Metal battery cell, battery device, electric device and separator

Abstract

Provided in the present application are a metal battery cell, a battery device, an electric device and a separator. The metal battery cell comprises an electrode assembly and a shell for accommodating the electrode assembly, wherein the electrode assembly 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, and comprises a porous base film and a coating arranged on at least one side of the porous base film; the coating comprises organic compound particles and a first binder; the first binder is used for bonding the organic compound particles to the porous base film; the organic compound particles have a spherical or near-spherical morphology; and the roundness A of the organic compound particles satisfies: 0.5≤A≤1.0. The technical solution of the present application is beneficial for improving the dendrite resistance of the separator, thereby improving the storage performance and cycle performance of the battery cell.

Description

Metal battery, battery device, electric device, separator Cross-reference to related applications

[0001] This application claims priority to Chinese Patent Application No. 202411388765.7, filed on September 30, 2024, entitled “Silicon-containing organic resin particle, method for producing silicon-containing organic resin particle, silicon-containing organic resin particle dispersion, 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 metal battery, a battery device, an electric device, and a separator. BACKGROUND

[0003] In recent years, with the increasingly wide range of applications of batteries, batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind, and solar power stations, as well as in electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields.

[0004] The development of battery technology needs to consider various design factors, such as energy density, cycle life, storage performance, charge-discharge rate, reliability, etc. While metal batteries have made great progress, higher requirements have been placed on their various performance. Among them, the separator is an important component that supports the completion of the charge-discharge electrochemical process of the secondary battery. However, the heat-resistant coating particles on its surface are usually irregular particles, which can easily cause preferential nucleation and growth of dendrites, and thus cause thermal runaway of the metal battery, affecting the storage performance and cycle performance of the metal battery.

[0005] Therefore, how to improve the dendrite resistance of the separator and thus improve the storage performance and cycle performance of the metal battery is a technical problem that needs to be solved. SUMMARY

[0006] The present application is made in view of the above-mentioned problem, and provides a metal battery, a battery device, an electric device, and a separator, which is beneficial to improve the dendrite resistance of the separator and thus improve the storage performance and cycle performance of the metal battery.

[0007] In a first aspect, a metal battery cell is provided, comprising: an electrode assembly, and a housing for accommodating the electrode assembly, the electrode assembly comprising a positive electrode sheet, a negative electrode sheet, and a separator membrane between the positive electrode sheet and the negative electrode sheet; the negative electrode sheet comprising a negative electrode current collector and an interface modification layer on at least one side of the negative electrode current collector, the interface modification layer being configured to guide the formation of a metal layer on the negative electrode current collector; the separator membrane comprising a porous base membrane and a coating layer on at least one side of the porous base membrane; the coating layer comprising organic compound particles and a first binder; the first binder being configured to bind the organic compound particles to the porous base membrane; the organic compound particles having a spherical or spheroid morphology; and a roundness A of the organic compound particles satisfying 0.5≤A≤1.0.

[0008] In the embodiments of the present application, by setting the range of the roundness of the organic compound particles in the coating layer, the organic compound particles are facilitated to have a highly spherical morphology. Such highly spherical particles can achieve a more orderly packed arrangement, thereby reducing the pore size and distribution non-uniformity in the coating layer to form a more dense and uniform microstructure. On the one hand, this can balance the spatial distribution of active metal ions, effectively eliminating local current density differences, thereby reducing the area where dendrites preferentially nucleate. On the other hand, this can also shorten the ion transport path and reduce the concentration polarization effect in the electrolyte, thereby maintaining the stability of the metal ion deposition process. In addition, since the spherical particles can reduce the angular structures commonly found in irregular particles, the electric field concentration phenomenon caused by geometric protrusions can be fundamentally reduced. Such uniform electric field distribution can guide the uniform deposition of metal ions on the electrode surface, thereby reducing the directional growth of dendrites. Therefore, the above technical solution can improve the dendrite resistance of the separator membrane, thereby reducing the probability of thermal runaway of the metal battery cell and improving the storage performance and cycle performance of the battery cell in a high temperature environment.

[0009] In a possible implementation, a particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles satisfies 0.5≤(Dn90-Dn10) / Dn50≤2.0; wherein Dn10, Dn50, and Dn90 refer to particle sizes corresponding to 10%, 50%, and 90% of the cumulative number distribution of the particles in a particle size number distribution curve of the organic compound particles.

[0010] In the embodiments of the present application, the particle size concentration of the organic compound particles is set in the above range, which is beneficial to make the organic compound particles have a suitable size distribution, can reduce the mechanical defects that may be caused by large particles piercing the base film, and can also reduce the situation that small particles cause uneven coating and local insufficient strength. This can reduce the penetration of dendrites and reduce the risk of short circuit. At the same time, this is also beneficial to make the organic compound particles have a suitable packing tightness between particles and maintain their porosity. This can promote sodium ion transmission, reduce the internal resistance of the battery cell, and improve the rate performance. Therefore, the particle size concentration of the organic compound particles meets the above range, which can balance the mechanical strength, ion conductivity and structural stability, and improve the dendrite resistance of the separator, thereby reducing the probability of thermal runaway of the metal battery cell.

[0011] In a possible implementation, the concavity B of the organic compound particles satisfies: 0≤B≤0.5.

[0012] In the embodiments of the present application, the concave structure of the organic compound particles can direct the deposition of metal ions, the convex in the curved electric field distribution is more gentle, and the local electric field can be dispersed to effectively reduce the local current density peak. In the case that the concavity of the organic compound particles is in the above range, the pore structure formed can balance the electrolyte distribution, shorten the ion transmission path, reduce the concentration polarization, and reduce the current uneven situation. At the same time, this will not hinder ion transmission and cause local electrolyte depletion. In addition, this is also beneficial to improve the mechanical strength of the coating and reduce the formation of new dendrite nucleation sites in the deposition process. Therefore, by controlling the particle concavity in a moderate range, both the electric field adjustment advantage and the dendrite phenomenon caused by structural defects can be reduced, thereby reducing the probability of thermal runaway of the metal battery cell.

[0013] In a possible implementation, the interface modification layer includes one or more of carbon materials and metal materials.

[0014] In the embodiments of the present application, in the actual application of the metal battery cell, the material of the interface modification layer can be selected according to specific needs.

[0015] In a possible implementation, the carbon material includes one or more of carbon black, activated carbon, carbon nanotube, carbon fiber and graphite; and / or, the metal material includes one or more of In, Bi, Ag, Zn, Al, Mg, Ga, Ge and Sb, or a metal alloy, a metal oxide or a metal carbide of at least one element in In, Bi, Ag, Zn, Al, Mg, Ga, Ge and Sb.

[0016] In the embodiments of the present application, the carbon material can construct a network structure with excellent conductivity, buffer volume expansion, and conduct ions and electrons; and the metal material is a lithium- or sodium-philic material, which can reduce nucleation energy, induce uniform deposition, and inhibit the formation of dendrites.

[0017] In a possible implementation, the thickness C of the interface modification layer satisfies: 0.2 μm≤C≤10 μm.

[0018] In the embodiments of the present application, the thickness of the interface modification layer is set in the above range, which can effectively cover the defects on the surface of the current collector and provide sufficient nucleation sites. This is conducive to reducing the local current density, forming effective uniform lithium / sodium flow, and improving the inhibition effect of dendrites. At the same time, this can also reduce the overall internal resistance of the battery cell, promote ion transmission, reduce polarization, and thus reduce dendrite growth. In addition, the above thickness can also improve the interface stability, which is conducive to uniform deposition and reduces the risk of dendrites penetrating the separator.

[0019] In a possible implementation, the metal battery cell is a negative-electrode-free lithium metal battery cell or a negative-electrode-free sodium metal battery cell.

[0020] In the embodiments of the present application, the negative-electrode-free lithium metal battery cell or the negative-electrode-free sodium metal battery cell can directly deposit metal on the negative electrode current collector during the first charging process. At the same time, since there is no initial active material in the negative electrode sheet, this can improve the energy density of the metal battery cell.

[0021] 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%.

[0022] In the embodiments of the present application, the cross-linking degree of the cross-linked polymer satisfies the above range, the formed cross-linked polymer has a three-dimensional network structure, which is conducive to limiting the free movement of molecular chains, thereby improving the structural stability of the organic compound particles and increasing the mechanical strength of the particles, thereby increasing the structural stability of the coating.

[0023] In a possible implementation, the cross-linked polymer includes a silicone polymer containing a siloxane structure.

[0024] In the embodiments of the present application, the organosilicon polymer containing a siloxane structure is used as the cross-linked polymer. The siloxane bond has high bond energy, and the three-dimensional cross-linked network formed by the cross-linking of the molecular chains of the organosilicon polymer has high mechanical strength, so that the organosilicon polymer containing a siloxane structure has high mechanical strength, thereby improving the dendrite resistance of the metal battery cell and the storage performance and cycle performance in a high-temperature environment. Specifically, the rigid-Si-O-Si-inorganic skeleton remains stable in a high-temperature environment, effectively reducing dendrite puncture and separator thermal contraction. At the same time, the polymer also has good electrolyte wettability and ion uniform distribution capability, which can reduce the dendrite growth caused by local current concentration. In addition, compared with inorganic particles, the density of the organosilicon polymer is lower, and the overall mass of the coating can be reduced under the same thickness, thereby improving the energy density of the battery cell.

[0025] In a possible implementation, the organosilicon polymer containing a siloxane structure includes a benzene group, and the organosilicon polymer containing a siloxane structure is obtained by polymerization of a monomer represented by formula (I) and a cross-linking agent,

[0026]

[0027] 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) acryloyloxyalkyl, and R4 includes C2-C8 alkenyl or C4-C8 (meth) acryloyloxyalkyl; and the cross-linking agent includes divinylbenzene.

[0028] In the embodiments of the present application, the polymerization of the monomer represented by formula (I) and the cross-linking agent divinylbenzene can take into account the material stability and interface characteristics. Specifically, the polymer obtained by the polymerization of the monomer represented by formula (I) and the cross-linking agent divinylbenzene has the rigidity of the aromatic ring and the high-energy siloxane bond, and the three-dimensional cross-linked network formed by the cross-linking of the molecular chains of the organosilicon polymer, so that it has excellent structural stability and high mechanical strength, thereby reducing the physical puncture phenomenon of the dendrite. In addition, the polar siloxane segment improves the electrolyte wettability, promotes the uniform distribution of sodium ions, and reduces the dendrite growth caused by local concentration polarization. Therefore, in a high-temperature environment, the coating can effectively reduce electrolyte thermal decomposition and metal lithium side reactions, maintain interface stability, thereby promoting the storage performance and cycle performance in a high-temperature environment.

[0029] In a possible implementation, the organosilicon polymer containing siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing siloxane structure is 75% to 95%; (2) the mass content of silicon elements in the organosilicon polymer containing siloxane structure is 10% to 25%; and (3) the mass content of phenyl groups in the organosilicon polymer containing siloxane structure is 2% to 12%.

[0030] In the embodiments of the present application, by limiting the crosslinking degree, the mass content of silicon elements, and the mass content of phenyl groups, the dendrite resistance of the metal battery cell, and the storage performance and cycle performance of the battery cell in a high-temperature environment are improved.

[0031] In a possible implementation, the organosilicon polymer containing siloxane structure includes a skeleton composed of a compound shown in formula (II),

[0032] R a [SiO 3 / 2 ] n formula (II),

[0033] wherein n is at least one of integers 4 to 12, R a including cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; optionally, n is 8, and R a includes C1-C3 alkyl.

[0034] In the embodiments of the present application, by introducing the structural unit shown in formula (II) into the organosilicon polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. The structure has a highly symmetrical rigid covalent bond network, which can effectively reduce the shrinkage of the coating under high-temperature conditions, thereby providing stable mechanical support for the uniform deposition of metal ions, and physically preventing dendrite penetration. At the same time, the three-dimensional polyhedral skeleton structure can enhance the electrolyte wettability and ion flow uniformity, and reduce dendrite growth caused by local current overload. By selecting C1-C3 alkyl as the R1 substituent, the thermal stability and interface compatibility of the material are further improved, thereby improving the storage performance and cycle performance of the battery cell in a high-temperature environment.

[0035] In a possible implementation, the organosilicon polymer containing siloxane structure includes one or more of monomers shown in formula (III) obtained by hydrolysis and polycondensation,

[0036]

[0037] wherein R'1 includes C1-C3 alkyl.

[0038] In the embodiments of the present application, the hydrolysis-polycondensation reaction of the monomer of formula (III) can obtain the organic silicon polymer with a cage structure. The polymer forms a three-dimensional network with high mechanical strength and thermal stability in the coating, which can effectively reduce the shrinkage of the coating at high temperature, provide stable rigid support for the uniform deposition of metal ions, and physically effectively block the dendrite penetration. In addition, the three-dimensional polyhedral skeleton structure formed by polymerization can enhance the high-temperature wettability and ion distribution uniformity of the electrolyte, and reduce the dendrite growth and aggravation of side reactions caused by local current overload. Therefore, the above-mentioned organic silicon polymer can improve the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance of the battery monomer at high temperature.

[0039] In a possible implementation, the organic silicon polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organic silicon polymer containing a siloxane structure is 85% to 97%; (2) the mass content of silicon elements in the organic silicon polymer containing a siloxane structure is 25% to 45%; (3) the mass content of the skeleton formed by the compound of formula (II) in the organic silicon polymer containing a siloxane structure is 40% to 60%.

[0040] In the embodiments of the present application, by limiting the crosslinking degree, the mass fraction of silicon elements, and the mass content of phenyl groups, the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance at high temperature can be improved.

[0041] In a possible implementation, the organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammetry curve of the organic compound particles in the first cycle does not have an oxidation peak in the voltage range of 0 to 4.4 V; (2) the organic compound particles do not have a glass transition temperature at 300°C; (3) the initial thermal weight loss temperature T 3d satisfies: T 3d ≥ 250°C; (4) the dissolution rate of the organic compound particles in a mixed solvent composed 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°C for 7 days; (5) the true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 .

[0042] In the embodiments of the present application, by limiting the oxidation peak of the cyclic voltammetry curve of the organic compound particles in the first cycle, the glass transition temperature, the initial thermal weight loss temperature, the dissolution rate of the organic compound particles when soaked at 60°C for 7 days, and the true density, the overall performance of the battery monomer can be improved.

[0043] In a possible implementation, the mass content of the organic compound particles in the coating layer is 50% to 97%.

[0044] In the embodiments of the present application, the mass content of the organic compound particles in the coating layer is set within the above range, which is beneficial to improve the mechanical strength of the coating layer, thereby effectively blocking the penetration of lithium dendrites and reducing the short circuit of the electrode. At the same time, this can also promote the uniform distribution of ions during the cycle process and reduce the growth of dendrites. On the other hand, this is also beneficial to reduce the agglomeration of particles to block the pores and cause the local current density to increase to induce dendrites.

[0045] In a possible implementation, the first binder satisfies one or more 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; (2) the mass content of the first binder in the coating layer is 3% to 15%.

[0046] In the embodiments of the present application, the organic compound particles in the coating layer are connected and fixed to each other by the first binder, reducing the falling off of the organic compound particles during coating and use. The mass content of the first binder is set within the above range, which can reduce the proportion of the organic compound particles in the coating layer due to the excessive binder while taking into account the adhesion, thereby taking into account the stability and dendrite resistance of the separation film and improving the cycle performance of the battery cell.

[0047] In a possible implementation, the separation film further includes second binder particles, and the second binder particles are located in the coating layer, or the separation film further includes a bonding layer, the bonding layer is arranged on at least one side of the coating layer away from the porous 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 include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), polyacrylate, polymethyl methacrylate, and polyacrylonitrile; (2) the average volume particle size of the second binder particles is 5 μm to 20 μm.

[0048] In the embodiments of the present application, by adding second binder particles in the coating or in the adhesive layer of the separator film, 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. In addition, the average volume particle size of the second binder particles is set in the above range, which is beneficial to the uniform distribution of the second binder particles while also having moderate flowability, thereby further improving the cycle performance of the battery cell.

[0049] In a possible implementation, the separator film satisfies one or more of the following conditions: (1) the thickness of the coating layer is 0.5 μm to 10 μm; (2) the area density of the coating layer is 1.5 g / m 2 ~ 6 g / m 2 ; (3) the longitudinal thermal shrinkage rate of the separator film is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage rate of the separator film is less than or equal to 5% when heated at 130°C for 1 h; and (5) the air permeability of the separator film is 150 s / 100 mL to 500 s / 100 mL.

[0050] In the embodiments of the present application, by limiting the thickness, area density, longitudinal thermal shrinkage rate, transverse thermal shrinkage rate and air permeability of the coating layer, the overall performance of the separator film is improved.

[0051] In a second aspect, a battery device is provided, which includes the battery cell in the first aspect and any possible implementation manner thereof.

[0052] In a third aspect, a power utilization device is provided, which includes the battery device in the second aspect.

[0053] In a fourth aspect, a separator film is provided, 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 and a first binder; the first binder is used to bond the organic compound particles to the porous base film; the morphology of the organic compound particles is spherical or spheroidal; and the roundness A of the organic compound particles satisfies: 0.5 ≤ A ≤ 1.0.

[0054] In the embodiments of the present application, by setting the range of the roundness of the organic compound particles in the coating, the organic compound particles are facilitated to present a highly spherical morphology. Such highly spherical particles can realize a more closely ordered packing arrangement, thereby reducing the pore size and unevenness of distribution in the coating to form a more dense and uniform microstructure. On the one hand, this can balance the spatial distribution of active metal ions, effectively eliminating local current density differences, thereby reducing the area where dendrites preferentially nucleate. On the other hand, this can also shorten the ion transport path and reduce the concentration polarization effect in the electrolyte, thereby maintaining the stability of the metal ion deposition process. In addition, since the spherical particles can reduce the angular structure commonly seen in irregular particles, the electric field concentration phenomenon caused by geometric protrusions can be fundamentally reduced. Such uniform electric field distribution can guide the uniform deposition of metal ions on the electrode surface, thereby reducing the directional growth of dendrites. Therefore, the above technical solution can improve the dendrite resistance of the separator film, thereby reducing the probability of thermal runaway of the metal battery cell and improving the storage performance and cycle performance of the battery cell in a high temperature environment.

[0055] In a possible implementation, the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles satisfies: 0.5≤(Dn90-Dn10) / Dn50≤2.0; wherein Dn10, Dn50 and Dn90 refer to the particle sizes corresponding to the cumulative particle number distribution of 10%, 50% and 90% in the particle size number distribution curve of the organic compound particles.

[0056] In the embodiments of the present application, by setting the particle size concentration of the organic compound particles within the above range, the organic compound particles are facilitated to have a suitable size distribution, which can reduce the mechanical defects that may be caused by large particles piercing the base film and also reduce the situation that small particles cause the coating to be uneven and locally insufficient in strength. This can reduce the penetration of dendrites and reduce the risk of short circuit. At the same time, this is also conducive to the organic compound particles having a suitable packing tightness between particles to maintain their porosity. This can promote the transport of sodium ions, reduce the internal resistance of the battery cell and improve the rate performance. Therefore, the particle size concentration of the organic compound particles satisfying the above range can take into account the mechanical strength, ion conductivity and structural stability, and improve the dendrite resistance of the separator film, thereby reducing the probability of thermal runaway of the metal battery cell.

[0057] In a possible implementation, the concavity B of the organic compound particles satisfies: 0≤B≤0.5.

[0058] In the embodiments of the present application, the concave structure of the organic compound particles can direct the deposition of metal ions, the convex in the curved electric field distribution is more gentle, and the local electric field is dispersed, which can effectively reduce the local current density peak. In the case that the concave degree of the organic compound particles is in the above range, the pore structure formed can balance the electrolyte distribution, shorten the ion transmission path, reduce the concentration polarization, and reduce the current unevenness. At the same time, this will not hinder the ion transmission and cause local electrolyte depletion. In addition, this is also conducive to improving the mechanical strength of the coating and reducing the formation of new dendritic nucleation sites during the deposition process. Therefore, by controlling the concave degree of the particles within a moderate range, the advantages of electric field adjustment can be utilized, and the dendritic phenomenon caused by structural defects can be reduced, thereby reducing the probability of thermal runaway of the metal battery cell.

[0059] In a possible implementation, the organic compound particles include a cross-linked polymer, and a cross-linking degree of the cross-linked polymer is 70% to 98%.

