiments of the present application, the mass content of the second binder particles can be lower than that of the first binder particles. For example, the mass content of the second binder is less than that of the first binder particles, which is beneficial to the first binder particles to form a basic bonding network, and the second binder particles with less content can further strengthen the bonding effect as high-strength anchor points. Wherein, setting less content will not affect the ion conductivity of the battery cell due to the high content of the binder particles.

[0282] In some embodiments, the coating layer further comprises a third binder, and the third binder comprises at least one of polyimide, polyetherimide, polyacrylic acid, polyacrylate, ethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluorine rubber.

[0283] In the above technical solution, the third binder is a water-based binder, which can wrap the solid particles in the slurry and form a continuous network structure after drying, filling the gaps between the particles, thereby enhancing the cohesion of the coating layer itself and reducing the powdering phenomenon. At the same time, it can also wet the base film and the pole piece, thereby improving the interface compatibility. Therefore, the use of the third binder in the coating layer is beneficial to improve the overall structural stability and interface adhesion of the coating layer, thereby improving the cycle life of the battery.

[0284] In some embodiments, the mass content of the third binder in the coating layer is 3% to 15%. For example, the mass content of the third binder in the coating layer is 3%, 5%, 7%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value within the above range. Setting the mass content of the third binder in the coating layer within the above range is conducive to improving the binding force between the organic compound particles, reducing the cracking and falling off of the coating layer in high-temperature cycles, thereby improving the storage performance and cycle performance of the battery cell. In addition, this also makes the binder appropriately fill the pores without affecting its ionic conductivity, thereby reducing polarization.

[0285] In some embodiments, the organic compound particles Dn50 satisfies: 100 nm≤Dn50≤700 nm; wherein Dn50 refers to the particle size corresponding to the cumulative amount distribution of 50% in the particle size number distribution curve of the organic compound particles. For example, the organic compound particle Dn50 is 100 nm, 120 nm, 150 nm, 180 nm, 200 nm, 220 nm, 250 nm, 280 nm, 300 nm, 350 nm, 380 nm, 400 nm, 500 nm, 600 nm, 700 nm. For the organic compound particles, setting their Dn50 within the above range can reduce local defects. In this way, it is conducive to reducing the penetration of the electrolyte in a high-temperature environment, reducing the occurrence of interface side reactions, reducing the storage gas production and impedance in the cycle. At the same time, this can also reduce the situation that the particles easily agglomerate and block the pores, promote ionic conductivity, reduce polarization in high-temperature cycles, and thus alleviate capacity decay.

[0286] In some embodiments, the organic compound particles include a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%. For example, the cross-linking degree of the cross-linked polymer is 70%, 75%, 78%, 80%, 83%, 85%, 87%, 89%, 90%, 92%, 94%, 96%, 97%, 98%, or any value within the above range. The cross-linking degree of the cross-linked polymer satisfies the above range, which is conducive to making the organic compound particles have good structural stability at high temperatures, so that the separator film remains stable under high-temperature conditions, thereby improving the cycle stability of the battery cell.

[0287] In some embodiments, the cross-linking polymer comprises a silicone polymer containing a siloxane structure. By employing a silicone polymer containing a siloxane structure as the cross-linking polymer, the storage performance and cycle performance of the battery cell under high temperature environment are improved. Specifically, the stable Si-O bond has a high bond energy and is not prone to decomposition under high temperature adjustment, which is conducive to improving the stability of the material under high temperature environment. In addition, compared with inorganic particles, the density of the silicone polymer is relatively low, and the overall mass of the coating can be reduced under the same thickness, which is conducive to improving the energy density of the battery cell.

[0288] In some embodiments, the silicone polymer containing a siloxane structure comprises a phenyl group, the silicone polymer containing a siloxane structure is polymerized from a monomer and a cross-linking agent represented by formula (I),

[0289]

[0290] wherein R1, R2 each independently comprises a C1-C4 alkyl group, a C2-C4 alkenyl group, R3 comprises a C1-C4 alkyl group or a C4-C8 (meth)acryloxyalkyl group, and R4 comprises a C2-C8 alkenyl group or a C4-C8 (meth)acryloxyalkyl group; and the cross-linking agent comprises a divinylbenzene.

[0291] In the embodiments of the present application, R1 and R2 each independently comprises at least one of a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an ethenyl group, a 1-propenyl group, a 2-propenyl (allyl) group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 1-methyl-1-propenyl group, and a 2-methyl-1-propenyl group.

[0292] R3 comprises at least one of a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a (meth)acryloyloxy methyl group, a 2-((meth)acryloyloxy) ethyl group, a 3-((meth)acryloyloxy) propyl group, or a 4-((meth)acryloyloxy) butyl group.

[0293] In some embodiments, R3 is a methyl group or a (meth)acryloxyalkyl group. When R3 is a methyl group, the stability of the main chain of the cross-linking polymer is improved. When R3 is an acryloyloxypropyl group, the cross-linking degree of the cross-linking polymer is improved. R4 is an alkenyl group or an acryloxyalkyl group, which can be efficiently cross-linked through a free radical polymerization reaction, thereby further improving the cross-linking degree of the cross-linking polymer and the high temperature stability of the cross-linking polymer.

[0294] R4 comprises at least one of an ethenyl group, a propenyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, an octenyl group, a (meth)acryloyloxymethyl group, a 2-((meth)acryloyloxy) ethyl group, a 3-((meth)acryloyloxy) propyl group, or a 4-((meth)acryloyloxy) butyl group.

[0295] The polymerization of the monomer shown in formula (I) and the crosslinking agent divinylbenzene is conducive to improving the storage performance and cycle performance of the battery monomer in a high temperature environment. Specifically, in a high temperature environment, the particle has a three-dimensional network skeleton formed by the phenyl structure and the monomer and the crosslinking agent, and the rigid silicon-oxygen skeleton can maintain structural integrity. This is conducive to improving the mechanical properties of the coating, thereby improving the storage performance and cycle performance of the battery monomer in a high temperature environment.

[0296] In some embodiments, the siloxane structure-containing organosilicon polymer satisfies one or more of the following conditions: (1) the crosslinking degree of the siloxane structure-containing organosilicon polymer is 75% to 95%; (2) the mass content of silicon elements in the siloxane structure-containing organosilicon polymer is 10% to 25%; (3) the mass content of phenyl groups in the siloxane structure-containing organosilicon polymer is 2% to 12%.

[0297] For example, the crosslinking degree of the siloxane structure-containing organosilicon polymer is 75%, 77%, 79%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 95% or any value within the above range; the mass content of silicon elements in the siloxane structure-containing organosilicon polymer is 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25% or any value within the above range; the mass content of phenyl groups in the siloxane structure-containing organosilicon polymer is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 7%, 9%, 10%, 11%, 12% or any value within the above range.

[0298] In the above embodiments, the crosslinking degree of the siloxane structure-containing organosilicon polymer is set within the above range, which is conducive to promoting chain segment movement. This can reduce the case that the coating is prone to micro-cracks, thereby improving the cycle performance; at the same time, this can also promote ion transmission and alleviate the polarization phenomenon at high temperatures. In addition, this is also conducive to maintaining the mechanical strength of the coating, thereby promoting the cycle performance of the battery monomer.

[0299] The mass content of silicon elements in the siloxane structure-containing organosilicon polymer is set within the above range, which is conducive to improving the proportion of inorganic silicon-oxygen skeleton in the organosilicon polymer. In this way, the silicon-oxygen skeleton including silicon elements provides a higher thermal decomposition temperature and oxidation resistance, so that the isolation film has structural stability in a high temperature environment.

