Battery cell, battery apparatus, and electric device

Abstract

The present application provides a battery cell, a battery apparatus, and an electric device. 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 membrane and a coating arranged on at least one side of the porous base membrane, wherein the coating comprises organic compound particles. The morphology of the organic compound particles is spherical or quasi-spherical; and the Dn50 of the organic compound particles satisfies: 100 nm≤Dn50≤700 nm, wherein Dn50 refers to the corresponding particle size when the cumulative number distribution of particles reaches 50% in a particle size number distribution curve of the organic compound particles. The technical solution of the present application is beneficial for improving the cycle performance of the battery cell.

Description

Battery cell, battery device, and electric device 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, dispersion liquid of silicon-containing organic resin particles, separator, secondary battery cell, battery device, and electric 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, and an electric device. BACKGROUND

[0003] In recent years, battery technology has been widely applied to energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, as well as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields, thereby achieving great development.

[0004] With the development and application of battery technology, higher requirements are placed on the cycle performance of battery cells. Electrolyte is an important development part of battery cells, and the wettability of electrolyte in the separator will affect the wettability of electrolyte in the entire electrode sheet, and thus affect the cycle performance of the battery cell. Therefore, how to improve the cycle performance of the battery cell is a technical problem to be solved. SUMMARY

[0005] The present application is made in view of the above-mentioned problem, and aims to provide a battery cell, a battery device, and an electric device, which are advantageous in improving the cycle performance of the battery cell. In a first aspect, the present application provides a battery cell, which includes a positive electrode sheet, a negative electrode sheet, and a separator between the positive electrode sheet and the negative electrode sheet; the separator includes a porous base film and a coating layer provided on at least one side of the porous base film; the coating layer includes organic compound particles; the morphology of the organic compound particles is spherical or spheroidal; and in a cross section of the coating layer along the thickness direction of the separator, the Dn50 of the organic compound particles satisfies 100 nm ≤ Dn50 ≤ 700 nm, where Dn50 refers to the particle size corresponding to the cumulative amount of particles reaching 50% in the particle size number distribution curve of the organic compound particles.

[0006] In the embodiments of the present application, the organic compound particles with spherical or spherical-like morphology are more easily arranged uniformly in the dispersion and stacking process, reducing the problem of uneven stacking of particles in the coating caused by irregular particle morphology. The particles can form a uniform and continuous electrolyte infiltration channel structure, thereby facilitating the improvement of the electrolyte infiltration performance. When the electrolyte passes through the coating, it can penetrate into the inside of the electrode sheet along the relatively uniform electrolyte infiltration channel, the electrolyte infiltration resistance is smaller, and the local retention phenomenon is reduced. The spherical or spherical-like morphology can increase the contact area between the electrolyte and the particle surface, reduce the surface wetting resistance, and make the electrolyte more easily infiltrate in the coating. By controlling the Dn50 of the spherical or spherical-like particles to be 100 nm-700 nm, the electrolyte infiltration efficiency and the penetration efficiency in the coating can be considered, the electrolyte infiltration performance in the separator film is improved, thereby facilitating the improvement of the cycle performance of the battery cell.

[0007] In a possible implementation, the Dn90 of the organic compound particles satisfies: 200 nm≤Dn90≤1000 nm, Dn90 refers to the particle size corresponding to the cumulative number distribution of 90% in the particle size number distribution curve of the organic compound particles, and / or the Dn10 of the organic compound particles satisfies: 50 nm≤Dn10≤400 nm, Dn10 refers to the particle size corresponding to the cumulative number distribution of 10% in the particle size number distribution curve of the organic compound particles.

[0008] In the embodiments of the present application, the Dn90 is 200 nm-1000 nm, which can reduce the local protrusions formed by the too large particles on the surface of the coating. Such protrusions are easy to damage the uniformity of the coating, or cause stress concentration in the subsequent rolling or winding process, resulting in the weakening or even tearing of the bonding interface between the coating and the separator film base film, thereby damaging the pore structure of the porous base film and reducing the electrolyte infiltration performance. The Dn10 is 50 nm-400 nm, which can reduce the excessive filling of too fine particles between the infiltration channels of the coating, and maintain the good electrolyte penetration efficiency in the separator film. When the Dn10 is less than or equal to 50 nm, there are too many superfine particles, which are easy to block the originally connected electrolyte infiltration channels, which can reduce the electrolyte infiltration rate or even cause local blockage, thereby reducing the electrolyte infiltration performance.

[0009] In a possible implementation, the roundness of the organic compound particles is 0.5-1.0.

[0010] In the embodiments of the present application, when the roundness of the organic compound particles is high, the shape of the particles is closer to a regular sphere, the friction and stacking resistance between the particles are small during the dispersion of the slurry, and thus the slurry flows more uniformly, which can form a coating with uniform thickness and good pore structure after coating and drying, so that the electrolyte can enter the interior more quickly and uniformly when contacting the coating, thereby facilitating the improvement of the wettability of the electrolyte in the separator membrane. The particles with regular morphology have fewer corners and irregular protrusions, and the probability of local stress concentration or micro-cracks in the coating is low, which is beneficial to the structural stability of the coating. At the same time, the surface of the particles with high roundness can fully contact with the electrolyte, the surface wetting resistance is low, the electrolyte can quickly penetrate along the uniform and continuous electrolyte infiltration channel between the particles, and the local retention and uneven infiltration phenomenon is reduced, thereby achieving good electrolyte wetting effect and ion conduction efficiency. Therefore, the roundness of the organic compound particles meets the above range, which can improve the wettability of the electrolyte in the separator membrane, thereby improving the cycle performance of the battery cell.

[0011] In a possible implementation, the organic compound particles include a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%.

[0012] On the one hand, the cross-linked polymer has a three-dimensional network structure and can maintain a stable spatial configuration under thermal stress, so that the separator membrane has good heat resistance. On the other hand, by controlling the cross-linking degree of the cross-linked polymer to be 70% to 98%, the coating particles can have good heat resistance at high temperatures, the heat resistance of the separator membrane is improved, the overall structural integrity of the separator membrane at high temperatures is ensured, and thus the reliability of the battery cell at high temperatures is improved.

[0013] In a possible implementation, the cross-linked polymer includes a silicone polymer containing a siloxane structure.

[0014] In the embodiments of the present application, the siloxane structure of the silicone polymer can improve the surface polarity of the cross-linked polymer, produce strong interaction with the solvent molecules in the electrolyte, improve the affinity of the coating for the electrolyte, and thus improve the wettability of the electrolyte. The cross-linked polymer includes a silicone polymer containing a siloxane structure, and because the silicone polymer contains a siloxane bond, the bond energy of the siloxane bond is high and the siloxane bond is not easy to decompose at high temperatures, which can be beneficial to further improving the thermal stability of the material, thereby enhancing the heat resistance of the coating of the separator membrane. In addition, compared with inorganic particles, the density of the silicone polymer is low, and the overall mass of the coating can be reduced at the same thickness, which is beneficial to improving the energy density of the battery cell. Therefore, the cross-linked polymer includes a silicone polymer containing a siloxane structure, which can improve the structural stability of the coating and also improve the wettability of the electrolyte, thereby improving the cycle performance of the battery cell.

[0015] In a possible implementation, the organosilicon polymer containing siloxane structure includes phenyl groups, the organosilicon polymer containing siloxane structure is polymerized by monomers and a crosslinking agent represented by formula (I), and the crosslinking agent includes divinylbenzene. In formula (I), R1 and R2 are each independently selected from C1-C4 alkyl groups and C2-C4 alkenyl groups, R3 includes C1-C4 alkyl groups or C4-C8 (meth)acryloxyalkyl groups, and R4 includes C2-C8 alkenyl groups or C4-C8 (meth)acryloxyalkyl groups; and the crosslinking agent includes divinylbenzene.

[0016] In the embodiments of the present application, the affinity of the organosilicon polymer to the electrolyte can be improved by polymerization of the monomers represented by formula (I) and the crosslinking agent divinylbenzene, so that the organosilicon polymer has better electrolyte wettability while maintaining structural stability. The electrolyte can quickly penetrate into the pores of the coating in the coating, thereby improving the wettability of the electrolyte, and thus being beneficial to the cycle performance of the battery cell.

[0017] In a possible implementation, the organosilicon polymer containing siloxane structure satisfies at least one of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing siloxane structure is 75% to 95%; (2) the mass fraction of silicon elements in the organosilicon polymer containing siloxane structure is 10% to 25%; (3) the mass fraction of phenyl groups in the organosilicon polymer containing siloxane structure is 2% to 12%; (4) the organosilicon polymer containing siloxane structure includes silicon hydroxyl groups; and (5) the mass fraction of the silicon hydroxyl groups in the organosilicon polymer containing siloxane structure is 100 ppm to 1500 ppm.

[0018] In the embodiments of the present application, the organosilicon polymer containing siloxane structure is 75% to 95%, which has good heat resistance at high temperatures, so that the isolation film has better heat resistance, thereby improving the reliability of the battery cell. The mass fraction of silicon elements is 10% to 25%, which is helpful to improve the proportion of inorganic siloxane skeleton in the organosilicon polymer. The siloxane 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. The mass fraction of phenyl groups is 2% to 12%, which can introduce a rigid structure of aromatic structure and conjugate effect, and further be beneficial to improve the heat resistance of the isolation film.

[0019] In a possible implementation, the organosilicon polymer containing siloxane structure includes a skeleton composed of a compound represented by formula (II), R a [SiO 3 / 2 ] n Formula (II), wherein n is an integer of any value in the range of 4 to 12, R a including cycloalkyl groups, aryl groups, C1-C12 Alkyl groups, C1-C 12 alkenyl, C1-C 12 The alkynyl group; can be selected as n=8, R a Including C1 to C3 alkyl groups.

[0020] In this embodiment of the application, by introducing the covalent polyhedral framework shown in formula (II) into the organic compound, a stable three-dimensional structure can be formed inside the molecule of the organic compound. This type of polyhedral framework has high symmetry and regularity, and the internal atoms are connected by strong covalent bonds. The molecular structure is not easily broken or collapsed under high temperature conditions, which is beneficial to improving the heat resistance of the isolation membrane. Moreover, the covalent polyhedral framework shown in formula (II) contains Si-O bonds, which have high bond energy and are not easily decomposed at high temperatures, which can further improve the thermal stability of the material. By selecting n as 8, R a The presence of C1 to C3 alkyl groups can further improve the rigidity and thermal stability of organic compounds. Organic compound particles can act as rigid support points at high temperatures, improving the heat resistance of the separator and thus enhancing the reliability of battery cells.

[0021] In one possible implementation, the organosilicon polymer containing a silicon-oxygen structure comprises one or more monomers of formula (II) obtained by hydrolysis and condensation polymerization. R'1 includes C1 to C3 alkyl groups.

[0022] In this embodiment, an organosilicon polymer with a complete cage-like structure and uniformly dispersed molecular chains can be obtained by employing the hydrolysis-condensation reaction of the monomer of formula (III). The resulting organosilicon polymer particles are uniformly distributed in the separator coating, forming a coating structure with good pore connectivity, which facilitates continuous electrolyte penetration and improves the wetting performance of the separator. Sufficient electrolyte wetting in the separator ensures uniform utilization of the negative electrode active material during charging and discharging, reducing low utilization or capacity decay of the negative electrode active material due to insufficient local wetting, thereby slowing down the battery capacity decay rate and improving the cycle performance of the battery cell.

[0023] In a possible implementation, the organosilicon polymer containing a siloxane structure satisfies at least one of the following conditions: (1) the cross-linking degree of the organosilicon polymer containing a siloxane structure is 85% to 97%; (2) the mass fraction of silicon in the organosilicon polymer containing a siloxane structure is 25% to 45%; (3) the mass fraction of a skeleton composed of the compound shown in the formula (II) in the organosilicon polymer containing a siloxane structure is 40% to 60%; (4) the organosilicon polymer containing a siloxane structure includes a silicon hydroxyl group; and (5) the mass fraction of the silicon hydroxyl group in the organosilicon polymer containing a siloxane structure is 100 ppm to 2000 ppm.

[0024] In the embodiment, the cross-linking degree of the organosilicon polymer containing a siloxane structure is 85% to 97%, which guarantees the structural stability of the organosilicon polymer at high temperature; the high mass fraction of silicon makes the polarity of the organosilicon polymer higher, and the affinity of the organosilicon polymer to the electrolyte is enhanced, thereby improving the diffusion speed and wetting capacity of the electrolyte in the coating; the mass fraction of the skeleton composed of the compound shown in the formula (II) in the organosilicon polymer containing a siloxane structure is 40% to 60%, which can ensure that the cross-linked polymer has good rigidity and structural stability, reduces the structural collapse of the separator film at high temperature, and is beneficial to improving the heat resistance of the separator film, thereby improving the reliability of the battery cell at high temperature; the silicon hydroxyl group can increase the interaction between the polymer and the electrolyte molecules, and further improve the wettability and interface stability of the coating. The organosilicon polymer includes the silicon hydroxyl group, which can provide additional active sites. On the one hand, the silicon hydroxyl group and the polar solvent molecules in the electrolyte can easily form hydrogen bonds or strong dipole interactions, thereby further improving the liquid affinity and wettability of the coating; on the other hand, the silicon hydroxyl group can undergo condensation or cross-linking reaction with other functional groups (such as epoxy group and carboxyl group) in the process of heat treatment or cross-linking, thereby reducing the structural collapse or shedding phenomenon of the coating at high temperature and long cycle conditions, and improving the wetting performance of the electrolyte in the separator film.

[0025] By limiting the organosilicon polymer to satisfy at least one of the above conditions, the wettability of the electrolyte to the separator film and the heat resistance of the separator film can be improved, thereby improving the reliability and cycle performance of the battery cell.

[0026] In a possible implementation, the organic compound particles satisfy at least one of the following conditions: (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; and (3) the initial thermal weight loss temperature T 3dgreater than or equal to 250 DEG C; (4) the dissolution rate of the organic compound particles is less than or equal to 5% after the organic compound particles are soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60 DEG C for 7 days; (5) the true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 .

[0027] In the embodiment of the application, the cyclic voltammogram of the organic compound particles in the first cycle does not have an oxidation peak in the voltage range of 0 V to 4.40 V, indicating that the organic compound particles are stable in the voltage range of 0 V to 4.40 V and have good electrochemical stability, and can be applied to high-voltage battery cells, so that the battery cells have good capacity performance at high voltage, and the working voltage and energy density of the battery cells are improved.

[0028] The organic compound particles have no glass transition temperature below 300 DEG C, that is, the DSC curve of the organic compound particles remains rigid in the solid state below 300 DEG C, and no molecular chain segment movement or softening occurs, so that the heat resistance of the isolation film is improved.

[0029] The initial thermal weight loss temperature T 3d greater than or equal to 250 DEG C, indicating that the weight of the organic compound particles does not change significantly at high temperature, so that the organic compound particles have high thermal stability during the use of the battery cell and in a high-temperature environment, and are not prone to thermal decomposition.

[0030] The dissolution of the organic compound particles is less than 5% after the organic compound particles are soaked in the electrolyte at 60 DEG C for 7 days, and the organic compound particles are not prone to precipitation or dissolution in the electrolyte environment, reducing the occurrence of electrolyte contamination or side reactions between the organic compound particles and the electrolyte during the cycle of the battery cell, and the isolation film has good structural stability, which is beneficial to the cycle performance and reliability of the battery cell.

[0031] The true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 , which is beneficial to improve the capacity of the battery cell and obtain a battery cell with high energy density.

[0032] In one possible implementation, the mass fraction of the organic compound particles in the coating is 50% to 97%.

[0033] In the embodiment of the application, by limiting the mass fraction of the organic compound particles in the coating to satisfy the above range, the coating has structural stability and air permeability, and the heat resistance of the isolation film is improved, thereby improving the reliability of the battery cell.

[0034] In a possible implementation, the coating further comprises a first binder, and the first binder satisfies at least one of the following conditions: (1) the first 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; and (2) the mass fraction of the first binder in the coating is 3% to 15%.

[0035] In the embodiments of the present application, the organic compound particles in the coating are connected and fixed to each other by the first binder, reducing the situation that the organic compound particles fall off during coating and use. The mass fraction of the first binder satisfies the above range, which can reduce the proportion of the organic compound particles in the coating while ensuring the adhesion, so as to balance the stability and heat resistance of the coating, and improve the heat resistance of the isolation film.

[0036] In a possible implementation, the isolation film further comprises second binder particles, and the second binder particles are located in the coating, or the isolation film further comprises a bonding layer, the bonding layer is arranged on at least one side of the coating away from the base film, and the second binder particles are located in the bonding layer. The second binder particles satisfy one or more of the following conditions: (1) 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), polyacrylate, polymethyl methacrylate, and polyacrylonitrile; and (2) the volume average particle size of the second binder particles is 5 μm to 20 μm.

[0037] In the embodiments of the present application, the second binder particles are added in the coating or the bonding layer of the isolation film. The second binder particles can fill the gap between the negative electrode sheet and the isolation film, form a relatively firm bonding interface, and help to improve the bonding strength between the isolation film and the negative electrode sheet, so as to improve the overall stability of the isolation film, reduce the interlayer peeling phenomenon between the isolation film and the negative electrode sheet caused by thermal stress or electrochemical action in the cycle process, and thus improve the cycle performance of the battery cell. The volume average particle size Dv50 of the second binder particles satisfies the above range, which ensures that the second binder particles can be uniformly distributed and can maintain moderate fluidity during hot pressing, thereby further improving the cycle performance of the battery cell.