[0060] In the embodiments of the present application, the cross-linking degree of the cross-linked polymer meets the above range, and the formed cross-linked polymer has a three-dimensional network structure, which is conducive to limiting the free movement of molecular chains, thereby improving the structural stability of the organic compound particles and increasing the mechanical strength of the particles, thereby increasing the structural stability of the coating.

[0061] In a possible implementation, the cross-linked polymer includes a silicone polymer containing a siloxane structure.

[0062] In the embodiments of the present application, by using the silicone polymer containing a siloxane structure as the cross-linked polymer, the high bond energy of the siloxane bond and the three-dimensional cross-linked network formed by the cross-linking between the molecular chains of the silicone polymer make the silicone polymer containing a siloxane structure have high mechanical strength, thereby being conducive to improving the dendrite resistance of the metal battery cell and the storage performance and cycle performance in a high-temperature environment. Specifically, the rigid-Si-O-Si-inorganic skeleton remains stable in a high-temperature environment, effectively reducing dendritic puncture and diaphragm thermal contraction. At the same time, the polymer also has good electrolyte wettability and ion uniform distribution capability, which can reduce the dendritic growth caused by local current concentration. In addition, compared with inorganic particles, the density of the silicone polymer is relatively low, and the overall mass of the coating can be reduced under the same thickness, thereby being conducive to improving the energy density of the battery cell.

[0063] In a possible implementation, the silicone polymer containing a siloxane structure includes a phenyl group, and the silicone polymer containing a siloxane structure includes a monomer and a cross-linking agent represented by formula (I) and polymerized to obtain,

[0064]

[0065] wherein R1, R2 are each independently selected from C1-C4 alkyl, R3 comprises C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, R4 comprises C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; the crosslinking agent comprises divinylbenzene.

[0066] In the embodiments of the present application, the polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene can take into account both material stability and interface characteristics. Specifically, the polymer obtained by polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene has both the rigidity of the aromatic ring and the high bond energy of the siloxane bond, and a three-dimensional crosslinked network formed by the mutual crosslinking between the molecular chains of the silicone polymer, so that it has excellent structural stability and high mechanical strength, thereby reducing the physical puncture phenomenon of dendrites. In addition, the polar siloxane segment improves the electrolyte wettability, promotes the uniform distribution of sodium ions, and reduces the dendrite growth caused by local concentration polarization. Therefore, in a high temperature environment, the coating can effectively reduce the thermal decomposition of the electrolyte and the metal lithium side reaction, maintain the interface stability, and thus promote the storage performance and cycle performance in a high temperature environment.

[0067] In a possible implementation, the silicone polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the silicone polymer containing a siloxane structure is 75% to 95%; (2) the mass content of silicon elements in the silicone polymer containing a siloxane structure is 10% to 25%; (3) the mass content of phenyl groups in the silicone polymer containing a siloxane structure is 2% to 12%.

[0068] In the embodiments of the present application, by limiting the crosslinking degree, the mass content of silicon elements, and the mass content of phenyl groups, the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance in a high temperature environment are improved.

[0069] In a possible implementation, the silicone polymer containing a siloxane structure comprises a skeleton composed of a compound represented by formula (II),

[0070] R a [SiO 3 / 2 ] n formula (II),

[0071] wherein n is at least one of integers 4 to 12, R a comprises cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; optionally n is 8, R a comprises C1-C3 alkyl.

[0072] In the embodiments of the present application, by introducing the structural unit shown in formula (II) into the organosilicon polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. The structure has a highly symmetrical rigid covalent bond network, which can effectively reduce the shrinkage of the coating under high temperature conditions, thereby providing stable mechanical support for the uniform deposition of metal ions and physically facilitating the barrier to dendrite penetration. At the same time, the three-dimensional polyhedral skeleton structure can enhance the electrolyte wettability and ion flow uniformity, and reduce the dendrite growth caused by local current overload. By selecting the R1 substituent group as C1-C3 alkyl, the thermal stability and interfacial compatibility of the material can be further improved, thereby improving the storage performance and cycle performance of the battery cell under high temperature environment.

[0073] In a possible implementation, the organosilicon polymer containing a siloxane structure is obtained by hydrolysis and polycondensation of one or more monomers shown in formula (II),

[0074]

[0075] wherein R'1 includes C1-C3 alkyl.

[0076] In the embodiments of the present application, by using the hydrolysis-polycondensation reaction of the monomer of formula (III), an organosilicon polymer with a cage-like structure can be obtained. The polymer forms a three-dimensional network with high mechanical strength and thermal stability in the coating, which can effectively reduce the shrinkage of the coating under high temperature conditions, thereby providing stable rigid support for the uniform deposition of metal ions and physically effectively blocking dendrite penetration. In addition, the three-dimensional polyhedral skeleton structure formed by polymerization can enhance the high temperature wettability of the electrolyte and the uniformity of ion distribution, thereby reducing the dendrite growth and aggravation of side reactions caused by local current overload. Therefore, the above-mentioned organosilicon polymer can improve the dendrite resistance of the metal battery cell and the storage performance and cycle performance of the battery cell under high temperature environment.

[0077] In a possible implementation, 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 content of silicon element in the organosilicon polymer containing a siloxane structure is 25% to 45%; (3) the mass content of the skeleton composed of the compound shown in formula (II) in the organosilicon polymer containing a siloxane structure is 40% to 60%.

[0078] In the embodiments of the present application, by limiting the crosslinking degree, the mass fraction of silicon element and the mass content of phenyl group, the dendrite resistance of the metal battery cell and the storage performance and cycle performance under high temperature environment can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0079] 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 constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the drawings.

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

[0081] FIG. 2 is a structural schematic diagram of a battery cell according to an embodiment of the present application;

[0082] FIG. 3 is a structural schematic diagram of a battery cell according to another embodiment of the present application;

[0083] FIG. 4 is a schematic diagram of a battery device according to an embodiment of the present application;

[0084] FIG. 5 is a structural schematic diagram of a battery device according to an embodiment of the present application;

[0085] FIG. 6 is a structural schematic diagram of a power consumption device according to an embodiment of the present application;

[0086] FIG. 7 is a pyrolysis spectrum of an organic compound powder according to Embodiment 1 of the present application;

[0087] FIG. 8 is an SEM image of an organic compound particle according to Embodiment 1 of the present application;

[0088] FIG. 9 is an SEM image of an inorganic particle according to Comparative Example 1 of the present application.

[0089] Reference Signs:

[0090] 1 - vehicle; 11 - housing; 12 - electrode assembly; 121 - positive electrode tab; 1211 - positive electrode current collector; 1212 - positive electrode film layer; 13 - cover plate; 100 - battery cell; 400 - battery device; 401 - upper case; 402 - lower case; 500 - motor; 600 - controller.

[0091] In the drawings, the drawings are not drawn according to the actual proportions. DETAILED DESCRIPTION

[0092] Hereinafter, embodiments of a metal battery cell, a battery device, and a power consumption device according to 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 that are well known and repeated description of structures that are actually the same are omitted. This is to avoid the following description becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided in order for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0093] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges are also intended to include any and all sub-ranges of the range, i.e., all combinations of any two of the range limits, unless the context clearly dictates otherwise. For example, a range of "0-10" is intended to include any and all sub-ranges, e.g., 1-10, 2-10, 3-10, etc. of the same integers within the same integers. Also, unless otherwise indicated, use of the "or" nomenclature in the disclosed aspects herein is used to describe a disjunctive array of elements i.e., the term "X employs A or B" means a selection of A or B or a selection of A and B. All numerical values are "approximate", meaning that the value of the quantity can vary from the stated value by as much as 1%, unless otherwise stated. Numerical ranges include all values and subranges between the stated range limits, unless otherwise indicated.

[0094] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used in the specification herein is for describing particular embodiments only and is not intended to be limiting of the application; the use herein of "including," "comprising," "having" and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of "first," "second," and the like in the specification herein is for descriptive purposes and does not necessarily connote any order or priority.

[0095] 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.

[0096] 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.

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

[0098] The development of battery technology needs to consider various design factors, such as energy density, cycle life, discharge capacity, charge-discharge rate, reliability, etc. Among them, the separator film is an important component to support the charge-discharge electrochemical process of the secondary battery cell. The commonly used separator film is usually a polyolefin material. However, the heat resistance of the polyolefin material is poor, which is easy to soften or melt at high temperature, thereby causing internal short circuit of the secondary battery cell. In order to improve the heat resistance of the separator film, a coating layer is usually coated on the separator film to improve the heat resistance of the separator film. Among them, boehmite, alumina and other inorganic particles are currently commonly used heat-resistant fillers. However, the density of such heat-resistant fillers is large, and the mass under the same packing volume is large, which will affect the energy density of the secondary battery cell.

[0099] In order to further improve the energy density of the secondary battery cell, the inorganic particles such as boehmite and alumina are usually replaced by organic heat-resistant fillers. However, the morphology of the organic particles in the coating layer is usually irregular particles, and these irregular particles may form a non-uniform pore structure when packed. On the one hand, the penetration speed of the electrolyte in the non-uniform pore structure may be non-uniform, which will make the electrolyte transmission fast in the wide pore area and slow in the narrow pore area, thereby causing uneven local current density distribution. On the other hand, the irregular morphology of the particles may have sharp edges, and these edges may cause electric field concentration effect, which makes metal ions (such as Li + , Na + ) preferentially deposit in these areas. Therefore, for metal battery cells, the above non-uniform pore structure not only causes local aggregation of active metal ions during charge-discharge process, but also causes preferential nucleation and growth of dendrites (such as lithium dendrites, sodium dendrites). These dendrites will reduce the dendrite puncture strength of the separator film, and in the case of dendrite penetrating the separator film, it will cause internal short circuit of the metal battery cell, thereby increasing the probability of thermal runaway of the metal battery cell, affecting the storage performance and cycle performance of the battery cell.

[0100] Therefore, the related art usually performs a passivation treatment (e.g., a thermal reflow treatment) or a surface coating on the surface of the organic particles, thereby improving the morphology of the organic particles. However, the above method not only increases the ion transport impedance, but also is prone to cracking and peeling in long-term cycling, so that the original particle surface is exposed, which in turn aggravates the growth of dendrites.

[0101] Therefore, the related art usually performs a passivation treatment (e.g., a thermal reflow treatment) or a surface coating on the surface of the organic particles, thereby improving the morphology of the organic particles. However, the above method not only increases the ion transport impedance, but also is prone to cracking and peeling in long-term cycling, so that the original particle surface is exposed, which in turn aggravates the growth of dendrites.

[0102] In the above technical solution, by setting the range of the roundness of the organic compound particles in the coating, the organic compound particles are made to have a highly spherical morphology. Such highly spherical particles can achieve a more orderly and close-packed arrangement, thereby reducing the pore size and distribution non-uniformity in the coating to form a more dense and uniform microstructure. On the one hand, this can balance the spatial distribution of active metal ions, effectively eliminating local current density differences, thereby reducing the area where dendrites preferentially nucleate. On the other hand, this can also shorten the ion transport path and reduce the concentration polarization effect in the electrolyte, thereby maintaining the stability of the metal ion deposition process. In addition, since the spherical particles can reduce the angular structures commonly found in irregular particles, the electric field concentration phenomenon caused by geometric protrusions can be fundamentally reduced. Such uniform electric field distribution can guide the uniform deposition of metal ions on the electrode surface, thereby reducing the directional growth of dendrites. Therefore, the above technical solution can improve the dendrite resistance of the separator, thereby reducing the probability of thermal runaway of the metal battery cell and improving the storage performance and cycle performance of the battery cell in a high-temperature environment.

[0103] The metal battery cell, battery device, electric device, and separator of the present application will be described below with reference to the accompanying drawings.

[0104] [metal battery cell]

[0105] The metal battery cell provided by the embodiments of the present application generally comprises a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. During the charging and discharging of the metal battery cell, active ions are embedded and extracted between the positive electrode sheet and the negative electrode sheet. The electrolyte conducts the 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, and mainly prevents the short circuit of the positive electrode and the negative electrode, while allowing the active ions to pass through. In some embodiments, the metal battery cell is also referred to as a secondary battery, and the metal battery cell can be the smallest battery unit.

[0106] The technical solutions of the present application can be applied to various metal battery cells, such as lithium metal batteries, sodium metal batteries, potassium metal batteries and the like, and the present application does not make any limitation in this regard. For the convenience of description, the sodium metal battery is taken as an example for description.

[0107] During the charging of the sodium metal battery, sodium ions are extracted from the positive active material, diffuse and move to the surface of the negative current collector, and are reduced into sodium atoms under the action of the battery, and form a sodium metal layer on the current collector; and during the discharging, the sodium atoms in the sodium metal layer are oxidized into sodium ions, which diffuse and move and are embedded in the positive active material.

[0108] In some embodiments, the metal battery cell comprises an electrode assembly and a housing for accommodating the electrode assembly, and the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator between the positive electrode sheet and the negative electrode sheet.

[0109] Next, the negative electrode sheet, the separator, the positive electrode sheet and the electrolyte of the battery cell of the present application are described with reference to the accompanying drawings.

[0110] In some embodiments, the negative electrode sheet comprises a negative current collector. In the metal battery cell, the negative current collector is used to collect the current of the negative electrode sheet and conduct electrons. For the negative metal battery cell, the negative current collector can also provide a deposition substrate for metal ions (such as lithium, sodium), and promote the deposition uniformity and interface stability.

[0111] In some embodiments, the negative electrode tab further comprises an interface modification layer on at least one side of the negative current collector, which is used to guide the formation of a metal layer on the negative current collector. In one aspect, the interface modification layer can provide uniform nucleation sites, induce uniform deposition of metals such as lithium or sodium on the current collector, and inhibit the growth of dendrites. In another aspect, the interface modification layer can improve the interface stability, reduce electrolyte side reactions, form a stable solid electrolyte interphase (SEI) film, and prolong the cycle life of the battery cell. In addition, the interface modification layer can also reduce the interface impedance, improve the ion conduction efficiency, and optimize the rate performance of the battery. Therefore, the interface modification layer is beneficial to improve the energy density and cycle life of the metal battery cell, and can also reduce the growth of dendrites.

[0112] In some embodiments, the interface modification layer comprises one or more of carbon materials, metal materials. In the above embodiments, the carbon materials can provide a larger specific surface area and uniformly disperse the current, thereby effectively inhibiting dendrites. The metal materials can achieve alloying, reduce the nucleation barrier, and thereby induce dense deposition. In practical applications of metal battery cells, the materials of the interface modification layer can be selected according to specific needs.

[0113] In some embodiments, the carbon materials comprise one or more of carbon black, activated carbon, carbon nanotubes, carbon fibers, and graphite; and / or, the metal materials comprise the elemental In, Bi, Ag, Zn, Al, Mg, Ga, Ge, Sb, or one or more of metal alloys, metal oxides, and metal carbides of at least one element of In, Bi, Ag, Zn, Al, Mg, Ga, Ge, Sb. Among them, the above-mentioned carbon materials can construct a network structure with excellent electrical conductivity, buffer volume expansion, and conduct ions and electrons; and the above-mentioned metal materials are lithium / sodium-philic materials, which can reduce the nucleation energy, induce uniform deposition, and inhibit the formation of dendrites.

[0114] In some embodiments, the thickness C of the interface modification layer satisfies: 0.2 μm ≤ C ≤ 10 μm. For example, the thickness C of the interface modification layer is 0.2 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 7 μm, 10 μm, or any value within the above range. For the negative electrode tab, setting the thickness of the interface modification layer within the above range can effectively cover the defects on the surface of the current collector and provide sufficient nucleation sites. This is beneficial to reduce the local current density, form an effective uniform lithium / sodium flow, and improve the inhibition effect of dendrites. At the same time, this can also reduce the overall internal resistance of the battery cell, promote ion transport, reduce polarization, and thereby reduce the growth of dendrites. In addition, the above thickness can also improve the interface stability, which is beneficial to uniform deposition and reduces the risk of dendrites penetrating the separator.

[0115] In some embodiments, the metal battery cell is a negative electrode-free lithium metal battery cell or a negative electrode-free sodium metal battery cell.

[0116] The negative electrode-free lithium metal battery cell or the negative electrode-free sodium metal battery does not use a lithium metal sheet, a sodium metal sheet or other negative electrode active material, but only uses a negative electrode current collector as a negative electrode, completes negative electrode lithium / sodium plating during the first charging process, and returns to the positive electrode during discharging to realize charge and discharge cycles. Because there is no negative electrode material and only the negative electrode current collector is used, the negative electrode-free lithium metal battery cell or the negative electrode-free sodium metal battery can effectively overcome the defects of lithium / sodium metal batteries and obtain higher energy density than the metal lithium / sodium negative electrode. The technical solution proposed in the present application is particularly suitable for negative electrode-free lithium / sodium metal batteries, which can reduce the probability of dendrite growth and puncture of the isolation film to cause internal short circuit by regulating the uniformity of lithium / sodium metal deposition on the negative electrode side, so that the battery cell has high energy density, long cycle life, storage life and low storage gas production.

[0117] In some embodiments, the negative electrode sheet can be prepared by forming the interface modification layer on the negative electrode current collector by a dry process or a wet process, i.e. the negative electrode sheet is obtained. The dry process includes at least one of magnetron sputtering, vapor deposition and mechanical pressing. The wet process includes a coating method.

[0118] In some embodiments, the isolation film is located between the positive electrode sheet and the negative electrode sheet; the isolation film comprises a porous base film and a coating layer arranged on at least one side of the porous base film; the coating layer comprises organic compound particles and a first binder; the first binder is used to bond the organic compound particles to the porous base film; the morphology of the organic compound particles is spherical or spheroidal; the roundness A of the organic compound particles satisfies: 0.5≤A≤1.0. For example, A is 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.

[0119] In the embodiments of the present application, the porous base film refers to a thin film material with micrometer and / or nanometer pore structure. The porous base film can be a single-layer thin film or a multi-layer composite thin film. When the porous base film is a multi-layer composite thin film, the materials of the layers can be the same or different.

[0120] In some embodiments, the porous base film can comprise a film or nonwoven 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.

[0121] In some embodiments, the porous base film can have a thickness of 4 μm to 15 μm, optionally 4 μm to 9 μm.

[0122] In some embodiments, the porous base film can have a porosity of 25% to 60%, optionally 28% to 50%.

[0123] In some embodiments, the porous base film can have an average pore size of 25 nm to 82 nm.

[0124] As an example, the average pore size of the porous base film can be tested using a capillary porosimeter (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 press the wetting liquid in the pores of the sample to be tested, and the pressure and flow of the press are inversely proportional to the pore size, and the average pore size of the sample to be tested is obtained by software sampling and pressure and pore size conversion analysis. 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.

[0125] The "organic compound" in the embodiments of the present application refers to a carbon-containing compound, which generally includes hydrogen, oxygen, nitrogen, sulfur and other elements in addition to simple compounds such as carbon oxides, carbonic acid, carbonates, etc.

[0126] The "organic compound particles" in the embodiments of the present application refer to solid particles formed by covalent bonds of elements such as carbon (C), hydrogen (H), oxygen (O), nitrogen (N), etc. For the isolation film, the heat resistance of the isolation film can be increased by arranging organic compound particles in the coating layer thereof. The organic compound particles are the main component of the coating layer. These organic compound particles are micron or nanometer solid particles with high melting point, high thermal stability and high chemical inertness, which can be uniformly dispersed in the coating layer, thereby realizing the heat resistance of the isolation film.

[0127] The "morphology of the particles is spherical or spheroidal" in the embodiments of the present application refers to the particles being close to a sphere in geometric shape or being in an approximately spherical state as a whole.

[0128] As an example, the sphericity or spheroidicity of the particles can be tested by using instruments and methods known in the art. Specifically, as an example, after disassembling the battery cell, the separator film is peeled off, and the separator film in a regular and clear area is selected. Then, the micro-morphology of the coating on the separator film is measured by using a scanning electron microscope (SEM) and referring to the standard JY / T010 1996. Then, the two-dimensional projection profile, edge curvature, surface morphology and contrast variation of the particles in the coating are observed. If the particle edge is smooth, the curvature is consistent, the surface is uniform, and 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 may have slight undulations, then the particle morphology is determined to be spheroid.