[0300] Since the organosilicon polymer containing phenyl groups contains Si-O bonds, the bond energy is high. The mass content of phenyl groups in the siloxane structure-containing organosilicon polymer is set within the above range, which is not easy to decompose at high temperatures, and is conducive to further improving the stability of the battery monomer at high temperatures.

[0301] Therefore, by limiting the crosslinking degree, the mass content of silicon element, and the mass content of phenyl, the storage performance and the cycle performance of the battery cell in a high-temperature environment can be improved.

[0302] In some embodiments, the organosilicon polymer containing siloxane structures comprises a backbone of compounds represented by Formula (II),

[0303] R a [SiO 3 / 2 ] n Formula (II),

[0304] wherein n is at least one of the integers 4 to 12, and R a comprises one or more of cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; and optionally, n is 8 and R a comprises C1-C3 alkyl.

[0305] In embodiments of the present application, n can be 4, 5, 6, 7, 8, 9, 10, 11, 12, or any value within a range obtained by combining two numerical values of 4 to 12.

[0306] R a may comprise one or more of cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, phenyl, naphthyl, anthryl, phenanthryl, methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, ethenyl, 1- propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1,3-buten- dienyl, and pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, ethynyl, 1-propynyl, 2-propynyl (propargyl), 1-butynyl, 3-butynyl, 1-pentynyl, 3-pentynyl, and hexynyl, heptynyl, octynyl, nonynyl, decynyl, undecynyl, dodecynyl.

[0307] Optionally, n is 8 and R a comprises at least one of methyl, ethyl, n-propyl, i-propyl.

[0308] By introducing the structural unit shown in formula (II) into the organosilicon polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. The structure forms a uniform and stable rigid support framework through strong covalent bonds, thereby improving the storage and cycle performance of the battery under high temperature environment. Specifically, it can maintain structural integrity under high temperature conditions, effectively reducing the shrinkage of the coating, thereby maintaining the stability of the three-dimensional polyhedral skeleton. By selecting the R1 substituent group as C1-C3 alkyl, the thermal stability and chemical inertness of the polymer can be further enhanced, thereby improving the storage performance and cycle performance of the battery cell under high temperature environment.

[0309] In some embodiments, the organosilicon polymer containing siloxane structure comprises one or more hydrolyzed and polycondensed monomers of formula (II),

[0310]

[0311] wherein R'1 includes C1-C3 alkyl. For example, R'1 is methyl, ethyl or propyl.

[0312] By using the hydrolysis-polycondensation reaction of the monomer of formula (III), an organosilicon polymer with a cage-like structure can be obtained. The polymer forms a uniform and stable three-dimensional network in the coating, which can effectively reduce the shrinkage of the coating under high temperature conditions, thereby improving the integrity and stability of the coating, which is beneficial to improve the storage performance and cycle performance of the battery cell under high temperature environment. At the same time, the three-dimensional polyhedral skeleton structure formed by polymerization can also improve the high temperature wettability and retention capacity of the electrolyte, promote the uniform distribution of ions at the electrode interface, and reduce local lithium deposition and aggravation of side reactions. Therefore, the above-mentioned organosilicon polymer can improve the storage performance and cycle performance of the battery cell under high temperature environment.

[0313] Alternatively, R'1 is methyl. In this way, it is beneficial to further improve the storage performance and cycle performance of the battery cell under high temperature environment.

[0314] In some embodiments, the organosilicon polymer containing siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing siloxane structure is 85%-97%; (2) the mass content of silicon element in the organosilicon polymer containing siloxane structure is 25%-45%; (3) the mass content of the skeleton composed of the compound shown in formula (II) in the organosilicon polymer containing siloxane structure is 40%-60%.

[0315] For example, the cross-linking degree of the organosilicon polymer containing siloxane structure is 85%, 87%, 89%, 90%, 91%, 93%, 95%, 96%, 97%, or any value within the above range; the mass content of silicon element in the organosilicon polymer containing siloxane structure is 25%, 27%, 29%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 45%, or any value within the above range; the mass content of phenyl in the organosilicon polymer containing siloxane structure is 40%, 41%, 43%, 45%, 48%, 50%, 53%, 56%, 58%, 60%, or any value within the above range.

[0316] By controlling the cross-linking degree of the organosilicon polymer within the above range, the structural stability of the organosilicon polymer in a high-temperature environment can be enhanced, and the softening and deformation of the coating can be effectively reduced, thereby providing mechanical support for the battery cell. The above range of mass content of silicon element can maintain the material to have high thermal stability, thereby improving the storage performance and cycle performance of the battery cell in a high-temperature environment.

[0317] Therefore, by limiting the cross-linking degree, the mass fraction of silicon element, and the mass content of the skeleton formed by the compound represented by formula (II), the storage performance and cycle performance of the battery cell under high-temperature conditions can be improved.

[0318] In some embodiments, the organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammogram of the organic compound particles in the first cycle has no oxidation peak in the voltage range of 0 to 4.4 V; (2) the organic compound particles have no glass transition temperature at 300°C; (3) the initial thermal weight loss temperature T 3d satisfies: T 3d ≥ 250°C; (4) the dissolution rate of the organic compound particles is less than or equal to 5% when the organic compound particles are soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days; and (5) the true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 .

[0319] For example, the glass transition temperature Tg of the organic compound particles is 200°C, 220°C, 240°C, 280°C, 300°C, 350°C, 400°C, 500°C, or any value within the above range; the initial thermal weight loss temperature T 3d0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 4.5%, 5% or any value within the above range; the true density of the organic compound particles is 0.8 g / cm 3 , 1.0 g / cm 3 , 1.2 g / cm 3 , 1.4 g / cm 3 , 1.6 g / cm 3 , 1.8 g / cm 3 , 1.9 g / cm 3 , 2.0 g / cm 3 or any value within the above range.

[0320] By limiting the oxidation peak of the cyclic voltammetry curve of the first cycle of the organic compound particles, the glass transition temperature, the initial thermal weight loss temperature, the dissolution rate of 7 days of constant temperature immersion at 60°C, and the true density, the overall performance of the battery cell is improved.

[0321] In some embodiments, the coating does not include inorganic particles.

[0322] In some embodiments, the coating includes inorganic particles, and the mass fraction of the inorganic particles is 0.1% to 50% based on the total mass of the coating.

[0323] In other embodiments, the coating includes inorganic particles, and the mass fraction of the inorganic particles is 50% to 92% based on the total mass of the coating.

[0324] In one example, the inorganic particles include at least one of SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, ZrO2, Y2O3, Al2O3, boehmite (AlO(OH)), Al(OH)3, TiO2, SiC, and the like. The above inorganic particles have a large dielectric constant, which is conducive to improving the ion transport efficiency in the coating.

[0325] In some embodiments, the separator film satisfies one or more of the following conditions: (1) the thickness of the coating is 0.5 μm to 10 μm; (2) the areal density of the coating is 1.5 g / m 2 to 6 g / m 2 ; (3) the longitudinal thermal shrinkage rate of the separator film is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage rate of the separator film is less than or equal to 5% when heated at 130°C for 1 h; (5) the air permeability of the separator film is 150 s / 100 mL to 500 s / 100 mL.