[0038] In a possible implementation, the isolation film satisfies at least one 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 2 2 to 6 g / m; (3) the longitudinal thermal shrinkage of the isolation film is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage of the isolation film is less than or equal to 5% when heated at 130°C for 1 h; and (5) the air permeability of the isolation film is 150 s / 100 mL to 500 s / 100 mL.

[0039] In the embodiments of the present application, the coating layer is too thin to form an effective thermal insulation layer, and is too thick to increase the thickness of the diaphragm and reduce the energy density of the battery cell. The thickness of the coating layer is 0.5 μm to 10 μm, which can provide a uniform and dense heat-resistant coating layer, improve the heat resistance of the isolation film, and thus improve the reliability of the battery cell.

[0040] The area density of the coating layer is 1.5 g / m 2 2 2 to 6 g / m, which can ensure that the coating layer has moderate quality, can improve the stability and heat resistance of the isolation film, and will not significantly increase the weight of the isolation film, thereby being conducive to the energy density and reliability of the battery cell.

[0041] The isolation film still has very low longitudinal thermal shrinkage and transverse thermal shrinkage at 130°C, that is, the isolation film has good heat resistance at high temperatures.

[0042] The air permeability of the isolation film is 150 s / 100 mL to 500 s / 100 mL, which ensures that the electrolyte can be uniformly infiltrated and maintain the rapid transmission of ions, ensures the ion transmission efficiency of the isolation film, reduces the case that the air permeability of the isolation film is too low to cause electrochemical polarization and reduce the reliability of the battery cell.

[0043] In a second aspect, a battery device is provided, which includes the battery cell in any possible implementation of the first aspect.

[0044] In a third aspect, a power consumption device is provided, which includes the battery cell in any possible implementation of the first aspect or the battery device of the second aspect.

[0045] In a fourth aspect, the embodiments of the present application provide an isolation film, which includes a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer includes organic compound particles, the morphology of the organic compound particles is spherical or spherical-like, and the Dn50 of the organic compound particles satisfies 100 nm≤Dn50≤700 nm, where Dn50 refers to the particle size corresponding to the cumulative particle amount distribution of 50% in the particle size number distribution curve of the organic compound particles.

[0046] In the embodiments of the present application, the organic compound particles with spherical or spherical-like morphology are more easily arranged uniformly in the dispersion and stacking processes, reducing the problem of uneven stacking of particles in the coating caused by irregular particle morphology. The particles can form a uniform and continuous electrolyte infiltration channel structure, thereby facilitating the improvement of the electrolyte infiltration performance. When the electrolyte passes through the coating, it can penetrate into the inside of the electrode sheet along the relatively uniform electrolyte infiltration channel, the electrolyte infiltration resistance is smaller, and the local retention phenomenon is reduced. The spherical or spherical-like morphology can increase the contact area between the electrolyte and the particle surface, reduce the surface wetting resistance, and make the electrolyte more easily infiltrate in the coating. By controlling the Dn50 of the spherical or spherical-like particles to be 100 nm to 700 nm, the electrolyte infiltration efficiency and the penetration efficiency in the coating can be considered, and the electrolyte infiltration performance in the separator film is improved, thereby facilitating the improvement of the cycle performance of the battery cell.

[0047] In a possible implementation, the Dn90 of the organic compound particles satisfies: 200 nm≤Dn90≤1000 nm, where Dn90 refers to the particle size corresponding to the cumulative number distribution of 90% in the particle size number distribution curve of the organic compound particles, and / or the Dn10 of the organic compound particles satisfies: 50 nm≤Dn10≤400 nm, where Dn10 refers to the particle size corresponding to the cumulative number distribution of 10% in the particle size number distribution curve of the organic compound particles.

[0048] In the embodiments of the present application, the Dn90 is 200 nm to 1000 nm, which can reduce the local protrusions formed by the too large particles on the surface of the coating. Such protrusions can easily damage the uniformity of the coating, or cause stress concentration in the subsequent rolling or winding process, resulting in the weakening or even tearing of the bonding interface between the coating and the separator film base film, thereby damaging the pore structure of the porous base film and reducing the electrolyte infiltration performance. The Dn10 is 50 nm to 400 nm, which can reduce the excessive filling of too fine particles between the infiltration channels of the coating, and maintain the good electrolyte penetration efficiency in the separator film. When the Dn10 is less than or equal to 50 nm, there are too many superfine particles, which can easily block the originally connected electrolyte infiltration channels, resulting in a decrease in the electrolyte infiltration rate or even local blockage, and reducing the electrolyte infiltration performance.

[0049] In a possible implementation, the roundness of the organic compound particles is 0.5 to 1.0.

[0050] In the embodiments of the present application, when the roundness of the organic compound particles is high, the shape of the particles is closer to a regular sphere, the friction and stacking resistance between the particles are small during the dispersion of the slurry, and thus the slurry flows more uniformly, which can form a coating with uniform thickness and good pore structure after coating and drying, so that the electrolyte can enter the interior more quickly and uniformly when contacting the coating, thereby facilitating the improvement of the wettability of the electrolyte in the separator membrane. The particles with regular morphology have fewer corners and irregular protrusions, and the probability of local stress concentration or micro-cracks in the coating is low, which is beneficial to the structural stability of the coating. At the same time, the surface of the particles with high roundness can fully contact with the electrolyte, the surface wetting resistance is low, the electrolyte can quickly penetrate along the uniform and continuous electrolyte infiltration channel between the particles, and the local retention and uneven infiltration phenomenon is reduced, thereby achieving good electrolyte wetting effect and ion conduction efficiency. Therefore, the roundness of the organic compound particles meets the above range, which can improve the wettability of the electrolyte in the separator membrane, thereby improving the cycle performance of the battery cell.

[0051] In a possible implementation, the organic compound particles include a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%.

[0052] On the one hand, the cross-linked polymer has a three-dimensional network structure and can maintain a stable spatial configuration under thermal stress, so that the separator membrane has good heat resistance. On the other hand, by controlling the cross-linking degree of the cross-linked polymer to be 70% to 98%, the coating particles can have good heat resistance at high temperatures, the heat resistance of the separator membrane is improved, the overall structural integrity of the separator membrane at high temperatures is ensured, and thus the reliability of the battery cell at high temperatures is improved.

[0053] In a possible implementation, the cross-linked polymer includes a silicone polymer containing a siloxane structure.

[0054] In the embodiments of the present application, the siloxane structure of the silicone polymer can improve the surface polarity of the cross-linked polymer, produce strong interaction with the solvent molecules in the electrolyte, improve the affinity of the coating for the electrolyte, and thus improve the wettability of the electrolyte. The cross-linked polymer includes a silicone polymer containing a siloxane structure, and because the silicone polymer contains a siloxane bond, the bond energy of the siloxane bond is high and the siloxane bond is not easy to decompose at high temperatures, which can be beneficial to further improving the thermal stability of the material, thereby enhancing the heat resistance of the coating of the separator membrane. In addition, compared with inorganic particles, the density of the silicone polymer is low, and the overall mass of the coating can be reduced at the same thickness, which is beneficial to improving the energy density of the battery cell. Therefore, the cross-linked polymer includes a silicone polymer containing a siloxane structure, which can improve the structural stability of the coating and also improve the wettability of the electrolyte, thereby improving the cycle performance of the battery cell.

[0055] In a possible implementation, the organosilicon polymer containing siloxane structure includes a phenyl group, the organosilicon polymer containing siloxane structure is obtained by polymerization of a monomer shown in formula (I) and a crosslinking agent, and the crosslinking agent includes divinylbenzene. In formula (I), R1 and R2 are each independently selected from C1-C4 alkyl and C2-C4 alkenyl, R3 includes C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, and R4 includes C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; and the crosslinking agent includes divinylbenzene.

[0056] In the embodiments of the present application, the organosilicon polymer containing siloxane structure is obtained by polymerization of the monomer shown in formula (I) and the crosslinking agent divinylbenzene, the particle has a three-dimensional network skeleton formed by the phenyl structure and the monomer and the crosslinking agent, and the material has higher glass transition temperature and thermal decomposition temperature, thereby improving the heat resistance of the isolation film and the reliability of the battery cell.

[0057] In a possible implementation, the organosilicon polymer containing siloxane structure satisfies at least one of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing siloxane structure is 75% to 95%; (2) the mass fraction of silicon in the organosilicon polymer containing siloxane structure is 10% to 25%; (3) the mass fraction of phenyl in the organosilicon polymer containing siloxane structure is 2% to 12%; (4) the organosilicon polymer containing siloxane structure includes a silicon hydroxyl group; and (5) the mass fraction of the silicon hydroxyl group in the organosilicon polymer containing siloxane structure is 100 ppm to 1500 ppm.

[0058] In the embodiments of the present application, the organosilicon polymer containing siloxane structure is 75% to 95%, and has good heat resistance at high temperature, so that the isolation film has good heat resistance, thereby improving the reliability of the battery cell. The mass fraction of silicon is 10% to 25%, which helps to improve the proportion of inorganic siloxane skeleton in the organosilicon polymer. The siloxane skeleton including silicon provides high thermal decomposition temperature and oxidation resistance, so that the isolation film has structural stability in a high-temperature environment. The mass fraction of phenyl is 2% to 12%, which can introduce a rigid structure of aromatic structure and conjugate effect, and further helps to improve the heat resistance of the isolation film.

[0059] In a possible implementation, the organosilicon polymer containing siloxane structure includes a skeleton composed of a compound shown in formula (II) a [SiO 3 / 2 ] n Formula (II), wherein n is at least one of integers 4 to 12, R a including cycloalkyl, aryl, C1-C12 Alkyl groups, C1-C 12 alkenyl, C1-C 12 The alkynyl group; can be selected as n=8, R a Including C1 to C3 alkyl groups.

[0060] In this embodiment, by introducing the covalent polyhedral framework shown in formula (II) into the organic compound, a stable three-dimensional structure can be formed inside the molecule of the organic compound. This type of polyhedral framework has high symmetry and regularity, and the internal atoms are connected by strong covalent bonds. The molecular structure is not easily broken or collapsed under high temperature conditions, which is beneficial to improving the heat resistance of the isolation film. Moreover, the covalent polyhedral framework shown in formula (II) contains Si-O bonds, which have high bond energy and are not easily decomposed at high temperatures, which can further improve the thermal stability of the material. By selecting n as 8, R a The presence of C1 to C3 alkyl groups can further improve the rigidity and thermal stability of organic compounds. Organic compound particles can act as rigid support points at high temperatures, improving the heat resistance of the separator and thus enhancing the reliability of battery cells.

[0061] In one possible implementation, the organosilicon polymer containing a silicon-oxygen structure is obtained by hydrolysis and polycondensation of one or more monomers of formula (ⅠII). R'1 includes C1 to C3 alkyl groups.

[0062] In this embodiment, an organosilicon polymer with a complete cage-like structure and uniformly dispersed molecular chains can be obtained by employing the hydrolysis-condensation reaction of the monomer of formula (III). The resulting organosilicon polymer particles are uniformly distributed in the separator coating, forming a coating structure with good pore connectivity, which facilitates continuous electrolyte penetration and improves the wetting performance of the separator. Sufficient electrolyte wetting in the separator ensures uniform utilization of the negative electrode active material during charging and discharging, reducing low utilization or capacity decay of the negative electrode active material due to insufficient local wetting, thereby slowing down the battery capacity decay rate and improving the cycle performance of the battery cell.

[0063] In a possible implementation, the organosilicon polymer containing the siloxane structure satisfies at least one of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing the siloxane structure is 85% to 97%; (2) the mass fraction of silicon in the organosilicon polymer containing the siloxane structure is 25% to 45%; (3) the mass fraction of the skeleton composed of the compound shown in the formula (II) in the organosilicon polymer containing the siloxane structure is 40% to 60%; (4) the organosilicon polymer containing the siloxane structure includes a silicon hydroxyl group; and (5) the mass fraction of the silicon hydroxyl group in the organosilicon polymer containing the siloxane structure is 100 ppm to 2000 ppm.

[0064] In the embodiment, the crosslinking degree of the organosilicon polymer containing the siloxane structure is 85% to 97%, which guarantees the structural stability of the organosilicon polymer at high temperature; the higher mass fraction of silicon makes the polarity of the organosilicon polymer higher, and the affinity of the organosilicon polymer to the electrolyte is enhanced, thereby improving the diffusion speed and wetting capacity of the electrolyte in the coating; the mass fraction of the skeleton composed of the compound shown in the formula (II) in the organosilicon polymer containing the siloxane structure is 40% to 60%, which can ensure that the crosslinked polymer has good rigidity and structural stability, reduces the structural collapse of the separator film at high temperature, and is beneficial to improving the heat resistance of the battery monomer, thereby improving the reliability of the battery monomer at high temperature; the silicon hydroxyl group can increase the interaction between the polymer and the electrolyte molecules, and further improve the wettability and interface stability of the coating. The organosilicon polymer includes the silicon hydroxyl group, which can provide additional active sites. On the one hand, the silicon hydroxyl group and the polar solvent molecules in the electrolyte can easily form hydrogen bonds or strong dipole interactions, thereby further improving the liquid affinity and wettability of the coating; on the other hand, the silicon hydroxyl group can undergo condensation or crosslinking reaction with other functional groups (such as epoxy groups and carboxyl groups) in the process of heat treatment or crosslinking, thereby reducing the structural collapse or shedding phenomenon of the coating at high temperature and long cycle conditions, and improving the wetting performance of the electrolyte in the separator film.

[0065] In a possible implementation, the mass fraction of the organic compound particles in the coating is 50% to 97%.

[0066] By limiting the mass fraction of the organic compound particles in the coating to satisfy the above range, the coating can have a relatively uniform electrolyte infiltration channel, the electrolyte infiltration performance in the separator film is improved, and the cycle performance of the battery monomer is improved. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below only show some of the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the drawings.

[0068] FIG. 1 is a schematic view of a battery cell according to an embodiment of the present application.

[0069] FIG. 2 is a schematic view of a structure of a battery cell according to another embodiment of the present application.

[0070] FIG. 3 is a schematic view of a battery device according to an embodiment of the present application.

[0071] FIG. 4 is a schematic view of an electric device according to an embodiment of the present application.

[0072] FIG. 5 is a schematic view of an electric device according to another embodiment of the present application.

[0073] FIG. 6 is a pyrolysis spectrum of an organic compound powder according to Embodiment 1 of the present application.

[0074] FIG. 7 is an SEM view of an organic compound particle according to Embodiment 1 of the present application.

[0075] Reference Signs:

[0076] 3: battery cell; 30: outer case; 31: case; 313: pressure relief mechanism; 32: end cap; 322: electrode terminal; 33: electrode assembly; 331: tab; 34: connecting member; 10: battery device; 11: box; 111: first box portion; 112: second box portion; 1: vehicle; 4: controller; 5: motor; 2: energy storage device. DETAILED DESCRIPTION

[0077] Hereinafter, the embodiments of the battery cell, the battery device, and the electric device of the present application will be described in detail with appropriate reference to the accompanying drawings, but there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters known well and repeated description of substantially the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided so that those skilled in the art can fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0078] "RANGES" disclosed herein are defined by both a lower and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, the selected lower limit and upper limit defining the boundaries of a particular range. Ranges defined in this manner can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" means a range of any combination of the numbers a and b, in which a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein, "0-5" is merely a shorthand for listing all of these numerical combinations. Also, when a parameter is stated to be an integer > 2, it is equivalent to disclose that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0079] 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 this application as well as the above

[0080] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0081] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, if not specifically stated otherwise.

[0082] The following terms have the following meanings, if not specifically stated otherwise. Any undefined terms have their art-recognized meaning.

[0083] "Alkyl" in the embodiments of the present application means to encompass straight-chain and branched-chain alkyl groups. For example, alkyl can be C1-C 20alkyl, C1-C12 alkyl, C1-C10 alkyl, C1-C6 alkyl, C1-C4 alkyl. In some embodiments, alkyl includes methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, cyclobutyl, pentyl, isopentyl, neopentyl, t-pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, cycloheptyl, octyl, cyclooctyl, nonyl, and decyl, among others. Additionally, alkyl groups can be optionally substituted, for example, alkyl groups substituted with halogen are haloalkyl groups. The term "haloalkyl" refers to an alkyl group in which some or all of the hydrogen atoms are replaced with halogen atoms, where the term "halogen atom" refers to fluorine, chlorine, bromine, iodine, and the like.

[0084] In embodiments of the present application, substituents of compounds are disclosed in combination ranges. For example, "C1-C12 alkyl" can represent C1, C2, C3, C4, C5, C6, C7, C8, C9, C10, C11, C12, C1-C12, C1-C11, C1-C10, C1-C9, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C12, C2-C11, C2-C10, C2-C9, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C12, C3-C11, C3-C10, C3-C9, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C12, C4-C11, C4-C10, C4-C9, C4-C8, C4-C7, C4-C6, C4-C5, C5-C12, C5-C11, C5-C10, C5-C9, C5-C8, C5-C7, C5-C6, C6-C12, C6-C11, C6-C10, C6-C9, C6-C8, C6-C7, C7-C12, C7-C11, C7-C10, C7-C9, C7-C8, C8-C12, C8-C11, C8-C10, C8-C9, C9-C12, C9-C11, C9-C10, C10-C12, C10-C11, and C11-C12 alkyl.