[0129] In embodiments of the present application, the roundness (SC) refers to the degree of smoothness of the edges of the particle profile and the degree of closeness to a perfect sphere of the overall shape. Specifically, the roundness (SC) = (4π x area) / (perimeter x perimeter) = area equivalent diameter x area equivalent diameter / quasi-circular diameter x quasi-circular diameter. In the case of a roundness of 1, it means that the particle is a perfect sphere, having the smallest surface area to volume ratio among all possible shapes; in the case of a roundness close to 0, it means that the shape of the particle deviates greatly from a sphere (e.g., flaky, needle-like, fibrous, etc.), and the surface area to volume ratio is large.

[0130] As an example, the roundness of the organic compound particles in the coating is a meaning known in the art, which can be tested by using instruments and methods known in the art. Specifically, as an example, after disassembling the battery cell, the separator film is peeled off, and the separator film in 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±50 nm interval are counted, and the roundness of the organic compound particles in the SEM morphology map is fitted by using the Image J software. Wherein, the roundness (SC) = (4π x area) / (perimeter x perimeter) = area equivalent diameter x area equivalent diameter / quasi-circular diameter x quasi-circular diameter. Then, the average value of the roundness of the organic compound particles in the Dn50±50 nm interval is calculated (the roundness of each single organic compound particle in the Dn50±50 nm 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 particles of the organic compound particles in the Dn50±50 nm interval), to obtain the roundness of the organic compound particles.

[0131] By setting the range of the roundness of the organic compound particles in the coating, the organic compound particles are made to have a highly spherical morphology, thereby improving the dendrite resistance of the metal battery cell and improving the storage performance and cycle performance of the metal battery cell in a high-temperature environment.

[0132] In some embodiments, the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles satisfies: 0.5≤(Dn90-Dn10) / Dn50≤2.0. For example, the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles is 0.5, 0.6, 0.7, 0.8, 1.0, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8, 2.0, or any value within the above range.

[0133] For the organic compound particles, the particle size concentration (Dn90-Dn10) / Dn50 can measure the uniformity of the particle size distribution. Among them, Dn10, Dn50, Dn90 refer to the particle size corresponding to the cumulative amount distribution of 10%, 50%, and 90% of the particle size amount distribution curve of the organic compound particles, and the particle size concentration can reflect the degree of deviation of the particle size of larger particles and the particle size of smaller particles from Dv50. Dn50 is the median particle size, representing the average size of the particles; the difference between Dn90 and Dn10 reflects the width range of the particle size distribution. The smaller the ratio of the particle size concentration, the more concentrated the particle size of the organic compound particles, and the more uniform the distribution; the larger the ratio of the particle size concentration, the wider the particle size distribution of the organic compound particles, and the greater the difference in particle size.

[0134] As an example, the particle size concentration of the organic compound particles is the meaning known in the art, which can be tested by instruments and methods known in the art. Specifically, as an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film of a regular and clear area is selected. Then, the surface morphology of the coating is measured by a scanning electron microscope (SEM) and reference to the standard JY / T0101996, and the Dn10, Dn50, Dn90 of the organic compound particles are counted. For example, a test sample of 50 mm x 100 mm is randomly selected on the separator film. Using a scanning electron microscope (for example, ZEISS Sigma 300), reference to JY / T010-1996, a plurality of test areas (for example, 5) are randomly selected in the test sample, and the particle size of the organic compound particles in each test area is read (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 (for example, 500 times or 1000 times when measuring the organic compound particles), the number and particle size value of the organic compound particles in each test area are counted, and the arithmetic mean of the organic compound particles in each test area is taken, that is, the number average particle size of the organic compound particles in the test sample. In order to ensure the accuracy of the test results, a plurality of test samples (for example, 10) can be repeatedly tested as described above, and the average value of each test sample is taken as the final test result, that is, the particle size number distribution curve of the organic compound particles can be obtained. Through statistics, Dn10, Dn50, Dn90 are obtained respectively. Among them, in the particle size number distribution curve of the organic compound particles, Dn10, Dn50, Dn90 respectively refer to the particle size corresponding to the cumulative number distribution of 10%, 50%, and 90%.

[0135] Setting the particle size concentration of the organic compound particles in the above range is beneficial to make the organic compound particles have a suitable size distribution, which can reduce the possibility of large particles piercing the base film to form mechanical defects, and also can reduce the case of small particles leading to uneven coating and local insufficient strength. This can reduce the penetration of dendrites and reduce the risk of short circuit. At the same time, this is also beneficial to make the organic compound particles have a suitable packing tightness between particles, and maintain its porosity. This can promote sodium ion transmission, reduce the internal resistance of the battery monomer, and improve the rate performance. Therefore, the particle size concentration of the organic compound particles meets the above range, which can balance the mechanical strength, ion conductivity and structural stability, and improve the dendrite resistance of the separator film, thereby reducing the probability of thermal runaway of the metal battery monomer.

[0136] In some embodiments, the concavity B of the organic compound particles satisfies: 0≤B≤0.5. For example, the concavity B of the organic compound particles is 0, 0.05, 0.08, 0.09, 0.1, 0.11, 0.13, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, or any value within the above range.

[0137] For spherical or spherical-like particles, the concavity is characterized by calculating the deviation of the concave part of the particle surface, usually by comparing the difference between the volume of the particle and the volume of the convex hull. Specifically, the concavity B = 1 - the actual surface area of the particle / the surface area of its convex hull. The convex hull is the smallest circumscribed convex surface that contains the particle, i.e., the shape after all concave parts of the particle surface are "filled in". The concavity B ranges from 0 to 1, and the closer the value of the concavity B is to 0, the less concave the particle surface is, and the closer it is to a perfect sphere, i.e., a sphere. The closer the value of the concavity B is to 1, the more significant concave or notched the particle surface is, and the more irregular the shape is.

[0138] As an example, the concavity of the organic compound particles in the coating layer is the meaning known in the art, which can be tested by instruments and methods known in the art. Specifically, as an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film in a regular and clear area is selected. Then, the micro-morphology of the coating layer on the separator film is measured by a scanning electron microscope (SEM) and in reference to the standard JY / T010 1996. Then, the number of organic compound particles in the Dn50±50nm interval is counted, and the concavity of the organic compound particles in the SEM morphology is fitted by the Image J software. Then, the average value of the concavity of the organic compound particles in the Dn50±50nm interval is calculated (the concavity value of each single organic compound particle in the Dn50±50nm interval is obtained, the total sum of the concavity values is calculated, and the average value of the concavity = the total sum of the concavity values / the total number of the particles in the Dn50±50nm interval), to obtain the concavity of the organic compound particles.

[0139] The concave structure of organic compound particles can directionally guide metal ion deposition. The smoother protrusions in their curved electric field distribution disperse the local electric field, effectively reducing local current density peaks. When the concavity of the organic compound particles is within the aforementioned range, the resulting porous structure can evenly distribute the electrolyte, shorten ion transport paths, mitigate concentration polarization, and reduce current unevenness. Simultaneously, this does not hinder ion transport or lead to local electrolyte depletion. Furthermore, it improves the mechanical strength of the coating and reduces the likelihood of new dendrite nucleation sites forming during metal deposition. Therefore, controlling the particle concavity within a suitable range leverages its electric field modulation advantage while reducing dendrite formation caused by structural defects, thereby lowering the probability of thermal runaway in individual metal battery cells.

[0140] In some embodiments, the organic compound particles comprise a crosslinked polymer with a crosslinking degree of 70% to 98%. For example, the crosslinking degree of the crosslinked polymer is 70%, 75%, 78%, 80%, 83%, 85%, 87%, 89%, 90%, 92%, 94%, 96%, 97%, 98%, or any value within the above range.

[0141] In this application, "crosslinked polymer" refers to a polymer material in which molecular chains are crosslinked through chemical bonds to form a three-dimensional network structure. This structure is typically formed by the crosslinking of multiple reactive functional groups during polymerization or post-processing, resulting in a stable spatial structure for the polymer as a whole. The degree of crosslinking refers to the extent to which the molecular chains of the crosslinked polymer are crosslinked through chemical bonds. A higher degree of crosslinking results in more crosslinking points between molecular chains, leading to a more stable polymer structure, which can improve the stability of the separator membrane under high-temperature conditions.

[0142] It should be noted that the degree of crosslinking in the embodiments of this application refers to the proportion of molecular chain segments bound by the crosslinking network in the crosslinked polymer, obtained by software fitting at a specific temperature and frequency using nuclear magnetic resonance (NMR). By performing NMR testing on the polymer, it can be observed that different components within the polymer backbone have different relaxation kinetics. For example, monomers or solvents have high fluidity and decay the slowest; non-crosslinked segments have certain molecular motion characteristics and decay relatively slowly; while crosslinked segments are more bound, have lower molecular motion characteristics, and decay faster. Therefore, by acquiring the signal of the entire polymer and calculating the proportion of the crosslinked portion, the degree of crosslinking of the polymer backbone can be obtained.

[0143] As an example, in the embodiments of the present application, the crosslinking degree of the crosslinked polymer can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21 MHz, 0.5 g of the cleaned and dried sample (the organic compound particles described above) is taken, is loaded into a clean sample tube and is inserted into a probe at a specified depth, the probe coil diameter is 13 mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the crosslinking degree of the crosslinked polymer is obtained by collecting the entire polymer signal, calculating the proportion of the crosslinking signal by fitting software, and selecting the "crosslinking degree" or "T2 relaxation" test mode in the software, and the PQ001 nuclear magnetic resonance analyzer automatically obtains the relaxation decay curve. During data processing, the software decomposes the relaxation components by exponential fitting, calculates and outputs the crosslinking degree result according to the degree of restriction of molecular chain movement.

[0144] The crosslinking degree of the crosslinked polymer meets the above range, and the crosslinked polymer formed has a three-dimensional network structure, which is beneficial to limit the free movement of the molecular chain, thereby improving the structural stability of the organic compound particles and increasing the mechanical strength of the particles, thereby increasing the structural stability of the coating.

[0145] In some embodiments, the crosslinked polymer includes a silicone polymer containing a siloxane structure.

[0146] In the embodiments of the present application, the siloxane structure refers to a Si-O-Si bond skeleton formed by alternating connection of silicon atoms and oxygen atoms. The silicone polymer can refer to a high molecular polymer containing a silicon-oxygen bond (Si-O-Si) and / or a silicon-carbon bond (Si-C) in the main chain or side chain.

[0147] As an example, the chemical structure and type of the silicone polymer are well known in the art, and can be tested by using instruments and methods known in the art. Specifically, as an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film in a regular and clear area is selected. Then, the separator film is soaked in N,N-dimethylformamide, and after centrifugal separation, the supernatant is taken, and then the supernatant is coated on a potassium bromide wafer. After drying the potassium bromide wafer, the silicone polymer is obtained. The silicone polymer is placed into an infrared spectrum analyzer (for example, model: Thermo Nicolet iS5 Fourier infrared spectrometer) for analysis, and the test is performed according to GB / T6040-2002, and according to the measurement result, it is found that the silicone polymer contains a stretching vibration peak of Si-O.

[0148] By adopting the organosilicon polymer containing a siloxane structure as the crosslinked polymer, the bond energy of the siloxane bond is high, and the three-dimensional crosslinked network formed by the mutual crosslinking between the molecular chains of the organosilicon polymer, so that the organosilicon polymer containing a siloxane structure can have high mechanical strength, thereby being beneficial to improving the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance under high temperature environment. Specifically, the rigid-Si-O-Si-inorganic skeleton remains stable structure under high temperature environment, effectively reducing dendrite puncture and separator thermal contraction. At the same time, the polymer also has good electrolyte wettability and ion uniform distribution ability, which can reduce the dendrite growth caused by local current concentration. In addition, compared with inorganic particles, the density of the organosilicon polymer is lower, and the overall mass of the coating can be reduced under the same thickness, thereby being beneficial to improving the energy density of the battery monomer.

[0149] In some embodiments, the organosilicon polymer containing a siloxane structure includes a benzene group, the organosilicon polymer containing a siloxane structure includes a monomer and a crosslinking agent represented by formula (I) and is polymerized to obtain,

[0150]

[0151] wherein R1 and R2 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, R3 includes C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, and R4 includes C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; the crosslinking agent includes divinylbenzene.

[0152] In the embodiments of the present application, R1 and R2 are each independently selected from at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, ethenyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, and 2-methyl-1-propenyl.

[0153] R3 includes at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, (meth)acryloyloxy methyl, 2-((meth)acryloyloxy)ethyl, 3-((meth)acryloyloxy)propyl, or 4-((meth)acryloyloxy)butyl.

[0154] In some embodiments, R3 is methyl or (meth)acryloxyalkyl, R3 being methyl is beneficial to the stability of the main chain in the crosslinked polymer, and R3 being acryloyloxypropyl can further participate in crosslinking to improve the crosslinking degree of the crosslinked polymer; R4 is alkenyl or acryloxyalkyl, which can realize efficient crosslinking through a free radical polymerization reaction, and is further beneficial to improving the crosslinking degree of the crosslinked polymer, thereby improving the high temperature stability of the crosslinked polymer.

[0155] R4 includes at least one of vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, (meth)acryloyloxy methyl, 2-((meth)acryloyloxy)ethyl, 3-((meth)acryloyloxy)propyl, or 4-((meth)acryloyloxy)butyl.

[0156] Acryloyloxyalkyl refers to an alkyl chain structure functional group containing an acryloyloxy end group, (meth)acryloyloxyalkyl refers to a (meth)acryloyloxy group replacing one hydrogen atom on a carbon atom directly connected to a carbonyl (C=O) group, providing a reaction site through a molecular chain end acrylate double bond (C=C), which can further undergo a free radical polymerization reaction with a crosslinking agent, which is conducive to improving the crosslinking degree of the silicone polymer.

[0157] In the embodiments of the present application, the crosslinking agent refers to a compound containing two or more functional groups capable of reacting with the functional groups on the polymer chain in the molecule, thereby forming covalent bridges between the polymer molecular chains and constructing a three-dimensional network structure. For example, the divinylbenzene in the embodiments of the present application can crosslink with alkenyl or acryloyl groups to form covalent bonds between molecular chains with ethylene bridges and benzene rings as connecting points, forming a three-dimensional network structure of the phenyl-containing silicone polymer, thereby improving the heat resistance of the phenyl-containing silicone polymer.

[0158] Through the polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene, the material stability and interface properties can be considered. Specifically, the polymer obtained by the polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene has the rigidity of aromatic ring and the high bond energy of siloxane bond, and the three-dimensional crosslinked network formed by the crosslinking between the molecular chains of the silicone polymer, so that it has excellent structural stability and high mechanical strength, thereby reducing the physical puncture phenomenon of dendrites. In addition, the polar siloxane segment improves the electrolyte wettability, promotes the uniform distribution of sodium ions, and reduces the dendrite growth caused by local concentration polarization. Therefore, in a high temperature environment, the coating can effectively reduce the thermal decomposition of the electrolyte and the metal lithium side reaction, maintain the interface stability, thereby promoting the storage performance and cycle performance in a high temperature environment.

[0159] In some embodiments, the preparation method of the phenyl-containing silicone polymer includes the following steps: providing a pre-emulsion containing monomers, a crosslinking agent, an emulsifier, an initiator, and water, and performing an emulsion polymerization reaction under the conditions of heating, inert gas protection, and stirring to obtain silicone resin particles. The monomers include silane coupling agents containing alkenyl and / or acryloyloxy groups, and the mass fraction of the crosslinking agent is 3%-30% based on the total mass of the monomers and the crosslinking agent being 100%.

[0160] By setting the mass fraction of the crosslinking agent within the above range, the organosilicon polymer has a three-dimensional network structure, which is advantageous for limiting the free movement of molecular chains, thereby improving the structural stability of the organic compound particles and increasing the mechanical strength of the particles, thereby increasing the structural stability of the coating.

[0161] The monomer includes a silane coupling agent containing an alkenyl group and / or an acryloxy group, so radicals are generated between the monomers, crosslinking reactions occur, and the monomers also crosslink with the crosslinking agent. Thus, a phenyl-containing organosilicon polymer having a three-dimensional network structure can be formed using the monomer and the crosslinking agent of the present disclosure, which is not easily softened or deformed at high temperatures and has high heat resistance and electrochemical stability.

[0162] The mass fraction of the crosslinking agent is 3% to 30%, for example, 3%, 4%, 5%, 6%, 7%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, or a range composed of any of the above values, based on 100% of the total mass of the monomer and the crosslinking agent.

[0163] By setting the mass fraction of the crosslinking agent within the above range, a silicon-containing organic resin particle having high electrochemical stability and good heat resistance can be obtained.

[0164] Alternatively, the mass fraction of the crosslinking agent can be 8% to 14%, 8% to 13%, 8% to 12%, 9% to 14%, 9% to 13%, 9% to 12%.

[0165] In some embodiments, the monomer can include an acryloxy silane coupling agent.

[0166] Alternatively, the monomer represented by formula (I) can include one or more of γ-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, γ-methacryloxypropyl triisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyl tris(methoxyethoxy)silane, 3-methacryloxypropyl methyl dimethoxysilane, 3-acryloxypropyl methyl dimethoxysilane, methacryloxypropyl dimethyl methoxysilane, (3-acryloxy)dimethyl methoxysilane, 3-methacryloxypropyl dimethyl ethoxysilane, 3-(methacryloxy)propyl methyl diethoxysilane.

[0167] In some embodiments, the monomer represented by Formula (I) can include a first monomer and a second monomer.

[0168] The first monomer can include one or more of gamma-methacryloxypropyl tris(trimethylsiloxy)silane, (3-acryloyloxypropyl)tris(trimethylsiloxy)silane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, acryloxypropyltriethoxysilane, gamma-methacryloxypropyl triisopropoxysilane, 3-(acryloxy)propyltrimethoxysilane, 3-methacryloxypropyl tris(methoxyethoxy)silane.

[0169] The second monomer can include one or more of 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, methacryloxypropyldimethylmethoxysilane, (3-acryloxy)dimethylmethoxysilane, 3-methacryloxypropyldimethylethoxysilane, 3-(methacryloxy)propylmethyldiethoxysilane.

[0170] The first monomer and the second monomer are different in activity, by combining the two and reacting with a crosslinking agent, a silicone polymer with a suitable roundness and siloxane structure can be obtained.

[0171] In some embodiments, the emulsifier can include, but is not limited to, one or more of alkyl sulfate, alkyl sulfonate, Tween emulsifier, fatty alcohol polyoxyethylene ether, fatty alcohol polyoxypropylene ether, cetyl stearyl alcohol polyether, oleyl ether. Alternatively, the emulsifier includes one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, Tween 20, Tween 40, laureth-7, laureth-9, laureth-10, oleyl ether-10.

[0172] 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, azobisisobutylimidazoline hydrochloride, azobisisopropylimidazoline.

[0173] In some embodiments, the heating temperature of the maturation stage of the emulsion polymerization reaction can be 75-95°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, or a range consisting of any of the above values.

[0174] In some embodiments, the heating time of the maturation stage of the emulsion polymerization reaction can be 1h-4h, for example, can be 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, 3.2h, 3.4h, 3.6h, 3.8h, 4h, or a range consisting of any of the aforementioned values.

[0175] In some embodiments, the emulsion polymerization reaction can include the following steps: under the conditions of a first heating temperature, inert gas protection and stirring, the pre-emulsion is added dropwise into a reactor containing water, and after a first 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.

[0176] Optionally, the first heating temperature can be 55-95℃.

[0177] Optionally, the first time can be 3-8h.

[0178] In some embodiments, the pre-emulsion can further include a PH adjuster. Optionally, the PH adjuster can include one or more of, but not limited to, sodium bicarbonate, sodium hydroxide, ammonia, etc. By adding the PH adjuster, the PH value of the pre-emulsion can be adjusted.

[0179] In some embodiments, the PH of the pre-emulsion is 7.5-10. For example, the PH of the pre-emulsion can be 7.5, 8, 9, 10, or any value within the aforementioned range.

[0180] By controlling the PH of the pre-emulsion within an appropriate range, the emulsifier can be fully ionized, the interfacial tension is reduced, the latex particles nucleate uniformly during the polymerization process, the monomer diffusion is smooth, and the particle surface energy tends to be at a minimum, so that the organic compound particles with smooth surface and appropriate roundness can be formed. At the same time, the appropriate PH environment helps to stabilize the reactivity of the crosslinking agent, improve the crosslinking degree, and promote the effective polymerization of the phenyl monomer, so that the mass fraction of the phenyl monomer in the particles can be controlled.