[0326] For example, the thickness of the coating layer can be 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value within the above range; the areal density of the coating layer can be 1.5 g / m 2 , 1.8 g / m 2 , 2 g / m 2 , 2.2 g / m 2 , 2.4 g / m 2 , 2.6 g / m 2 , 2.8 g / m 2 , 3 g / m 2 , 3.2 g / m 2 , 3.5 g / m 2 , 3.8 g / m 2 , 4 g / m 2 , 4.5 g / m 2 , 5 g / m 2 , 5.3 g / m 2 , 5.7 g / m 2 , 6 g / m 2 or any value within the above range; the longitudinal thermal shrinkage of the separator film after being heated at 130 °C for 1 h can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range; the transverse thermal shrinkage of the separator film after being heated at 130 °C for 1 h can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range; the air permeability of the separator film can be 150 s / 100 mL, 200 s / 100 mL, 250 s / 100 mL, 300 s / 100 mL, 350 s / 100 mL, 400 s / 100 mL, 450 s / 100 mL, 500 s / 100 mL or any value within the above range.

[0327] Setting the thickness of the coating layer within the above range can form a uniform and dense thermal insulation layer, thereby balancing the energy density and cycle performance of the battery cell.

[0328] Setting the areal density of the coating layer within the above range is conducive to balancing the stability and high-pressure resistance of the separator film while not increasing the weight of the separator film, thereby being conducive to the energy density and reliability of the battery cell.

[0329] The longitudinal thermal shrinkage and transverse thermal shrinkage of the separator film after being heated at 130 °C for 1 h meet the above range, which is conducive to maintaining the stability of the separator film and improving its mechanical integrity in a high-temperature environment. In this way, the short circuit caused by the exposure of the pole piece can be reduced, thereby reducing the probability of thermal runaway and improving the cycle performance of the battery cell.

[0330] The air permeability of the separator film is set in the above range, which is conducive to promoting the uniform wetting of the electrolyte and maintaining the rapid transmission of ions, reducing the air permeability of the separator film, which is too low to cause electrochemical polarization, thereby reducing the cycle performance of the battery cell.

[0331] Therefore, by limiting the thickness, areal density, longitudinal thermal shrinkage, transverse thermal shrinkage and air permeability of the coating, the overall performance of the separator film can be improved.

[0332] In some embodiments, the peeling force between the coating and the porous base film of the separator film can be greater than or equal to 28 N / m. For example, the peeling force between the coating and the porous base film of the separator film can be 28 N / m, 30 N / m, 32 N / m, 34 N / m, 36 N / m, 38 N / m, or any value within the above range. In this way, the coating can reduce the occurrence of delamination or peeling during the expansion and contraction of the electrode tab, thereby maintaining the integrity of the pore structure and promoting uniform ion transmission. At the same time, this can also reduce the direct contact of the electrolyte with the base film caused by local peeling of the coating, reducing the interface side reaction and impedance growth.

[0333] It should be noted that the coating parameters of the separator film described above are the coating parameters of one side of the porous base film. When the coating is provided on both sides of the porous base film, the coating parameters of any one side meet the present disclosure, which is considered to fall within the protection scope of the present disclosure.

[0334] In some embodiments, the separator film can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, without particular limitation.

[0335] The separator film can be prepared according to methods known in the art.

[0336] [Positive electrode tab]

[0337] The positive electrode tab can include a positive electrode current collector and at least one positive electrode film layer disposed on the positive electrode current collector, the positive electrode film layer including a positive electrode active material.

[0338] FIG. 1 is a schematic structural diagram of a positive electrode tab according to an embodiment of the present application. As shown in FIG. 1, the positive electrode tab 121 includes a positive electrode current collector 1211 and a positive electrode film layer 1212 disposed on at least one side surface of the positive electrode current collector 1211.

[0339] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector. As an example, as shown in FIG. 1, the positive electrode film layer 1212 is disposed on both side surfaces of the positive electrode current collector 1211.

[0340] In some embodiments, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as a metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0341] In some embodiments, the positive electrode active material can employ a positive electrode active material for a battery known in the art. As an example, the positive electrode active material can include at least one of a lithium-containing transition metal oxide, a lithium-containing phosphate of an olivine structure, or one or more of a material of a spinel structure. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery can also be used. These positive electrode active materials can be used alone only one or in combination of two or more. Among them, examples of the lithium-containing transition metal oxide can include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to simply as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be referred to simply as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be referred to simply as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be referred to simply as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be referred to simply as NCM811), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05O2) and modified compounds thereof, etc. Examples of the lithium-containing phosphate of olivine structure can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (which can also be referred to simply as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0342] In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0343] In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent can include at least one of super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0344] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, coating the positive electrode slurry on a positive electrode current collector, and subjecting the same to processes such as drying, cold pressing, etc. to obtain the positive electrode tab.

[0345] [Negative electrode tab]

[0346] The negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0347] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0348] In some embodiments, the negative electrode current collector can employ a metal foil or a composite current collector. As a metal foil, for example, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (such as a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0349] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As an example, the negative active material can include one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from one or more of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from one or more of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. These negative active materials can be used alone or in combination of two or more.

[0350] In some embodiments, the negative film layer can further optionally include a binder. The binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0351] In some embodiments, the negative film layer can further optionally include a conductive agent. The conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0352] In some embodiments, the negative film layer can further optionally include other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0353] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned components for preparing the negative electrode sheet, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry on a negative current collector, and after processes such as drying, cold pressing, and the like, the negative electrode sheet can be obtained.

[0354] [Electrolyte]

[0355] The electrolyte plays a role of conducting ions between the positive electrode sheet and the negative electrode sheet. The present application does not have a specific limitation on the type of electrolyte, which can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0356] In some embodiments, the electrolyte employs an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0357] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorobisoxalate phosphate, and lithium tetrafluorobisoxalate phosphate.

[0358] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0359] In some embodiments, the electrolyte solution can further optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can further include an additive capable of improving certain performance of the battery, such as an additive for improving overcharge performance of the battery, an additive for improving high-temperature or low-temperature performance of the battery, etc.

[0360] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be made into an electrode assembly through a roll-pressing process or a stacking process.

[0361] In some embodiments, the battery cell can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte described above.

[0362] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0363] The shape of the battery cell according to the present application is not particularly limited, and can be cylindrical, square, or any other arbitrary shape. For example, FIG. 2 is a schematic view of the structure of a battery cell according to an embodiment of the present application.

[0364] FIG. 3 is a structural schematic diagram of a battery cell according to another embodiment of the present application. As shown in FIG. 3, the outer package of the battery cell 100 includes a casing 11 and a cover plate 13. The casing 11 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The casing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be arranged on the opening to seal the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator film can be wound or stacked to form an electrode assembly 12. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 12. The number of the electrode assemblies 12 contained in the battery cell 100 can be one or more, which can be selected by those skilled in the art according to specific actual needs.

[0365] In some embodiments, the battery cell 100 can also be assembled into a battery module. The number of the battery cells 100 contained in the battery module can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0366] [Battery device]

[0367] The embodiments of the present application provide a battery device including one or more battery cells according to the above embodiments. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in a mixed manner through a current collecting component.

[0368] In some embodiments, the battery device can be a battery pack including a box body and battery cells, and the battery cells or battery modules are contained in the box body.

[0369] In some embodiments, the battery device can be located in an energy storage equipment. The energy storage equipment includes an energy storage container, an energy storage cabinet, etc.

[0370] FIG. 4 is a schematic diagram of a battery device according to an embodiment of the present application, and FIG. 5 is a structural schematic diagram of the battery device according to an embodiment of the present application. Referring to FIGS. 4 and 5, the battery device 400 can include a battery box and multiple battery cells 100 arranged in the battery box. The battery box includes an upper box body 401 and a lower box body 402, and the upper box body 401 can be arranged on the lower box body 402 to form a closed space for containing the battery cells 100. The multiple battery cells 100 can be arranged in the battery box in any manner.

