Diaphragm and battery

Abstract

The diaphragm is configured to be matched with a gel electrolyte for use, the diaphragm comprises a base membrane and a ceramic layer, the porosity of the base membrane is larger than or equal to 15%, the average pore size of a first through hole is larger than or equal to 25 nm, and through the requirements for the porosity and the average pore size, the porosity of the ceramic layer is larger than or equal to 10%. A molecular chain of the gel electrolyte can effectively penetrate through the first through hole to form a continuous ion transmission channel; meanwhile, in the formation process of the gel electrolyte, part of monomers can react with residual groups in the coupling agent, so that the compounding effect among the diaphragm, the gel electrolyte and a pole piece is effectively improved, and the inhibition of electrode expansion in the circulation process is facilitated, thereby ensuring the performance of a battery in subsequent application.

Description

Technical Field

[0001] This application relates to the technical field of batteries, specifically to a separator and a battery. Background Technology

[0002] Due to their inherent safety characteristics, many battery companies have invested in the research and development of solid-state battery technology.

[0003] Currently, the main technical approaches fall into three categories: sulfide electrolytes, oxide electrolytes, and polymer electrolytes. However, in the fabrication of solid-state batteries, the wettability of the electrolyte to the separator is poorer compared to that of liquid electrolytes; therefore, targeted improvements to the separator are necessary. Summary of the Invention This application provides a separator and a battery designed to solve the problem of poor wettability of the separator by the existing electrolyte.

[0004] This application provides a diaphragm configured for use with a gel electrolyte; The diaphragm includes a base membrane and a ceramic layer, wherein the ceramic layer is disposed on at least one side of the base membrane; The base film has a first through-pore, the average pore diameter of the first through-pore is greater than or equal to 25 nm, and the porosity of the base film is greater than or equal to 15%. The ceramic layer comprises a ceramic material modified with a coupling agent.

[0005] Optionally, in some embodiments of this application, the average aperture of the first through-hole is greater than or equal to 25 nm and less than or equal to 90 nm; and / or The porosity of the base membrane is greater than or equal to 15% and less than or equal to 85%.

[0006] Optionally, in some embodiments of this application, the average aperture of the first through hole is greater than or equal to 45 nm and less than or equal to 90 nm; The porosity of the base membrane is greater than or equal to 40% and less than or equal to 80%.

[0007] Optionally, in some embodiments of this application, the ceramic material includes at least one of alumina, boehmite, silicon dioxide, titanium dioxide, lithium titanium aluminum phosphate, and lithium lanthanum titanium oxide; and / or The coupling agent includes a silane coupling agent; Preferably, the silane coupling agent includes at least one of KH-550, KH-560, KH-570, KH-792, GR-SI151, GR-SI171, and GR-SI172.

[0008] Optionally, in some embodiments of this application, the diaphragm satisfies at least one of the following conditions: The thickness of the diaphragm is 3 μm to 35 μm; preferably, the thickness of the diaphragm is 7 μm to 20 μm. The tensile strength of the diaphragm is greater than or equal to 700 MPa; The puncture strength of the diaphragm is greater than or equal to 300 kgf; preferably, the puncture strength of the diaphragm is greater than or equal to 500 kgf.

[0009] Accordingly, this application also provides a battery comprising electrodes, a separator as described above, and a gel electrolyte.

[0010] Optionally, in some embodiments of this application, the gel electrolyte includes lithium salt, organic solvent, additives, and gel monomer; The gel monomer includes at least one of acrylate monomers, epoxy monomers, and amine monomers; Preferably, the acrylate monomers include at least one of methacrylates, polyol acrylates, and acrylates containing special functional groups; and / or The epoxy monomers include glycidyl ether monomers; and / or The amine monomers include alkylamines or arylamines.

[0011] Optionally, in some embodiments of this application, the gel electrolyte is prepared using the following method: The precursor was prepared by mixing lithium salt, organic solvent, additives and gel monomer; The precursor is injected into the battery cell, left to stand, and then heated to solidify, thus obtaining the gel electrolyte.

[0012] Optionally, in some embodiments of this application, the electrode includes a positive electrode, which includes at least one of lithium nickel manganese cobalt oxide, lithium cobalt oxide, and lithium iron phosphate; and / or The electrode includes a negative electrode, which includes at least one of graphite and silicon-based negative electrode materials.