[0181] In some embodiments, by changing the mass of the emulsifier, the roundness of the organic compound particles can be controlled. Specifically, by controlling the mass of the emulsifier, the concentration of the emulsifier can be controlled. When the concentration of the emulsifier is controlled within an appropriate range, it is beneficial to provide sufficient monomer and emulsifier to disperse the droplets uniformly, and the nucleation and growth process is smooth, and the particles are more likely to form regular spherical or spherical morphology under the action of surface tension, so that the roundness of the organic compound particles can be improved. At the same time, the appropriate amount can also promote the full reaction of the crosslinking agent and the monomer, help to control the crosslinking degree and the mass fraction of the phenyl group, make the particle structure more compact and stable, and thus improve the overall performance of the coating.

[0182] In some embodiments, the roundness of the organic compound particles can be controlled by changing the flow rate of the pre-emulsion. In order to control the nucleation and growth process of the particles, the pre-emulsion can be added in multiple times, for example, in three times. Specifically, the first segment is added at a low flow rate to form a sufficient number of uniform crystal nuclei in the system, which lays a foundation for the subsequent generation of monodisperse particles. The second and third segments are added by adjusting the flow rate to control the growth rate, thereby reducing the secondary nucleation or particle aggregation caused by local over-concentration of monomers, and obtaining organic compound particles with appropriate roundness.

[0183] In some embodiments, the method for preparing the silicon-containing organic resin particles can further include a step of removing the magnetic treatment after the emulsion polymerization reaction is completed.

[0184] In some embodiments, the silicon-oxygen structure-containing organosilicon polymer satisfies one or more of the following conditions: (1) the crosslinking degree of the silicon-oxygen structure-containing organosilicon polymer is 75% to 95%; (2) the mass content of silicon elements in the silicon-oxygen structure-containing organosilicon polymer is 10% to 25%; and (3) the mass content of phenyl groups in the silicon-oxygen structure-containing organosilicon polymer is 2% to 12%.

[0185] For example, the crosslinking degree of the silicon-oxygen structure-containing organosilicon polymer is 75%, 77%, 79%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 95%, or any value within the above range; the mass content of silicon elements in the silicon-oxygen structure-containing organosilicon polymer is 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25%, or any value within the above range; and the mass content of phenyl groups in the silicon-oxygen structure-containing organosilicon polymer is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 7%, 9%, 10%, 11%, 12%, or any value within the above range.

[0186] In the embodiments of the present application, the crosslinking degree of the silicon-oxygen structure-containing organosilicon polymer can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21MHz, 0.5g of the cleaned and dried sample (the above-mentioned organic silicon compound particles) is taken, is loaded into a clean sample tube and is inserted into a probe at a specified depth, the probe coil diameter is 13mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the entire polymer signal is collected, the proportion of the crosslinked signal is calculated by fitting software to obtain the crosslinking degree of the crosslinked polymer; 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, calculates and outputs the crosslinking degree results according to the degree of restriction of molecular chain movement.

[0187] In the above embodiments, the cross-linking degree of the organosilicon polymer containing siloxane structure is set in the above range, which is beneficial to make the coating have appropriate rigidity. This can effectively buffer the volume change in the sodium deposition / peeling process, thereby reducing the stress concentration of dendrite tip and improving the dendrite resistance of the battery cell. At the same time, this is also beneficial to promote ion transmission and reduce polarization and capacity decay in high temperature cycling.

[0188] As an example, in the embodiments of the present application, a powder sample (usually a few milligrams) of the organosilicon polymer containing siloxane structure is ultrasonically cleaned with anhydrous ethanol or deionized water for 1-2 minutes to remove surface impurities; then it is placed in an oven and dried at 60-80°C for 1-2 hours to completely remove moisture (to avoid the influence of sample volatilization on the vacuum environment during testing). The dried powder is evenly spread on the conductive glue (ensure that the powder does not accumulate or scatter); then a layer of 5-10 nm thick gold is sprayed on its surface using an ion sputtering instrument; or after the battery cell is disassembled, the separator film is peeled off, and a regular and clear area of the separator film is selected. Then, the separator film sample is fixed on the sample stage and subjected to gold spraying or carbon spraying treatment to make its surface conductive; the sample stage containing the sample to be tested is placed in the SEM sample chamber, and after the door is closed, the vacuum system is started to be pumped to the required high vacuum state (usually 10 -3 -10 -5 Pa). After the vacuum is reached, the electron gun voltage (usually 5-20 kV) and working distance (usually 5-15 mm) are adjusted, the sample stage is moved by the control software to find the target observation area. The focus and magnification (from low magnification 100 times positioning to high magnification for observing details) are gradually adjusted to obtain clear SEM morphology images, and the feature points or areas that need to be analyzed by EDS are marked. In the SEM software, the EDS detector is started, the marked analysis area (single-point analysis, line scanning or area scanning can be selected) is selected, and the collection time (usually 10-30 seconds, the longer the time, the more accurate the element signal) is set. The surface of the organosilicon polymer containing siloxane structure is analyzed by Energy-Dispersive X-ray Spectroscopy (EDS) to detect the content of silicon element in the organosilicon polymer containing siloxane structure. According to the data results of the instrument, the distribution of each element can be obtained, and the mass fraction of silicon element can be obtained.

[0189] The mass content of silicon element in the organosilicon polymer containing siloxane structure is set in the above range, which is beneficial to maintain the stability of the coating in a high temperature environment, making it difficult for dendrites to penetrate the separator, thereby improving the storage performance and cycle performance of the battery cell in a high temperature environment.

[0190] As an example, the mass content of phenyl groups in the organosilicon polymer can be tested using instruments and methods known in the art, in the meaning well known in the art. As an example, after disassembling the battery cell, the separator film is peeled off. Then, the organic compound particle powder of the coating in the separator film is scraped off as the sample to be tested, dried to remove adsorbed water, and then placed in a desiccator to cool for standby. Specifically, a pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) instrument can be used to test the mass content of phenyl groups in the organosilicon polymer. Specifically, 0.5-1 mg of the organosilicon polymer described above is weighed as a test sample, loaded into a quartz cracking tube of a pyrolysis instrument, cracked at 550°C for 1.2 s, and then introduced into a gas chromatograph-mass spectrometer, with a HP-5ms (30 m x 0.25 mm x 0.25 μm) chromatographic column, a temperature setting of 30°C for 5 min, a temperature increase of 10°C / min to 250°C, a temperature holding of 250°C for 5 min, a carrier gas of high-purity helium, and a flow rate of 1.0 mL / min. The mass spectrometer uses electrochemical ionization, with an ion source temperature of 230°C and a fragment scan range of m / z 25-200. By comparing with the EVA standard cracking spectrum in the NIST library, the characteristic ions corresponding to the phenyl groups are detected, and it can be inferred that the organosilicon polymer includes phenyl structures. The internal standard method is used to calculate the mass content of the phenyl groups in the organosilicon polymer based on the area of the above-mentioned fragment peak corresponding to the characteristic phenyl groups.

[0191] Setting the mass content of phenyl groups in the organosilicon polymer containing siloxane structures within the above range is beneficial to reduce the motion ability of the chain segments and reduce the occurrence of micro-cracks in the coating under dendrite growth stress. At the same time, this can also reduce the oxidation of the coating in a high-temperature environment, thereby reducing the decomposition of the electrolyte and the interface failure. In addition, this is also beneficial to reduce the polarity of the material and reduce the excessive swelling of the electrolyte, thereby improving the ability of the battery cell to suppress dendrites.

[0192] Therefore, by limiting the crosslinking degree, the mass content of silicon elements, and the mass content of phenyl groups as described above, the dendrite resistance of the metal battery cell, as well as the storage performance and cycle performance in a high-temperature environment, can be improved.

[0193] In some embodiments, the organosilicon polymer containing siloxane structures includes a backbone composed of a compound represented by formula (II),

[0194] R a [SiO 3 / 2 ] n formula (II),

[0195] wherein n is at least one of an integer from 4 to 12, R a including cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C12 alkynyl; optionally, n is 8, R a including C1-C3 alkyl.

[0196] By introducing the structural unit shown in formula (II) into the silicone polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. This structure has a highly symmetrical rigid covalent bond network that can effectively reduce coating shrinkage under high temperature conditions, thereby providing stable mechanical support for the uniform deposition of metal ions and physically facilitating the barrier to dendrite penetration. At the same time, its three-dimensional polyhedral skeleton structure can enhance the electrolyte wettability and ion flow uniformity, reducing dendrite growth caused by local current overload. By selecting C1-C3 alkyl as the R1 substituent, the thermal stability and interfacial compatibility of the material can be further improved, thereby improving the storage performance and cycle performance of the battery cell under high temperature environment.

[0197] In some embodiments, the silicone polymer containing a siloxane structure includes one or more of the monomers shown in formula (III) that are hydrolyzed and polycondensed to obtain a silicone polymer containing a siloxane structure,

[0198]

[0199] wherein R'1 includes C1-C3 alkyl. For example, R'1 is methyl, ethyl, or propyl.

[0200] By using the hydrolysis-polycondensation reaction of the monomer of formula (III), a silicone polymer with a cage-like structure can be obtained. This polymer forms a three-dimensional network with high mechanical strength and thermal stability in the coating, which can effectively reduce the shrinkage of the coating under high temperature conditions, providing stable rigid support for the uniform deposition of metal ions, thereby physically effectively blocking dendrite penetration. In addition, the three-dimensional polyhedral skeleton structure formed by its polymerization can enhance the high temperature wettability of the electrolyte and the uniformity of ion distribution, reducing dendrite growth and exacerbation of side reactions caused by local current overload. Therefore, the above-mentioned silicone polymer can improve the dendrite resistance of the metal battery cell, as well as the storage performance and cycle performance of the battery cell under high temperature environment.

[0201] Optionally, R'1 is methyl. In this way, the dendrite resistance of the metal battery cell, as well as the storage performance and cycle performance of the battery cell under high temperature environment, can be further improved.

[0202] In the embodiments of the present application, the silicone polymer containing a siloxane structure is prepared by hydrolyzing the monomer shown in formula (III), then adding a catalyst, and conducting polycondensation under heating conditions to obtain a silicone polymer containing a siloxane structure.

[0203] Thus, by hydrolysis and polycondensation reaction, a silicone polymer containing a siloxane structure is obtained.

[0204] In some embodiments of the present application, the temperature for hydrolysis of the monomer of formula (III) is 10-40°C. For example, the temperature for hydrolysis can be 20-29°C, 21-28°C, 22-27°C, 23-26°C, 24-25°C, etc.

[0205] In some embodiments, the stirring rate for hydrolysis is 300-500 rpm. For example, the stirring rate can be 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, or any value within the above range. Controlling the stirring rate within the above range, the shear force is moderate, and the particles are not easily broken or deformed, which is conducive to uniform dispersion of the droplets and stable nucleation, and promotes the particles to form smooth spherical or spheroidal morphology. At the same time, the above rotation speed makes the droplets uniformly dispersed and not easily aggregated, so that particles of the organic compound with regular morphology and appropriate roundness can be formed.

[0206] In some embodiments of the present application, the heating temperature is 30-100°C. For example, the heating temperature can be 30-99°C, 35-95°C, 40-90°C, 45-85°C, 50-80°C, 55-75°C, 60-70°C, etc.

[0207] In some embodiments of the present application, the heating time is 2-48 h. For example, the heating time can be 2 h, 3 h, 8 h, 10 h, 15 h, 20 h, 24 h, 36 h, 48 h, etc.

[0208] Specifically, the monomer of 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. Then, under the action of the catalyst, the silanol starts to condense, and Si-O-Si bonds are formed between the silanols, further forming a network structure, and nucleation begins. Finally, these nuclei continuously absorb silanol from the solution and continue to grow until the organosilicon polymer containing a cage-like polysilsesquioxane skeleton is formed. The nucleation process and the nucleus growth process are competitive, and the reaction temperature affects these two processes. When the nucleation process dominates, more nuclei are generated, and the particle size of the final organosilicon polymer is smaller; when the nucleus growth dominates, the particle size of the final microspheres is larger. The increase of the temperature accelerates 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 final organosilicon polymer is smaller. Controlling the heating temperature within the range of 30-100°C can promote the uniform particle size of the organosilicon polymer, and can improve the cycle performance of the secondary battery.

[0209] In some embodiments, organic compound particles with different degrees of roundness can be obtained by controlling the temperature and time during the polycondensation reaction. Specifically, carrying out the polycondensation reaction within a suitable temperature and time range is beneficial for the formation of a uniform nucleation and growth process in the organic compound particles. Under the influence of surface tension, the particles tend to become spherical, thereby improving roundness. At the same time, reaction conditions within a suitable range can promote the full formation of cross-linked structures, increase the degree of cross-linking, and effectively control the degree of polymerization of phenyl monomers, thereby optimizing the phenyl mass ratio.

[0210] In some embodiments of this application, the catalyst includes at least one of ammonia, triethylamine, sodium hydroxide, magnesium hydroxide, or ammonium hydroxide.

[0211] In some embodiments, the pH of the polycondensation can be adjusted by adding the catalyst described above, and the polycondensation pH can be 7.5–10. For example, the polycondensation pH can be 7.5, 8, 8.3, 8.6, 9, 10, or any value within the above range. Under acidic conditions, the polycondensation reaction rate is slow, the particle growth process is insufficient, and irregular morphologies are easily formed. Therefore, setting the polycondensation environment in a neutral or weakly alkaline environment results in a moderate reaction rate, more uniform monomer diffusion and cross-linking network formation, and particles are more likely to tend towards spherical shapes during nucleation and growth, thus enabling the control of the roundness of the organic compound particle size.

[0212] Specifically, the organosilicon polymer formed from the monomer of formula (III) is relatively regular and stable at the molecular scale. During the polycondensation process, the polyhedral units are uniformly connected by covalent bonds, reducing local stacking and entanglement of molecular chains. The organosilicon polymer exhibits a high degree of uniform dispersion. The uniform dispersion of molecular chains not only facilitates the uniform distribution of crosslinking points and reduces internal stress concentration, but also improves the dispersibility and bonding stability of crosslinked polymer particles in the separator coating. This makes the organosilicon polymer particles in the coating less prone to structural breakage or collapse at high temperatures, improving the overall heat resistance of the separator and thus enhancing the reliability of the battery cell.

[0213] In some embodiments, the organosilicon polymer containing a silicon-oxygen structure satisfies one or more of the following conditions: (1) the degree of crosslinking of the organosilicon polymer containing a silicon-oxygen structure is 85% to 97%; (2) the mass content of silicon element in the organosilicon polymer containing a silicon-oxygen structure is 25% to 45%; (3) the mass content of the skeleton composed of the compound shown in formula (II) in the organosilicon polymer containing a silicon-oxygen structure is 40% to 60%.

[0214] For example, the cross-linking degree of the organosilicon polymer containing siloxane structure is 85%, 87%, 89%, 90%, 91%, 93%, 95%, 96%, 97% or any value within the above range; the mass content of silicon element in the organosilicon polymer containing siloxane structure is 25%, 27%, 29%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 45% or any value within the above range; the mass content of the skeleton composed of the compound represented by formula (II) in the organosilicon polymer containing siloxane structure is 40%, 41%, 43%, 45%, 48%, 50%, 53%, 56%, 58%, 60% or any value within the above range.

[0215] In the embodiments of the present application, the cross-linking degree of the organosilicon polymer containing siloxane structure can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21MHz, 0.5g of the cleaned and dried sample (the above-mentioned organosilicon compound particles) to be tested is taken, is loaded into a clean sample tube and is inserted into a probe to a specified depth, the diameter of the probe coil 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 entire 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, and the PQ001 nuclear magnetic resonance analyzer automatically acquires the relaxation decay curve. During data processing, the software decomposes the relaxation components by exponential fitting, calculates and outputs the cross-linking degree result according to the degree of restriction of molecular chain movement.

[0216] By controlling the cross-linking degree of the organosilicon polymer in the above range, the coating has excellent structural stability at high temperature, and the damage of the separator caused by dendrite penetration can be effectively reduced.

[0217] As an example, in the embodiments of the present application, a powder sample (usually a few milligrams) of the organosilicon polymer containing siloxane structure is taken, is cleaned with anhydrous ethanol or deionized water for 1-2 minutes to remove surface impurities; then is placed in an oven and dried at 60-80°C for 1-2 hours to completely remove water (to avoid the influence of sample volatilization on the vacuum environment during testing). The dried powder is uniformly spread on conductive glue (to ensure that the powder does not accumulate or scatter); then a layer of 5-10nm thick gold is sprayed on the surface thereof by an ion sputtering instrument; or after the battery monomer is disassembled, the separator is peeled off, and a regular and clear area of the separator is selected. Then, the separator sample is fixed on a sample stage and is subjected to gold spraying or carbon spraying treatment to make the surface conductive; the sample stage containing the sample to be tested is placed in the SEM sample chamber, the door is closed, the vacuum system is started, and the instrument is pumped to the required high vacuum state (usually 10-3-10 -5Pa). After the vacuum is up to the standard, adjust the electron gun voltage (usually 5-20 kV), working distance (usually 5-15 mm), move the sample stage by the control software to find the target observation area. Adjust the focus and magnification (from low 100 times positioning to high magnification to observe details) step by step to obtain clear SEM morphology images, and mark the feature points or areas that need to be analyzed by EDS. Start the EDS detector in the SEM software, select the marked analysis area (single-point analysis, line scanning or area scanning can be performed), set the collection time (usually 10-30 seconds, the longer the time, the more accurate the element signal). Using the energy-dispersive x-ray spectroscopy (EDS) matched with ZEISS sigma300, the surface of the silicone polymer containing siloxane structure is analyzed to detect the content of silicon element in the silicone polymer containing siloxane structure. According to the data results of the instrument, the distribution of each element can be obtained, and thus the mass percentage of silicon element can be obtained.

[0218] The above-mentioned range of silicon element mass content can maintain the thermal stability of the material, thereby facilitating the uniform deposition of metal ions and reducing the formation of dendrites.

[0219] As an example, the mass content of the skeleton composed of the compound represented by formula (II) in the silicone polymer is the meaning known in the art, which can be tested by using the instruments and methods known in the art. As an example, after the battery monomer is disassembled, the separator film is peeled off. Then, the organic compound particle powder of the coating in the separator film is scraped off as the sample to be tested, dried to remove adsorbed water, and then placed in a desiccator for cooling standby. Specifically, the mass content of phenyl in the silicone polymer can be tested by using a pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS) instrument. Specifically, 0.5-1 mg of the above-mentioned silicone polymer is weighed as a test sample, loaded into a quartz cracking tube of a pyrolysis instrument, cracked at 550°C for 1.2 s, and tested in an inert gas (such as helium) to crack the sample into volatile small molecules, which are then introduced into a gas chromatograph-mass spectrometer. The HP-5ms (30m x 0.25mm x 0.25μm) chromatographic column is selected, the temperature is set to 30°C for 5 min, the temperature is increased at 10°C / min to 250°C, and the temperature is maintained at 250°C for 5 min. The carrier gas is high-purity helium with a flow rate of 1.0 mL / min. The mass spectrometry uses electrochemical ionization, the ion source temperature is 230°C, and the fragment scanning range is m / z 25-200. By comparing with the EVA standard cracking spectrum in the NIST library, the characteristic ions corresponding to the skeleton composed of the compound represented by formula (II) are detected, and it can be inferred that the silicone polymer includes the skeleton composed of the compound represented by formula (II). The internal standard method is used to calculate the mass content of the skeleton composed of the compound represented by formula (II) in the silicone polymer by using the above-mentioned fragment peak area corresponding to the skeleton composed of the compound represented by formula (II).

[0220] Because the organosilicon polymer containing the skeleton of the compound shown in formula (II) contains cage-like skeletal bonds, it has a three-dimensional structure with stable spatial structure. The mass content of the skeleton composed of the compound shown in formula (II) in the aforementioned organosilicon polymer containing silicon-oxygen structures within the above-mentioned range can make it less prone to decomposition at high temperatures, which is beneficial for further improving the stability of the battery cell at high temperatures.

[0221] Therefore, by limiting the degree of crosslinking, the mass fraction of silicon, and the mass content of phenyl, it is beneficial to improve the dendrite resistance of metal battery cells, as well as their storage and cycle performance under high temperature conditions.