[0371] [Power consumption device]

[0372] The application also provides a power utilization device comprising the battery as described above. The power utilization device comprises at least one of the battery cell 100 or the battery device 400 provided by the application. The battery cell 100 or the battery device 400 can be used as a power source of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0373] For example, FIG. 6 is a schematic structural diagram of a power utilization device according to an embodiment of the application. As shown in FIG. 6, the power utilization device is a vehicle 1, which can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric vehicle, a hybrid electric vehicle, or a range extended vehicle, etc. The vehicle 1 can be provided with a motor 500, a controller 600, and a battery device 400 inside, and the controller 600 is used to control the battery device 400 to supply power to the motor 500. For example, the battery device 400 can be arranged at the bottom, the front, or the rear of the vehicle 1. The battery device 400 can be used to supply power to the vehicle 1, for example, the battery device 400 can be used as an operating power source of the vehicle 1, and is used for the circuit system of the vehicle 1, for example, for the power demand of the vehicle 1 during starting, navigation, and operation. In another embodiment of the application, the battery device 400 can not only be used as an operating power source of the vehicle 1, but also can be used as a driving power source of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0374] As the power utilization device, the battery cell 100 or the battery device 400 can be selected according to the use demand thereof.

[0375] The power utilization device can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the demand of high power and high energy density of the battery for the power utilization device, the battery cell 100 or the battery device 400 can be used.

[0376] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the battery cell 100 can be used as a power source.

[0377] Hereinafter, the embodiments of the application will be described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If a specific technology or condition is not specified in the embodiments, it is performed according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument used is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0378] [Examples and Comparative Examples]

[0379] [Example 1]

[0380] (1) Preparation of the negative electrode tab:

[0381] Preparation of the negative electrode tab: The negative electrode active material artificial graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickening agent sodium hydroxymethyl cellulose (CMC-Na) were dispersed in deionized water at a weight ratio of 95:2.3:1.5:1.2, and after being fully stirred and mixed uniformly, a negative electrode slurry was prepared. The negative electrode slurry was uniformly coated on a negative electrode current collector copper foil, and then dried, cold-pressed, and cut to obtain the negative electrode tab. The solid content of the negative electrode slurry was 62%.

[0382] (2) Preparation of the positive electrode tab:

[0383] Lithium iron phosphate (LiFePO4), polyvinylidene fluoride (PVDF), conductive carbon black (Super-P), and dispersant polyvinylpyrrolidone (PVP) were mixed at a mass ratio of 95.5:2.4:1.5:0.6, and stirred uniformly in a vacuum stirrer to obtain a positive electrode slurry. The slurry was coated on both sides of an aluminum foil, dried, cold-pressed, and cut to obtain the positive electrode tab.

[0384] (3) Preparation of the separator:

[0385] ① Preparation of organic compound particles (organic silicon polymer containing a cage polysilsesquioxane skeleton):

[0386] In a 5L flask equipped with a stirrer, a thermometer, and a reflux condenser, 2000g of deionized water and 5.5ml of hydrochloric acid were added. After stirring started, 80g of methyltrimethoxysilane was added. After hydrolysis reaction at 30°C for 2h, 50ml of ammonia water was added, and the reaction was continued at 30°C for 2h. The temperature was then increased to 90°C, and the reaction was continued for 12h to obtain the organic compound particles. The water content was then evaporated to obtain a dispersion liquid with a solid content of 20% for standby use. The corresponding organic compound particle powder was obtained by drying treatment of the standby dispersion liquid.

[0387] The powder was tested for crosslinking degree by a PQ001 nuclear magnetic resonance analyzer. The organic compound particles were crosslinked polymers, and the calculated crosslinking degree was 93.6%.

[0388] The powder of the organic compound particles was tested by pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS). As shown in FIG. 7, by comparing with the standard pyrolysis spectrum of EVA in the NIST library, it was detected that The corresponding characteristic ions suggest that the organic compound particles include a cage-like polysilsesquioxane skeleton.

[0389] Differential scanning calorimetry (DSC) was used to test the glass transition temperature (Tg) and melting point of organic compound particles. The organic compound particles had no Tg and no melting point below 300℃.

[0390] The true density of the organic compound particles was tested using a true density meter, and the true density of the organic compound particles was 1.33 g / cm³. 3 .

[0391] The volume number average particle size (Dn50) of the organic compound particles was measured using a scanning electron microscope (e.g., ZEISS Sigma 300), and the volume number average particle size (Dn50) of the organic compound particles was 260 nm.

[0392] Organic compound particles were immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days. The dissolution rate of the organic compound particles after immersion at 60°C for 7 days was tested, and the dissolution rate was 0.1%.

[0393] Figure 8 is a SEM image of the organic compound particles in Example 1. As shown in Figure 8, the organic compound particles are spherical or near-spherical in shape and have a relatively regular shape.

[0394] ② Preparation of the first binder particles: Methyl acrylate, acrylamide, and acrylic acid were mixed uniformly in a mass ratio of 80:10:10 to obtain a mixed monomer. Then, 200g of the mixed monomer, 6g of sodium dodecyl sulfate emulsifier, 2g of ammonium persulfate initiator, and 300g of deionized water were added to a 1000mL four-necked flask equipped with a mechanical stirrer, thermometer, and condenser, and emulsified at high speed for 30min. Under nitrogen protection, the mixture was heated to 75℃ and reacted for 4h, then cooled to below 40℃, the pH was adjusted to neutral, and the mixture was filtered out. The resulting product was then spray-dried to obtain the first binder particles, polyacrylate (methyl acrylate-acrylic acid-acrylamide copolymer). The spray-drying conditions were: inlet air temperature 115℃, outlet air temperature 55℃, and air pressure 0.5kPa.

[0395] ③ Preparation of the separator membrane: A commercially available polyethylene microporous membrane (Zhuogao Electronic Technology Co., Ltd.) with a thickness of 7 μm and an average pore size of 50 nm was used as the porous base membrane. The dispersion of the organic compound particles prepared above, the first binder particles, and the third binder polyacrylic acid were mixed evenly in deionized water at a mass ratio of 67:25:8 to obtain a separator slurry (solid content of 15%).

[0396] The separator slurry was uniformly coated on both surfaces of the substrate, and the solvent was removed by drying. The coating density of the coating composition on the substrate (single side) was 3.0 g / m 2 , to obtain a coating. Then, through drying and slitting processes, a separator film was obtained. The average number average particle size of the first binder particles was 6.0 pm, and the air permeability of the separator film was 210 s / 100 mL. The specific parameters in the separator film are shown in Table 1.

[0397] (4) Preparation of electrolyte:

[0398] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene carbonate (EC), methyl ethyl carbonate (EMC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. Then, LiPF6 and the additive vinylene carbonate (VC) were dissolved in the above mixed organic solvent to obtain an electrolyte. The concentration of LiPF6 was 1 mol / L, and the mass fraction of vinylene carbonate (VC) was 2%.

[0399] (5) Preparation of battery monomer:

[0400] The positive electrode sheet, the separator film, and the negative electrode sheet were stacked in order, with the separator film between the positive and negative electrode sheets to separate the positive and negative electrode sheets. The electrode assembly was obtained by winding. The tab of the electrode assembly was connected to the end cover (for example, the tab and the end cover were welded and connected by a connecting member). The electrode assembly was placed in an aluminum shell, and after drying, the electrolyte was injected, and then packaged to obtain a battery monomer.