[0085] In embodiments of the present application, "alkenyl" refers to a non-aromatic unsaturated hydrocarbon group containing one or more carbon-carbon double bonds (C=C), for example, alkenyl can be C2-C20 alkenyl, C2-C12 alkenyl, C2-C10 alkenyl, C2-C6 alkenyl, C2-C4 alkenyl. In some embodiments, alkenyl includes ethenyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butanedienyl, pentenyl, hexenyl, cyclohexenyl, heptenyl, octenyl, nonenyl, and decenyl, among others.

[0086] The "cycloalkyl" in the embodiments of the present application refers to saturated cyclic alkyl groups with single ring, double ring and multiple rings. Specifically, the cycloalkyl group is a hydrocarbon group composed of one or more saturated carbon rings, which can be a single ring structure or a fused ring structure formed by connecting multiple rings through sharing one or more atoms. For example, the cycloalkyl group with a single ring structure can be cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, etc.; the cycloalkyl group with a fused ring structure can be cyclopentenyl, cyclohexenyl, tricycloalkyl, etc.

[0087] The "alkynyl" in the embodiments of the present application refers to a hydrocarbon group with carbon-carbon triple bond (C≡C).

[0088] In the present application, the terms "a plurality of" and "a plurality of" refer to two or more than two.

[0089] Generally, the battery monomer includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the charging and discharging process of the battery monomer, the active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. Among them, the electrolyte plays a role in conducting active ions between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, which prevents the positive and negative electrodes from short-circuiting while allowing the active ions to pass through, so that the electrochemical reaction of the battery monomer proceeds normally.

[0090] The development of battery technology needs to consider many 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 completion of the charge-discharge electrochemical process of the secondary battery monomer, and the commonly used separator film is mostly polyolefin material, but the heat resistance of polyolefin material is poor, which is easy to soften or melt at high temperature, which will cause the secondary battery monomer to short circuit. In order to improve the heat resistance of the separator film, a coating layer is usually coated on the separator film to improve the heat resistance of the separator film. Boehmite, alumina and other inorganic particles are currently commonly used coating fillers, but nano boehmite and alumina have poor dispersibility and are easy to agglomerate to form secondary particles. Due to the close accumulation inside the secondary particles, it is difficult for the electrolyte to penetrate into the small gaps inside, resulting in local areas that cannot be infiltrated. In addition, due to the irregular morphology of boehmite and alumina, irregular pore structures may be formed during accumulation, especially causing the flow resistance of the electrolyte in the narrow pore structure to increase, and the penetration speed to slow down, thereby affecting the infiltration of the electrolyte. The uneven penetration of the electrolyte will affect the conduction of lithium ions, and thus affect the cycle performance of the battery monomer. How to improve the infiltration performance of the electrolyte in the separator film to improve the cycle performance of the battery monomer is a technical problem to be solved at present.

[0091] Therefore, the application provides a battery monomer, which comprises a positive electrode sheet, a negative electrode sheet and a separator, the separator is located between the positive electrode sheet and the negative electrode sheet; the separator comprises a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer comprises organic compound particles; the morphology of the organic compound particles is spherical or spheroidal; and Dn50 of the organic compound particles satisfies 100nm≤Dn50≤700nm, wherein Dn50 refers to a particle size corresponding to 50% of cumulative particle quantity distribution in a particle size quantity distribution curve of the organic compound particles.

[0092] In the technical solution, the organic compound particles with spherical or spheroidal morphology are more easily arranged uniformly in the dispersion and accumulation process, the problem of uneven accumulation of the particles in the coating layer caused by irregular particle morphology is reduced, and uniform and continuous electrolyte infiltration channel structures can be formed between the particles, thereby facilitating improvement of the electrolyte infiltration performance. When the electrolyte passes through the coating layer, the electrolyte can penetrate into the interior of the electrode sheet along the relatively uniform electrolyte infiltration channel, the electrolyte infiltration resistance is small, and the local retention phenomenon is reduced. The spherical or spheroidal morphology can increase the contact area between the electrolyte and the particle surface, reduce the surface wetting resistance, and make the electrolyte more easily infiltrate in the coating layer. Meanwhile, if Dn50 of the organic compound particles is too small, the particles are too closely accumulated in the coating layer, which can easily lead to reduction of the porosity of the coating layer and reduction of the electrolyte permeation rate in the separator; if Dn50 is too large, the particles are not densely accumulated, the electrolyte permeation path is long, the combination between the particles is poor, the structural stability of the coating layer is reduced, and the coating layer can be easily detached from the porous base film. By controlling Dn50 of the spherical or spheroidal particles to be 100nm-700nm, the electrolyte infiltration efficiency and the permeation efficiency in the coating layer can be considered, the electrolyte infiltration performance in the separator is improved, and the cycle performance of the battery monomer is facilitated to be improved.

[0093] Next, the battery monomer provided by the application is introduced.

[0094] [Battery monomer]

[0095] The application provides a battery monomer, which comprises a positive electrode sheet, a negative electrode sheet and a separator, the separator is located between the positive electrode sheet and the negative electrode sheet; the separator comprises a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer comprises organic compound particles; the morphology of the organic compound particles is spherical or spheroidal; and Dn50 of the organic compound particles satisfies 100nm≤Dn50≤700nm, wherein Dn50 refers to a particle size corresponding to 50% of cumulative particle quantity distribution in a particle size quantity distribution curve of the organic compound particles.

[0096] In the embodiments of the present application, the porous base film refers to a film material having a micrometer and / or nanometer level pore structure. The porous base film can be a single-layer film or a multi-layer composite film. When the porous base film is a multi-layer composite film, the materials of the layers can be the same or different.

[0097] 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.

[0098] In some embodiments, the thickness of the porous base film can be 4 μm to 15 μm, and optionally 4 μm to 9 μm.

[0099] In some embodiments, the porosity of the porous base film can be 25% to 60%, and optionally 28% to 50%.

[0100] In some embodiments, the average pore size of the porous base film can be 25 nm to 82 nm.

[0101] 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, and 3-5 drops of wetting liquid are dropped thereon, and after the sample is completely wetted, it is placed in a mold, and then an inert gas (such as nitrogen) is used to extrude the wetting liquid in the pore channel of the sample to be tested, and 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 of PMI Company, and the testing pressure can be 100 psi to 350 psi. In the embodiments of the present application, the “organic compound” refers to a carbon-containing compound, in addition to simple compounds such as carbon oxides, carbonic acid, carbonates, etc., the organic compound usually also includes hydrogen, oxygen, nitrogen and sulfur elements.

[0102] In the embodiments of the present application, the “morphology of the particles is spherical or spheroidal” refers to that the particles are close to a spherical body in geometric shape or are in an approximately spherical state as a whole.

[0103] As an example, the morphology of the particles can be tested using instruments and methods known in the art. Specifically, after the battery cell is disassembled, the separator film is peeled off, and the separator film of a regular and clear area is selected. Then, the micro-morphology of the coating on the separator film is measured using a scanning electron microscope (SEM) and with reference to the standard JY / T010 1996. Then, the two-dimensional projection profile, edge curvature, surface morphology, and contrast variation of the particles in the coating 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, then the particle morphology is determined to be spherical. If the particle profile is close to circular, the edge is slightly irregular, and the surface can have slight undulations, then the particle morphology is determined to be spheroidal.

[0104] For example, the Dn50 of the organic compound particles can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, or any value within the above ranges.

[0105] In the above embodiments, the organic compound particles with spherical or spheroidal morphology are more easily arranged uniformly during dispersion and stacking, reducing the problem of uneven stacking of particles in the coating caused by irregular particle morphology, and the particles can form a uniform and continuous electrolyte infiltration channel structure, thereby facilitating improvement of the electrolyte infiltration performance. When the electrolyte passes through the coating, it can penetrate into the inside of the electrode sheet along the relatively uniform electrolyte infiltration channel, the electrolyte infiltration resistance is smaller, and the local retention phenomenon is reduced. The spherical or spheroidal morphology can increase the contact area between the electrolyte and the particle surface, reduce the surface wetting resistance, and make the electrolyte more easily infiltrate in the coating. By controlling the Dn50 of the spherical or spheroidal particles to be 100 nm to 700 nm, the electrolyte infiltration efficiency and penetration efficiency in the coating can be considered, and the electrolyte infiltration performance in the separator film is improved, thereby facilitating improvement of the cycle performance of the battery cell.

[0106] In some embodiments, the Dn90 of the organic compound particles satisfies: 200 nm≤Dn90≤1000 nm, Dn90 refers to the particle size corresponding to the cumulative number distribution of 90% of the particle size number distribution curve of the organic compound particles, and / or the Dn10 of the organic compound particles satisfies: 50 nm≤Dn10≤400 nm, Dn10 refers to the particle size corresponding to the cumulative number distribution of 10% of the particle size number distribution curve of the organic compound particles.

[0107] For example, the organic compound particle Dn90 can be 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, or any value within the above range. The organic compound particle Dn10 can be 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, or any value within the above range.

[0108] By limiting the Dn90 and / or Dn10 of the organic compound particles, the range of the particle size distribution of the organic compound particles can be controlled, the overall particle distribution can be more concentrated, the particle size distribution of the organic compound particles can be narrowed, the size distribution of the electrolyte infiltration channels in the coating can be more uniform, the influence of local structural defects on the electrolyte infiltration efficiency can be reduced, the electrolyte infiltration performance in the separator membrane can be improved, and thus the cycle performance of the battery cell can be improved.

[0109] Specifically, the Dn90 is 200 nm to 1000 nm, which can reduce the local protrusions formed by the excessively large particles on the surface of the coating. Such protrusions can easily damage the uniformity of the coating, or cause stress concentration in the subsequent rolling or winding process, which can weaken or even tear the bonding interface between the coating and the separator membrane base film, thereby damaging the pore structure of the porous base film and reducing the electrolyte infiltration performance. The Dn10 is 50 nm to 400 nm, which can reduce the excessive filling of the excessively fine particles between the electrolyte infiltration channels of the coating and maintain the good electrolyte permeation efficiency in the separator membrane. When the Dn10 is less than or equal to 50 nm, there are too many ultra-fine particles, which can easily block the originally connected electrolyte infiltration channels, which can reduce the electrolyte infiltration rate and even cause local blockage, thereby reducing the electrolyte infiltration performance.

[0110] It should be noted that the Dn90, Dn10, and Dn50 obtained by testing the scanning electron microscope image of the cross section of the separator membrane along the thickness direction can be different from the Dn90, Dn10, and Dn50 selected during the preparation of the battery cell. For example, the larger the single crystal particle, the greater the deviation.

[0111] In the embodiments of the present application, the Dn90, Dn10, and Dn50 can be tested by the following methods.

[0112] After disassembling the battery monomer, the separator film is obtained, and the Dn50 / Dn10 / Dn90 of the organic compound particles is the meaning known in the art, which can be tested by using the instruments and methods known in the art. For example, a scanning electron microscope (such as ZEISS Sigma300) is used to obtain a scanning electron microscope (SEM) picture of the separator film according 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 under a certain magnification (for example, 500x or 1000x when measuring the organic compound particles), the particle size of the organic compound particles in each test region is obtained 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, that is, the particle size number distribution curve of the organic compound particles is obtained. Through software analysis, the results of Dn50, Dn10 and Dn90 are obtained. In the particle size number distribution curve of the organic compound particles, Dn90, Dn10 and Dn50 refer to the particle size of the organic compound particles when the cumulative particle size concentration reaches 90%, 50% and 10%, respectively.

[0113] In some embodiments, the roundness of the organic compound particles is 0.5-1.0.

[0114] In the embodiments of the present application, the roundness refers to the ratio of the surface area of a sphere with the same volume to the actual surface area of the particle. The closer the roundness is to the value 1, the more round and regular the shape of the particle is. For example, the roundness can be 0.5, 0.55, 0.6, 0.65, 0.7, 0.73, 0.76, 0.78, 0.8, 0.83, 0.86, 0.87, 0.88, 0.9, 0.93, 0.95, 0.97, 1.0, or any value within the above range.

[0115] As an example, the roundness of the organic compound particles 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, after the battery cell is disassembled, the separator film is peeled off, and the separator film of a regular and clear area is selected. Then, the surface morphology of the coating is measured by using a scanning electron microscope (SEM) and referring to the standard JY / T010 1996. Then, the particles of the organic compound particles in the Dn50±50nm interval are counted, and the roundness of the organic compound particles in the SEM morphology is fitted by using the Image J software. Wherein, the roundness (SC) = (4π×area) / (perimeter×perimeter) = area equivalent diameter×area equivalent diameter / fitting circle diameter×fitting circle diameter. Then, the average value of the roundness of the organic compound particles in the Dn50±50nm interval is calculated (the roundness of each single organic compound particle in the Dn50±50nm interval is obtained, the total sum of the roundness is calculated, and the average value of the roundness = the total sum of the roundness value / the total number of the particles of the organic compound particles in the Dn50±50nm interval), to obtain the roundness of the organic compound particles.

[0116] When the roundness of the organic compound particles is high, the shape of the particles is closer to a regular sphere, the friction and accumulation resistance between the particles are small during the dispersion of the slurry, and thus the slurry flows more uniformly, so that a coating with a uniform thickness and a good pore structure can be formed after coating and drying, and the electrolyte can enter the interior more quickly and uniformly when contacting the coating, thereby facilitating the improvement of the wettability of the electrolyte in the separator film. The particles with a regular morphology have fewer edges and irregular protrusions, and the probability of generating local stress concentration or micro-cracks in the coating is low, which is beneficial to the structural stability of the coating. At the same time, the particles with high roundness have a surface energy that can fully contact the electrolyte, and the surface wetting resistance is low, so that the electrolyte can quickly penetrate along the relatively uniform and continuous electrolyte infiltration channel between the particles, reducing local retention and uneven infiltration, thereby achieving a good electrolyte wetting effect and ion conduction efficiency. Therefore, when the roundness of the organic compound particles meets the above range, the wettability of the electrolyte in the separator film can be improved, thereby improving the cycle performance of the battery cell.

[0117] In some embodiments, the organic compound particles comprise a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%.

[0118] 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 of 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, which is beneficial to improve the heat resistance and thermal decomposition temperature of the organic compound particles, thereby improving the heat resistance of the isolation film. The cross-linking degree in the embodiments of the present application refers to the proportion of the molecular chain segment bound by the cross-linked network in the total chain segment obtained by fitting the software according to the test of the cross-linked polymer by nuclear magnetic resonance (NMR) at a specific temperature and a specific test frequency. Through nuclear magnetic resonance testing of the polymer, 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. The cross-linked segment is highly restricted and has small molecular motion characteristics, and decays relatively quickly. Therefore, by collecting the whole polymer signal and calculating the proportion of the cross-linked signal, the cross-linking degree of the polymer backbone can be obtained.

[0119] For example, the cross-linking degree of the cross-linked polymer can be 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 97%, 98%, or a value within the range obtained by any two of the above combinations.

[0120] In the embodiments of the present application, the cross-linking degree of the cross-linked 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 21MHz, 0.5g of the cleaned and dried sample (the above organic compound particles) is taken, and the sample is loaded into a clean sample tube and inserted into the probe to a specified depth. The probe coil diameter is 13mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the cross-linking degree of the cross-linked polymer is obtained by collecting the whole polymer signal, calculating the proportion of the cross-linked signal by fitting software, and selecting the "cross-linking degree" or "T2 relaxation" test mode in the software. 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 cross-linking degree according to the degree of restriction of molecular chain movement.

[0121] By controlling the cross-linking degree of the cross-linked polymer to be 70% to 98%, it can be ensured that the organic compound particles have good structural stability at high temperatures, and the isolation film remains stable under high temperature conditions, thereby improving the cycle stability of the battery cell.

[0122] In some embodiments, the cross-linked polymer includes a silicone polymer containing a siloxane structure.

[0123] 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 organosilicon 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.

[0124] In the above embodiments, the siloxane structure of the organosilicon polymer can improve the surface polarity of the cross-linked polymer, produce strong interaction with solvent molecules in the electrolyte, improve the affinity of the coating to the electrolyte, and thus improve the wettability of the electrolyte. The cross-linked polymer includes the organosilicon polymer containing the siloxane structure, and due to the presence of the silicon-oxygen bond, the bond energy of the silicon-oxygen bond is high and the silicon-oxygen bond is not easy to decompose at high temperature, which can be beneficial to further improve the thermal stability of the material, thereby enhancing the heat resistance of the coating of the separator film. In addition, compared with inorganic particles, the organosilicon polymer has a lower density, which can reduce the overall mass of the coating under the same thickness, and is beneficial to improve the energy density of the battery cell. Therefore, the cross-linked polymer including the organosilicon polymer containing the siloxane structure can improve the structural stability of the coating while improving the wettability of the electrolyte, thereby improving the cycle performance of the battery cell.

[0125] In some embodiments, the organosilicon polymer containing the siloxane structure includes a phenyl group, the organosilicon polymer containing the siloxane structure is obtained by polymerization of a monomer and a cross-linking agent represented by formula (I),

[0126] In formula (I), R1 and R2 each independently include a C1-C4 alkyl group, a C2-C4 alkenyl group, R3 includes a C1-C4 alkyl group or a C4-C8 (meth)acryloxyalkyl group, and R4 includes a C2-C8 alkenyl group or a C4-C8 (meth)acryloxyalkyl group; the cross-linking agent includes a divinylbenzene.

[0127] In the embodiments of the present application, R1 and R2 each independently include 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.

[0128] R3 includes 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.