[0222] In some embodiments, the organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammetry curve of the organic compound particles in the first cycle does not have an oxidation peak in the voltage range of 0 to 4.4 V; (2) the organic compound particles have no glass transition temperature at 300 °C; (3) the initial thermogravimetric temperature T of the organic compound particles is [missing information]. 3d Satisfy: T 3d ≥250℃; (4) The dissolution rate of organic compound particles in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7, after being soaked at 60℃ for 7 days, is less than or equal to 5%; (5) The true density of organic compound particles is 0.8 g / cm³. 3 ~2.0g / cm 3 .

[0223] For example, the glass transition temperature Tg of the organic compound particles is 320℃, 350℃, 400℃, 500℃ or any value within the above range; the initial thermogravimetric temperature T of the organic compound particles is... 3d The temperatures are 250℃, 270℃, 290℃, 300℃, 320℃, 350℃, 370℃, 400℃, 500℃, or any value within the above ranges; the dissolution rate of organic compound particles in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7, after being soaked at 60℃ for 7 days, is less than or equal to 5% (0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 4.5%, 5%, or any value within the above ranges); the true density of the organic compound particles is 0.8 g / cm³. 3 1.0g / cm 3 1.2g / cm 3 1.4g / cm 3 1.6g / cm 3 1.8g / cm 3 1.9g / cm 3 2.0g / cm 3 Or any value within the above range.

[0224] The cyclic voltammogram of the organic compound particles in the embodiment of the present application circulates for the first time without an oxidation peak in the voltage range of 0 to 4.40 V, indicating that the organic compound particles are stable in the voltage range of 0 to 4.40 V and have good electrochemical stability.

[0225] As an example, the oxidation peak potential of the cyclic voltammogram of the organic compound particles can be tested as follows: take the organic compound particles, the binder polyacrylate, and the conductive agent conductive carbon black, and dissolve them in water according to a solid content mass ratio of 64:7:29 to configure a slurry, coat the slurry on an aluminum foil as a positive electrode, take a lithium foil as a negative electrode, and assemble a coin cell. Perform a cyclic voltammetry (CV) test on the coin cell at a scan rate of 0.10 mV / s, a voltage range of 2.50 V-5.00 V, and 3 cycles, and take the voltage corresponding to the peak point of the first cycle cyclic voltammogram 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.

[0226] Because the electrochemical stability of conventional organic particles is generally poor, they are easily decomposed at high temperatures. Therefore, the organic compound particles in the embodiment of the present application can be applied to high-temperature battery monomers, so that the battery monomers have good capacity performance at high temperatures, and the working voltage and energy density of the battery monomers are improved.

[0227] The glass transition temperature Tg refers to the transition temperature at which a material changes from a glass state to a high-elasticity state, which shows a step change on a DSC curve.

[0228] As an example, the glass transition temperature T g can be tested as follows: take an appropriate amount of sample (for example, 5 mg-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, and protective gas 20 mL / min. Program settings: increase the temperature from 25°C to 200°C at a rate of 10°C / min, hold for 5 min to eliminate thermal history, then decrease the temperature from 200°C to -40°C at a rate of 10°C / min, and then increase the temperature to 300°C at a rate of 10°C / min. Determine the glass transition temperature T g of the organic compound particles by the DSC curve.

[0229] The organic compound particles have no glass transition temperature at 300℃, which means that the DSC curve of the organic compound particles remains solid and rigid below 300℃, and no molecular chain segment movement or softening occurs, so as to improve the thermal stability of the isolation film. In this way, the isolation film can maintain its structural integrity and mechanical properties at high temperatures, thereby improving the storage performance and cycle performance of the battery cell in a high-temperature environment.

[0230] The initial thermal weight loss temperature T of the organic compound particles 3d Greater than or equal to 250℃, 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 use of the battery cell.

[0231] As an example, the initial thermal weight loss temperature T of the organic compound particles 3d The initial thermal weight loss temperature T of the organic compound particles 3d The initial thermal weight loss temperature T of the organic compound particles can be tested as follows: take an appropriate amount of sample (for example, 5mg-15mg) 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 60mL / min, protective gas 20mL / min; temperature rising program: temperature rising rate 10℃ / min, temperature range 35℃-600℃; from the test curve, the temperature corresponding to the loss of 3% of the initial mass of the sample (i.e., 97% of the initial mass) is obtained, which is the initial thermal weight loss temperature T 3d .

[0232] The organic compound particles are used in the isolation film, and the organic compound particles can better generate a force to resist the shrinkage of the isolation film. In this way, the isolation film can maintain the stability of the pore structure at high temperatures, thereby reducing the phenomenon of electrode contact short circuit. At the same time, this can also reduce the oxidative decomposition of the electrolyte, thereby improving the high-temperature storage performance and cycle life.

[0233] The dissolution rate can refer to the proportion of the particles dissolved or decomposed in the electrolyte.

[0234] As an example, the swelling degree of the organic compound particles in the embodiments of the present application can be tested as follows: take an appropriate amount of sample (for example, about 1g), and record the mass as m1, and place it in a semi-permeable membrane sample bag, seal it, and the sample bag can permeate the solvent but cannot permeate the sample; immerse the sample bag in an appropriate amount of solvent (for example, about 50g) and immerse it at 60℃ for 7 days, then take out the sample bag, take out the sample from the sample bag, wipe off the excess solvent, and weigh the mass of the sample again m2; 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.

[0235] The organic compound particles have a dissolution rate of less than 5% after being soaked in electrolyte at 60°C for 7 days, and are not easy to precipitate or dissolve in the electrolyte environment, reducing the occurrence of electrolyte pollution or side reactions between the organic compound particles and the electrolyte during the cycle process of the battery cell, and the separator film has good structural stability, which is conducive to the cycle performance and reliability of the battery cell.

[0236] 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.

[0237] As an example, the true density can be tested by the following method. As an example, organic compound particles with a mass of M are weighed, and the carbon base is placed in a true density tester (AccuPyc II 1340 analyzer) at room temperature (15-25°C), the test system is closed, and helium is introduced 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, which is the true volume V of the organic compound particles. The true density of the organic compound particles is the mass M of the organic compound particles / the true volume V of the organic compound particles, and the unit of the true density is g / cm 3 .

[0238] 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.

[0239] Therefore, by limiting the oxidation peak of the cyclic voltammetry curve of the first cycle of the organic compound particles, the glass transition temperature, the initial thermal weight loss temperature, the dissolution rate after 7 days of constant temperature soaking at 60°C, and the true density, the overall performance of the battery cell can be improved.

[0240] In some embodiments, the mass content of the organic compound particles in the coating is 50%-97%. For example, the mass content of the organic compound particles in the coating is 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 87%, 89%, 90%, 92%, 94%, 96%, 97% or any value within the above range. By setting the mass content of the organic compound particles in the coating within the above range, the mechanical strength of the coating can be improved, thereby effectively blocking the penetration of lithium dendrites and reducing the short circuit of the electrode. At the same time, this can also promote uniform ion distribution during the cycle process and reduce dendrite growth. On the other hand, this is also conducive to reducing the agglomeration of particles to block the pores and cause local current density to increase to induce dendrites.

[0241] In some embodiments, 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-diene copolymer, ethylene-propylene-diene terpolymer, sulfonated ethylene-propylene-diene terpolymer, styrene-butadiene rubber, fluoroelastomer; (2) the mass content of the first binder in the coating layer is 3% to 15%.

[0242] For example, the mass content of the first binder in the coating layer is 3%, 5%, 7%, 9%, 10%, 12%, 13%, 14%, 15%, or any value within the above range.

[0243] In the above embodiments, the organic compound particles in the coating layer are connected and fixed to each other by the first binder, reducing the situation of the organic compound particles falling off during coating and use. By setting the mass content of the first binder within the above range, the adhesion can be considered while reducing the situation of reducing the proportion of organic compound particles in the coating layer due to excessive binder, so that the stability and dendrite resistance of the separator film are considered, and the cycle performance of the battery cell is improved.

[0244] 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 arranged on at least one side of the coating layer away from the porous 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 average volume particle size of the second binder particles is 5 μm to 20 μm.

[0245] For example, the average volume particle size of the second binder particles in the coating layer is 5 μm, 7 μm, 8 μm, 10 μm, 11 μm, 13 μm, 14 μm, 15 μm, 18 μm, 20 μm, or any value within the above range.

[0246] In the above embodiments, by adding the second binder particles in the coating layer or adding the second binder particles in the adhesive layer of the separator film, 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. In addition, the average volume particle size of the second binder particles is set in the above range, which is beneficial to the uniform distribution of the second binder particles while also having moderate flowability, thereby further improving the cycle performance of the battery cell.

[0247] As an example, the average volume particle size of the second binder particles has the meaning known in the art and can be tested by instruments and methods known in the art. For example, the volume average particle size Dv50 of the second binder particles can be tested by referring to GB / T 19077-2016 and using a laser particle size analyzer. During testing, a clean small beaker is taken and 1 g of the sample to be tested is added, 20 ml of deionized water is added, and ultrasonic treatment is performed at 53 KHz / 120 W for 5 min to ensure that the sample is completely dispersed. After turning on the laser particle size analyzer and cleaning the light path system, the background is automatically tested. The ultrasonically treated sample solution is stirred to make it uniformly dispersed, and then it is placed in the sample cell as required to start measuring the particle size. The testing instrument can be a MasterSizer 3000 laser particle size analyzer.

[0248] It should be understood that the "first binder" in the embodiments of the present application plays a role of bonding between the organic compound particles in the porous coating layer of the separator film, and the "second binder particles" play a role of improving the adhesion between the separator film and the electrode sheet in the porous coating layer of the separator film.

[0249] In some embodiments, the coating layer of the separator film includes organic compound particles and second binder particles, and the second binder particles can be embedded in the organic compound particles and form protrusions on the surface of the coating layer.

[0250] In some embodiments, the coating layer of the separator film includes a heat-resistant layer and an adhesive layer, the heat-resistant layer is arranged on the porous base film, the adhesive layer is arranged on at least a part of the surface of the side of the heat-resistant layer away from the porous base film, the organic compound particles are arranged in the heat-resistant layer, and the second binder particles are arranged in the adhesive layer.

[0251] In some embodiments, the coating layer of the separator film includes a heat-resistant layer and an adhesive layer, the heat-resistant layer is arranged on one side of the porous base film, the adhesive layer is arranged on at least a part of the surface of the other side of the porous base film, the organic compound particles are arranged in the heat-resistant layer, and the second binder particles are arranged in the adhesive layer.

[0252] In some embodiments, the coating of the separation membrane includes a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on one side of the porous base film, the bonding layer is disposed on at least a portion of the surface of the heat-resistant layer away from the porous base film 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.

[0253] In some embodiments, the coating does not include inorganic particles.

[0254] 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.

[0255] In some other embodiments, the coating includes inorganic particles, and the mass fraction of the inorganic particles is 50% to 92% based on the total mass of the coating.

[0256] 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, and the above inorganic particles have a large dielectric constant, which is conducive to improving the ion transport efficiency in the coating.

[0257] In some embodiments, the separation membrane satisfies one or more of the following conditions: (1) the thickness of the coating is 0.5 μm to 10 μm; (2) the areal density of the coating is 1.5 g / m 2 to 6 g / m 2 ; (3) the longitudinal thermal shrinkage of the separation membrane is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage of the separation membrane is less than or equal to 5% when heated at 130°C for 1 h; and (5) the air permeability of the separation membrane is 150 s / 100 mL to 500 s / 100 mL.

[0258] For example, the thickness of the coating can be 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value within the above range; the areal density of the coating can be 1.5 g / m 2 , 1.8 g / m 2 , 2 g / m 2 , 2.2 g / m 2 , 2.4 g / m 2 , 2.6 g / m 2 , 2.8 g / m 2 , 3 g / m 2 , 3.2 g / m 2 , 3.5 g / m 2 , 3.8 g / m 24.5 g / m2 2 4.5 g / m2 2 5 g / m2 2 5.3 g / m2 2 5.7 g / m2 2 6 g / m2 2 or any value within the above range; the heat shrinkage rate of the isolation film in the longitudinal direction can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range after constant heating at 130°C for 1h; the heat shrinkage rate of the isolation film in the transverse direction can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range after constant heating at 130°C for 1h; the air permeability of the isolation film can be 150 s / 100mL, 200 s / 100mL, 250 s / 100mL, 300 s / 100mL, 350 s / 100mL, 400 s / 100mL, 450 s / 100mL, 500 s / 100mL or any value within the above range.

[0259] The thickness of the coating refers to the thickness of the coating on one side of the porous base film. By setting the thickness of the coating within the above range, a uniform and dense thermal insulation layer can be formed, thereby balancing the energy density and cycle performance of the battery cell.

[0260] By setting the area density of the coating within the above range, it is beneficial to balance the stability and dendrite resistance of the isolation film while not increasing the weight of the isolation film, thereby benefiting the energy density and reliability of the battery cell.

[0261] As an example, the area density of the coating can be tested by the following method: first, stack the single isolation film containing the coating in the embodiments of the present application and the single isolation film substrate without the coating independently to 6 layers, and apply pressure to make each layer tightly adhere and without bubbles. Then, cut the two groups of stacks according to the sample cutting template, each obtaining 6 samples. Then measure the total mass M1 of the 6 samples with coating and the total mass M2 of the 6 samples without coating substrate, and calculate the average mass of the coating on the single isolation film by the formula M = (M1-M2) / 6. Then, measure the area S of a single sample, and the area density of the coating can be obtained according to the formula "coating area density = M / S".

[0262] The heat shrinkage rate refers to the percentage of size change of the isolation film at high temperature, which is an important indicator for measuring the thermal stability of the isolation film.

[0263] As an example, the release film is punched into a sample with a width of 50 mm and a length of 100 mm by a punch press, 5 parallel samples are placed on an A4 paper, and then the A4 paper with the samples is placed on the corrugated paper with a thickness of 1 mm to 5 mm. The temperature of the air oven is set to 130°C, and after the temperature reaches the set temperature and stabilizes for 60 min, the A4 paper placed on the corrugated paper is placed in the air oven, and the timing starts. After reaching the set time (1 h in the present disclosure), the length and width of the release film are measured, and the values are marked as a and b, respectively. The longitudinal (MD) heat shrinkage rate = [(100-a) / 100] x 100%, and the transverse (TD) heat shrinkage rate = [(50-b) / 50] x 100%. The average value of 3 parallel samples is taken as the test result.

[0264] The release film is heated at 130°C for 1 h, and the longitudinal and transverse heat shrinkage rates meet the above range, which is beneficial to maintaining the stability of the release film in a high temperature environment and improving its mechanical integrity. In this way, the short circuit caused by the exposure of the pole piece can be reduced, thereby reducing the probability of thermal runaway and improving the cycle performance of the battery cell.

[0265] The air permeability (Gurley value) of the release film refers to the time required for 100 mL of air to pass through the release film, which characterizes the resistance of the pore structure of the release film to gas / liquid transmission.

[0266] As an example, the air permeability value of the release film can be tested according to GB / T 36363-2018. Specifically, the release film is cut into a square of 5 cm in size, and a gas permeameter is used to test the time required for 100 ml of air to pass through 6.45 cm 2 of the release film under a pressure of 1.21 kPa, as the air permeability value of the release film, in s / 100 ml. The average value of 3 parallel samples is taken as the test result.

[0267] By setting the air permeability of the release film within the above range, it is beneficial to promote the uniform wetting of the electrolyte and maintain the rapid transmission of ions, and to reduce the electrochemical polarization caused by too low air permeability of the release film, thereby reducing the cycle performance of the battery cell.

[0268] Therefore, by limiting the thickness, areal density, longitudinal heat shrinkage rate, transverse heat shrinkage rate, and air permeability of the coating, the overall performance of the release film is improved.

[0269] In some embodiments, the peeling force between the coating layer of the separation film and the porous base film can be greater than or equal to 28 N / m. For example, the peeling force between the coating layer of the separation film and the porous base film can be 28 N / m, 30 N / m, 32 N / m, 34 N / m, 36 N / m, 38 N / m, or any value within the above range. In this way, the coating layer can reduce the occurrence of delamination or peeling during the expansion and contraction of the electrode plate, thereby maintaining the integrity of the pore structure and promoting uniform ion transmission. At the same time, this can also reduce the direct contact of the electrolyte with the base film caused by local peeling of the coating layer, and reduce the interface side reaction and impedance growth.

[0270] As an example, the peeling force between the coating layer of the separation film and the porous base film can be tested as follows: cut the separation 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 separation film to be tested, use a tensile testing machine, clamp the steel plate on one side and the tape on the other side for 180° peeling test, take the average value of the peeling force of the 3 pieces as the peeling force between the coating layer of the separation film and the porous base film. The tensile rate is 50 mm / min.

[0271] It should be noted that the coating parameters of the above separation 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.

[0272] In some embodiments, the thickness of the separation film can be 5 μm-20 μm, optionally 5 μm-12 μm, 6 μm-12 μm. This is beneficial to improve the energy density of the secondary battery cell.

[0273] In some embodiments, the material of the porous base film of the separation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0274] In some embodiments, the porous base film can be a single-layer film or a multi-layer composite film, without particular limitation. When the porous base film is a multi-layer composite film, the materials of the layers can be the same or different, without particular limitation.

[0275] The separation film can be prepared according to methods known in the art.

[0276] In some embodiments, a slurry including organic compound particles and first binder particles can be coated on at least one side of the porous base film, and after drying, the separation film is obtained.

[0277] In some embodiments, the slurry can further include 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.

[0278] 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.

[0279] 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 another side of the porous base film to obtain a separation film including a bonding layer after drying.

[0280] In some embodiments, the solvent of the slurry can be water, for example, deionized water.

[0281] In some embodiments, the slurry can further include other components, for example, can further include dispersants and / or wetting agents, etc.

[0282] [Separation film]

[0283] The embodiments of the present application provide a separation film.

[0284] In some embodiments, the separation film is located between a positive electrode sheet and a negative electrode sheet; the separation film 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 and a first binder; the first binder is used to bond the organic compound particles to the porous base film; the morphology of the organic compound particles is spherical or spheroidal; and the roundness A of the organic compound particles satisfies: 0.5≤A≤1.0. For example, A is 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.

[0285] By setting the range of the roundness of the organic compound particles in the coating layer, the organic compound particles are facilitated to present a highly spherical morphology, thereby facilitating to improve the dendrite resistance of the metal battery cell and to improve the storage performance and cycle performance thereof in a high temperature environment.

[0286] In some embodiments, the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles satisfies: 0.5≤(Dn90-Dn10) / Dn50≤2.0. For example, the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles is 0.5, 0.6, 0.7, 0.8, 1.0, 1.2, 1.3, 1.4, 1.5, 1.6, 1.8, 2.0, or any value within the above range.

[0287] Setting the particle size concentration of the organic compound particles in the above range is conducive to making the organic compound particles have a suitable size distribution, which can reduce the mechanical defects that may be caused by large particles piercing the base film, and also can reduce the case of uneven coating and local insufficient strength caused by small particles. This can reduce the penetration of dendrites and reduce the risk of short circuit. At the same time, this is also conducive to making the organic compound particles have suitable packing tightness between particles, maintaining the porosity thereof. This can promote sodium ion transmission, reduce the internal resistance of the battery cell, and improve the rate performance. Therefore, the particle size concentration of the organic compound particles meeting the above range can take into account the mechanical strength, ion conductivity and structural stability, and improve the dendrite resistance of the separator film, thereby reducing the probability of thermal runaway of the metal battery cell.

[0288] In some embodiments, the concavity B of the organic compound particles satisfies: 0≤B≤0.5. For example, the concavity B of the organic compound particles is 0, 0.05, 0.08, 0.09, 0.1, 0.11, 0.13, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or any value in the above range.

[0289] In the case where the concavity of the organic compound particles is in the above range, the pore structure formed can balance the electrolyte distribution, shorten the ion transmission path, reduce the concentration polarization, and reduce the case of uneven current. At the same time, this also does not hinder ion transmission and cause local electrolyte depletion. In addition, this is also conducive to improving the mechanical strength of the coating and reducing the formation of new dendrite nucleation sites by the metal during the deposition process. Therefore, controlling the particle concavity in a moderate range can both take advantage of its electric field adjustment and reduce the dendrite phenomenon caused by structural defects, thereby reducing the probability of thermal runaway of the metal battery cell.