[0401] [Example 2]

[0402] The difference between Example 2 and Example 1 is that:

[0403] (3) Preparation of separator film:

[0404] 2. Preparation of first binder particles: 5 kg of deionized water and 0.3 g of methyl cellulose ether were added to a 10 L autoclave, vacuumed and replaced with N2 three times, then 6 g of t-butyl peroxypivalate and 2.2 g of sodium bicarbonate were added, and 1.2 kg of vinylidene fluoride monomer was filled to make the pressure reach 7 MPa, mixed and stirred for 30 min, and then the temperature was raised to 45°C for polymerization reaction. After 8 h of reaction, 25 g of cyclohexane was added for continuous reaction, and the reaction was stopped when the pressure in the reaction kettle dropped to 2 MPa. The solid phase was collected after centrifugation of the reaction system, washed and dried to obtain the first binder particles polyvinylidene fluoride (PVDF). The average number average particle size of the first binder particles was 6.2 pm. The specific parameters in the separator film are shown in Table 1.

[0405] [Example 3]

[0406] Example 3 differs from Example 2 in that:

[0407] (3) Preparation of the separator membrane:

[0408] ② Preparation of the first binder particles: 5 kg of deionized water and 0.3 g of methyl cellulose ether were added to a 10 L autoclave, vacuumed and replaced with N2 three times, 6 g of t-butyl peroxy neopentanoate and 2.2 g of sodium bicarbonate were added again, and 1.2 kg of vinylidene fluoride monomer was filled to make the pressure reach 7 MPa, mixed and stirred for 30 min, and the temperature was raised to 45°C for polymerization reaction; 25 g of cyclohexane was added after 8 h of reaction to continue the reaction, and the reaction was stopped when the pressure in the reaction kettle dropped to 2 MPa; the solid phase was collected after centrifugation of the reaction system, washed and dried to obtain the first binder particles polyvinylidene fluoride (PVDF). The average number average particle size of the first binder particles was 6.2 μm.

[0409] Preparation of the second binder particles: 80:10:10 of methyl acrylate, acrylamide and acrylic acid by mass ratio were mixed uniformly to obtain a mixed monomer. Then, 200 g of the mixed monomer, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water were added to a 1000 mL four-necked flask equipped with mechanical stirring, thermometer and condenser, and emulsified at high speed for 30 min. After being heated to 75°C for 4 h under nitrogen protection, the temperature was lowered to below 40°C, the PH was adjusted to neutral, and the filtrate was filtered out. Then, the second binder particles polyacrylate (methyl acrylate-acrylic acid-acrylamide copolymer) were obtained by spray drying process. The conditions of the spray drying process were inlet air temperature 115°C, outlet air temperature 55°C, and air pressure 0.5 kPa. The average number average particle size of the second binder particles was 6.0 μm.

[0410] ③ Preparation of the separator membrane: commercially available PE microporous film (from Zhuogao Electronics Technology Co., Ltd.) with a thickness of 7 μm and an average pore size of 50 nm was used as the base film. The dispersion liquid of the organic compound particles, the first binder particles and the second binder particles, and the third binder polyacrylic acid prepared above were mixed uniformly in deionized water at a mass ratio of 67:25:8 to obtain a separator slurry (solid content of 15%). The mass ratio of the first binder particles and the second binder particles was 3:7. The slurry was uniformly coated on both surfaces of the substrate, and the solvent was removed by drying to obtain a coating with a (single-sided) coating density of 3.0 g / m 2 , on the substrate. Then, the separator membrane was obtained by drying and slitting processes. The air permeability of the separator membrane was 205 s / 100 mL. The specific parameters in the separator membrane are shown in Table 1.

[0411] [Examples 4-5]

[0412] Example 4 differs from Example 3 in that, in the preparation of the organic compound particles, the "mass ratio of the first binder particles to the second binder particles is 3:7" in Example 3 is changed to "mass ratio of the first binder particles to the second binder particles is 5:5".

[0413] Example 5 differs from Example 3 in that, in the preparation of the organic compound particles, the "mass ratio of the first binder particles to the second binder particles is 3:7" in Example 3 is changed to "mass ratio of the first binder particles to the second binder particles is 7:3".

[0414] [Examples 6-8]

[0415] Example 6 differs from Example 3 in that, in the preparation of the organic compound particles, the "start stirring and add 80 g of methyltrimethoxysilane" in Example 3 is changed to "start stirring and add 90 g of methyltrimethoxysilane" to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 3.

[0416] Example 7 differs from Example 3 in that, in the preparation of the organic compound particles, the "start stirring and add 80 g of methyltrimethoxysilane" in Example 3 is changed to "start stirring and add 120 g of methyltrimethoxysilane" to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 3.

[0417] Example 8 differs from Example 3 in that, in the preparation of the organic compound particles, the "start stirring and add 80 g of methyltrimethoxysilane" in Example 3 is changed to "start stirring and add 60 g of methyltrimethoxysilane" to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 3.

[0418] [Example 9]

[0419] Example 9 differs from Example 1 in that:

[0420] (3) Preparation of the separation film:

[0421] ① Preparation of the organic compound particles (silicon-oxygen structure-containing silicone polymer):

[0422] A pre-emulsion was prepared using 0.3 g of potassium persulfate, 0.3 g of sodium bicarbonate, 0.9 g of sodium dodecyl sulfate, 30 g of deionized water, and emulsifying 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, and divinylbenzene (wherein the mass of 3-methacryloxypropylmethyldimethoxysilane added was 1.8 g) in a mass ratio of 3%:85%:12%. A reactor was taken, 400 g of deionized water was added, and the temperature was raised to 75°C. The pre-emulsion was added dropwise under the conditions of nitrogen protection and stirring speed of 350 rpm / min. After 4 h of reaction, the temperature was raised to 88°C for 4 h of curing reaction, and an emulsion containing organic compound particles was obtained.

[0423] The crosslinking degree of the organic compound particle powder was tested using a PQ001 nuclear magnetic resonance analyzer. The organic compound particle was a crosslinked polymer, and the calculated crosslinking degree was 90.7%.

[0424] The organic compound particle powder was tested using a pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) method. By comparing with the EVA standard pyrolysis spectrum in the NIST library, the characteristic ions corresponding to were detected, and it was speculated that the organic compound particle included a benzene ring.

[0425] The Dn50 of the organic compound particle was tested using a scanning electron microscope (ZEISS Sigma 300). The Dn50 of the organic compound particle was 245 nm.

[0426] The glass transition temperature T g and the melting point of the organic compound particle were tested using differential scanning calorimetry (DSC). There was no Tg and no melting point below 300°C.

[0427] The density of the organic compound particle was tested using a true density tester. The density of the organic compound particle was 1.32 g / cm 3 .

[0428] The organic compound particle was placed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 and soaked at 60°C for 7 days. The dissolution rate of the organic compound particle was tested. The dissolution rate of the organic compound particle after soaking at 60°C for 7 days was 0.5%.

[0429] (2) Preparation of the first binder particles: 200 g of the mixed monomers, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water were added into a 1000 mL four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser, and emulsified at high speed for 30 min. The temperature was raised to 75°C under nitrogen protection, and the reaction was carried out for 4 h. Then the temperature was lowered to below 40°C, the pH was adjusted to neutral, and the product was filtered out. The first binder particles, polyacrylate (methyl acrylate-acrylic acid-acrylamide copolymer), were obtained by spray drying. The conditions of the spray drying process were as follows: inlet air temperature 115°C, outlet air temperature 55°C, and air pressure 0.5 kPa. The average number average particle size of the first binder particles was 6.0 μm.