[0013] Optionally, in some embodiments of this application, the peel force between the electrode and the diaphragm is greater than or equal to 0.3N; and / or The battery achieved a pass rate of 30 / 50 or higher in the hot chamber test; and / or The battery has a pass rate of 30 / 50 or higher in the nail penetration test; and / or In discharge tests at different rates, the battery maintained a capacity retention rate of over 99% at 1C, over 90% at 3C, over 85% at 5C, over 75% at 7C, and over 65% at 10C; and / or The battery requires at least 450 cycles to reach 80% of its initial capacity at a 1C charge / discharge rate.

[0014] The separator in this embodiment includes a base membrane and a ceramic layer. The porosity of the base membrane is ≥15%, and the average pore size of the first through-pore is ≥25nm. By meeting the requirements for porosity and average pore size, the molecular chains of the gel electrolyte can effectively pass through the first through-pore to form a continuous ion transport channel. At the same time, during the formation of the gel electrolyte, some of its monomers can react with the residual groups in the coupling agent, effectively improving the composite effect between the separator, gel electrolyte, and electrode, which is beneficial to suppressing electrode expansion during cycling, thereby ensuring the battery performance in subsequent applications. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is an SEM image of the base membrane portion of the diaphragm provided in Embodiment 1 of this disclosure; Figure 2 This is a schematic diagram of the cycle performance of the battery provided in Embodiment 1 of this disclosure. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] Liquid lithium-ion batteries have problems such as easy leakage, liquid leakage, combustion and explosion, while solid-state batteries have attracted widespread attention due to their inherent safety characteristics, and many leading battery companies have invested in the research and development of solid-state battery technology.

[0019] In lithium-ion batteries using gel electrolytes, especially in processes where gels are formed by in-situ curing of liquid precursors, the microstructure of the separator has a crucial impact on the initial wettability, distribution uniformity, and interfacial stability of the gel electrolyte after curing.

[0020] Therefore, embodiments of this application provide a separator and a battery, which can effectively improve the wettability, distribution uniformity and interface stability of the gel electrolyte.

[0021] According to a first aspect of the embodiments of this application, a diaphragm is provided, configured for use with a gel electrolyte; the diaphragm includes a base membrane and a ceramic layer, the ceramic layer being disposed on at least one side of the base membrane; The base film has a first through-pore with an average pore diameter of 25 nm or greater and a porosity of 15% or greater. The ceramic layer includes ceramic materials modified with coupling agents.

[0022] By adopting the above scheme, the separator in this embodiment includes a base film and a ceramic layer. The porosity of the base film is ≥15%, and the average pore size of the first through-pore is ≥25nm. By meeting the requirements for porosity and average pore size, the molecular chains of the gel electrolyte can effectively pass through the first through-pore to form a continuous ion transport channel. At the same time, during the formation of the gel electrolyte, some of its monomers can react with the residual groups in the coupling agent, effectively improving the composite effect between the separator, gel electrolyte, and electrode, which is beneficial to suppressing electrode expansion during cycling, thereby ensuring the battery performance in subsequent applications.

[0023] In some embodiments of this application, the base film is obtained by modifying polyethylene with a small amount of fiber.

[0024] In some embodiments of this application, the average aperture of the first via is greater than or equal to 25 nm and less than or equal to 90 nm. Further, the average aperture of the first via is greater than or equal to 45 nm and less than or equal to 90 nm. Exemplarily, the average aperture of the first via can be 45 nm, 48 nm, 50 nm, 53 nm, 57 nm, 60 nm, 63 nm, 65 nm, 68 nm, 70 nm, 73 nm, 75 nm, 80 nm, 82 nm, 85 nm, 87 nm, 90 nm, or any value between two adjacent values ​​mentioned above.

[0025] By adopting the above scheme, the average pore size of the first through-hole is within a suitable range, which helps to ensure that the monomers of the gel electrolyte quickly, fully, and uniformly wet the membrane during the liquid injection stage. At the same time, a suitable average pore size also facilitates the passage of monomers through the first through-hole, which helps to ensure stable lithium-ion transport. If the average pore size of the first through-hole is too large, although rapid wetting can be achieved, it may weaken the mechanical strength of the membrane; if the average pore size of the first through-hole is too small, it will lead to difficulties in monomer wetting, uneven distribution, obstructed ion transport channels after curing, and increased interfacial impedance.

[0026] In some embodiments of this application, the porosity of the base membrane ranges from greater than or equal to 15% to less than or equal to 85%. Further, the porosity of the base membrane ranges from greater than or equal to 40% to less than or equal to 80%. Exemplarily, the porosity of the base membrane can be 40%, 43%, 45%, 47%, 50%, 53%, 55%, 58%, 60%, 63%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 85%, and any value between two adjacent values.