[0290] In some embodiments, the organic compound particles comprise a crosslinked polymer, and the crosslinking degree of the crosslinked polymer is 70% to 98%. For example, the crosslinking degree of the crosslinked polymer is 70%, 75%, 78%, 80%, 83%, 85%, 87%, 89%, 90%, 92%, 94%, 96%, 97%, 98% or any value in the above range. The crosslinking degree of the crosslinked polymer meeting the above range makes the formed crosslinked polymer have a three-dimensional network structure, which is conducive to limiting the free movement of molecular chains, thereby improving the structural stability of the organic compound particles and increasing the mechanical strength of the particles, thereby increasing the structural stability of the coating.

[0291] In some embodiments, the cross-linking polymer comprises a silicone polymer containing a siloxane structure. By employing a silicone polymer containing a siloxane structure as the cross-linking polymer, the high bond energy of the siloxane bond and the three-dimensional cross-linked network formed by the cross-linking between the molecular chains of the silicone polymer, the silicone polymer containing a siloxane structure can have high mechanical strength, thereby facilitating the improvement of the dendrite resistance of the metal battery cell and the storage performance and cycle performance in a high-temperature environment. Specifically, the rigid-Si-O-Si-inorganic skeleton remains stable in a high-temperature environment, effectively reducing dendrite puncture and separator thermal contraction. At the same time, the polymer also has good electrolyte wettability and ion uniform distribution capability, which can reduce the dendrite growth caused by local current concentration. In addition, compared with inorganic particles, the density of the silicone polymer is lower, and the overall mass of the coating can be reduced under the same thickness, thereby facilitating the improvement of the energy density of the battery cell.

[0292] In some embodiments, the silicone polymer containing a siloxane structure comprises a phenyl group, the silicone polymer containing a siloxane structure is obtained by polymerization of a monomer and a cross-linking agent represented by formula (I),

[0293]

[0294] wherein R1, R2 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, R3 comprises C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, and R4 comprises C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; the cross-linking agent comprises divinylbenzene.

[0295] In the embodiments of the present application, R1 and R2 are each independently selected from at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, ethenyl, 1-propenyl, 2-propenyl (allyl), 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, and 2-methyl-1-propenyl.

[0296] R3 comprises at least one of methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, (meth)acryloyloxy methyl, 2-((meth)acryloyloxy)ethyl, 3-((meth)acryloyloxy)propyl, or 4-((meth)acryloyloxy)butyl.

[0297] R4 comprises at least one of ethenyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl (meth)acryloyloxymethyl, 2-((meth)acryloyloxy)ethyl, 3-((meth)acryloyloxy)propyl, or 4-((meth)acryloyloxy)butyl.

[0298] The polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene can take into account both material stability and interface characteristics. Specifically, the polymer obtained by polymerization of the monomer represented by formula (I) and the crosslinking agent divinylbenzene has both the rigidity of the aromatic ring and the high bond energy of the silicon-oxygen bond, and a three-dimensional crosslinked network formed by the mutual crosslinking between the molecular chains of the silicone polymer, so that it has excellent structural stability and high mechanical strength, thereby being able to reduce the physical puncture phenomenon of dendrites. In addition, the polar silicon-oxygen chain segment improves the electrolyte wettability, promotes the uniform distribution of sodium ions, and reduces the dendrite growth caused by local concentration polarization. Therefore, in a high temperature environment, the coating can effectively reduce the electrolyte thermal decomposition and metal lithium side reactions, maintain the interface stability, thereby promoting the storage performance and cycle performance in a high temperature environment.

[0299] In some embodiments, the silicone polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the silicone polymer containing a siloxane structure is 75% to 95%; (2) the mass content of silicon elements in the silicone polymer containing a siloxane structure is 10% to 25%; (3) the mass content of phenyl groups in the silicone polymer containing a siloxane structure is 2% to 12%.

[0300] For example, the crosslinking degree of the silicone polymer containing a siloxane structure is 75%, 77%, 79%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 95% or any value within the above range; the mass content of silicon elements in the silicone polymer containing a siloxane structure is 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 25% or any value within the above range; the mass content of phenyl groups in the silicone polymer containing a siloxane structure is 2%, 3%, 4%, 5%, 6%, 7%, 8%, 7%, 9%, 10%, 11%, 12% or any value within the above range.

[0301] In the above embodiments, the crosslinking degree of the silicone polymer containing a siloxane structure is set within the above range, which is beneficial to make the coating have a suitable rigidity. This can effectively buffer the volume change during sodium deposition / detachment, thereby reducing the stress concentration of dendrite tips and improving the dendrite resistance of the battery cell. At the same time, this is also beneficial to promote ion transmission and reduce polarization and capacity decay in high temperature cycling.

[0302] Setting the mass content of silicon elements in the silicone polymer containing a siloxane structure within the above range is beneficial to maintain the stability of the coating in a high temperature environment, making it difficult for dendrites to penetrate the separator, thereby improving the storage performance and cycle performance of the battery cell in a high temperature environment.

[0303] Setting the mass content of phenyl in the organosilicon polymer containing siloxane structure in the above range is conducive to reducing the increase in the mobility of the chain segment and reducing the occurrence of micro-cracks in the coating under the stress of dendrite growth. At the same time, this can also reduce the oxidation of the material in a high-temperature environment, thereby reducing the decomposition of the electrolyte and the interface failure. In addition, this is also conducive to reducing the polarity of the material and reducing the excessive swelling of the electrolyte, thereby improving the ability of the battery monomer to inhibit dendrites.

[0304] Therefore, by limiting the crosslinking degree, the mass content of silicon elements, and the mass content of phenyl described above, the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance in a high-temperature environment can be improved.

[0305] In some embodiments, the organosilicon polymer containing a siloxane structure includes a backbone composed of a compound shown in formula (II),

[0306] R a [SiO 3 / 2 ] n formula (II),

[0307] wherein n is at least one of an 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, and R a includes C1-C3 alkyl.

[0308] By introducing the structural unit shown in formula (II) into the organosilicon polymer, a three-dimensional polyhedral skeleton with high symmetry and regularity can be constructed. This structure has a highly symmetrical rigid covalent bond network that can effectively reduce the shrinkage of the coating under high-temperature conditions, thereby providing stable mechanical support for the uniform deposition of metal ions and physically facilitating the blocking of dendrite penetration. At the same time, the three-dimensional polyhedral skeleton structure can enhance the electrolyte wettability and ion flow uniformity, reducing dendrite growth caused by local current overload. By selecting R1 as a C1-C3 alkyl group, the thermal stability and interface compatibility of the material can be further improved, thereby improving the storage performance and cycle performance of the battery monomer in a high-temperature environment.

[0309] In some embodiments, the organosilicon polymer containing a siloxane structure includes one or more of the monomers shown in formula (III) obtained by hydrolysis and polycondensation,

[0310]

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

[0312] The hydrolysis-polycondensation reaction of the monomer of formula (III) can obtain a silicone polymer with a cage structure. The polymer forms a three-dimensional network with high mechanical strength and thermal stability in the coating, which can effectively reduce the shrinkage of the coating at high temperature, provide stable rigid support for the uniform deposition of metal ions, and physically effectively block the dendrite penetration. In addition, the three-dimensional polyhedral skeleton structure formed by polymerization can enhance the high-temperature wettability and ion distribution uniformity of the electrolyte, reduce the dendrite growth and aggravation of side reactions caused by local current overload. Therefore, the above-mentioned silicone polymer can improve the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance of the battery monomer under high temperature environment.

[0313] Optionally, R'1 is methyl. In this way, the dendrite resistance of the metal battery monomer, and the storage performance and cycle performance of the battery monomer under high temperature environment can be further improved.

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

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

[0316] By controlling the degree of crosslinking of the organosilicon polymer within the aforementioned range, the coating exhibits excellent structural stability at high temperatures, effectively reducing membrane damage caused by dendrite puncture. Simultaneously, the aforementioned range of silicon content maintains the material's thermal stability, thus promoting uniform metal ion deposition and reducing dendrite formation. Furthermore, the mass content of the framework composed of the compound shown in formula (II) balances rigidity and hydrophilicity, thereby enhancing electrolyte wettability and reducing interfacial side reactions at high temperatures. Therefore, by limiting the degree of crosslinking, the mass fraction of silicon, and the mass content of the framework composed of the compound shown in formula (II), it is beneficial to improve the dendrite resistance of metal battery cells, as well as their storage and cycle performance under high-temperature conditions.

[0317] In some embodiments, the organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammetry curve of the organic compound particles in the first cycle does not have an oxidation peak in the voltage range of 0 to 4.4 V; (2) the organic compound particles have no glass transition temperature at 300 °C; (3) the initial thermogravimetric temperature T of the organic compound particles is [missing information]. 3d Satisfy: T 3d ≥250℃; (4) The dissolution rate of organic compound particles in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7, after being soaked at 60℃ for 7 days, is less than or equal to 5%; (5) The true density of organic compound particles is 0.8 g / cm³. 3 ~2.0g / cm 3 .

[0318] For example, the glass transition temperature Tg of the organic compound particles is 320℃, 350℃, 400℃, 500℃ or any value within the above range; the initial thermogravimetric temperature T of the organic compound particles is... 3d The temperatures are 250℃, 270℃, 290℃, 300℃, 320℃, 350℃, 370℃, 400℃, 500℃, or any value within the above ranges; the dissolution rate of organic compound particles in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7, after being soaked at 60℃ for 7 days, is less than or equal to 5% (0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 4.5%, 5%, or any value within the above ranges); the true density of the organic compound particles is 0.8 g / cm³. 3 1.0g / cm 3 1.2g / cm 3 1.4g / cm 3 1.6g / cm 3 1.8g / cm 3 1.9g / cm 3 2.0g / cm 3or any value within the above range.

[0319] Since the electrochemical stability of conventional organic particles is generally poor, they are easily decomposed at high temperatures. Therefore, the organic compound particles in the embodiments of the present application can be applied to high-temperature battery cells, so that the battery cells have good capacity release characteristics at high temperatures, and the operating voltage and energy density of the battery cells are improved.

[0320] The fact that the organic compound particles have no glass transition temperature at 300°C means that the DSC curve of the organic compound particles remains in a solid state below 300°C, and no molecular chain segment movement or softening occurs, so that the thermal stability of the separator film can be improved. In this way, the separator film can maintain its structural integrity and mechanical properties at high temperatures, thereby improving the storage performance and cycle performance of the battery cell in a high-temperature environment.

[0321] The organic compound particles described above T 3d When the organic compound particles are used in the separator film, the organic compound particles can better generate a force to resist the shrinkage of the separator film. In this way, the separator film can maintain the stability of the pore structure at high temperatures, thereby reducing the phenomenon of short circuiting of the electrodes. At the same time, this can also reduce the oxidative decomposition of the electrolyte, thereby improving the high-temperature storage performance and cycle life.

[0322] The fact that the organic compound particles have a dissolution rate of less than 5% after 7 days of electrolyte immersion at 60°C means that 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 process of the battery cell, and the separator film has good structural stability, which is beneficial to the cycle performance and reliability of the battery cell.

[0323] Compared with inorganic particles with a larger density, such as boehmite and alumina, the true density of the organic compound particles is smaller, and the energy density of the battery cell can be improved without increasing the thickness of the coating.

[0324] Therefore, by limiting the oxidation peak of the cyclic voltammetry curve of the first cycle of the organic compound particles, the glass transition temperature, the initial thermal weight loss temperature, the dissolution rate after 7 days of constant temperature immersion at 60°C, and the true density, the overall performance of the battery cell can be improved.

[0325] In some embodiments, the mass content of the organic compound particles in the coating layer is 50% to 97%. For example, the mass content of the organic compound particles in the coating layer is 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 87%, 89%, 90%, 92%, 94%, 96%, 97%, or any value within the above range. Setting the mass content of the organic compound particles in the coating layer within the above range is conducive to improving the mechanical strength of the coating layer, thereby effectively blocking the penetration of lithium dendrites and reducing the short circuit of the electrode. At the same time, this can also promote uniform ion distribution during the cycle process and reduce dendrite growth. On the other hand, this is also conducive to reducing the agglomeration of particles to block the pores and cause local current density increase induced dendrites.

[0326] In some embodiments, 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, 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 content of the first binder in the coating layer is 3% to 15%.

[0327] For example, the mass content of the first binder in the coating layer is 3%, 5%, 7%, 9%, 10%, 12%, 13%, 14%, 15%, or any value within the above range.

[0328] In the above embodiments, the organic compound particles in the coating layer are connected and fixed to each other by the first binder, reducing the detachment of the organic compound particles during coating and use. Setting the mass content of the first binder within the above range can reduce the proportion of the organic compound particles in the coating layer due to excessive binder while taking into account the adhesion, thereby taking into account the stability and dendrite resistance of the separator film and improving the cycle performance of the battery cell.

[0329] 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 porous 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 average volume particle size of the second binder particles is 5 μm to 20 μm.

[0330] For example, the average volume particle size of the second binder particles is 5 μm, 7 μm, 8 μm, 10 μm, 11 μm, 13 μm, 14 μm, 15 μm, 18 μm, 20 μm or any value within the above range in terms of mass content in the coating layer.

[0331] In the above embodiments, by adding the second binder particles in the coating layer or the second binder particles in the bonding layer of the separator film, the second binder particles can fill the gap between the negative electrode sheet and the separator film, form a relatively 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 during the cycle process, and thereby improving the cycle performance of the battery cell. In addition, the average volume particle size of the second binder particles is set in the above range, which is conducive to the uniform distribution of the second binder particles while also having moderate flowability, thereby further improving the cycle performance of the battery cell.

[0332] In some embodiments, the coating layer of the separator film comprises organic compound particles and second binder particles, and the second binder particles can be embedded in the organic compound particles and form protrusions on the surface of the coating layer.

[0333] 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 on the side 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.

[0334] 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 one side of the porous base film, the bonding layer is disposed on at least a part of the surface on 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.

[0335] In some embodiments, the coating of the separation membrane includes a heat-resistant layer and a bonding layer, the heat-resistant layer is disposed on one side of the porous base film, the bonding layer is disposed on at least a portion of the surface of the heat-resistant layer away from the porous base film 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.

[0336] In some embodiments, the coating does not include inorganic particles.

[0337] 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.

[0338] In some other embodiments, the coating includes inorganic particles, and the mass fraction of the inorganic particles is 50% to 92% based on the total mass of the coating.

[0339] 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, and the above inorganic particles have a large dielectric constant, which is conducive to improving the ion transport efficiency in the coating.

[0340] In some embodiments, the separation membrane satisfies one or more of the following conditions: (1) the thickness of the coating is 0.5 μm to 10 μm; (2) the areal density of the coating is 1.5 g / m 2 to 6 g / m 2 ; (3) the longitudinal thermal shrinkage of the separation membrane is less than or equal to 5% when heated at 130°C for 1 h; (4) the transverse thermal shrinkage of the separation membrane is less than or equal to 5% when heated at 130°C for 1 h; and (5) the air permeability of the separation membrane is 150 s / 100 mL to 500 s / 100 mL.

[0341] For example, the thickness of the coating can be 0.5 μm, 0.7 μm, 0.9 μm, 1 μm, 2 μm, 3 μm, 5 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value within the above range; the areal density of the coating can be 1.5 g / m 2 , 1.8 g / m 2 , 2 g / m 2 , 2.2 g / m 2 , 2.4 g / m 2 , 2.6 g / m 2 , 2.8 g / m 2 , 3 g / m 2 , 3.2 g / m 2 , 3.5 g / m 2 , 3.8 g / m 24g / m 2 4.5g / m 2 5g / m 2 5.3g / m 2 5.7g / m 2 6g / m 2 Or any value within the above range; the longitudinal heat shrinkage rate of the separator after being heated at 130℃ for 1 hour can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range; the transverse heat shrinkage rate of the separator after being heated at 130℃ for 1 hour can be 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5% or any value within the above range; the air permeability of the separator can be 150s / 100mL, 200s / 100mL, 250s / 100mL, 300s / 100mL, 350s / 100mL, 400s / 100mL, 450s / 100mL, 500s / 100mL or any value within the above range.

[0342] By setting the coating thickness within the aforementioned range, a uniform and dense heat insulation layer can be formed, thereby balancing the energy density and cycle performance of the battery cells.

[0343] Setting the areal density of the coating within the above range is beneficial to balancing the stability and dendrite resistance of the separator without increasing its weight, thus improving the energy density and reliability of the battery cells.

[0344] Heating the separator at 130℃ for 1 hour ensures that the longitudinal and transverse thermal shrinkage rates meet the aforementioned ranges, which helps maintain the separator's stability and improve its mechanical integrity under high-temperature conditions. This reduces short circuits caused by exposed electrodes, thereby lowering the probability of thermal runaway and improving the cycle performance of individual battery cells.

[0345] Setting the permeability of the separator within the above range is beneficial for promoting uniform electrolyte wetting and maintaining rapid ion transport, while reducing electrochemical polarization caused by excessively low separator permeability, which in turn reduces the cycle performance of the battery cell.

[0346] Therefore, by limiting the coating thickness, areal density, longitudinal thermal shrinkage rate, transverse thermal shrinkage rate, and air permeability, it is beneficial to improve the overall performance of the separator.

[0347] In some embodiments, the peeling force between the coating layer of the isolation film and the porous base film can be greater than or equal to 28 N / m. For example, the peeling force between the coating layer of the isolation film and the porous base film can be 28 N / m, 30 N / m, 32 N / m, 34 N / m, 36 N / m, 38 N / m, or any value within the above range. In this way, the coating layer can reduce the occurrence of delamination or peeling during the expansion and contraction of the electrode plate, thereby maintaining the integrity of the pore structure and promoting uniform ion transmission. At the same time, this can also reduce the direct contact of the electrolyte with the base film caused by local peeling of the coating layer, and reduce the interface side reaction and impedance growth.

[0348] It should be noted that the coating parameters of the above-mentioned isolation film are the coating parameters of one side of the porous base film. When the coating layer is arranged on both sides of the porous base film, as long as the coating parameters of any one side meet the present disclosure, it is considered to fall within the protection scope of the present disclosure.

[0349] In some embodiments, the thickness of the isolation film can be 5 μm-20 μm, and can be 5 μm-12 μm, 6 μm-12 μm. This is beneficial to improve the energy density of the secondary battery cell.

[0350] In some embodiments, the material of the porous base film of the isolation film can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.

[0351] In some embodiments, the porous base film can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the porous base film is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0352] The isolation film can be prepared according to methods known in the art.

[0353] In some embodiments, a slurry including organic compound particles and first binder particles can be coated on at least one side of the porous base film, and after drying, the isolation film is obtained.

[0354] In some embodiments, the slurry can further include 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.

[0355] In some embodiments, the preparation method of the isolation film can include: coating a slurry including organic compound particles and first binder particles on at least one side of the porous base film, and after drying, forming a coating layer; coating a slurry including second binder particles on at least a part of the surface of the coating layer away from the porous base film, and after drying, obtaining an isolation film including a bonding layer.

[0356] In some embodiments, the preparation method of the isolation film can include: coating a slurry including organic compound particles and first binder particles on one side of a porous base film, coating a slurry including second binder particles on at least a part of the surface of the other side of the porous base film, and obtaining an isolation film including a bonding layer after drying.

[0357] In some embodiments, the solvent of the slurry can be water, for example, deionized water.

[0358] In some embodiments, the slurry can further include other components, for example, can further include dispersants and / or wetting agents, etc.

[0359] [Negative electrode tab]

[0360] In some embodiments, the negative electrode tab includes a negative current collector. In a metal battery cell, the negative current collector is used to collect the current of the negative electrode tab and conduct electrons. For a negative metal battery cell, the negative current collector can also provide a deposition substrate for metal ions (such as lithium, sodium), and promote deposition uniformity and interface stability.

[0361] In some embodiments, the negative 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 material. 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 material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0362] In some embodiments, the negative electrode tab further includes an interface modification layer on at least one side of the negative current collector. The interface modification layer is used to guide the formation of a metal layer on the negative current collector. On the one hand, the interface modification layer can provide uniform nucleation sites, induce uniform deposition of lithium or sodium metal on the current collector, and inhibit the growth of dendrites. On the other hand, the interface modification layer can improve the interface stability, reduce the electrolyte side reaction, form a stable solid electrolyte interphase (SEI) film, and prolong the cycle life of the battery cell. In addition, the interface modification layer can also reduce the interface impedance, improve the ion conduction efficiency, and optimize the rate performance of the battery. Therefore, the interface modification layer is beneficial to improve the energy density and cycle life of the metal battery cell, and can also reduce the growth of dendrites.