[0430] (3) Preparation of the separator membrane: A commercially available polyethylene microporous film (Zuogao Electronics Technology Co., Ltd.) with a thickness of 7 μm and an average pore size of 50 nm was used as the porous base film. The dispersion liquid of the organic compound particles, the first binder particles, and the third binder polyacrylate prepared above were mixed in deionized water at a mass ratio of 67:25:8 to obtain a separator slurry (solid content 15%).

[0431] The separator slurry was uniformly coated on both surfaces of the substrate, and the solvent was removed by drying. The coating density of the coating composition on the substrate (single side) was 3.0 g / m 2 , and a coating layer was obtained. The separator membrane was obtained by drying and slitting. The air permeability of the separator membrane was 212 s / 100 mL. The specific implementation parameters are shown in Table 3.

[0432] [Example 10]

[0433] The difference between Example 10 and Example 9 is that:

[0434] (1) Preparation of the separator membrane:

[0435] (2) Preparation of the first binder particles: 200 g of the mixed monomers, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water were added into a 1000 mL four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser, and emulsified at high speed for 30 min. The temperature was raised to 75°C under nitrogen protection, and the reaction was carried out for 4 h. Then the temperature was lowered to below 40°C, the pH was adjusted to neutral, and the product was filtered out. The first binder particles, polyacrylate (methyl acrylate-acrylic acid-acrylamide copolymer), were obtained by spray drying. The conditions of the spray drying process were as follows: inlet air temperature 115°C, outlet air temperature 55°C, and air pressure 0.5 kPa. The average number average particle size of the first binder particles was 6.0 μm.

[0436] [Example 11]

[0437] Example 11 differs from Example 10 in that:

[0438] (1) Preparation of the separator membrane:

[0439] ② Preparation of the first binder particles: 5 kg of deionized water and 0.3 g of methyl cellulose ether were added to a 10 L autoclave, vacuumed and replaced with N2 three times, 6 g of t-butyl peroxypivalate and 2.2 g of sodium bicarbonate were added again, and 1.2 kg of vinylidene fluoride monomer was filled to make the pressure reach 7 MPa, mixed and stirred for 30 min, and the temperature was raised to 45 °C for polymerization reaction; 25 g of cyclohexane was added after 8 h of reaction to continue the reaction, and the reaction was stopped when the pressure in the reaction kettle dropped to 2 MPa; the solid phase was collected after centrifugation of the reaction system, washed and dried to obtain the first binder particles polyvinylidene fluoride (PVDF). The average number average particle size of the first binder particles was 6.2 μm.

[0440] Preparation of the second binder particles: 80:10:10 of methyl acrylate, acrylamide and acrylic acid by mass ratio were mixed uniformly to obtain a mixed monomer. Then, 200 g of the mixed monomer, 6 g of sodium dodecyl sulfate emulsifier, 2 g of ammonium persulfate initiator, and 300 g of deionized water were added to a 1000 mL four-necked flask equipped with mechanical stirring, thermometer and condenser, and emulsified at high speed for 30 min. After being heated to 75 °C for 4 h under nitrogen protection, the temperature was lowered to below 40 °C, the PH was adjusted to neutral, and the filtrate was filtered out. Then, the second binder particles polyacrylate (methyl acrylate-acrylic acid-acrylamide copolymer) were obtained by spray drying process. The average number average particle size of the second binder particles was 6.0 μm. The conditions of the spray drying process were as follows: inlet air temperature 115 °C, outlet air temperature 55 °C, and air pressure 0.5 kPa.

[0441] ③ Preparation of the separator membrane: commercially available PE microporous film (from Zhuogao Electronics Technology Co., Ltd.) with a thickness of 7 μm and an average pore size of 50 nm was used as the base film. The dispersion liquid of the organic compound particles, the first binder particles and the second binder particles, and the third binder polyacrylic acid prepared above were mixed uniformly in deionized water at a mass ratio of 67:25:8 to obtain a separator slurry (solid content of 15%). The mass ratio of the first binder particles to the second binder particles was 3:7. The slurry was uniformly coated on both surfaces of the substrate, and the solvent was removed by drying to obtain a coating on the substrate (single side) with a coating density of 3.0 g / m 2 , to obtain a coating. Then, the separator membrane was obtained by drying and slitting processes. The air permeability of the separator membrane was 209 s / 100 mL. The specific parameters in the separator membrane are shown in Table 3.

[0442] [Example 12]

[0443] Example 12 is different from Example 11 in that, in the process of preparing the organic compound particles, the “0.9 g of sodium dodecyl sulfate” in Example 11 is adjusted to “0.3 g of sodium dodecyl sulfate”, and the rest of the preparation process is similar to that of Example 11 to obtain an emulsion containing organic compound particles.

[0444] [Comparative Example 1]

[0445] Comparative Example 1 is different from Example 1 in that the organic compound particles are modified into inorganic particles, and the inorganic particles are commercially available alumina with an average number average particle size Dn50 of 146 nm.

[0446] FIG. 9 is an SEM image of the inorganic particles in Comparative Example 1. As shown in FIG. 9, the morphology of the inorganic particles is non-spherical and irregularly shaped.

[0447] Table 1 shows the specific parameters of Examples 1-8 and Comparative Example 1; Table 2 shows the test results of Examples 1-8 and Comparative Example 1; Table 3 shows the specific parameters of Examples 9-12; and Table 4 shows the test results of Examples 9-12.

[0448] Table 1 shows the specific parameters of Examples 1-8 and Comparative Example 1; Table 2 shows the test results of Examples 1-8 and Comparative Example 1; Table 3 shows the specific parameters of Examples 9-12; and Table 4 shows the test results of Examples 9-12.

[0449] Table 2 shows the test results of Examples 1-8 and Comparative Example 1; Table 3 shows the specific parameters of Examples 9-12; and Table 4 shows the test results of Examples 9-12.

[0450] In combination with Tables 1 and 2, according to Examples 1-8 and Comparative Example 1, it can be seen that, by setting the first binder particles in the separator film according to the technical solutions of the present application, the adhesion of the separator film and the pole piece can be considered, and the storage performance and cycle performance of the battery monomer in a high-temperature environment can be considered.

[0451] Table 3 shows the specific parameters of Examples 9-12; and Table 4 shows the test results of Examples 9-12.

[0452] Table 4 shows the test results of Examples 9-12.

[0453] In combination with Tables 3 and 4, according to Examples 9-12 and the above Comparative Example 1, it can be seen that, in the technical solutions of the present application, within a certain range, by setting the first binder particles in the separator film, the adhesion of the separator film and the pole piece can be considered, and the storage performance and cycle performance of the battery monomer in a high-temperature environment can be considered.

[0454] The test methods of the physicochemical parameters and performance parameters involved in the embodiments of the present application are briefly introduced below. It should be understood that the following test methods are only examples, and other test methods known in the art can also be used for testing.

[0455] 1. Test of Dn50 of organic compound particles

[0456] After the battery monomer is discharged to 0% SOC at 0.33C, the battery monomer is disassembled to obtain a separator film, and the Dn50 of the organic compound particles is tested by using an instrument and a method known in the art. For example, a scanning electron microscope (e.g., ZEISS Sigma 300) is used to obtain a scanning electron microscope (SEM) picture of the separator film according to JY / T010-1996. As an example, the Dn50 of the organic compound particles can be tested as follows: an arbitrary test sample with a length x width = 50 mm x 100 mm is selected on the separator film, a plurality of test regions (e.g., 5) are randomly selected in the test sample, and the particle size of the organic compound particles in each test region is obtained by Image J software under a certain magnification (e.g., 500x or 1000x when measuring the organic compound particles), that is, the distance between the two farthest points on the organic compound particle is taken as the particle size of the organic compound particle, and the number and particle size values of the organic compound particles in each test region are counted, so as to obtain a particle size number distribution curve of the organic compound particles. The Dn50 result is obtained by software analysis. In the particle size number distribution curve of the organic compound particles, the Dn50 refers to the particle size of the organic compound particles corresponding to the cumulative particle size concentration reaching 50%.