[0129] In some embodiments, R3 is methyl, which is conducive to the stability of the main chain of the organosilicon polymer, is acryloyloxypropyl, which can further participate in crosslinking to improve the crosslinking degree of the organosilicon polymer; R4 is alkenyl or acryloyloxyalkyl, which can realize efficient crosslinking through free radical polymerization, further conducive to improving the crosslinking degree of the organosilicon polymer, thereby improving the structural stability of the organosilicon polymer, and conducive to the stability of the pore structure in the coating and improving the infiltration performance of the electrolyte.

[0130] R4 includes at least one of ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, (meth)acryloyloxy methyl, 2-((meth)acryloyloxy) ethyl, 3-((meth)acryloyloxy) propyl or 4-((meth)acryloyloxy) butyl.

[0131] The acryloyloxyalkyl refers to an alkyl chain structure functional group containing an acryloyloxy end group, the (meth)acryloyloxyalkyl refers to a hydrogen atom on a carbon atom directly connected to a carbonyl (C=O) substituted by a methyl group, which provides a reaction site through an acrylate double bond (C=C) at the end of the molecular chain, can further undergo a free radical polymerization reaction with a crosslinking agent, and is conducive to improving the crosslinking degree of the organosilicon polymer.

[0132] 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 a covalent bridge 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 a crosslinking reaction with alkenyl or acryloyl to form a covalent bond between the molecular chains with ethylene bridge and benzene ring as the connecting points, form a three-dimensional network structure of the organosilicon polymer containing a siloxane structure, and thereby improve the structural stability of the organosilicon polymer containing the siloxane structure.

[0133] The acryloyloxyalkyl refers to an alkyl chain structure functional group containing an acryloyloxy end group, the (meth)acryloyloxyalkyl refers to a hydrogen atom on a carbon atom directly connected to a carbonyl (C=O) substituted by a methyl group, which provides a reaction site through an acrylate double bond (C=C) at the end of the molecular chain, can further undergo a free radical polymerization reaction with a crosslinking agent, and is conducive to improving the crosslinking degree of the organosilicon polymer.

[0134] Through the polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene, the affinity of the organosilicon polymer for the electrolyte can be improved, so that the organosilicon polymer has a relatively good electrolyte wettability while maintaining structural stability. The electrolyte can quickly penetrate into the pores of the coating, improving the infiltration performance of the electrolyte, thereby being conducive to the cycle performance of the battery cell.

[0135] In some embodiments, a method for preparing a phenyl and siloxane structure-containing silicone polymer includes the steps of: providing a pre-emulsion containing monomers, a crosslinking agent, an emulsifier, an initiator, and water, and performing an emulsion polymerization reaction under conditions of heating, inert gas protection, and stirring to obtain a silicic organic resin particle. The monomers include a silane coupling agent containing an alkenyl group and / or an acryloyloxy group, and the mass fraction of the crosslinking agent is 2% to 30% based on the total mass of the monomers and the crosslinking agent being 100%. The mass fraction of the phenyl group in the phenyl and siloxane structure-containing silicone polymer and the crosslinking degree of the phenyl and siloxane structure-containing silicone polymer are adjusted by controlling the mass fraction of the crosslinking agent.

[0136] The monomers include a silane coupling agent containing an alkenyl group and / or an acryloyloxy group, so that free radicals are generated between the monomers to cause a crosslinking reaction, and the monomers also cause a crosslinking reaction with the crosslinking agent. Therefore, the phenyl and siloxane structure-containing silicone polymer with a three-dimensional network structure can be formed using the monomers and the crosslinking agent of the present disclosure, and the phenyl and siloxane structure-containing silicone polymer is not easily softened or deformed at high temperatures and has high heat resistance.

[0137] The mass fraction of the crosslinking agent is 2% to 30% based on the total mass of the monomers and the crosslinking agent being 100%, for example, 2%, 7%, 12%, 17%, 22%, 27%, 30%, or a range composed of any of the above values.

[0138] The mass fraction of the crosslinking agent in the above range can obtain the phenyl and siloxane structure-containing silicone polymer with a high crosslinking degree.

[0139] Alternatively, the mass fraction of the crosslinking agent can be 2% to 30%, 2% to 25%, 2% to 20%, 2% to 15%, 3% to 30%, 3% to 25%, 3% to 20%, or 3% to 15%.

[0140] In some embodiments, the monomers can include an acryloyloxy silane coupling agent.

[0141] Optionally, the monomer of Formula (I) can include one or more of gamma- methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloyloxypropyltriethoxysilane, gamma- methacryloxypropyltriisopropoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3- methacryloxypropyltris(methoxyethoxy)silane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloyloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3- (methacryloxy)propylmethyldiethoxysilane.

[0142] In some embodiments, the monomer of Formula (I) can include a first monomer and a second monomer.

[0143] The first monomer can include one or more of gamma-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3- methacryloxypropyltrimethoxysilane, acryloyloxypropyltrimethoxysilane, 3- methacryloxypropyltriethoxysilane, acryloyloxypropyltriethoxysilane, gamma- methacryloxypropyltriisopropoxysilane, 3-(acryloyloxy)propyltrimethoxysilane, 3- methacryloxypropyltris(methoxyethoxy)silane.

[0144] The second monomer can include one or more of 3-methacryloxypropylmethyldimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloyloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3- (methacryloxy)propylmethyldiethoxysilane.

[0145] The first monomer and the second monomer are active differently, by combining the two together and reacting with a crosslinking agent, a silicone polymer containing a siloxane structure with a narrow particle size distribution can be obtained.

[0146] 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. Optionally, 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.

[0147] In some embodiments of the present application, the emulsifier can be added in an amount of 0.1 g to 3.0 g. For example, the emulsifier can be added in an amount of 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 sites for polymer particles. The more micelles, the smaller the particle size and the more particles of the silicone-containing organic silicone polymer obtained. The fewer micelles, the larger the particle size and the fewer particles of the silicone-containing organic silicone polymer obtained. Therefore, by adjusting the amount of emulsifier added, a silicone-containing organic silicone polymer having a Dn50 of 100 nm to 700 nm can be obtained.

[0148] 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, and azobisisopropylimidazole.

[0149] In some embodiments, the heating temperature of the maturation stage of the emulsion polymerization reaction can be 75°C to 95°C, for example, can be 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, or a range formed by any of the above values, or a range formed by any of the above values.

[0150] In some embodiments, the heating time of the maturation stage of the emulsion polymerization reaction can be 1 h to 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 formed by any of the above values.

[0151] In some embodiments, the emulsion polymerization reaction can include the following steps: under the conditions of a second heating temperature, inert gas protection and stirring, the pre-emulsion is added dropwise into a reactor containing water, and after reacting for a second time, the temperature is raised to the heating temperature of the maturation stage to carry out the maturation reaction, to obtain the silicon-containing organic resin particles.

[0152] Optionally, the second heating temperature can be 55°C to 95°C.

[0153] Optionally, the second time can be 3 h to 8 h.

[0154] In some embodiments, the pre-emulsion can further include a pH adjuster. Optionally, the pH adjuster can include, but is not limited to, one or more of sodium bicarbonate, sodium hydroxide, ammonia, and the like.

[0155] In some embodiments, the method of preparing the silicon-containing organic resin particles can further include a step of removing the magnetic treatment after the emulsion polymerization reaction is completed.

[0156] In some embodiments, the silicon-oxygen structure-containing organosilicon polymer satisfies at least one of the following conditions: (1) the crosslinking degree of the silicon-oxygen structure-containing organosilicon polymer is 75% to 95%; (2) the mass fraction of silicon elements in the silicon-oxygen structure-containing organosilicon polymer is 10% to 25%; (3) the mass fraction of phenyl groups in the silicon-oxygen structure-containing organosilicon polymer is 2% to 12%; (4) the silicon-oxygen structure-containing organosilicon polymer includes silicon hydroxyl groups; and (5) the mass fraction of silicon hydroxyl groups in the silicon-oxygen structure-containing organosilicon polymer is 100 ppm to 1500 ppm.

[0157] For example, the crosslinking degree of the silicon-oxygen structure-containing organosilicon polymer can be 75%, 77%, 79%, 81%, 83%, 85%, 87%, 89%, 91%, 93%, 95%, or a value within a range obtained by combining any two of the above values. The mass fraction of silicon elements can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25%, or a value within a range obtained by combining any two of the above values. The mass fraction of phenyl groups in the silicon-oxygen structure-containing organosilicon polymer can be 5%, 7%, 9%, 11%, 12%, or a value within a range obtained by combining any two of the above values. The mass fraction of silicon hydroxyl groups in the silicon-oxygen structure-containing organosilicon polymer can be 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, or a value within a range obtained by combining any two of the above values.

[0158] In the embodiments of the present application, the silicon hydroxyl group refers to a hydroxyl group (Si-OH) directly connected to a silicon atom.

[0159] The crosslinking degree is controlled in the range of 75% to 95%, the crosslinking between the organosilicon polymer chain segments is uniform, which not only ensures that the coating is not prone to local swelling and cracking during electrolyte immersion, but also maintains a continuous electrolyte immersion channel structure, which is conducive to the rapid penetration of electrolyte in the separator coating, thereby improving the cycle performance of the battery monomer.

[0160] The silicon-oxygen segments are highly polar, enabling them to interact with solvent molecules in the electrolyte via dipoles, thus facilitating the spread and penetration of the electrolyte into the coating surface. A silicon mass fraction of 10%–25% enhances the coating's hydrophilicity, thereby improving the wetting effect of the electrolyte on the separator.

[0161] As an example, the mass content of silicon in the organosilicon polymer has a meaning known in the art and can be tested using instruments and methods known in the art. Specifically, as an example, after disassembling the battery cell, the separator is peeled off, and a regular, clear area of ​​the separator is selected. Then, the separator is immersed in N,N-dimethylformamide, centrifuged, and the supernatant is collected and coated onto a potassium bromide wafer. After drying the potassium bromide wafer, the organosilicon polymer is obtained. The organosilicon polymer is digested with a mixed acid solution (aqua regia and HF hydrofluoric acid), and the mass content of silicon in the digested solution is determined by inductively coupled plasma atomic emission spectrometry (ICP-OES), and the mass content of silicon in the organosilicon polymer is calculated.

[0162] The phenyl content is 2% to 12% by mass, which helps maintain the electrolyte wetting channels in the coating, allowing the electrolyte to penetrate the coating quickly, reducing local retention and uneven wetting, thereby improving the wetting performance of the electrolyte in the separator.

[0163] Organosilicon polymers contain silanol groups at a mass ratio of 100ppm-1500ppm, which can provide additional active sites. On the one hand, silanol groups readily form hydrogen bonds or strong dipole interactions with polar solvent molecules in the electrolyte, thereby further improving the hydrophilicity and wettability of the coating. On the other hand, silanol groups can undergo condensation or crosslinking reactions with other functional groups (such as epoxy groups and carboxyl groups) during heat treatment or crosslinking, reducing structural collapse or detachment of the coating under high temperature and long cycling conditions, thereby improving the wettability of the electrolyte in the separator.

[0164] As an example, the mass percentage of silanol groups can be determined by acid-base titration. The silanol groups in organosilicon polymers are weakly acidic and can neutralize with strong bases (such as sodium hydroxide) in non-aqueous solvents (such as a methanol-water system saturated with sodium chloride). By titrating the sample suspension with a standard sodium hydroxide solution to a specific pH endpoint (typically from pH 4 to pH 9), and subtracting the blank test value from the volume of standard alkali solution consumed, the total amount of silanol groups titrable on the sample surface can be calculated.

[0165] Specifically, the separator film of the battery monomer is taken as a sample, and the powder of the coating part in the separator film is scraped off as the sample to be tested. The sample to be tested is subjected to drying treatment to remove the physically adsorbed moisture on the surface, and is placed in a desiccator after cooling for standby. Control group: a certain volume (such as 50 mL) of titration solvent is added to a clean titration cell, a calibrated pH electrode is inserted into the solution, titration is performed using a sodium hydroxide standard solution, the titration curve is recorded, and the volume of NaOH consumed from pH = 4.00 to pH = 9.00 is accurately read as a blank value V0 (unit: mL). A certain amount of the sample subjected to drying treatment is added to the titration cell, the same volume of titration solvent as the control group is added, the titration cell is placed in an ultrasonic cleaner for ultrasonic treatment for 3-5 minutes to make the sample fully dispersed, the titration cell is placed back on the titration table, a stirring rod is inserted, a calibrated pH electrode is inserted into the solution, titration is performed using a sodium hydroxide standard solution, the titration curve is recorded, and the volume of NaOH consumed from pH = 4.00 to pH = 9.00 is accurately read as a blank value V ph+2 , and the mass percentage of silicon hydroxyl is calculated according to the following formula: , wherein a(out) represents the surface silicon hydroxyl content (μg / g), C Aout represents the actual concentration of the NaOH standard solution (mol / L), V pH+2 represents the volume of NaOH solution consumed by the sample during titration from pH = 4 to pH = 9 (mL), m represents the mass of the sample to be tested (g), represents the mass percentage of volatile components (such as the amount of reduction after drying treatment) in the sample to be tested (%). The same sample needs to be determined at least twice in parallel, and the arithmetic mean of the two parallel determination results is taken as the final result.

[0166] Therefore, by limiting the crosslinking degree, the mass fraction of silicon elements, the mass fraction of phenyl groups, and the mass percentage of silicon hydroxyl, the structure of the organosilicon polymer containing a siloxane structure can be better controlled, so that the coating in the separator film can maintain structural stability while having good electrolyte wetting performance.

[0167] In some embodiments, the organosilicon polymer containing a siloxane structure comprises a skeleton composed of a compound represented by formula (II), R a [SiO 3 / 2 ] n Formula (II), wherein n is any value in the integer range of 4 to 12, R a comprises at least one of a cycloalkyl group, an aryl group, a C1-C 12 alkyl group, a C1-C 12 alkenyl group, and a C1-C 12 alkynyl group; and optionally, n is 8, and R aincluding C1-C3 alkyl groups.

[0168] 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 the two values of 4 to 12.

[0169] 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, t-butyl, n-pentyl, isopentyl, neopentyl, t-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, vinyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1,3-butadienyl, 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.

[0170] Optionally, n is 8, R a including at least one of methyl, ethyl, n-propyl, isopropyl.

[0171] By introducing structural units represented by formula (II) into the silicone polymer, a stable three-dimensional structure can be formed inside the molecule of the silicone polymer. Such polyhedral skeleton has high symmetry and regularity, and the internal atoms are connected by strong covalent bonds. In the coating of the isolation film, it can provide uniform and stable rigid support, which is not easy to break or collapse in high temperature environment, reduces the shrinkage phenomenon of the coating in the cycle process, and improves the integrity of the electrolyte infiltration channel in the coating. Moreover, the covalent polyhedral skeleton represented by formula (I) contains Si-O bonds, which have high bond energy and are not easy to decompose at high temperature, which can further improve the thermal stability of the material. By selecting R a as C1-C3 alkyl groups, the structural stability of the silicone polymer can be further improved. Through the above structure design, the silicone polymer particles can inhibit the thermal shrinkage of the isolation film, help to improve the infiltration performance of the electrolyte in the isolation film, thereby improving the cycle performance of the battery monomer.

[0172] In some embodiments, the silicone polymer containing siloxane structure is obtained by hydrolysis and polycondensation of one or more monomers represented by formula (II), wherein R'1 includes C1-C3 alkyl groups.

[0173] In the embodiments of the present application, R'1 specifically includes at least one of methyl, ethyl, n-propyl, and isopropyl.

[0174] By using the hydrolysis-polycondensation reaction of the monomer of formula (III), the organosilicon polymer with complete cage structure and uniform molecular chain dispersion can be obtained. The organosilicon polymer particles obtained in this way are uniformly distributed in the coating of the separator film, and can form a coating structure with good pore connectivity, which is conducive to the continuous penetration of the electrolyte, thereby improving the wettability of the electrolyte on the separator film. The full wettability of the electrolyte in the separator film can ensure that the negative active material is uniformly utilized during the charging and discharging process, reduce the low utilization rate of the negative active material or capacity attenuation caused by insufficient local wettability, thereby delaying the capacity attenuation rate of the battery and improving the cycle performance of the battery cell.

[0175] In some embodiments, the method for preparing the organosilicon polymer containing siloxane structure includes the following steps: (1) hydrolyzing the monomer shown in formula (III), then adding an emulsifier and a catalyst, and performing polycondensation under heating to obtain the organosilicon polymer containing siloxane structure.

[0176] Thus, by hydrolysis and polycondensation reaction, the organosilicon polymer containing siloxane structure is obtained.

[0177] Specifically, the monomer shown in formula (III) is first hydrolyzed to generate silanol, and at the same time, alcohol is released to form a mixed solution. The alcohol increases the solubility of the organosiloxane monomer in the solution to obtain a pre-emulsion. Then, under the action of a catalyst, the silanol starts to polycondense, and Si-O-Si bonds are formed between the silanols to further form a network structure, and nucleation begins at this time. Finally, these nuclei continuously absorb silanol from the solution and continue to grow until the organosilicon polymer containing siloxane structure is formed. The nucleation process and the nucleus growth process are competitive, and the reaction temperature will affect these two processes. When the nucleation process dominates, more nuclei are generated, and the final particle size of the microspheres is larger. The increase of the temperature intensifies the reaction, so that more nuclei are generated in the initial stage of the reaction, and more silanol is consumed, thereby limiting the growth of the nuclei in the later stage, so that the particle size of the organosilicon polymer containing siloxane structure generated finally is smaller.

[0178] In some embodiments, the heating temperature is controlled in the range of 30-100℃, for example, the heating temperature can be 30-99℃, 35-95℃, 40-90℃, 45-85℃, 50-80℃, 55-75℃, 60-70℃, etc.