[0363] In some embodiments, the interface modification layer comprises one or more of carbon materials, metal materials. In the above embodiments, the carbon materials can provide a larger specific surface area, uniformly disperse the current, thereby effectively inhibiting dendrites. The metal materials can achieve alloying, reduce the nucleation barrier, thereby inducing dense deposition. In practical applications of metal battery cells, the material of the interface modification layer can be selected according to specific needs.

[0364] In some embodiments, the carbon materials comprise one or more of carbon black, activated carbon, carbon nanotubes, carbon fibers, graphite; and / or, the metal materials comprise elemental In, Bi, Ag, Zn, Al, Mg, Ga, Ge, Sb, or one or more of metal alloys, metal oxides, metal carbides of at least one element of In, Bi, Ag, Zn, Al, Mg, Ga, Ge, Sb. Among them, the above-mentioned carbon materials can construct a network structure with excellent electrical conductivity, buffer volume expansion, and conduct ions and electrons; and the above-mentioned metal materials are lithium / sodium-philic materials, which can reduce the nucleation energy, induce uniform deposition, and inhibit the formation of dendrites.

[0365] In some embodiments, the thickness C of the interface modification layer satisfies: 0.2 μm≤C≤10 μm. For example, the thickness C of the interface modification layer is 0.2 μm, 0.5 μm, 1 μm, 2 μm, 4 μm, 7 μm, 10 μm or any value within the above range. For the negative electrode sheet, setting the thickness of the interface modification layer within the above range can effectively cover the defects on the surface of the current collector, providing sufficient nucleation sites. This is conducive to reducing the local current density, forming effective uniform lithium / sodium flow, and improving the inhibition effect of dendrites. At the same time, this also reduces the overall internal resistance of the battery cell, promotes ion transmission, reduces polarization, and thus reduces dendrite growth. In addition, the above thickness can also improve the interface stability, which is conducive to uniform deposition and reduces the risk of dendrites penetrating the separator.

[0366] In some embodiments, the anode-free lithium metal battery cell or the anode-free sodium metal battery does not use metal lithium sheets, metal sodium sheets or other anode active materials, but only uses the anode current collector as the anode, completes the anode plating of lithium / sodium during the first charging process, and returns to the positive electrode during discharging, to realize the charging and discharging cycle. Since there is no anode material, only the anode current collector is used, the anode-free lithium metal battery cell or the anode-free sodium metal battery can effectively overcome the defects of lithium / sodium metal batteries, and obtain higher energy density than metal lithium / sodium anodes. The technical solution proposed in the present application is especially suitable for anode-free lithium / sodium metal batteries, which can regulate the uniformity of lithium / sodium metal deposition on the anode side, reduce the probability of dendrite growth and puncture the isolation film to cause internal short circuit, so that the battery cell has high energy density, long cycle life, storage life and low storage gas production.

[0367] In some embodiments, the negative electrode sheet can be prepared by: forming an interface modification layer on the negative electrode current collector using the aforementioned material for preparing the interface modification layer of the negative electrode sheet through a dry process or a wet process, thereby obtaining the negative electrode sheet. The dry process includes at least one of magnetron sputtering, vapor deposition, and mechanical pressing; the wet process includes coating.

[0368] [Positive electrode plate]

[0369] The positive electrode sheet may include a positive current collector and a positive electrode film layer disposed on at least one layer of the positive current collector, the positive electrode film layer including a positive electrode active material.

[0370] Figure 1 is a schematic diagram of the structure of a positive electrode sheet according to an embodiment of this application. As shown in Figure 1, the positive electrode sheet 121 includes a positive current collector 1211 and a positive electrode film layer 1212 disposed on at least one side surface of the positive current collector 1211.

[0371] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector. As an example, as shown in FIG1, the positive electrode film layer 1212 is disposed on both sides of the positive current collector 1211.

[0372] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0373] In some embodiments, the positive electrode active material may be a known battery positive electrode active material. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing transition metal oxides, lithium phosphates with an olivine structure, or materials with a spinel structure. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium-containing transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNiO2). 1 / 3 Co1 / 3 Mn 1 / 3 O2(also can be referred to as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM811), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05 O2), and modified compounds thereof, etc. Examples of the lithium-containing phosphate of olivine structure can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also can be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite of lithium manganese iron phosphate and carbon.

[0374] In some embodiments, the positive electrode film 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.

[0375] In some embodiments, the positive electrode film layer can further optionally include 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.

[0376] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, coating the positive electrode slurry on a positive electrode current collector, and then performing processes such as drying, cold pressing, etc. to obtain the positive electrode tab.

[0377] [Electrolyte]

[0378] The electrolyte functions to conduct ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not particularly limited in the present application and can be selected as needed. For example, the electrolyte can be liquid, gel, or all-solid.

[0379] In some embodiments, the electrolyte employs an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0380] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro oxalato borate, lithium di-oxalato borate, lithium difluoro di-oxalato phosphate, and lithium tetrafluoro oxalato phosphate.

[0381] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclobutane sulfone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0382] 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 that can improve certain properties of the battery, such as an additive that improves overcharge performance of the battery, an additive that improves high or low temperature performance of the battery, etc.

[0383] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator film can be made into an electrode assembly through a roll-pressing process or a stacking process.

[0384] In some embodiments, the battery cell can include an outer package. The outer package can be used to encapsulate the electrode assembly and the electrolyte described above.

[0385] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the battery cell can also be a soft package, such as a pouch. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, etc. can be listed.

[0386] The shape of the battery cell is not particularly limited in the present application and can be cylindrical, square, or any other arbitrary shape. For example, FIG. 2 is a schematic diagram of the structure of a battery cell according to an embodiment of the present application.

[0387] FIG. 3 is a structural schematic diagram of a battery cell according to another embodiment of the present application. As shown in FIG. 3, the outer package of the battery cell 100 includes a casing 11 and a cover plate 13. The casing 11 can include a bottom plate and side plates connected to the bottom plate, which enclose a receiving cavity. The casing 11 has an opening communicating with the receiving cavity, and the cover plate 13 can be arranged on the opening to seal the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator film can be wound or stacked to form an electrode assembly 12. The electrode assembly 12 is encapsulated in the receiving cavity. The electrolyte is impregnated in the electrode assembly 12. The number of the electrode assemblies 12 contained in the battery cell 100 can be one or more, which can be selected by those skilled in the art according to specific actual needs.

[0388] In some embodiments, the battery cell 100 can also be assembled into a battery module. The number of the battery cells 100 contained in the battery module can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0389] [Battery device]

[0390] The embodiments of the present application provide a battery device including one or more battery cells according to the above embodiments. When there are multiple battery cells, the multiple battery cells are connected in series, in parallel, or in a mixed manner through a current collecting component.

[0391] In some embodiments, the battery device can be a battery pack including a box body and battery cells, and the battery cells or battery modules are contained in the box body.

[0392] In some embodiments, the battery device can be located in an energy storage device. The energy storage device includes an energy storage container, an energy storage cabinet, etc.

[0393] FIG. 4 is a schematic diagram of a battery device according to an embodiment of the present application, and FIG. 5 is a structural schematic diagram of the battery device according to an embodiment of the present application. Referring to FIGS. 4 and 5, the battery device 400 can include a battery box and multiple battery cells 100 arranged in the battery box. The battery box includes an upper box body 401 and a lower box body 402. The upper box body 401 can be arranged on the lower box body 402 to form a closed space for containing the battery cells 100. The multiple battery cells 100 can be arranged in the battery box in any manner.

[0394] [Power consumption device]

[0395] The application also provides a power utilization device comprising the battery as described above. The power utilization device comprises at least one of the battery cell 100 or the battery device 400 provided by the application. The battery cell 100 or the battery device 400 can be used as a power source of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0396] For example, FIG. 6 is a schematic structural diagram of a power utilization device according to an embodiment of the application. As shown in FIG. 6, the power utilization device is a vehicle 1, which can be a fuel automobile, a gas automobile, or a new energy automobile, and the new energy automobile can be a pure electric vehicle, a hybrid electric vehicle, or a range extended vehicle, etc. The vehicle 1 can be provided with a motor 500, a controller 600, and a battery device 400 inside, and the controller 600 is used to control the battery device 400 to supply power to the motor 500. For example, the battery device 400 can be arranged at the bottom, the front, or the rear of the vehicle 1. The battery device 400 can be used to supply power to the vehicle 1, for example, the battery device 400 can be used as an operating power source of the vehicle 1, and is used for the circuit system of the vehicle 1, for example, for the power demand of the vehicle 1 during starting, navigation, and operation. In another embodiment of the application, the battery device 400 can not only be used as an operating power source of the vehicle 1, but also can be used as a driving power source of the vehicle 1, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 1.

[0397] As the power utilization device, the battery cell 100 or the battery device 400 can be selected according to the use demand thereof.

[0398] The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the demand of high power and high energy density of the battery for the power utilization device, the battery cell 100 or the battery device 400 can be used.

[0399] As another example of the device, it can be a mobile phone, a tablet computer, a notebook computer, etc. The device usually requires thinning, and the battery cell 100 can be used as a power source.

[0400] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application, and cannot be understood as a limitation of the application. If the specific technology or condition is not indicated in the embodiments, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument is not indicated by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0401] [Examples and Comparative Examples]

[0402] [Example 1]

[0403] (1) Preparation of the negative electrode tab:

[0404] Preparation of the negative electrode tab: 5 g of CMC was weighed and dissolved in 1000 mL of water by stirring, then 5 g of single-walled carbon nanotubes was added and dispersed by ultrasonic, to prepare a slurry, which was then coated on the surface of a copper foil and transferred to a vacuum drying oven for complete drying. After that, the initial and die cutting were performed to prepare a negative electrode tab without a negative electrode structure, and the coating thickness was about 1 μm.

[0405] (2) Preparation of the positive electrode tab:

[0406] 5wt% polyvinylidene fluoride binder was fully dissolved in N-methyl pyrrolidone, 5wt% carbon black conductive agent and 90wt% positive electrode active material NaNi 0.20 Fe 0.22 Cu 0.13 Mn 0.45 O2 were made into a uniformly dispersed slurry. The slurry was uniformly coated on the surface of an aluminum foil, and then transferred to a vacuum drying oven for complete drying. The obtained tab was rolled and then die cut to obtain a positive electrode tab. The coating weight was 10 mg / cm 2 .

[0407] (3) Preparation of the separator:

[0408] ① Preparation of organic compound particles (organic silicon polymer containing cage polysilsesquioxane skeleton):

[0409] In a 500 ml flask equipped with a stirrer, a thermometer and a reflux condenser, deionized water was added, and hydrochloric acid was added to adjust the hydrolysis PH to 5.5. The stirring rate was set to 300 rpm, and methyltrimethoxysilane was added so that the mass ratio of methyltrimethoxysilane to deionized water was 1:24. Then, after hydrolysis reaction at 30℃ for 2h, sodium hydroxide was added to adjust the PH to 9.5, and the reaction was continued at 30℃ for 2h, and then the temperature was raised to 90℃ for 12h to obtain the organic compound particles. The water content was evaporated to obtain a dispersion liquid with a solid content of 20% for standby. The corresponding organic compound particle powder was obtained by drying treatment of the standby dispersion liquid.

[0410] The PQ001 nuclear magnetic resonance analyzer was used to test the crosslinking degree of the organic compound particle powder. The organic compound particle was a crosslinked polymer, and the calculated crosslinking degree was 93.5%.

[0411] The organic compound particle powder was tested by pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS), and the pyrolysis spectrum of the organic compound particle powder of the embodiment of the application is shown in FIG. 7. As shown in FIG. 7, by comparing with the EVA standard pyrolysis spectrum in the NIST library, it is detected that The corresponding characteristic ions can be inferred that the organic compound particle comprises a cage-like polysilsesquioxane skeleton.

[0412] The glass transition temperature Tg and the melting point of the organic compound particle were tested by differential scanning calorimetry (DSC), and the organic compound particle had no Tg and no melting point below 300℃.

[0413] The true density of the organic compound particle was tested by a true density tester, and the true density of the organic compound particle was 1.32 g / cm 3 .

[0414] The particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particle was tested by a scanning electron microscope (such as ZEISS Sigma 300), and the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particle was 0.8. Wherein, the Dn50 of the organic compound particle was 220 nm.

[0415] The organic compound particle was placed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7, and soaked at 60℃ 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℃ for 7 days was 0.1%.

[0416] FIG. 8 is a SEM image of the organic compound particle in Example 1. As shown in FIG. 8, the morphology of the organic compound particle presents a spherical or spherical-like shape, and the shape is relatively regular.

[0417] ②Preparation of the isolation 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 a porous base film; the dispersion liquid containing the organic compound particles and the binder polyacrylic acid prepared above were mixed uniformly in deionized water at a solid mass ratio of 92:8 to obtain a coating slurry.

[0418] The commercially available polyvinylidene fluoride particles (Arkema), the binder polyacrylic acid, and the dispersant sodium carboxymethyl cellulose were stirred uniformly in deionized water at a solid content mass ratio of 90:9:1 to obtain a binder layer slurry. Wherein, the Dv50 of the polyvinylidene fluoride particles was 6.8 μm.

[0419] The coating slurry was coated on the porous base film at a coating amount of 2.6 g / m 2The load amount (single side) of the organic compound particles was uniformly coated on both surfaces of the porous base film, the solvent was removed by drying, the thickness of the single side coating was 1.5 pm, then the adhesive layer slurry was coated on both surfaces of the coating at a load amount of 1.2 g / m 2 The load amount (single side) of the organic compound particles was uniformly coated on both surfaces of the porous base film, the solvent was removed by drying, the thickness of the single side coating was 1.5 pm, then the adhesive layer slurry was coated on both surfaces of the coating at a load amount of 1.2 g / m

[0420] (4) Preparation of electrolyte:

[0421] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), ethylene glycol dimethyl ether and ethylene glycol diethyl ether were used as solvents (with a mass ratio of 1:1), then a certain amount of sodium hexafluorophosphate was dissolved in the above mixed solvents, the concentration of sodium hexafluorophosphate was controlled to be 1 mol / L, and stirred uniformly, then a certain amount of sodium tetrafluoroborate was dissolved in the above solvents, the concentration of sodium tetrafluoroborate was controlled to be 0.2 mol / L, and stirred uniformly, to form the electrolyte.

[0422] (5) Preparation of battery monomer:

[0423] Preparation of battery monomer: the positive electrode sheet, the separator film, and the negative electrode sheet were stacked in order, the separator film was between the positive and negative electrode sheets to play a separating role, the bare battery core was welded with tabs, and the bare battery core was loaded into an aluminum shell, and was baked at 80°C to remove water, then the above electrolyte was injected and sealed to obtain a non-charged battery. The non-charged battery was sequentially subjected to standing, hot and cold pressing, formation, shaping, capacity testing and other processes to obtain a negative electrode-free sodium secondary battery monomer.

[0424] [Example 2-3]

[0425] The difference between Example 2 and Example 1 is that in the preparation process of organic compound particles, the "stirring rate of 300 rpm" in Example 1 is adjusted to "stirring rate of 200 rpm" to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 1.

[0426] The difference between Example 3 and Example 1 is that in the preparation process of organic compound particles, the "stirring rate of 300 rpm" in Example 1 is adjusted to "stirring rate of 400 rpm" to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 1.

[0427] [Example 4]

[0428] The difference between Example 4 and Example 1 is that in the preparation process of organic compound particles, the "adding sodium hydroxide to adjust the pH to 9.5" in Example 1 is adjusted to "adding sodium hydroxide to adjust the pH to 8" to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 1.

[0429] [Example 5-6]

[0430] The difference between Example 5 and Example 1 is that in the preparation of the organic compound particles, the "temperature is raised to 90℃ and the reaction is continued for 12h" in Example 1 is adjusted to "temperature is raised to 90℃ and the reaction is continued for 24h", to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 1.

[0431] The difference between Example 6 and Example 1 is that in the preparation of the organic compound particles, the "temperature is raised to 90℃ and the reaction is continued for 12h" in Example 1 is adjusted to "temperature is raised to 75℃ and the reaction is continued for 12h", to obtain an organic compound particle dispersion liquid, and the rest of the preparation process is similar to Example 1.

[0432] [Example 7]

[0433] The difference between Example 7 and Example 1 is that:

[0434] (3) Preparation of the isolation film:

[0435] ① Preparation of organic compound particles (organic silicon polymer containing phenyl group):

[0436] A pre-emulsion is obtained by using 0.3g of potassium persulfate, 0.9g of sodium dodecyl sulfate, 30g of deionized water, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane and divinylbenzene (wherein the mass ratio of the three is 90%:5%:5, and the amount of divinylbenzene is 3g), and then adding sodium bicarbonate to emulsify, and the sodium bicarbonate is used to adjust the pH of the pre-emulsion to 8. Take a reactor, add 300g of deionized water, and heat to 80℃. Under the conditions of nitrogen protection and a reaction kettle stirring speed of 150rpm, drop the above-mentioned pre-emulsion (the dropping process is divided into two stages, the first stage is at a flow rate of 200ml / min to make micelles nucleate, and the second stage is at a flow rate of 400ml / min), and after reaction for 4h, heat to 90℃ for curing reaction for 4h, to obtain an emulsion containing organic compound particles.

[0437] The crosslinking degree of the organic compound particle powder is tested by PQ001 nuclear magnetic resonance analyzer. The organic compound particle is a crosslinked polymer, and the calculated crosslinking degree is 90.4%.

[0438] The powder of the organic compound particles is tested by pyrolysis-gas chromatography-mass spectrometry (Py-GC / MS), and by comparing with the EVA standard pyrolysis spectrum in the NIST library, the characteristic ions corresponding to It can be inferred that the organic compound particles include benzene rings.

[0439] Differential scanning calorimetry (DSC) was used to test the glass transition temperature (Tg) and melting point of organic compound particles. The organic compound particles had no Tg and no melting point below 300℃.

[0440] The density of the organic compound particles was tested using a true density meter, and the true density of the organic compound particles was 1.35 g / cm³. 3 .

[0441] The number-average particle size (Dn50) of the organic compound particles was measured using a scanning electron microscope (e.g., ZEISS Sigma 300), and the number-average particle size (Dn50) of the organic compound particles was 230 nm.

[0442] Organic compound particles were immersed in a mixed solvent of ethylene carbonate and methyl ethyl carbonate in a volume ratio of 3:7 at 60°C for 7 days. The dissolution rate of the organic compound particles was tested, and the dissolution rate of the organic compound particles after immersion at 60°C for 7 days was 0.3%.

[0443] ② Preparation of the isolation membrane: A commercially available polyethylene microporous membrane (Zhuogao Electronic Technology Co., Ltd.) with a thickness of 7μm and an average pore size of 50nm was used as the porous base membrane; the dispersion containing organic compound particles prepared above and the binder polyacrylic acid were stirred and mixed evenly in deionized water at a solid mass ratio of 93:7 to obtain the coating slurry.

[0444] Commercially available polyvinylidene fluoride (PVDF) granules (Arkema), binder polyacrylic acid, and dispersant sodium carboxymethyl cellulose were mixed evenly in deionized water at a solid content mass ratio of 90:9:1 to obtain a binder slurry. The PVDF granules had a Dv50 of 6.8 μm.

[0445] The coating slurry was applied at a concentration of 2.6 g / m³. 2 The loading amount (one-sided) was uniformly coated on both surfaces of the porous base membrane. After drying to remove the solvent, the thickness of the one-sided coating was 1.5 μm. Then, the adhesive layer slurry was applied at a loading of 1.2 g / m². 2 The loading capacity (single-sided) is applied to both sides of the coating, followed by drying and slitting processes to obtain the release membrane. The air permeability of the release membrane is 205 s / 100 mL. Specific implementation parameters are shown in Table 3.