[0457] 2. Test method of crosslinking degree

[0458] As an example, the crosslinking degree of the crosslinked polymer can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21 MHz, 0.5 g of the cleaned and dried sample (the above-mentioned organic compound particles) to be tested is taken, is loaded into a clean sample tube and is inserted into a probe to a specified depth, the probe coil diameter is 13 mm, and the measurement is performed according to the manufacturer's instructions. Specifically: the proportion of the crosslinked portion signal is calculated by fitting software to obtain the crosslinking degree of the crosslinked polymer by collecting the entire polymer signal; the relaxation decay curve is automatically obtained by the PQ001 nuclear magnetic resonance analyzer in the software selection of the "crosslinking degree" or "T2 relaxation" test mode. During data processing, the software decomposes the relaxation components by exponential fitting, and calculates and outputs the crosslinking degree result according to the degree of restriction of molecular chain movement.

[0459] 3. Test method of phenyl and cage skeleton structure

[0460] In the embodiments of the present application, a pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) can be used to test the rigid structure phenyl and cage skeleton structure in the organic compound particles. Specifically, 0.5-1 mg of the organic compound particles described above is weighed as a test sample, and is loaded into a quartz cracking tube of a pyrolysis instrument, and is cracked at 550°C for 1.2 s. The sample is tested to be cracked into volatile small molecules in an inert gas (such as helium), and then is introduced into a gas chromatograph-mass spectrometer. An HP-5ms (30 m x 0.25 mm x 0.25 μm) chromatographic column is selected, and the temperature is set to 30°C for 5 min, 10°C / min to 250°C, and 250°C for 5 min. The carrier gas is high-purity helium, and the flow rate is 1.0 mL / min. The mass spectrometry uses electrochemical ionization, the ion source temperature is 230°C, and the fragment scan range is m / z 25-200. By comparing with the EVA standard cracking spectrum in the NIST library, the characteristic ions corresponding to the benzene ring and the characteristic ions corresponding to the cage skeleton are detected, and it can be inferred that the organic silicon polymer includes the phenyl or cage skeleton structure. The internal standard method is used to calculate the mass proportion of the characteristic benzene ring or cage skeleton in the organic compound particles according to the above fragment peak area.

[0461] 4. Test of the adhesion of the separator film

[0462] The adhesion of the separator film is a meaning known in the art, and can be measured by using instruments and methods known in the art. Specifically, as an example, after the battery monomer is disassembled, the separator film and the positive electrode tab are peeled off. The separator film and the positive electrode tab are placed on a hot press, and the parameters of the hot press are set as follows: the temperature is 65°C, the pressure is 5 MPa, and the time is 10 s. The adhesion of the separator film / electrode tab sample is prepared by pressing. Then, the separator film / electrode tab sample is cut into a rectangular sample with a length of 150 mm and a width of 20 mm. The electrode tab of the above rectangular sample is pasted on a steel plate by double-sided tape, and the separator film and the electrode tab are separated by 2 cm in length along the length direction at one end of the rectangular sample, to obtain a test sample.

[0463] The steel plate is kept horizontal, the lower clamp of a universal testing machine (Changjiang Instrument & Equipment Manufacturing (Shanghai) Co., Ltd., model: CTM2100) is fixed, the peeled end of the separator film described above is fixed by the upper clamp of the universal testing machine, and is connected to a tension machine. The test conditions are set as follows: the tensile speed is 20 mm / min, and the horizontal tension is 10 cm. After the tension is stable, the tension value is recorded, and the adhesion of the separator film and the positive electrode tab, i.e., the adhesion of the separator film, is obtained by the ratio of the tension value to the width of the sample.

[0464] 5. Test of the storage performance of the battery monomer

[0465] As an example, at 25℃, the secondary battery cell is charged at 1 / 3C constant current to 3.6V, then charged at 3.6V constant voltage to 0.05C current, and left for 5 min, then discharged at 1 / 3C constant current to 2.8V, and the obtained discharge capacity is recorded as the pre-storage capacity C0; then the secondary battery cell is charged at 1 / 3C constant current to 3.6V, then charged at 3.6V constant voltage to 0.05C current, at this time the secondary battery cell is in a full charge state; the full charge state secondary battery cell is placed in a 60℃ constant temperature oven for storage for 100 days, after which the secondary battery cell is taken out, and when the temperature of the secondary battery cell drops to 25℃, it is discharged at 1 / 3C constant current to 2.8V, and the obtained discharge capacity is recorded as the post-storage capacity C1. The capacity retention rate of the secondary battery cell stored at 60℃ for 100 days = post-storage capacity C1 / pre-storage capacity C0 x 100%, that is, the storage performance of the battery cell.

[0466] 6. Test of cycle performance of battery cell

[0467] At 45℃, the battery cell is charged at 1 / 3C constant current to 3.6V, then charged at 3.6V constant voltage to 0.05C current, and left for 5 min, then discharged at 1 / 3C to 2.8V, which is one charge-discharge process, and the discharge capacity at this time is recorded as the discharge capacity of the first cycle of the battery. The charging and discharging cycles are repeated for 500 times, and the capacity retention rate (%) of the battery after 500 cycles at 45℃ is calculated = (discharge capacity of the Nth cycle of the battery / discharge capacity of the first cycle of the battery) x 100%.

[0468] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the application, and equivalent parts can be substituted for the parts thereof. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A battery cell, characterized by, The application relates to a positive electrode sheet, a negative electrode sheet and a separator film between the positive electrode sheet and the negative electrode sheet. The separator film comprises a porous base film and a coating layer arranged on at least one side of the porous base film. The coating layer comprises heat-resistant particles and first binder particles. The first binder particles are embedded in the heat-resistant particles and form protrusions on the surface of the coating layer. The heat-resistant particles comprise organic compound particles with a spherical or quasi-spherical morphology. The mass content of the organic compound particles in the coating layer is 50% to 80%.

2. The battery cell of claim 1, wherein, The first binder particles comprise at least one of polyvinylidene fluoride, poly (vinylidene fluoride-co-trichloroethylene), poly (vinylidene fluoride-co-trifluorochloroethylene), poly (vinylidene fluoride-co-trifluoroethylene), poly (vinylidene fluoride-co-tetrafluoroethylene), poly (vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-hydroxymethyl acrylamide copolymer, lauryl methacrylate-methacrylic acid-N-hydroxymethyl acrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-hydroxymethyl acrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-hydroxymethyl acrylamide-acrylonitrile copolymer.

3. The battery cell according to claim 1 or 2, characterized in that, The average number average particle size of the first binder particles is 5 mu m to 15 mu m.

4. The battery cell according to any one of claims 1 to 3, characterized in that, The first binder particles are secondary particles.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The mass content of the first binder particles in the coating layer is 5% to 30%.