[0179] In some embodiments, the heating time is 2-8h, for example, the heating time can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, etc.

[0180] By controlling the temperature and the time of heating to satisfy the above range, the degree of the lock reaction can be controlled, and a silicone polymer with high crosslinking degree can be obtained.

[0181] In some embodiments, the mass ratio of the monomer and water can be 2% to 8%. The larger the value of the mass ratio, the higher the concentration of the monomer in the system, and the more easily the particles are bonded to each other, so that the silicone polymer with siloxane structure with larger particle size can be obtained. Therefore, by adjusting the mass ratio, the silicone polymer with siloxane structure with Dn50 of 100 nm to 700 nm can be obtained.

[0182] For example, the mass ratio of the monomer and water can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, or any value within the above range.

[0183] In some embodiments, the silicone polymer with siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the silicone polymer with siloxane structure is 85% to 97%; (2) the mass fraction of silicon element in the silicone polymer with siloxane structure is 25% to 45%; (3) the mass fraction of the skeleton composed of the compound represented by formula (II) in the silicone polymer with siloxane structure is 40% to 60%; (4) the silicone polymer with siloxane structure includes silicon hydroxyl; and (5) the mass fraction of silicon hydroxyl in the silicone polymer with siloxane structure is 100 ppm to 2000 ppm.

[0184] For example, the crosslinking degree of the silicone polymer with siloxane structure can be 85%, 87%, 89%, 91%, 93%, 95%, 97%, or a value within the range obtained by any two value combinations. The mass fraction of silicon element can be 25%, 27%, 29%, 31%, 33%, 35%, 37%, 39%, 41%, 43%, 45%, or a value within the range obtained by any two value combinations. The mass fraction of the skeleton composed of the compound represented by formula (II) in the silicone polymer with siloxane structure can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or a value within the range obtained by any two value combinations. The mass fraction of silicon hydroxyl in the silicone polymer with siloxane structure can be 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 1900 ppm, 2000 ppm, or a value within the range obtained by any two value combinations.

[0185] The cross-linking degree of the organosilicon polymer containing a siloxane structure is 85% to 97%, which ensures the structural stability of the organosilicon polymer at high temperatures; a higher mass fraction of silicon makes the polarity of the organosilicon polymer higher, which enhances the affinity of the organosilicon polymer to the electrolyte, thereby improving the diffusion speed and wetting ability of the electrolyte in the coating; a suitable proportion of the cage-like skeleton provides rigid support for the organosilicon polymer, thereby improving the structural stability of the coating; and the silicon hydroxyl group can increase the interaction between the polymer and electrolyte molecules, thereby further improving the wettability and interface stability of the coating.

[0186] The organosilicon polymer contains 100 ppm to 2000 ppm of silicon hydroxyl groups in terms of mass ratio, which can provide additional active sites. On the one hand, the silicon hydroxyl group can form hydrogen bonds or strong dipole interactions with polar solvent molecules in the electrolyte, thereby further improving the liquid affinity and wettability of the coating; on the other hand, the silicon hydroxyl group can undergo condensation or cross-linking reactions with other functional groups (such as epoxy groups and carboxyl groups) during heat treatment or cross-linking, thereby reducing the structural collapse or shedding of the coating at high temperatures and under long cycle conditions, thereby improving the wettability of the electrolyte in the separator film.

[0187] By limiting the organosilicon polymer to meet at least one of the above conditions, the wettability of the electrolyte to the separator film can be improved. The good wettability of the organosilicon polymer allows the electrolyte to quickly and uniformly infiltrate the entire separator film coating, reducing the phenomenon of local electrolyte retention and ion transmission obstruction, thereby improving the cycle performance of the battery cell.

[0188] In some embodiments, the organic compound particles satisfy at least one of the following conditions: (1) the cyclic voltammetry curve 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 glass transition temperature of the organic compound particles has no glass transition temperature T g at 300°C; (3) the initial thermal weight loss temperature T 3d of the organic compound particles is greater than or equal to 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 .

[0189] For example, the initial thermal weight loss temperature T 3d5%, 4%, 3%, 2%, 1%, or a value within a range obtained by any two of the above-mentioned numerical combinations. The dissolution rate of the organic compound particles can be 5%, 4%, 3%, 2%, 1%, or a value within a range obtained by any two of the above-mentioned numerical combinations. The true density of the organic compound particles can be 0.8 g / cm3, 0.9 g / cm3, 1.0 g / cm3, 1.1 g / cm3, 1.2 g / cm3, 1.3 g / cm3, 1.4 g / cm3, 1.5 g / cm3, 1.6 g / cm3, 1.7 g / cm3, 1.8 g / cm3, 1.9 g / cm3, 2.0 g / cm3, or a value within a range obtained by any two of the above-mentioned numerical combinations. 3 3 3 3 3 3 3 3

[0190] Compared with inorganic particles with a larger density, such as boehmite and alumina, the true density of the organic compound particles is smaller, which can improve the energy density of the battery cell without increasing the thickness of the coating.

[0191] The electrochemical stability of conventional organic particles is generally poor and is prone to decomposition under high pressure. The cyclic voltammetry curve of the organic compound particles in the first cycle in the present application does not have an oxidation peak in the voltage range of 0V to 4.40V, indicating that the organic compound particles are stable in the voltage range of 0V to 4.40V and have good electrochemical stability, which can be applied to high-voltage battery cells, so that the battery cell has good capacity performance under high pressure and improves the working voltage and energy density of the battery cell.

[0192] 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 according to 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 0V-5.00V, and the cycle is 3 cycles, and the voltage corresponding to the peak point of the cyclic voltammetry curve in the first cycle 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) according to a volume ratio of 3:7.

[0193] ​​​​​​​​The glass transition temperature Tg refers to the transition temperature of a material from a glassy state to a high-elasticity state, which presents a step change on the DSC curve. The organic compound particles having no glass transition temperature below 300°C means that the DSC curve of the organic compound particles remains solid and rigid below 300°C, without molecular chain segment movement or softening, so as to improve the heat resistance of the isolation film.

[0194] As an example, the glass transition temperature T g The test can be performed as follows: take an appropriate amount of sample (for example, 5-15 mg) 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 60 mL / min, protective gas 20 mL / min; program settings: temperature rise from 25°C to 200°C at a rate of 10°C / min, hold for 5 min to eliminate thermal history, temperature drop from 200°C to -40°C at a rate of 10°C / min, and temperature rise from -40°C to 300°C at a rate of 10°C / min. The glass transition temperature T g .

[0195] The initial thermal weight loss temperature T 3d of the organic compound particles is greater than or equal to 250°C, indicating that the weight of the organic compound particles does not change significantly at high temperatures, so that the organic compound particles have high heat resistance and thermal stability and are not prone to thermal decomposition during the use of the battery cell and during thermal abuse. When the organic compound particles are used in the isolation film, the organic compound particles can better generate a force to resist the shrinkage of the isolation film, thereby improving the overall thermal shrinkage of the isolation film, improving the heat resistance of the isolation film, and improving the reliability of the battery cell.

[0196] The initial thermal weight loss temperature T 3d is the temperature corresponding to a 3% loss in the mass of the sample relative to the initial mass in the thermal gravimetric analysis. The initial thermal weight loss temperature T 3d of the organic particles can be tested as follows: take an appropriate amount of sample (for example, 5-15 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 rise program: temperature rise rate 10°C / min, temperature range 35°C-600°C; obtain the temperature corresponding to a 3% loss in the mass of the sample 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 .

[0197] The dissolution rate can refer to the proportion of the particles dissolved or decomposed in the electrolyte. After the organic compound particles are soaked in the electrolyte at 60°C for 7 days, the dissolution is less than 5%, the organic compound particles are not easy to precipitate or dissolve in the electrolyte environment, the electrolyte pollution or the side reaction between the organic compound particles and the electrolyte is reduced in the cycle process of the battery cell, the isolation film has good structural stability, and the cycle performance and reliability of the battery cell are improved.

[0198] As an example, the swelling degree of the organic compound particles can be tested according to the following method: 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 the bag, and the sample bag can permeate the solvent but cannot permeate the sample; soak the sample bag in an appropriate amount of solvent (for example, about 50 g) at 60°C 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; the 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.

[0199] The true density refers to the mass of a material per unit actual volume (excluding internal voids, i.e., not including open and closed pores and inter-particle voids) in an absolutely dense state. The true density of the organic compound particles is 0.8 g / cm 3 ~2.0 g / cm 3 , which is beneficial to improve the capacity of the battery cell and obtain a battery cell with high energy density.

[0200] The true density of the organic compound particles has the meaning known in the art and can be tested by methods known in the art. As an example, take an organic compound particle with a mass of M, place the carbon base in a true density tester (AccuPyc II 1340 analyzer) at room temperature (15°C-25°C), close the test system, and pass helium gas according to the program. By detecting the gas pressure in the sample chamber and the expansion chamber, the gas volumes in the sample chamber and the expansion chamber are calculated respectively according to the ideal gas state equation, and the difference between the two is the gas volume displaced by the carbon base under certain temperature and pressure conditions, i.e., 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 / cm 3 .

[0201] In some embodiments, the mass fraction of the organic compound particles in the coating is 50%-97%.

[0202] The mass fraction of the organic compound particles in the coating can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 97%, or a value within a range obtained by combining any two of the above values.

[0203] By limiting the mass fraction of the organic compound particles in the coating to be within the above range, the coating can have more uniform electrolyte infiltration channels, improve the electrolyte infiltration performance in the separator film, and thus improve the cycle performance of the battery cell.

[0204] In some embodiments, the coating further includes a first binder, and the first binder satisfies at least one of the following conditions: (1) the first binder includes 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; and (2) the mass fraction of the first binder in the coating is 3% to 15%.

[0205] For example, the mass fraction of the first binder in the coating can be 3%, 5%, 7%, 9%, 11%, 13%, 15%, or a value within a range obtained by combining any two of the above values.

[0206] The organic compound particles in the coating are connected and fixed to each other by the first binder, reducing the situation of falling off of the organic compound particles during coating and use. The mass fraction of the first binder satisfies the above range, which can reduce the situation of reducing the proportion of the organic compound particles in the coating due to excessive binder while ensuring adhesion, so as to balance the stability and heat resistance of the coating and improve the heat resistance of the separator film.

[0207] In some embodiments, the separator film further comprises second binder particles, the second binder particles being located in the coating layer, or the separator film further comprises a bonding layer, the bonding layer being disposed on at least one side of the coating layer away from the base film, and the second binder particles being located in the bonding layer; the second binder particles satisfy one or more of the following conditions: (1) 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), polyacrylate, polymethyl methacrylate, polyacrylonitrile; (2) the number average particle size of the second binder particles is 5 μm to 20 μm.

[0208] For example, the number average particle size of the second binder particles can be 5 μm, 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 17 μm, 19 μm, 20 μm, or a value within a range obtained by combining any two of the above values.

[0209] The addition of the second binder particles in the coating layer or the bonding layer of the separator film can fill the gap between the negative electrode sheet and the separator film, form a more firm bonding interface, and help to improve the bonding strength between the separator film and the negative electrode sheet, thereby improving the overall stability of the separator film, reducing the interlayer peeling phenomenon between the separator film and the negative electrode sheet caused by thermal stress or electrochemical action during the cycle process, and thereby improving the cycle performance of the battery cell. The number average particle size of the second binder particles satisfies the above range, which ensures that it can be uniformly distributed and maintain moderate fluidity during hot pressing, thereby further improving the cycle performance of the battery cell.

[0210] It should be understood that the "first binder" in the embodiments of the present application plays a bonding role between the organic compound particles in the porous coating layer of the separator film, and the "second binder particles" play a role in improving the adhesion between the separator film and the electrode sheet.

[0211] In some embodiments, the coating layer of the separator film comprises organic compound particles and second binder particles, the second binder particles can be embedded in the organic compound particles and form protrusions on the surface of the coating layer.

[0212] In some embodiments, the coating layer of the separator film comprises a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on the porous base film, the bonding layer is disposed on at least a part of the surface of the heat-resistant layer away from the porous base film, the organic compound particles are disposed in the heat-resistant layer, and the second binder particles are disposed in the bonding layer.

[0213] In some embodiments, the coating of the separator film comprises a heat-resistant layer disposed on one side of the porous base film and a bonding layer disposed on at least a portion of the surface of the other side of the porous base film, the organic compound particles are disposed in the heat-resistant layer, and the second binder particles are disposed in the bonding layer.

[0214] In some embodiments, the coating of the separator film comprises a heat-resistant layer disposed on one side of the porous base film and a bonding layer disposed on at least a portion of the surface of the other side of the heat-resistant layer and on at least a portion of the surface of the other side of the porous base film, the organic compound particles are disposed in the heat-resistant layer, and the second binder particles are disposed in the bonding layer.

[0215] In some embodiments, the inorganic particles are included in the coating, and the mass fraction of the inorganic particles is 0.1 wt.% to 50 wt.% based on the total mass of the coating.

[0216] In other embodiments, the inorganic particles are included in the coating, and the mass fraction of the inorganic particles is 50 wt.% to 92 wt.% based on the total mass of the coating. 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, and SiC, which have a large dielectric constant and are beneficial to improving the ion transport efficiency in the coating.

[0217] 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 ~ 6 g / m 2 ; (3) the longitudinal thermal shrinkage of the separator film is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage of the separator film is less than or equal to 5% when heated at 130°C for 1 h; and (5) the air permeability of the separator film is 150 s / 100 mL to 500 s / 100 mL.

[0218] The thickness of the coating refers to the thickness of the coating on one side of the porous base film. For example, the thickness of the coating can be 0.5 μm, 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, or a value within the range obtained by combining any two of the above values.

[0219] A coating that is too thin cannot form an effective heat-resistant layer, and a coating that is too thick increases the thickness of the separator film and reduces the energy density of the battery cell. A coating with a thickness of 0.5 μm to 10 μm can provide a uniform and dense heat-resistant coating, improve the heat-resistant performance of the separator film, and thus improve the reliability of the battery cell.

[0220] The coating has a surface density of 1.5 g / m 2 ~ 6 g / m 2 , which can ensure a moderate coating quality, and can improve the stability and heat resistance of the separator film without significantly increasing the weight of the separator film, thereby being conducive to the energy density and reliability of the battery cell. For example, the surface density of the coating can be 0.5 g / m 2 , 0.7 g / m 2 , 0.9 g / m 2 , 1.1 g / m 2 , 1.3 g / m 2 , 1.5 g / m 2 , 1.7 g / m 2 , 1.9 g / m 2 , 2.1 g / m 2 , 2.3 g / m 2 , 2.5 g / m 2 , 2.7 g / m 2 , 2.9 g / m 2 , 3.1 g / m 2 , 3.3 g / m 2 , 3.5 g / m 2 , 3.7 g / m 2 , 3.9 g / m 2 , 4.1 g / m 2 , 4.3 g / m 2 , 4.5 g / m 2 , 4.7 g / m 2 , 4.9 g / m 2 , 5 g / m 2 , 5.1 g / m 2 , 5.3 g / m 2 , 5.5 g / m 2 , 5.7 g / m 2 , 5.9 g / m 2 , 6 g / m 2 , or a value within a range obtained by any two of the above combinations.

[0221] The areal density of the coating can be controlled during the preparation of the separator film by controlling the amount of coating slurry applied to the porous base film. As an example, the areal density of the coating can be tested by first stacking 6 layers of the single separator film containing the coating according to the embodiments of the present application and 6 layers of the single separator film substrate without the coating, respectively, and applying pressure to make the layers tightly adhere and free of air bubbles. Subsequently, the two groups of stacks are cut according to the sample cutting template, respectively, to obtain 6 samples. The total mass of the 6 samples of the group with the coating M1 and the total mass of the 6 samples of the group without the coating M2 are measured, and the average mass of the coating on the single separator film is calculated by the formula M = (M1-M2) / 6. Then, the area S of a single sample is measured, and the areal density of the coating can be obtained according to the formula “coating areal density = M / S”.

[0222] The heat shrinkage rate refers to the percentage of the dimensional change of the separator film at high temperature, which is an important indicator for measuring the thermal stability of the separator film. The separator film can still maintain very low longitudinal and transverse heat shrinkage rates at 130°C, i.e., the separator film according to the embodiments of the present application has good heat resistance at high temperature.

[0223] As an example, the heat shrinkage rate of the separator film can be tested according to GB / T 36363-2018. As an example, the separator film is cut into samples with a width of 50 mm and a length of 100 mm by a punch machine, 5 parallel samples are placed on an A4 paper, and the A4 paper containing the samples is placed on a corrugated paper with a thickness of 1 mm to 5 mm. The temperature of the air blast 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 blast oven, and the timing starts. After reaching the set time (1 h in the present disclosure), the length and width of the separator 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.

[0224] The air permeability (Gurley value) of the separator film refers to the time required for 100 mL of air to pass through the separator film, which represents the resistance of the pore structure of the separator film to gas / liquid transmission. The air permeability of the separator film is 150 s / 100 mL to 500 s / 100 mL, which ensures that the electrolyte can be uniformly infiltrated and maintain fast ion transmission, ensures the ion transmission efficiency in the separator film, and reduces the case that the air permeability of the separator film is too low to cause electrochemical polarization and reduce the reliability of the battery cell.