[0446] [Examples 8-9]

[0447] Example 8 differs from Example 7 in that in the process of preparing the organic compound particles, "sodium bicarbonate is used to adjust the pH of the pre-emulsion to 8" in Example 7 is adjusted to "sodium bicarbonate is used to adjust the pH of the pre-emulsion to 7.5", to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0448] Example 9 differs from Example 7 in that in the process of preparing the organic compound particles, "sodium bicarbonate is used to adjust the pH of the pre-emulsion to 8" in Example 7 is adjusted to "sodium bicarbonate is used to adjust the pH of the pre-emulsion to 10", to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0449] [Example 10]

[0450] Example 10 differs from Example 7 in that in the process of preparing the organic compound particles, "0.9g of sodium dodecyl sulfate" in Example 7 is adjusted to "0.8g 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.

[0451] [Example 11]

[0452] Example 11 differs from Example 7 in that in the process of preparing the organic compound particles, "the flow rate of the first section is 200ml / min" in Example 7 is adjusted to "the flow rate of the first section is 250ml / min", to obtain an emulsion containing organic compound particles, and the rest of the preparation process is similar to that of Example 7.

[0453] [Comparative Example 1]

[0454] Comparative Example 1 differs from Example 1 in that the organic compound particles are adjusted to inorganic particles, and the inorganic particles are commercially available alumina with an average number average particle size Dn50 of 145nm.

[0455] FIG. 9 is an SEM image of the inorganic particles in Comparative Example 1. As shown in FIG. 9, the morphology of the inorganic particles presents a non-spherical shape and irregular shape.

[0456] Table 1 shows the specific parameters of Examples 1-6 and Comparative Example 1; Table 2 shows the test results of Examples 1-6 and Comparative Example 1; Table 3 shows the specific parameters of Examples 7-11; and Table 4 shows the test results of Examples 7-11.

[0457] Table 1 Specific parameters of Examples 1-6 and Comparative Example 1

[0458] In Table 1, "A" represents the roundness of the organic compound particles; and "(Dn90-Dn10) / Dn50" represents the particle size concentration of the organic compound particles.

[0459] Table 2 Test results of Examples 1-6 and Comparative Example 1

[0460] As shown in Table 1 and Table 2, according to Examples 1-6 and Comparative Example 1, the organic compound particles have suitable roundness, particle size concentration, concavity, crosslinking degree, and suitable mass ratio of cage-like skeleton according to the technical solutions of the present application. This not only helps to improve the heat resistance and puncture strength of the isolation film, but also improves the storage performance and cycle performance of the battery monomer in a high temperature environment.

[0461] Table 3 Specific parameters of Examples 7-11

[0462] In Table 3, "A" represents the roundness of the organic compound particles; "(Dn90-Dn10) / Dn50" represents the particle size concentration of the organic compound particles.

[0463] Table 4 Test results of Examples 7-11

[0464] As shown in Table 3 and Table 4, according to Examples 7-11 and the above-mentioned Comparative Example 1, in the technical solutions of the present application, within a certain range, using a phenyl-containing organosilicon polymer as an organic compound particle makes the organic compound particle have suitable roundness, particle size concentration, concavity, Dn50, crosslinking degree, and mass ratio of phenyl. This helps to improve the heat resistance and puncture strength of the isolation film, and also improves the storage performance and cycle performance of the metal battery monomer at high temperature.

[0465] The following briefly introduces the test methods of the physicochemical parameters and performance parameters involved in the examples of the present application. 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.

[0466] 1. Test method of crosslinking degree

[0467] As an example, the crosslinking degree of the crosslinked polymer can be tested by a PQ001 nuclear magnetic resonance analyzer. The test temperature is 60°C, the resonance frequency of the nuclear magnetic resonance analyzer is set to 21 MHz, 0.5 g of the cleaned and dried sample (the organic compound particles described above) is taken, is loaded into a clean sample tube and is inserted into the probe to the specified depth, the probe coil diameter is 13 mm, and the measurement is performed according to the manufacturer's instructions. Specifically, the crosslinking degree of the crosslinked polymer is obtained by collecting the entire polymer signal, calculating the proportion of the crosslinking signal by fitting software, and selecting the "crosslinking degree" or "T2 relaxation" test mode in the software, and the PQ001 nuclear magnetic resonance analyzer automatically obtains the relaxation decay curve. During data processing, the software decomposes the relaxation components by exponential fitting, and calculates and outputs the crosslinking degree result according to the degree of restriction of molecular chain movement.

[0468] 2. Test method of phenyl and cage skeleton structure

[0469] In the embodiments of the present application, a thermal cracking-gas chromatography-mass spectrometry (Py-GC / MS) instrument can be used to test the rigid structure phenyl and cage skeleton structure in the organic compound particles. Specifically, 0.5-1 mg of the organic compound particles described above is taken as a test sample, is loaded into a quartz cracking tube of a thermal cracking instrument, is cracked at 550°C for 1.2 s, and the sample is tested to be cracked into volatile small molecules in an inert gas (such as helium). Then, the sample is introduced into a gas chromatograph-mass spectrometer, an HP-5ms (30 m x 0.25 mm x 0.25 μm) chromatographic column is selected, the temperature is set to 30°C for 5 min, is increased to 250°C at a rate of 10°C / min, and 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 benzene ring and the characteristic ions corresponding to the cage skeleton are detected, and it can be inferred that the organic silicon polymer includes a phenyl or cage skeleton structure. The internal standard method is used to calculate the mass proportion of the characteristic benzene ring or cage skeleton in the organic compound particles by the area of the above-mentioned fragment peak.

[0470] 3. Test of roundness of organic compound particles

[0471] As an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film of a regular and clear area is selected. Subsequently, 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 thereof are counted, and the roundness of the organic compound particles in the SEM morphology diagram is fitted by using the Image J software. Among them, the roundness (SC) = (4π×area) / (perimeter×perimeter) = area equivalent diameter×area equivalent diameter / quasi-circular diameter×quasi-circular diameter. Then, the average value of the roundness of the organic compound particles in the Dn50±50nm interval thereof is calculated (the roundness of each single organic compound particle in the Dn50±50nm interval thereof 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), so as to obtain the roundness of the organic compound particles.

[0472] 4. Test of particle size concentration of organic compound particles

[0473] As an example, the particle size concentration of the organic compound particles is the meaning known in the art, which can be tested by instruments and methods known in the art. Specifically, as an example, after the battery monomer is disassembled, the separator film is peeled off, and the separator film of a regular and clear area is selected. Then, the surface morphology of the coating is measured by a scanning electron microscope (SEM) and in reference to the standard JY / T010 1996, and the Dn10, Dn50, Dn90 of the organic compound particles are counted. For example, a test sample of 50 mm x 100 mm in length x width is randomly selected on the separator film. Using a scanning electron microscope (for example, ZEISS Sigma 300), in reference to JY / T010-1996, a plurality of test areas (for example, 5) are randomly selected in the test sample, and under a certain magnification (for example, 500 times or 1000 times when measuring the organic compound particles), the particle size of the organic compound particles in each test area is read (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), the number and particle size values of the organic compound particles in each test area are counted, and the arithmetic mean of the organic compound particles in each test area is taken, i.e., the number average particle size of the organic compound particles in the test sample. In order to ensure the accuracy of the test results, a plurality of test samples (for example, 10) can be taken to repeat the above test, and the average value of each test sample is taken as the final test result, i.e., the particle size number distribution curve of the organic compound particles can be obtained. Through statistics, Dn10, Dn50, Dn90 are obtained respectively. Among them, in the particle size number distribution curve of the organic compound particles, Dn10, Dn50, Dn90 respectively refer to the particle size corresponding to the cumulative number distribution of 10%, 50%, and 90%.

[0474] 5. Test of concavity of organic compound particles

[0475] As an example, the concavity of the organic compound particles in the coating layer can be tested by using instruments and methods known in the art, in the meaning known in the art. Specifically, as an example, after the battery cell is disassembled, the separator film is peeled off, and the separator film in a regular and clear area is selected. Then, the micro-morphology of the coating layer on the separator film is measured by using a scanning electron microscope (SEM) and referring to the standard JY / T010 1996. Then, the number of the organic compound particles in the Dn50±50nm interval thereof is counted, and the concavity of the organic compound particles in the SEM morphology is fitted by using the Image J software. Then, the average value of the concavity of the organic compound particles in the Dn50±50nm interval thereof is calculated (the average value of the concavity of the organic compound particles in the Dn50±50nm interval thereof is obtained by obtaining the concavity value of each single organic compound particle in the Dn50±50nm interval thereof, calculating the total sum of the concavity values, and the average value of the concavity = the total sum of the concavity values / the total number of the particles of the organic compound particles in the Dn50±50nm interval thereof), to obtain the concavity of the organic compound particles.

[0476] 6. Test of heat resistance of the separator film

[0477] The separator film prepared above is cut into circular samples with a diameter of 50 mm, and 5 samples are taken. A diaphragm puncture force tester (model: PMT-C type) is used, and the samples are arranged on the equipment. A steel needle with a diameter of 1 mm is used, and a pressure is applied vertically to the separator film sample at a speed of 100 mm / min at 400°C until penetration, and the maximum pressure value at this time is recorded.

[0478] 7. Test of puncture strength of the separator film

[0479] The separator film prepared above is cut into circular samples with a diameter of 50 mm, and 5 samples are taken. A diaphragm puncture force tester (model: PMT-C type) is used, and the samples are arranged on the equipment. A steel needle with a diameter of 1 mm is used, and a pressure is applied vertically to the separator film sample at a speed of 100 mm / min until penetration, and the maximum pressure value at this time is recorded.

[0480] 8. Test of dendrite resistance of the metal battery cell

[0481] The storage performance and the cycle performance of the metal battery cell are used by the embodiments of the present application to represent the dendrite resistance of the metal battery cell. For example, the higher the storage performance and the cycle performance of the metal battery cell, the better the dendrite resistance of the metal battery cell.

[0482] (1) Storage performance

[0483] As an example, at 25℃, the secondary battery cell is charged at 1 / 3C constant current to 3.65V, then charged at 3.65V constant voltage to 0.05C current, and left for 5 min, then discharged at 1 / 3C constant current to 2.8V, and the obtained discharge capacity is recorded as the pre-storage capacity C0; then the secondary battery cell is charged at 1 / 3C constant current to 3.65V, then charged at 3.65V constant voltage to 0.05C current, at this time the secondary battery cell is in a full charge state; the full charge state secondary battery cell is placed in a 60℃ constant temperature oven for storage for 30 days, after which the secondary battery cell is taken out, and when the temperature of the secondary battery cell drops to 25℃, it is discharged at 1 / 3C constant current to 2.8V, and the obtained discharge capacity is recorded as the post-storage capacity C1. The capacity retention rate of the secondary battery cell after storage at 60℃ for 30 days = post-storage capacity C1 / pre-storage capacity C0 x 100%, that is, the storage performance of the metal battery cell.

[0484] (2) Cycle performance

[0485] At 60℃, the battery is charged at 1 / 3C constant current to 3.65V, then charged at 3.65V constant voltage to 0.05C current, left for 5 min, and then discharged at 1 / 3C to 2.8V, which is one charge-discharge process, and the discharge capacity at this time is recorded as the discharge capacity of the first cycle of the battery. The charging and discharging cycles are repeated in this way, and the cycle number corresponding to the capacity retention rate of 80% is calculated.

[0486] The capacity retention rate (%) of the battery after N cycles at 60℃ = (discharge capacity of the Nth cycle of the battery / discharge capacity of the first cycle of the battery) x 100%.

[0487] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the application, and equivalent parts can be substituted for the parts thereof. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A metal battery cell characterized by The metal battery cell comprises an electrode assembly and a housing for accommodating the electrode assembly, the electrode assembly comprises a positive electrode sheet, a negative electrode sheet and a separator membrane, the separator membrane is located between the positive electrode sheet and the negative electrode sheet; The negative electrode sheet comprises a negative electrode current collector and an interface modification layer located on at least one side of the negative electrode current collector, the interface modification layer is used to guide the formation of a metal layer on the negative electrode current collector; The separator membrane comprises a porous base membrane and a coating layer arranged on at least one side of the porous base membrane; The coating layer comprises organic compound particles and a first binder; the first binder is used to bond the organic compound particles to the porous base membrane; The morphology of the organic compound particles is spherical or spheroidal; The roundness A of the organic compound particles satisfies: 0.5≤A≤1.

0. The metal battery cell of claim 1, wherein The particle size concentration degree (Dn90-Dn10) / Dn50 of the organic compound particles satisfies: 0.5≤(Dn90-Dn10) / Dn50≤2.0; Wherein, Dn10, Dn50, Dn90 refer to the particle size corresponding to the cumulative amount distribution of 10%, 50%, 90% respectively in the particle size number distribution curve of the organic compound particles. The metal battery cell according to claim 1 or 2, characterized in that The concavity B of the organic compound particles satisfies: 0≤B≤0.

5. The metal battery cell according to any one of claims 1 to 3, characterized in that The interface modification layer comprises one or more of carbon materials and metal materials. The metal battery cell of claim 4, wherein The carbon materials comprise one or more of carbon black, activated carbon, carbon nanotubes, carbon fibers and graphite; and / or, the metal materials comprise the single substance of In, Bi, Ag, Zn, Al, Mg, Ga, Ge and Sb, or comprise one or more of metal alloys, metal oxides and metal carbides of at least one element in In, Bi, Ag, Zn, Al, Mg, Ga, Ge and Sb. The metal battery cell of any one of claims 1 to 5, wherein, The thickness C of the interface modification layer satisfies: 0.2μm≤C≤10μm. The metal battery cell of any one of claims 1 to 6, wherein, The metal battery cell is a negative electrode-free lithium metal battery cell or a negative electrode-free sodium metal battery cell. The metal battery cell of any one of claims 1 to 7, wherein, The organic compound particles comprise a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%. The metal battery cell of claim 8, wherein The cross-linked polymer comprises a silicone polymer containing a siloxane structure. The metal battery cell of claim 9, 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), Wherein, R1, R2 are each independently selected from C1-C4 alkyl and C2-C4 alkenyl, R3 comprises C1-C4 alkyl or C4-C8 (meth) acryloyloxyalkyl, and R4 comprises C2-C8 alkenyl or C4-C8 (meth) acryloyloxyalkyl; the cross-linking agent comprises divinylbenzene. The metal battery cell according to claim 9 or 10, characterized in that The silicone polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the cross-linking degree of the silicone polymer containing a siloxane structure is 75% to 95%; (2) the mass content of silicon in the silicone polymer containing a siloxane structure is 10% to 25%; (3) the mass content of phenyl in the silicone polymer containing a siloxane structure is 2% to 12%. The metal battery cell of claim 9, wherein The silicone 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 at least one of the integers 4 to 12, R a including cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; Optionally, n is 8, R a comprises C1-C3alkyl. The metal battery cell of claim 9, wherein The organosilicon polymer containing siloxane structures includes one or more of the monomers represented by Formula (III) that are hydrolyzed and polycondensed, Wherein, R'1 comprises C1-C3 alkyl. The metal battery cell according to claim 12 or 13, characterized in that The organosilicon polymer containing siloxane structure satisfies one or more of the following conditions: (1) the crosslinking degree of the organosilicon polymer containing siloxane structure is 85% to 97%; (2) the mass content of silicon element in the organosilicon polymer containing siloxane structure is 25% to 45%; (3) the mass content of the skeleton composed of the compound represented by formula (II) in the organosilicon polymer containing siloxane structure is 40% to 60%. The metal battery cell of any one of claims 1 to 14, wherein, The organic compound particles satisfy at least one of the following conditions (1) to (5): (1) the cyclic voltammogram of the organic compound particles in the first cycle has no oxidation peak in the voltage range of 0 to 4.4V; (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 satisfies: T 3d ≥ 250°C; (4) the dissolution rate of the organic compound particles is less than or equal to 5% when the organic compound particles are soaked in a mixed solvent composed of ethylene carbonate and methyl ethyl carbonate at a volume ratio of 3:7 at 60℃ for 7 days; (5) the true density of the organic compound particles is 0.8 g / cm 3 ~ 2.0 g / cm 3 . The metal battery cell of any one of claims 1 to 15, wherein The mass content of the organic compound particles in the coating is 50% to 97%. The metal battery cell of any one of claims 1 to 16, wherein, The first adhesive satisfies one or more of the following conditions: (1) the first adhesive 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; (2) the mass content of the first adhesive in the coating is 3% to 15%. The metal battery cell of any one of claims 1 to 17, wherein, The separation membrane further includes second adhesive particles, and the second adhesive particles are located in the coating, or the separation membrane further includes a bonding layer, and the bonding layer is arranged on at least one side of the coating away from the porous base film, and the second adhesive particles are located in the bonding layer; the second adhesive particles satisfy one or more of the following conditions: (1) the second adhesive particles include at least one of polyvinylidene fluoride, poly(vinylidene fluoride-co-trichloroethylene), poly(vinylidene fluoride-co-trifluorochloroethylene), poly(vinylidene fluoride-co-trifluoroethylene), poly(vinylidene fluoride-co-tetrafluoroethylene), poly(vinylidene fluoride-co-hexafluoropropylene), polyacrylate, polymethyl methacrylate, and polyacrylonitrile; (2) the average volume particle size of the second adhesive particles is 5μm to 20μm. The metal battery cell of any one of claims 1 to 18, wherein The separation membrane satisfies one or more of the following conditions: (1) the thickness of the coating is 0.5μm to 10μm; (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 membrane is less than or equal to 5% when the separation membrane is heated at 130℃ for 1h; (4) the transverse heat shrinkage rate of the separation membrane is less than or equal to 5% when the separation membrane is heated at 130℃ for 1h; (5) the air permeability of the separation membrane is 150s / 100mL to 500s / 100mL. A battery device characterized by Comprise: The metal battery cell according to any one of claims 1 to 19. An electric power utilization device characterized by comprising: Comprise: The metal battery cell according to any one of claims 1 to 19 or the battery device according to claim 20. An isolation film characterized by Comprising: a porous base film and a coating layer disposed on at least one side of the porous base film; the coating layer comprises organic compound particles and a first binder; the first binder is used to bond the organic compound particles to the porous base film; the morphology of the organic compound particles is spherical or spheroidal; the roundness A of the organic compound particles satisfies: 0.5≤A≤1.

0. The separator film according to claim 22, wherein the particle size concentration (Dn90-Dn10) / Dn50 of the organic compound particles satisfies: 0.5≤(Dn90-Dn10) / Dn50≤2.0; wherein, Dn10, Dn50, Dn90 refer to the particle size corresponding to the cumulative amount distribution of 10%, 50%, and 90% respectively in the particle size number distribution curve of the organic compound particles. The separator film according to claim 22 or 23, characterized in that, the concavity B of the organic compound particles satisfies: 0≤B≤0.

5. The isolating film according to any one of claims 22 to 24, characterized in that, the organic compound particles comprise a cross-linked polymer, and the cross-linking degree of the cross-linked polymer is 70% to 98%. The separator film according to claim 25, wherein the cross-linked polymer comprises a silicone polymer containing a siloxane structure. The separator film according to claim 26, 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), wherein, R1, R2 are each independently selected from C1-C4 alkyl, C2-C4 alkenyl, R3 comprises C1-C4 alkyl or C4-C8 (meth)acryloxyalkyl, and R4 comprises C2-C8 alkenyl or C4-C8 (meth)acryloxyalkyl; the cross-linking agent comprises divinylbenzene. The separator film according to claim 26 or 27, characterized in that, the silicone polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the cross-linking degree of the silicone polymer containing a siloxane structure is 75% to 95%; (2) the mass content of silicon in the silicone polymer containing a siloxane structure is 10% to 25%; (3) the mass content of phenyl in the silicone polymer containing a siloxane structure is 2% to 12%. The separator film according to claim 26, wherein the silicone 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 at least one of the integers 4 to 12, R a including cycloalkyl, aryl, C1-C 12 alkyl, C1-C 12 alkenyl, C1-C 12 alkynyl; Optionally n is 8, R a comprises C1-C3alkyl. The separator film according to claim 26, wherein The organosilicon polymer containing siloxane structures includes one or more of the monomers represented by Formula (III) that are hydrolyzed and polycondensed, wherein, R'1 comprises C1-C3 alkyl. The separator film according to claim 29 or 30, characterized in that, the silicone polymer containing a siloxane structure satisfies one or more of the following conditions: (1) the cross-linking degree of the silicone polymer containing a siloxane structure is 85% to 97%; (2) the mass content of silicon in the silicone polymer containing a siloxane structure is 25% to 45%; (3) the mass content of the skeleton composed of a compound represented by formula (II) in the silicone polymer containing a siloxane structure is 40% to 60%.

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