6. The battery cell according to any one of claims 1 to 5, characterized in that, The coating layer further comprises second binder particles, and the second binder particles comprise at least one of polyvinylidene fluoride, poly (vinylidene fluoride-co-trichloroethylene), poly (vinylidene fluoride-co-trifluorochloroethylene), poly (vinylidene fluoride-co-trifluoroethylene), poly (vinylidene fluoride-co-tetrafluoroethylene), poly (vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-hydroxymethyl acrylamide copolymer, lauryl methacrylate-methacrylic acid-N-hydroxymethyl acrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-hydroxymethyl acrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-hydroxymethyl acrylamide-acrylonitrile copolymer.

7. The battery cell according to any one of claims 1 to 6, characterized in that, The average number average particle size of the second binder particles is 5 mu m to 15 mu m.

8. The battery cell of claim 7, wherein, The second binder particles are secondary particles.

9. The battery cell according to claim 7 or 8, characterized in that, The mass content of the second binder particles in the coating layer is 5% to 30%.

10. The battery cell according to any one of claims 7 to 9, characterized in that, The coating layer further comprises third binder particles, 11. The battery cell of any one of claims 1 to 10, wherein, ​ The third adhesive comprises at least one of polyimide, polyetherimide, polyacrylic acid, polyacrylate, ethylene-vinyl acetate copolymer, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluorine rubber.

12. The battery cell of claim 11, wherein, The mass content of the third adhesive in the coating layer is 3% to 15%.

13. The battery cell of any one of claims 1 to 12, wherein, The organic compound particle Dn50 satisfies 100 nm≤Dn50≤700 nm; wherein Dn50 refers to a particle size corresponding to a cumulative particle quantity distribution of 50% in a particle size quantity distribution curve of the organic compound particle.

14. The battery cell of any one of claims 1 to 13, wherein, The organic compound particle comprises a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%.

15. The battery cell of claim 14, wherein, The cross-linked polymer comprises a silicon-oxygen structure-containing organosilicon polymer.

16. The battery cell of claim 15, wherein, The silicone polymer containing siloxane structure includes a phenyl group, the silicone polymer containing siloxane structure is polymerized by a monomer and a crosslinking agent shown in formula (I), R1, R2 are each independently selected from C1-C4 alkyl and C2-C4 alkenyl, R3 comprises C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, and R4 comprises C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; and the cross-linking agent comprises divinylbenzene.

17. The battery cell of any one of claims 15 or 16, wherein, The silicon-oxygen structure-containing organosilicon polymer satisfies one or more of the following conditions: (1) the cross-linking degree of the silicon-oxygen structure-containing organosilicon polymer is 75% to 95%; (2) the mass content of silicon in the silicon-oxygen structure-containing organosilicon polymer is 10% to 25%; and (3) the mass content of phenyl in the silicon-oxygen structure-containing organosilicon polymer is 2% to 12%.

18. The battery cell of any one of claims 15-17, wherein, The silicon-oxygen structure-containing organosilicon polymer comprises a skeleton formed by a compound represented by formula (II), R a [SiO 3 / 2 ] n Formula (II), wherein n is at least one of the integers 4 to 12, R a including cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; Optionally, n is 8, R a comprises C1-C3alkyl.

19. The battery cell of claim 18, wherein, The organosilicon polymer containing siloxane structures includes one or more of the monomers represented by Formula (III) that are hydrolyzed and polycondensed, R'1 comprises C1-C3 alkyl.

20. The battery cell of claim 18 or 19, wherein, The silicon-oxygen structure-containing organosilicon polymer satisfies one or more of the following conditions: (1) the cross-linking degree of the silicon-oxygen structure-containing organosilicon polymer is 85% to 97%; (2) the mass content of silicon in the silicon-oxygen structure-containing organosilicon polymer is 25% to 45%; and (3) the mass content of the skeleton formed by the compound represented by formula (II) in the silicon-oxygen structure-containing organosilicon polymer is 40% to 60%.

21. The battery cell of any one of claims 1-20, wherein, The organic compound particle satisfies at least one of the following conditions (1) to (5): (1) the cyclic voltammogram of the organic compound particle in the first cycle has no oxidation peak in the voltage range of 0 to 4.4 V; (2) the organic compound particle has no glass transition temperature at 300°C; (3) the initial thermal weight loss temperature T of the organic compound particles 3d satisfies: T 3d ≥ 250°C; (4) the dissolution rate of the organic compound particle is less than or equal to 5% when the organic compound particle is soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days; and (5) the true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 .

22. The battery cell of any one of claims 1-21, wherein, The isolation film satisfies one or more of the following conditions: (1) the thickness of the coating layer is 0.5 μm to 10 μm; (2) the coating has an areal density of 1.5 g / m 2 ~ 6 g / m 2 ; (3) the longitudinal heat shrinkage rate of the isolation film is less than or equal to 5% when the isolation film is heated at 130°C for 1 h; and (5) the dissolution rate of the isolation film is less than or equal to 5% when the isolation film is soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days. (4) the separation film has a transverse heat shrinkage of less than or equal to 5% when heated at 130°C for 1 hour; (5) the separation film has an air permeability of 150 s / 100 mL to 500 s / 100 mL.

23. A battery device characterized by comprising: Comprising: The battery cell according to any one of claims 1 to 22.

24. An electrical device, comprising: Comprising: The battery cell according to any one of claims 1 to 22 or the battery device according to claim 23.

25. A separator film characterized by comprising: Comprising: A porous base film and a coating layer disposed on at least one side of the porous base film; The coating layer comprises heat-resistant particles and first binder particles; The first binder particles are embedded in the heat-resistant particles, and form protrusions on the surface of the coating layer; The heat-resistant particles comprise organic compound particles, and the organic compound particles have a spherical or spherical-like morphology.

26. The separator membrane of claim 25, wherein, The mass content of the organic compound particles in the coating layer is 50% to 80%.

27. The separator membrane according to claim 25 or 26, characterized in that, The first binder particles comprise at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-methacrylic acid-N-methylol acrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol acrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

28. The separator membrane of any one of claims 25 to 27, wherein, The average number average particle size of the first binder particles is 5 μm to 15 μm.

29. The separator membrane according to any one of claims 25 to 28, characterized in that, The first binder particles are secondary particles.

30. The separator membrane of any one of claims 25 to 29, wherein, The mass content of the first binder particles in the coating layer is 5% to 30%.

31. The separator membrane of any one of claims 25 to 30, wherein, The coating layer further comprises second binder particles, and the second binder particles comprise at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), methyl acrylate-acrylic acid-acrylamide copolymer, ethyl acrylate-acrylic acid-acrylamide copolymer, isooctyl acrylate-acrylic acid-acrylamide copolymer, n-butyl acrylate-acrylic acid-N-methylol acrylamide copolymer, lauryl methacrylate-methacrylic acid-N-methylol acrylamide copolymer, methyl acrylate-acrylamide-acrylonitrile copolymer, n-butyl methacrylate-N-methylol acrylamide-methacrylonitrile copolymer, t-butyl acrylate-N-methylol acrylamide-acrylonitrile copolymer.

32. The separator membrane of claim 31, wherein, The average number average particle size of the second binder particles is 5 μm to 15 μm.

33. The separator membrane of claim 31 or 32, wherein, The second binder particles are secondary particles.

34. The separator membrane of any one of claims 31 to 33, wherein, The mass content of the second binder particles in the coating layer is 5% to 30%.

35. The separator membrane of any one of claims 25 to 34, wherein, the coating further comprises a third binder, the third binder comprises at least one of polyimide, polyetherimide, polyacrylic acid, polyacrylate, ethylene vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl pullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene butadiene rubber, fluoroelastomer.

36. The separator membrane of claim 35, wherein, the mass content of the third binder in the coating is 3% to 15%.

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