[0225] As an example, the air permeability of the separator film can be tested according to GB / T 36363-2018. Specifically, the separator film is cut into a square of 5 cm in size, and an air permeability instrument is used to test 100 ml of air permeating through 6.45 cm of the separator film under a pressure of 1.21 kPa. The time required for the air to permeate through the separator film is taken as the air permeability of the separator film, in s / 100 ml. The average value of 3 parallel samples is taken as the test result. 2 The time required for the air to permeate through the separator film is taken as the air permeability of the separator film, in s / 100 ml. The average value of 3 parallel samples is taken as the test result.

[0226] In some embodiments, the thickness of the separator film can be 5-20 μm, optionally 5-12 μm, 6-12 μm. This is advantageous for improving the energy density of the secondary battery cell.

[0227] 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 thereof satisfying the present disclosure are considered to fall within the protection scope of the present disclosure.

[0228] The shape of the battery cell according to the embodiments of the present application is not particularly limited, and can be cylindrical, square, or any other shape. For example, FIG. 1 is a schematic structural diagram of a battery cell according to an embodiment of the present application, and the battery cell is square.

[0229] FIG. 2 is a schematic structural diagram of a battery cell according to another embodiment of the present application. As shown in FIG. 2, in some embodiments, the battery cell 3 can include an outer package. The outer package can be used to encapsulate the electrode assembly and the electrolyte described above.

[0230] In some embodiments, the outer package of the battery cell 3 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 3 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, and polybutylene succinate, etc. can be listed.

[0231] In some embodiments, referring to FIG. 2, the battery cell 3 includes a shell 30 and an electrode assembly 33 disposed in the shell 30, and the shell 30 includes a shell body 31 and a cover plate 32 for covering the opening of the shell body 31.

[0232] The electrode assembly 33 can be made of a positive electrode sheet, a negative electrode sheet, and a separator film by a winding process or a stacking process. The electrode assembly 33 can include an electrode assembly body and a tab 331 extending from the electrode assembly body.

[0233] The cover plate 32 includes an electrode terminal 322, and FIG. 3 is a schematic diagram of a battery device according to an embodiment of the present application. As shown in FIG. 3, the cover plate 32 includes two electrode terminals 322, one of which is a positive electrode terminal and the other of which is a negative electrode terminal.

[0234] The battery cell 3 further includes a connecting member 34 for connecting the tab 331 of the electrode assembly 33 and the electrode terminal 322. For example, one connecting member 34 is used to connect the tab of the positive electrode and the positive electrode terminal, and another connecting member 34 is used to connect the tab of the negative electrode and the negative electrode terminal.

[0235] In some embodiments, the battery cell 3 includes a pressure relief mechanism 313 for releasing substances in the battery cell 3 when the battery cell experiences thermal runaway, so as to reduce the risk that the emissions in the battery cell 3 cannot be timely released.

[0236] In some embodiments, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0237] [Positive electrode sheet]

[0238] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, and the positive electrode active material layer includes a positive electrode active material.

[0239] For example, the positive electrode current collector has two opposite surfaces in the thickness direction thereof, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0240] In some embodiments, the positive electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be used. 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 (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0241] The positive electrode active material layer can also optionally include at least one of the positive electrode active materials known in the art for batteries: lithium-containing phosphates of olivine structure, lithium transition metal oxides, and modified compounds of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries can also be used. These positive electrode active materials can be used alone only one or in combination of two or more. Examples of the lithium transition metal oxides can include, but are not limited to, at least one of 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(also referred to as NCM 333 )), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2), modified compounds thereof, and the like. Examples of the lithium-containing phosphates of olivine structure can include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4(also referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon. The battery undergoes Li deintercalation and consumption during charging and discharging, and the molar content of Li in the positive electrode active material is different when the battery is discharged to different states.

[0242] In some embodiments, the positive electrode active material layer 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.

[0243] In some embodiments, the positive electrode active material layer can further optionally include 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.

[0244] In some embodiments, the positive electrode sheet can be prepared by forming the above-described components for preparing the positive electrode sheet into a positive electrode slurry. For example, the positive electrode active material, the conductive agent, the binder, and any other components are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then coated on the positive electrode current collector, and after processes such as drying, cold pressing, etc., the positive electrode sheet is obtained.

[0245] The battery will be accompanied by Li deintercalation and consumption during charging and discharging, and the molar content of Li is different when the battery is discharged to different states. In the enumeration of the positive electrode material in this application, the molar content of Li is the initial state of the material, i.e., the state before feeding, and the positive electrode material is applied to the battery system. After charging and discharging cycles, the molar content of Li will change.

[0246] In the enumeration of the positive electrode material in this application, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will float.

[0247] [Negative electrode sheet]

[0248] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, and the negative electrode film layer includes a negative electrode active material.

[0249] 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.

[0250] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be used. 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, and 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.).

[0251] 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 at least one 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 at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one 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.

[0252] 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).

[0253] 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.

[0254] In some embodiments, the negative film layer can further optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0255] 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 spherical particles, 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, etc., the negative electrode sheet can be obtained.

[0256] [Electrolyte]

[0257] The electrolyte functions to conduct 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, semi-solid, or all-solid.

[0258] In some embodiments, the electrolyte employs an electrolyte solution. The electrolyte solution includes the catalyst in any of the above-mentioned possible embodiments.

[0259] In some embodiments, the electrolyte solution includes an electrolyte salt and a solvent.

[0260] For lithium-ion battery cells or lithium metal battery cells, the electrolyte salt can include one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalato borate, lithium bisoxalato borate, lithium difluoro bisoxalato phosphate, and lithium tetrafluoro oxalato phosphate.

[0261] For lithium-ion battery cells or lithium metal battery cells, the solvent can include one or more of ethylene carbonate, propylene carbonate, ethyl methyl 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, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0262] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl 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, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0263] In some embodiments, the electrolyte solution can also optionally include an additive. For example, the additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also 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.

[0264] [Separator]

[0265] The separator, i.e., the separator membrane, is not particularly limited in the present application, and any known porous structure separator membrane having good chemical stability and mechanical stability can be used.

[0266] In some embodiments, the separator includes the coating layer in any of the possible embodiments described above. The coating layer includes organic compound particles, the morphology of the organic compound particles is spherical or spherical-like; the organic compound particles satisfy: 100 nm ≤ Dn50 ≤ 700 nm, Dn50 refers to the particle size corresponding to the cumulative particle number distribution of 50% in the particle size number distribution curve of the organic compound particles.

[0267] In the above embodiments, the organic compound particles with spherical or spherical-like morphology are more easily arranged uniformly during dispersion and stacking, reducing the problem of uneven stacking of particles in the coating caused by irregular particle morphology, and the particles can form a uniform and continuous electrolyte infiltration channel structure, thereby facilitating improvement of the electrolyte infiltration performance. When the electrolyte passes through the coating, it can penetrate into the inside of the electrode sheet along the relatively uniform electrolyte infiltration channel, the electrolyte infiltration resistance is smaller, and the local retention phenomenon is reduced. The spherical or spherical-like morphology can increase the contact area between the electrolyte and the surface of the particles, reduce the surface wetting resistance, and make the electrolyte more easily infiltrate in the coating. By controlling the Dn50 of the spherical or spherical-like particles to be 100 nm to 70 nm, the electrolyte infiltration efficiency and the penetration efficiency in the coating can be considered, and the electrolyte infiltration performance in the separator film is improved, thereby facilitating improvement of the cycle performance of the battery cell.

[0268] In some embodiments, the Dn90 of the organic compound particles satisfies: 200 nm≤Dn90≤1000 nm, Dn90 refers to the particle size corresponding to the cumulative number distribution of 90% of the particles in the particle size number distribution curve of the organic compound particles, and / or the Dn10 of the organic compound particles satisfies: 50 nm≤Dn10≤400 nm, Dn10 refers to the particle size corresponding to the cumulative number distribution of 10% of the particles in the particle size number distribution curve of the organic compound particles.

[0269] By limiting the Dn90 and / or Dn10 of the organic compound particles, the range of the particle size distribution of the organic compound particles can be controlled, the overall particle distribution is more concentrated, the particle size distribution of the organic compound particles is narrowed, the size distribution of the electrolyte infiltration channel in the coating is more uniform, the influence of local structural defects on the electrolyte infiltration efficiency is reduced, the electrolyte infiltration performance in the separator film is improved, and the cycle performance of the battery cell is improved.

[0270] In some embodiments, the roundness of the organic compound particles is 0.5 to 1.0.

[0271] When the roundness of the organic compound particles is high, the particles are closer to regular spheres in shape, the friction and stacking resistance between the particles are small during slurry dispersion, and thus the slurry flows more uniformly, which can form a coating with uniform thickness and good pore structure after coating and drying, so that the electrolyte can enter the interior more quickly and uniformly when contacting the coating, thereby facilitating improvement of the wettability of the electrolyte in the separator membrane. The particles with regular morphology have fewer edges and irregular protrusions, and the probability of local stress concentration or micro-cracks in the coating is low, which is conducive to the structural stability of the coating. Meanwhile, the particles with high roundness have a surface that can fully contact the electrolyte, and the surface wetting resistance is low, so that the electrolyte can quickly penetrate along the relatively uniform and continuous electrolyte wetting channel between the particles, reducing local retention and uneven wetting, thereby achieving good electrolyte wetting effect and ion conduction efficiency. Thus, when the roundness of the organic compound particles satisfies the above range, the wettability of the electrolyte in the separator membrane can be improved, thereby improving the cycle performance of the battery cell.

[0272] In some embodiments, the organic compound particles include a crosslinked polymer, and the crosslinking degree of the crosslinked polymer is 70% to 98%.

[0273] By controlling the crosslinking degree of the crosslinked polymer to be 70% to 98%, it can be ensured that the organic compound particles have good structural stability at high temperatures, and the separator membrane remains stable under heat abuse, thereby improving the cycle stability of the battery cell.

[0274] In some embodiments, the crosslinked polymer includes a silicone polymer containing a siloxane structure.

[0275] The siloxane structure of the silicone polymer can improve the surface polarity of the crosslinked polymer, and produce strong interaction with solvent molecules in the electrolyte, thereby improving the affinity of the coating for the electrolyte and improving the wettability of the electrolyte. The crosslinked polymer including the silicone polymer containing a siloxane structure can further enhance the heat resistance of the separator membrane coating and the wettability of the electrolyte. In addition, compared with inorganic particles, the silicone polymer has a lower density, which can reduce the overall mass of the coating at the same thickness, thereby facilitating improvement of the energy density of the battery cell. Therefore, the crosslinked polymer including the silicone polymer containing a siloxane structure can improve the structural stability of the coating while improving the wettability of the electrolyte, thereby improving the cycle performance of the battery cell.

[0276] In some embodiments, the silicone polymer containing a siloxane structure includes a phenyl group, and the silicone polymer containing a siloxane structure is obtained by polymerization of a monomer and a crosslinking agent represented by formula (I), In formula (I), R1, R2 each independently includes C1-C4 alkyl, C2-C4 alkenyl, R3 includes C1-C4 alkyl or C4-C8 (methyl) acryloyloxyalkyl, and R4 includes C2-C8 alkenyl or C4-C8 (methyl) acryloyloxyalkyl; the crosslinking agent includes divinylbenzene.

[0277] Through the polymerization of the monomer shown in formula (I) and the crosslinking agent divinylbenzene, the affinity of the silicone polymer to the electrolyte can be improved, so that the silicone polymer has better electrolyte wettability while maintaining structural stability. The electrolyte can quickly penetrate into the coating pores in the coating, improving the wettability of the electrolyte, thereby improving the cycle performance of the battery cell.

[0278] In some embodiments, the silicone polymer containing a siloxane structure satisfies at least one of the following conditions: (1) the crosslinking degree of the silicone polymer containing a siloxane structure is 75% to 95%; (2) the mass fraction of silicon elements in the silicone polymer containing a siloxane structure is 10% to 25%; (3) the mass fraction of phenyl groups in the silicone polymer containing a siloxane structure is 2% to 12%; (4) the silicone polymer containing a siloxane structure includes silicon hydroxyl groups; (5) the mass fraction of silicon hydroxyl groups in the silicone polymer containing a siloxane structure is 100 ppm to 1500 ppm.

[0279] The crosslinking degree is controlled in the range of 75% to 95%, the crosslinking between the silicone polymer chain segments is uniform, which not only ensures that the coating does not easily expand and crack during electrolyte immersion, but also maintains a continuous electrolyte immersion channel structure, which is conducive to the rapid penetration of electrolyte in the separator coating, thereby improving the cycle performance of the battery cell.

[0280] The siloxane segment has strong polarity and can produce dipole interaction with solvent molecules in the electrolyte, making the electrolyte more easily spread on the surface of the coating and penetrate to the inside. The mass fraction of silicon elements is 10% to 25%, which can enhance the wettability of the coating, thereby improving the wetting effect of the electrolyte on the separator membrane.

[0281] The mass fraction of phenyl groups is 2% to 12%, which can help maintain the electrolyte immersion channel in the coating, allowing the electrolyte to quickly penetrate the coating, reducing local retention and uneven wetting problems, thereby improving the wettability of the electrolyte in the separator membrane.

[0282] The silicon hydroxyl in the organic silicon polymer with a mass ratio of 100 ppm to 1500 ppm can provide additional active sites. On the one hand, the silicon hydroxyl can easily form hydrogen bonds or strong dipole interactions with polar solvent molecules in the electrolyte, thereby further improving the wettability and wetting of the coating; on the other hand, the silicon hydroxyl can undergo condensation or cross-linking reaction with other functional groups (such as epoxy group, carboxyl group) during heat treatment or cross-linking process, reducing the structure collapse or shedding phenomenon of the coating under high temperature and long cycle conditions, thereby improving the wettability of the electrolyte in the isolation film.

[0283] Therefore, by limiting the cross-linking degree, the mass fraction of silicon element, the mass fraction of phenyl group and the mass fraction of silicon hydroxyl, the structure of the organic silicon polymer containing siloxane structure can be better controlled, so that the coating in the isolation film can maintain structural stability while having good electrolyte wettability.

[0284] In some embodiments, the organic silicon polymer containing siloxane structure comprises a skeleton composed of a compound represented by formula (II), R a [SiO 3 / 2 ] n Formula (II), wherein n is any value in the integer range of 4 to 12, R a comprises at least one of cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; optionally, n is 8, R a comprises C1-C3 alkyl.

[0285] By introducing the structural unit represented by formula (II) into the organic silicon polymer, a stable three-dimensional structure can be formed inside the molecule of the organic silicon polymer. Such polyhedral skeleton has high symmetry and regularity, and the internal atoms are connected by strong covalent bonds, which can provide uniform and stable rigid support in the coating of the isolation film, and is not easy to break or collapse in high temperature environment, reducing the shrinkage phenomenon of the coating during heat pressing or cycling, and improving the integrity of the electrolyte infiltration channel in the coating. By selecting R a as C1-C3 alkyl, the structural stability of the organic silicon polymer can be further improved. Through the above structure design, the organic silicon polymer particles can inhibit the thermal shrinkage of the isolation film, help to maintain the stability of the pore structure in the isolation film, improve the wettability of the electrolyte in the isolation film, and thereby improve the cycle performance of the battery cell. In some embodiments, the organic silicon polymer containing siloxane structure comprises a skeleton obtained by hydrolysis and polycondensation of one or more monomers represented by formula (II), wherein R'1 comprises C1-C3 alkyl.

[0286] The hydrolysis-polycondensation reaction of the monomer of formula (III) can obtain a silicone polymer with a complete cage structure and a uniform molecular chain. The silicone polymer particles obtained in this way are uniformly distributed in the coating of the separator film, can form a coating structure with good pore connectivity, and are conducive to the continuous penetration of the electrolyte, thereby improving the wettability of the electrolyte on the separator film. The full wettability of the electrolyte in the separator film can ensure that the negative active material is uniformly utilized during the charging and discharging process, reduce the low utilization rate of the negative active material or capacity attenuation caused by insufficient local wettability, thereby delaying the capacity attenuation rate of the battery and improving the cycle performance of the battery cell.

[0287] In some embodiments, the organosilicon polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing a siloxane structure is 85% to 97%; (2) the mass fraction of silicon elements in the organosilicon polymer containing a siloxane structure is 25% to 45%; (3) the mass fraction of the skeleton composed of the compound represented by formula (II) in the organosilicon polymer containing a siloxane structure is 40% to 60%; (4) the organosilicon polymer containing a siloxane structure includes silicon hydroxyl groups; (5) the mass fraction of silicon hydroxyl groups in the organosilicon polymer containing a siloxane structure is 100 ppm to 2000 ppm.

[0288] By limiting the organosilicon polymer to satisfy at least one of the above conditions, the wettability of the electrolyte on the separator film can be improved. The good wettability of the organosilicon polymer allows the electrolyte to quickly and uniformly wet the entire separator film coating, reducing the phenomenon of local electrolyte retention and ion transmission obstruction, thereby improving the cycle performance of the battery cell.

[0289] In some embodiments, the mass fraction of the organic compound particles in the coating is 50% to 97%.

[0290] By limiting the mass fraction of the organic compound particles in the coating to satisfy the above range, the coating can have a relatively uniform electrolyte wetting channel, improving the wettability of the electrolyte in the separator film, thereby improving the cycle performance of the battery cell.

[0291] In some embodiments, the coating does not include inorganic particles.

[0292] 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.

[0293] In some embodiments, the coating further comprises a first binder, and the first binder satisfies one or more of the following conditions: (1) the first 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, cyanoethylpullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluorine rubber; and (2) the mass fraction of the first binder in the coating is 3% to 15%.

[0294] In some embodiments, the coating further comprises a first binder, and the first binder satisfies one or more of the following conditions: (1) the first 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, cyanoethylpullulan, cyanoethylated polyvinyl alcohol, cyanoethyl cellulose, cyanoethylsucrose, pullulan, carboxymethyl cellulose, acrylonitrile-styrene-butadiene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, and fluorine rubber; and (2) the mass fraction of the first binder in the coating is 3% to 15%.

[0295] The organic compound particles in the coating are connected and fixed to each other by the first binder, reducing the situation of falling off of the organic compound particles during coating and use. The mass fraction of the first binder satisfies the above range, which can reduce the proportion of the organic compound particles in the coating due to excessive binder while ensuring adhesion, so as to balance the stability and heat resistance of the coating and improve the heat resistance of the isolation film.

[0296] In some embodiments, the isolation film further comprises second binder particles, and the second binder particles are located in the coating, or the isolation film further comprises a bonding layer, and the bonding layer is arranged on at least one side of the coating away from the base film, and the second binder particles are located in the bonding layer. The second binder particles satisfy one or more of the following conditions: (1) 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), polyacrylate, polymethyl methacrylate, and polyacrylonitrile; and (2) the number average particle size of the second binder particles is 5 μm to 20 μm.

[0297] The second binder particles can fill the gap between the negative electrode sheet and the separator film, form a more firm bonding interface, help to improve the bonding strength between the separator film and the negative electrode sheet, thereby improving the overall stability of the separator film, reducing the interlayer peeling phenomenon between the separator film and the negative electrode sheet caused by thermal stress or electrochemical action in the cycle process, and thereby improving the cycle performance of the battery cell. The number average particle size of the second binder particles meets the above range, which ensures that it can be uniformly distributed and can maintain moderate fluidity during hot pressing, thereby further improving the cycle performance of the battery cell.

[0298] In some embodiments, the second binder particles are disposed in the coating layer.

[0299] In other embodiments, the bonding layer can also be disposed on at least a part of the surface of the coating layer away from the porous base film, the organic compound particles are disposed in the coating layer, and the second binder particles are disposed in the bonding layer.

[0300] In yet other embodiments, the coating layer is disposed on one side of the porous base film, the bonding layer is disposed on at least a part of the surface of the other side of the porous base film, the organic compound particles are disposed in the coating layer, and the second binder particles are disposed in the bonding layer.

[0301] In some embodiments, the second binder particles are disposed in the coating layer.

[0302] In other embodiments, the bonding layer can also be disposed on at least a part of the surface of the heat-resistant layer away from the porous base film, the organic compound particles are disposed in the heat-resistant layer, and the second binder particles are disposed in the bonding layer.

[0303] In yet other embodiments, the coating layer is disposed on one side of the porous base film, the bonding layer is disposed on at least a part of the surface of the other side of the porous base film, the organic compound particles are disposed in the coating layer, and the second binder particles are disposed in the bonding layer.

[0304] The separator film can be prepared according to methods known in the art.

[0305] In some embodiments, a slurry including the organic compound particles and the first binder particles can be coated on at least one side of the porous base film, and after drying, the separator film is obtained.

[0306] In some embodiments, the slurry can further include the second binder particles, and after drying of the slurry, the polymer binder particles are embedded in the organic particles and form protrusions on the surface of the coating layer.

[0307] In some embodiments, the method for preparing the separation film can include: coating a slurry including organic compound particles and first binder particles on at least one side of a porous base film to form a coating layer after drying; and coating a slurry including second binder particles on at least a portion of a surface of the coating layer away from the porous base film to obtain a separation film including a bonding layer after drying.

[0308] In some embodiments, the method for preparing the separation film can include: coating a slurry including organic compound particles and first binder particles on one side of a porous base film, and coating a slurry including second binder particles on at least a portion of a surface of the other side of the porous base film to obtain a separation film including a bonding layer after drying.

[0309] In some embodiments, the solvent of the slurry can be water, for example, deionized water.

[0310] In some embodiments, the slurry can further include other components, for example, can further include dispersants and / or wetting agents, etc.

[0311] In some embodiments, the separation 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 areal density of the coating layer 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.

[0312] The thickness of the coating layer refers to the thickness of the coating layer on one side of the porous base film. For example, the thickness of the coating layer can be 1 μm, 3 μm, 5 μm, 7 μm, 9 μm, 10 μm, or a value within the range obtained by combining any two of the above values.

[0313] A coating layer that is too thin cannot form an effective thermal insulation layer, and a coating layer that is too thick increases the thickness of the separation film and reduces the energy density of the battery cell. A coating layer with a thickness of 1 μm to 10 μm can provide a uniform and dense heat-resistant coating layer, thereby improving the heat resistance of the separation film and the reliability of the battery cell.

[0314] The areal density of the coating layer is 0.5 g / m 2 ~ 5 g / m 2 , which can ensure that the coating layer has moderate quality, can improve the stability and heat resistance of the separation film, and will not significantly increase the weight of the separation film, thereby being conducive to the energy density and reliability of the battery cell.

[0315] The air permeability (Gurley value) of the separator film refers to the time required for 100 mL of air to pass through the separator film, and characterizes the resistance of the pore structure of the separator film to gas / liquid transmission. The air permeability of the separator film is 150 s / 100 mL-500 s / 100 mL, which ensures that the electrolyte can be uniformly infiltrated and maintain rapid ion transmission, ensures the ion transmission efficiency in the separator film, reduces the case of electrochemical polarization caused by too low air permeability of the separator film, and reduces the reliability of the battery cell.

[0316] In some embodiments, the peeling force between the coating layer and the porous base film of the separator film can be greater than or equal to 28 N / m.

[0317] In the embodiments of the present application, the peeling force between the coating layer and the porous base film of the separator film can be tested according to the following method: cut the separator 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 separator 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 forces of the 3 pieces as the peeling force between the coating layer and the porous base film of the separator film. The stretching rate is 50 mm / min.

[0318] It should be noted that the coating parameters of the above-mentioned separator 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.

[0319] In some embodiments, the material of the separator film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0320] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be made into an electrode assembly by a winding process or a stacking process.

[0321] [Battery device]

[0322] In some embodiments, the battery cell is a battery device, and the battery device can include one or more battery cells.

[0323] FIG. 3 is a structural schematic diagram of a battery device according to an embodiment of the present application. For example, as shown in FIG. 3, the battery device 10 is a battery pack. The battery pack can include a box body and a plurality of battery cells contained in the box body, and the plurality of battery cells are connected in series, in parallel, or in a mixed connection manner. Among them, the battery cells can directly form the battery pack, or first form a battery module, and then form the battery pack by a plurality of battery modules.

[0324] The battery device 10 can further include a box 11, which is a hollow structure inside which the plurality of battery cells 3 are accommodated. For example, the plurality of battery cells 3 are placed in the box 11 in parallel, series or mixed combination with each other. The box 11 can include a first box part 111 and a second box part 112, which are mutually covered to form the box 11. The shapes of the first box part 111 and the second box part 112 can be determined according to the shapes of the components accommodated inside, for example, according to the shape of the combination of the plurality of battery cells 3, at least one of the first box part 111 and the second box part 112 has an opening. For example, as shown in FIG. 3, the first box part 111 and the second box part 112 can each be a hollow cuboid and each have an opening face, the opening of the first box part 111 and the opening of the second box part 112 are oppositely arranged, and the first box part 111 and the second box part 112 are mutually buckled to form the box 11 having a closed cavity, which can be used to accommodate the plurality of battery cells 3. The plurality of battery cells 3 are placed in the box 11 formed by buckling the first box part 111 and the second box part 112 in parallel, series or mixed combination with each other.

[0325] For another example, unlike that shown in FIG. 3, only one of the first box part 111 and the second box part 112 can be a hollow cuboid having an opening, and the other can be a plate to cover the opening. Taking the second box part 112 as a hollow cuboid having an opening and the first box part 111 as a plate as an example, the first box part 111 is covered at the opening of the second box part 112 to form the box 11 having a closed cavity, which can be used to accommodate the plurality of battery cells 3.

[0326] In some embodiments, the battery device 10 can further include other components. For example, the battery device 10 can further include a current collecting component, which can be used to realize the electrical connection between the plurality of battery cells 3, for example, in parallel, series or mixed combination. Specifically, the current collecting component can realize the electrical connection between the battery cells 3 by connecting the electrode terminals of the battery cells 3; or the current collecting component can also realize the electrical connection between the battery cells 3 by connecting other components of the battery cells 3. The current collecting component can be fixed to the corresponding components of the battery cells 3 by welding, for example, can be fixed to the electrode terminals, the sealing structure or the shell, etc., and the embodiments of the present application are not limited thereto.

[0327] The battery cells 3 can directly constitute the battery device 10, or can first constitute a battery module, and then a plurality of battery modules constitute the battery device 10.

[0328] In some embodiments, the battery device 10 can be located in an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0329] [Electric device]

[0330] At least one of the battery cell, the battery module, or the battery pack provided in the present application is included. The lithium ion battery, the battery module, or the battery pack can be used as a power supply of an electric device, and can also be used as an energy storage unit of an electric device. The electric 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.

[0331] As an electric device, the battery cell, the battery module or the battery pack can be selected according to the use requirement thereof.

[0332] The electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy and an electric tool, etc. The vehicle can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile, etc.; the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, such as a game console, an electric automobile toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator and an electric planer, etc. The electric device is not specially limited in the embodiments of the present application.

[0333] FIG. 4 is a schematic diagram of an electric device according to an embodiment of the present application. As shown in FIG. 4, the present application provides an electric device, which can be a vehicle 1, and the electric device includes the battery cell in the above embodiments.

[0334] The vehicle 1 can be a fuel automobile, a gas automobile or a new energy automobile, and the new energy automobile can be a pure electric automobile, a hybrid electric automobile or a range extended automobile, etc. The vehicle 1 can be provided with a motor 5, a controller 4 and a battery device 10 inside, and the controller 4 is used to control the battery device 10 to supply power to the motor 5. For example, the battery device 10 can be arranged below the vehicle 1 or at the front or rear of the vehicle 1. The battery device 10 can be used for power supply of the vehicle 1, for example, the battery device 10 can be used as an operating power supply of the vehicle 1, and is used for the circuit system of the vehicle 1, for example, for the working power demand of the vehicle 1 during starting, navigation and running. In another embodiment of the present application, the battery device 10 can not only be used as an operating power supply of the vehicle 1, but also be used as a driving power supply of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0335] As another example, the device can be a mobile phone, a tablet computer, a notebook computer, etc. The device generally requires thinning, and a battery monomer can be used as a power source.

[0336] FIG. 5 is a schematic diagram of a power consumption device according to another embodiment of the present application. As shown in FIG. 5, the present application provides a power consumption device, which is a storage device 2. The storage device 2 can include a plurality of battery devices 10. The storage device 2 can be applied to a power storage station to store and release electric energy.

[0337] Optionally, the power consumption device can also be a storage device, a lighting device, a spacecraft, etc., and embodiments of the present application include but are not limited to the above.

[0338] Hereinafter, embodiments of the present application will be described. The embodiments described below are exemplary and are intended to explain the present application only, and should not be understood as limiting the present application. In the embodiments, specific techniques or conditions not mentioned are performed according to the techniques or conditions described in the literature in the art or according to the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained commercially.

[0339] [Examples and Comparative Examples]

[0340] Example 1

[0341] (1) Preparation of the negative electrode sheet:

[0342] Preparation of the negative electrode sheet: 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 96:1.3:1.5:1.2, and a negative electrode slurry was prepared after sufficient stirring and mixing. 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 sheet. The solid content of the negative electrode slurry was 62%.

[0343] (2) Preparation of the positive electrode sheet:

[0344] Lithium iron phosphate (LiFePO4), polyvinylidene fluoride (PVDF), conductive carbon black (Super-P), and dispersant polyvinylpyrrolidone (PVP) were mixed at a mass ratio of 95.1:2.8:1.5:0.6, 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 sheet.

[0345] (3) Preparation of the separator film (organic silicon polymer containing silicon-oxygen structure):

[0346]

[0347] The Dn50 of the organic compound particles was tested by using a scanning electron microscope (ZEISS Sigma 300), and the Dn50 of the organic compound particles was 261 nm.

[0348] The glass transition temperature Tg and the melting point of the organic compound particles were tested by using differential scanning calorimetry (DSC), and there was no Tg and no melting point below 300°C. g

[0349] The density of the organic compound particles was tested by using a true density tester, and the true density of the organic compound particles was 1.32 g / cm3. 3

[0350] The organic compound particles were soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days, and the dissolution rate of the organic compound particles was tested. The dissolution rate of the organic compound particles soaked at 60°C for 7 days was 0.1%.

[0351] The crosslinking degree of the organic compound particle powder was tested by using a PQ001 nuclear magnetic resonance analyzer, and the organic compound particles were crosslinked polymers, and the calculated crosslinking degree was 93.6%.

[0352] The organic compound particle powder was tested by pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS), and FIG. 6 is a pyrolysis spectrum of the organic compound particle powder of the present application. As shown in FIG. 6, corresponding characteristic ions were detected, which can be inferred that the organic compound particles include a cage-like polysilsesquioxane skeleton.

[0353] FIG. 7 is an SEM image of the organic compound particles in Example 1. As shown in FIG. 7, the morphology of the organic compound particles is spherical or spherical, the shape is regular, and the roundness is high.

[0354] ​​​​② Preparation of the separator film: A commercially available polyethylene microporous film (Zhao Gao 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 containing organic compound particles prepared above and the binder polyacrylate, polyacrylic acid were mixed uniformly in deionized water at a solid mass ratio of 91:3:6 to obtain a coating slurry.

[0355] The commercially available polyvinylidene fluoride particles (Arkema) and the binder polyacrylate were stirred uniformly in deionized water at a solid mass ratio of 90.5:9.5 to obtain a bonding layer slurry. The Dv50 of the polyvinylidene fluoride particles was 6.5 μm.

[0356] The coating slurry was uniformly coated on both surfaces of the porous base film at a loading (single side) of 2.6 g / m 2 , and the solvent was removed by drying. The thickness of the single-side coating was 1.5 μm. Then, the bonding layer slurry was sprayed on the coating at a loading (single side) of 1.0 g / m 2 . After drying and slitting, the separator film was obtained. The air permeability of the separator film was 196 s / 100 mL. The specific implementation parameters are shown in Table 1.

[0357] (4) Preparation of the electrolyte:

[0358] 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 the electrolyte. The concentration of LiPF6 was 1 mol / L, and the mass fraction of vinylene carbonate (VC) was 2%.

[0359] (5) Preparation of the battery cell:

[0360] Preparation of the battery cell: 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 the electrolyte was injected after drying. Then, the battery cell was obtained by packaging.

[0361] [Example 2-4]

[0362] Example 2 differs from Example 1 in that, in the preparation of the organic compound particle, "start stirring and add 80 g of methyltrimethoxysilane" in Example 1 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 1.

[0363] Example 3 differs from Example 1 in that, in the preparation of the organic compound particle, "start stirring and add 80 g of methyltrimethoxysilane" in Example 1 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 1.

[0364] Example 4 differs from Example 1 in that, in the preparation of the organic compound particle, "start stirring and add 80 g of methyltrimethoxysilane" in Example 1 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 1.

[0365] [Examples 5-6]

[0366] Example 5 differs from Example 1 in that, in the preparation of the organic compound particle, "raise the temperature to 90°C and continue to react for 12 h" in Example 1 is changed to "raise the temperature to 90°C and continue to react for 24 h" to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to Example 1.

[0367] Example 6 differs from Example 1 in that, in the preparation of the organic compound particle, "raise the temperature to 90°C and continue to react for 12 h" in Example 1 is changed to "raise the temperature to 75°C and continue to react for 12 h" to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to Example 1.

[0368] [Example 7]

[0369] ① Preparation of organic compound particles (silicon-oxygen structure-containing organosilicon polymer):

[0370] A pre-emulsion was prepared by mixing 0.3 g of potassium persulfate, 0.3 g of sodium bicarbonate, 0.9 g of sodium dodecyl sulfate, 30 g of deionized water, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and divinylbenzene (the mass ratio of 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and divinylbenzene was 3:85:12, and the added mass of 3-methacryloxypropylmethyldimethoxysilane was 1.8 g). 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.

[0371] The crosslinking degree of the organic compound particle powder was tested by a PQ001 nuclear magnetic resonance analyzer. The organic compound particle was a crosslinked polymer, and the calculated crosslinking degree was 90.7%.

[0372] The powder of the organic compound particle was tested by 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.

[0373] The Dn50 of the organic compound particle was tested by a scanning electron microscope (ZEISS Sigma 300). The Dn50 of the organic compound particle was 245 nm.

[0374] The glass transition temperature T g and the melting point of the organic compound particle were tested by a differential scanning calorimetry (DSC) method. There was no Tg and no melting point below 300°C.

[0375] The density of the organic compound particle was tested by a true density tester. The density of the organic compound particle was 1.36 g / cm 3 .

[0376] The organic compound particle was soaked in a mixed solvent of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60°C for 7 days, and the dissolution rate of the organic compound particle was tested. The dissolution rate of the organic compound particle soaked at 60°C for 7 days was 0.5%.

[0377] ② Preparation of the separation membrane: a commercially available polyethylene microporous film (Zhao Gao 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 emulsion containing organic compound particles prepared above and the binder polyacrylate, polyacrylic acid were mixed uniformly in deionized water at a solid mass ratio of 92:3:5 to obtain a coating slurry.

[0378] The commercially available polyvinylidene fluoride particles (Arkema) and the binder polyacrylate were stirred uniformly in deionized water at a solid mass ratio of 90:10 to obtain a binder layer slurry. The Dv50 of the polyvinylidene fluoride particles was 6.5 μm.

[0379] The coating slurry was uniformly coated on both surfaces of the porous base film at a loading (single side) of 2.5 g / m 2 , and the solvent was removed by drying, and the thickness of the single-side coating was 1.5 μm. Then the binder layer slurry was sprayed on the coating at a loading (single side) of 1.0 g / m 2 on both sides, and the separation membrane was obtained through drying and slitting processes. The air permeability of the separation membrane was 196 s / 100 mL. The specific implementation parameters are shown in Table 3.

[0380] [Examples 8-12]

[0381] Example 8 differs from Example 7 in that in the preparation of the organic compound particles, “0.9 g of sodium dodecyl sulfate” in Example 7 is adjusted to “0.3 g of sodium dodecyl sulfate” to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0382] Example 9 differs from Example 7 in that in the preparation of the organic compound particles, “0.9 g of sodium dodecyl sulfate” in Example 7 is adjusted to “0.6 g of sodium dodecyl sulfate” to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0383] Example 10 differs from Example 7 in that in the preparation of the organic compound particles, “0.9 g of sodium dodecyl sulfate” in Example 7 is adjusted to “0.8 g of sodium dodecyl sulfate” to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0384] Example 11 differs from Example 7 in that in the preparation of the organic compound particles, “0.9 g of sodium dodecyl sulfate” in Example 7 is adjusted to “1.5 g of sodium dodecyl sulfate” to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0385] Example 12 differs from Example 7 in that, in the process of preparing the organic compound particles, the "0.9 g of sodium dodecyl sulfate" in Example 7 is adjusted to "2.0 g of sodium dodecyl sulfate", to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0386] [Comparative Example 1]

[0387] Comparative Example 1 differs from Example 1 in that, in the process of preparing the organic compound particles, the "start stirring and add 80 g of methyltrimethoxysilane" in Example 1 is adjusted to "start stirring and add 220 g of methyltrimethoxysilane", to obtain an organic compound particle dispersion liquid. Among them, the Dn50 of the organic compound particles is 1320 nm.

[0388] [Comparative Example 2]

[0389] Comparative Example 2 differs from Example 7 in that, in the process of preparing the organic compound particles, the "0.9 g of sodium dodecyl sulfate" in Example 7 is adjusted to "5 g of sodium dodecyl sulfate", to obtain an organic compound particle dispersion liquid. Among them, the Dn50 of the organic compound particles is 756 nm.

[0390] Table 1 Product parameters of Examples 1-6 and Comparative Example 1

[0391] Table 2 Test data of Examples 1-6 and Comparative Example 1

[0392] As shown in Examples 1-6 and Comparative Example 1 in Tables 1 and 2, by limiting the Dn50 of the organic compound particles to 100 nm-700 nm, the Dn90 to 200 nm-1000 nm, and the Dn10 to 50 nm-400 nm, the overall distribution of the particles is more concentrated, the particle size distribution of the organic compound particles is narrowed, the size distribution of the electrolyte infiltration channels in the coating is more uniform, the electrolyte has good infiltration performance in the separator membrane, thereby improving the cycle performance of the battery monomer. In addition, the crosslinking degree of the organic compound particles is 85%-97%, and the mass fraction of the cage polysilsesquioxane skeleton is 40%-60%. The cage polysilsesquioxane skeleton can provide structural support and ensure that the organic compound particles have good structural stability, improve the overall structural integrity of the separator membrane at high temperatures, and further help to improve the cycle performance of the battery monomer.

[0393] Table 3 Product parameters of Examples 7-12 and Comparative Example 2

[0394] Table 4 Performance parameters of Examples 7-12 and Comparative Example 2

[0395] As shown in Examples 7-12 and Comparative Example 2 in Tables 3 and 4, by limiting the Dn50 of the organic compound particles to 100-700 nm, the Dn90 to 200-1000 nm, and the Dn10 to 50-400 nm, the particles are more concentrated in distribution, the particle size distribution of the organic compound particles is narrowed, the size distribution of the electrolyte infiltration channels in the coating is more uniform, the electrolyte has better infiltration performance in the separator, and thus the cycle performance of the battery cell is improved. In addition, the cross-linking degree of the organic compound particles is 75-95%, the mass fraction of phenyl groups is 2-12%, and the mass fraction of silicon elements is 9.98%, which can ensure that the organic compound particles have good structural stability, improve the overall structural integrity of the separator at high temperatures, and further help to improve the cycle performance of the battery cell.

[0396] The test methods of the physicochemical parameters and performance parameters involved in the examples 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.

[0397] 1. Test method of Dn50, Dn90, Dn10

[0398] The "Dn50, Dn90, Dn10" of the organic compound particles can be tested by the following method: after disassembling the battery cell, the Dn50 / Dn10 / Dn90 of the organic compound particles is obtained. The Dn50 / Dn10 / Dn90 has the meaning known in the art and can be tested by instruments and methods known in the art. For example, a scanning electron microscope (e.g., ZEISS Sigma 300) is used to obtain scanning electron microscope (SEM) pictures of the separator according to JY / T010-1996. As an example, the following method can be used for testing: an arbitrary test sample with a length x width of 50 mm x 100 mm is selected on the separator, 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 (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) under a certain magnification (e.g., 500x or 1000x when measuring the organic compound particles) by Image J software. The number and particle size values of the organic compound particles in each test region are counted, and the particle size number distribution curve of the organic compound particles is obtained. The results of Dn50, Dn10, and Dn90 are obtained by software analysis. In the particle size number distribution curve of the organic compound particles, Dn90, Dn10, and Dn50 refer to the particle size of the organic compound particles when the cumulative particle size concentration reaches 90%, 50%, and 10%, respectively.

[0399] 2. Test method of crosslinking degree

[0400] 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 sample to be tested (including at least one of the above-mentioned methyl, ethyl, n-propyl, and isopropyl) after cleaning and drying is taken, and is loaded into a clean sample tube and 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 calculating the proportion of the crosslinking signal from the entire polymer signal by fitting software; 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.

[0401] 3. Specific test method of phenyl and cage skeleton

[0402] The pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) can be used to test the phenyl and cage skeleton structure in the organic compound particles. Specifically, 0.5-1 mg of the above-mentioned organic compound particles is weighed as a test sample and loaded into a quartz cracking tube of a pyrolysis instrument, and is cracked at 550°C for 1.2 s. The sample is tested for cracking into volatile small molecules in an inert gas (such as helium), and then introduced into a gas chromatograph-mass spectrometer. The HP-5ms (30 m x 0.25 mm x 0.25 μm) chromatographic column is selected, the temperature is set to 30°C for 5 min, the temperature is increased to 250°C at 10°C / min, and the temperature is maintained at 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 phenyl and the characteristic ions corresponding to the cage skeleton are detected, and it can be inferred that the organic silicon polymer includes the phenyl and the cage skeleton structure. The internal standard method is used to calculate the mass proportion of the phenyl and the cage skeleton in the organic compound particles based on the above-mentioned fragment peak areas corresponding to the characteristic phenyl and the cage skeleton.

[0403] 4. Test method of infiltration performance

[0404] Take a piece of the above prepared flat, clean, crease-free separator film sample, cut the separator film into 3 samples of 5 mm x 100 mm, fix the sample on a flat substrate (such as a glass sheet, a culture dish), ensure that the test surface is upward and in a horizontal state. Take the average value of 3 parallel samples as the test result. In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), use a precision pipette (such as a microsyringe) to suck 0.5 mg of the above prepared electrolyte, and drop the droplet vertically and gently on the surface of the separator film. Let stand for 1 min, observe and record the length of the electrolyte diffusion, and take the arithmetic mean of the test results of 5 groups of samples as the final diffusion length. The larger the diffusion length value, the better the electrolyte wetting performance in the separator film.

[0405] 5. Test of thermal shrinkage

[0406] The thermal shrinkage test of the separator film can refer to GB / T 36363-2018. As an example, the separator film is punched into a sample with a width of 50 mm and a length of 100 mm by a punch machine, 5 parallel samples are placed on an A4 paper, and then the A4 paper with the samples is placed on corrugated paper with a thickness of 1 mm to 5 mm. The temperature of the air oven is set to 130℃, 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 separator film are measured, and the values are marked as a and b respectively. The longitudinal (MD) thermal shrinkage is [(100-a) / 100] x 100%, and the transverse (TD) thermal shrinkage is [(50-b) / 50] x 100%. The average value of 3 parallel samples is taken as the test result.

[0407] 6. Test of cycle performance

[0408] The above prepared battery monomer is charged to 3.65V at 1C under the condition that the test temperature is 25℃ and 2.5-3.65V, and then charged to 3.65V under constant voltage until the current is ≤0.05mA, and then discharged to 2.5V at 1C, which is one charge-discharge cycle process. The discharge capacity of this time is the discharge capacity of the first cycle, denoted as Cap1. The battery monomer is subjected to cycle charge-discharge test in the above manner, and the above operation is repeated for 500 cycles. The discharge capacity of the 500th cycle is taken as Cap500. The capacity retention rate C of the secondary battery monomer after 500 cycles is [Cap500 / Cap1] x 100%, and the capacity retention rate after cycling is recorded. The larger the capacity retention rate after cycling, the smaller the capacity loss of the battery monomer, and the better the cycle performance.

[0409] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration, function, and effect as the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications to the embodiments, or by combining part of the configurations of the embodiments, which can be conceived by those skilled in the art, without departing from the spirit of the present application, are also included in the scope of the present application.

Claims

1. A battery cell, characterized by, The battery cell comprises 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 provided on at least one side of the porous base film; the coating layer comprises organic compound particles, the morphology of the organic compound particles is spherical or spherical-like; the Dn50 of the organic compound particles satisfies: 100 nm≤Dn50≤700 nm, wherein Dn50 refers to the particle size corresponding to the cumulative particle number distribution of 50% in the particle size number distribution curve of the organic compound particles.

2. The battery cell of claim 1, wherein, The Dn90 of the organic compound particles satisfies: 200 nm≤Dn90≤1000 nm, wherein Dn90 refers to the particle size corresponding to the cumulative particle number distribution of 90% in the particle size number distribution curve of the organic compound particles, and / or the Dn10 of the organic compound particles satisfies: 50 nm≤Dn10≤400 nm, wherein Dn10 refers to the particle size corresponding to the cumulative particle number distribution of 10% in the particle size number distribution curve of the organic compound particles.

3. The battery cell according to claim 1 or 2, characterized in that, The roundness of the organic compound particles is 0.5-1.

0.

4. The battery cell of any one of claims 1-3, wherein, The organic compound particles comprise a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70%-98%.

5. The battery cell of claim 4, wherein, The cross-linked polymer comprises a siloxane-containing organic silicon polymer.

6. The battery cell of claim 5, 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), In formula (I), R1 and 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.

7. The battery cell according to claim 5 or 6, wherein the siloxane-containing organic silicon polymer satisfies at least one of the following conditions: (1) the cross-linking degree of the siloxane-containing organic silicon polymer is 75%-95%; (2) the mass fraction of silicon in the siloxane-containing organic silicon polymer is 10%-25%; (3) the mass fraction of phenyl in the siloxane-containing organic silicon polymer is 2%-12%; (4) the siloxane-containing organic silicon polymer comprises silicon hydroxyl groups; (5) the mass fraction of the silicon hydroxyl groups in the siloxane-containing organic silicon polymer is 100-1500 ppm.

8. The battery cell according to claim 1 or 2, characterized in that, The siloxane-containing organic silicon polymer comprises a skeleton formed by a compound represented by formula (II), R a [SuO 3 / 2 ] n Formula (II) wherein n is any integer from 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 including C1-C3 alkyl.

9. The battery cell of claim 8, wherein, The organosilicon polymer containing a siloxane structure includes, by hydrolysis and polycondensation of one or more of monomers represented by formula (III), wherein R'1includes a C1to C3alkyl group.

10. The battery cell of any one of claims 7-9, wherein, The siloxane-containing organic silicon polymer satisfies at least one of the following conditions: (1) the cross-linking degree of the siloxane-containing organic silicon polymer is 85%-97%; (2) the mass fraction of silicon in the siloxane-containing organic silicon polymer is 25%-45%; (3) the mass fraction of the skeleton formed by the compound represented by formula (II) in the siloxane-containing organic silicon polymer is 40%-60%; (4) the siloxane-containing organic silicon polymer comprises silicon hydroxyl groups; (5) the silicon hydroxyl accounts for 100 ppm-2000 ppm of the mass of the organosilicon polymer containing a siloxane structure.

11. The battery cell of any one of claims 1-9, wherein, The organic compound particles satisfy at least one of the following conditions: (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℃; (3) the initial thermal weight loss temperature T of the organic compound particles 3d greater than or equal to 250°C; (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% when the mixed solvent is soaked 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 .

12. The battery cell of any one of claims 1-11, wherein, The mass fraction of the organic compound particles in the coating layer is 50%-97%.

13. The battery cell of any one of claims 1-12, wherein, The coating layer further comprises a first binder, and the first binder satisfies at least one of the following conditions: (1) the first 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; (2) the mass fraction of the first binder in the coating layer is 3%-15%.

14. The battery cell of any one of claims 1-13, wherein, The separation film further comprises second binder particles, which are located in the coating layer, or the separation film further comprises a bonding layer, which is arranged on at least one side of the coating layer away from the base film, and the second binder particles are located in the bonding layer; the second binder particles satisfy one or more of the following conditions: (1) 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), polyacrylate, polymethyl methacrylate, and polyacrylonitrile; (2) the volume average particle size of the second binder particles is 5-20 μm.

15. The battery cell of any one of claims 1-14, wherein, The separation film satisfies at least one of the following conditions: (1) the thickness of the coating layer is 0.5-10 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 separation film is less than or equal to 5% when the separation film is heated at 130℃ for 1 h; (4) the transverse heat shrinkage rate of the separation film is less than or equal to 5% when the separation film is heated at 130℃ for 1 h; (5) the air permeability of the separation film is 150-500 s / 100 mL.

16. A battery device characterized by comprising: The battery cell comprises the battery cell as claimed in any one of claims 1-15.

17. An electrical device, characterized by The battery device comprises the battery cell as claimed in any one of claims 1-15 or the battery device as claimed in claim 16.

18. An isolating film, characterized by, The battery device comprises: a porous base film and a coating layer arranged on at least one side of the porous base film; The coating comprises organic compound particles, the morphology of the organic compound particles is spherical or spheroidal; the Dn50 of the organic compound particles satisfies: 100nm≤Dn50≤700nm, Dn50 refers to the particle size corresponding to the cumulative particle quantity distribution of 50% in the particle size quantity distribution curve of the organic compound particles.

19. The separator membrane of claim 18, wherein, The Dn90 of the organic compound particles satisfies: 200nm≤Dn90≤1000nm, Dn90 refers to the particle size corresponding to the cumulative particle quantity distribution of 90% in the particle size quantity distribution curve of the organic compound particles, and / or the Dn10 of the organic compound particles satisfies: 50nm≤Dn10≤400nm, Dn10 refers to the particle size corresponding to the cumulative particle quantity distribution of 10% in the particle size quantity distribution curve of the organic compound particles.

20. The separator membrane according to claim 18 or 19, characterized in that, The roundness of the organic compound particles is 0.5-1.

0.

21. The separator membrane according to any one of claims 18-20, characterized in that, The organic compound particles comprise a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70%-98%.

22. The separator membrane of claim 21, wherein, The cross-linked polymer comprises a silicone polymer containing a siloxane structure.

23. The separator membrane of claim 22, 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), In formula (I), R1 and 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.

24. The battery cell of claim 22 or 23, the silicone polymer containing a siloxane structure satisfies at least one of the following conditions: (1) the cross-linking degree of the silicone polymer containing a siloxane structure is 75%-95%; (2) the mass fraction of silicon in the silicone polymer containing a siloxane structure is 10%-25%; (3) the mass fraction of phenyl in the silicone polymer containing a siloxane structure is 2%-12%; (4) the silicone polymer containing a siloxane structure comprises silicon hydroxyl; (5) the mass fraction of the silicon hydroxyl in the silicone polymer containing a siloxane structure is 100-1500 ppm.

25. The separator membrane of claim 18 or 19, wherein, The silicone polymer containing a siloxane structure comprises a skeleton formed by a compound represented by formula (II), R a [SuO 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 including C1-C3 alkyl.

26. The separator membrane of claim 25, wherein, The silicone polymer containing a siloxane structure comprises one or more of monomers represented by formula (II) obtained through hydrolysis and polycondensation, wherein R'1 comprises C1-C3 alkyl.

27. The separator membrane of any one of claims 24-26, wherein, The silicone polymer containing a siloxane structure satisfies at least one of the following conditions: (1) the cross-linking degree of the silicone polymer containing a siloxane structure is 85%-97%; (2) the mass fraction of silicon in the silicone polymer containing a siloxane structure is 25%-45%; (3) the mass fraction of the skeleton formed by the compound represented by formula (II) in the silicone polymer containing a siloxane structure is 40%-60%; (4) the silicone polymer containing a siloxane structure comprises silicon hydroxyl; (5) the mass fraction of the silicon hydroxyl in the silicone polymer containing a siloxane structure is 100-2000 ppm.

28. The separator membrane of any one of claims 18-27, wherein, The mass fraction of the organic compound particles in the coating is 50% to 97%. The mass fraction of the organic compound particles in the coating is 50% to 97%.

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