[0027] By adopting the above scheme, the porosity of the base membrane is within a suitable range, which helps to ensure that the monomers of the gel electrolyte quickly, fully, and uniformly wet the membrane during the liquid injection stage. At the same time, a suitable porosity also facilitates the passage of more monomers from one side of the base membrane to the other, which is beneficial to ensuring stable lithium-ion transport. If the porosity of the base membrane is too large or too small, it will affect the mechanical strength of the base membrane or lead to difficulties in wetting and uneven distribution.

[0028] In some embodiments of this application, the ceramic material includes at least one of alumina, boehmite, silicon dioxide, titanium dioxide, lithium titanium aluminum phosphate, and lithium lanthanum titanium oxide.

[0029] By employing the above-mentioned methods, these ceramic materials exhibit excellent high-temperature resistance, significantly improving the dimensional stability of the separator under high-temperature battery conditions and preventing short circuits caused by melting and shrinkage of the separator during thermal runaway. Furthermore, the ceramic layer formed by these materials can substantially enhance the puncture strength and tensile strength of the separator. For example, alumina and titanium dioxide possess high mechanical strength, contributing to optimal puncture strength; boehmite and silica exhibit high dispersibility and flexibility, facilitating the formation of a uniform and flexible protective layer. Lithium aluminum titanium phosphate and lithium lanthanum titanium oxide possess high lithium-ion conductivity, serving as lithium-ion transport channels and improving the rate performance of subsequent battery applications.

[0030] In some embodiments of this application, the coupling agent includes a silane coupling agent. Exemplarily, the silane coupling agent includes, but is not limited to, at least one of γ-aminopropyltriethoxysilane (KH550), γ-glycidoxypropyltrimethoxysilane (KH560), 3-methacryloyloxypropyltrimethoxysilane (KH570), N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792), vinyltriethoxysilane (GR-SI151), vinyltrimethoxysilane (GR-SI171), and vinyltris(2-methoxyethoxy)silane (GR-SI172).

[0031] By adopting the above scheme, one end of the silane coupling agent forms a polysiloxane layer on the surface of the ceramic material, which can serve as a transport channel for lithium-ion transition. The other end of the silane coupling agent has double bonds, acrylate groups, amino groups, or epoxy groups. These groups can react with monomers to form covalent bonds, which helps to significantly improve the adhesion strength between the separator and the electrode, suppress the stress changes caused by the deformation of the electrode during cycling, and thus improve the cycle life of subsequent products such as battery cells.

[0032] In some embodiments of this application, the thickness of the diaphragm is from 3 μm to 35 μm. Further, the thickness of the diaphragm is from 7 μm to 20 μm. Exemplarily, the thickness of the diaphragm can be 7 μm, 9 μm, 11 μm, 13 μm, 15 μm, 18 μm, 20 μm, or any value between two adjacent values ​​mentioned above.

[0033] In some embodiments of this application, the tensile strength of the diaphragm is greater than or equal to 700 MPa. Further, the tensile strength of the diaphragm is greater than or equal to 1000 MPa. Exemplarily, the tensile strength of the diaphragm can be 1000 MPa, 1200 MPa, 1300 MPa, 1500 MPa, 1700 MPa, or any value between two adjacent values.

[0034] In some embodiments of this application, the puncture strength of the diaphragm is greater than or equal to 300 kgf. Further, the puncture strength of the diaphragm is greater than or equal to 500 kgf. Exemplarily, the puncture strength of the diaphragm can be 500 kgf, 600 kgf, 700 kgf, 800 kgf, 900 kgf, 1000 kgf, 1200 kgf, 1300 kgf, 1500 kgf, or any value between two adjacent values ​​mentioned above.

[0035] By adopting the above solution, the diaphragm thickness in this embodiment of the application should not be too large or too small, and the tensile strength and puncture strength of the diaphragm can both reach a high level.

[0036] According to a second aspect of the embodiments of this application, a battery is provided, the battery including electrodes, a separator as described above, and a gel electrolyte.

[0037] By adopting the above-described solution, the battery of this application embodiment possesses all the beneficial effects of the aforementioned separator, which will not be repeated here. Furthermore, the battery of this application embodiment exhibits excellent rate performance, long cycle life, and good high-temperature storage resistance.

[0038] In some embodiments of this application, the gel electrolyte includes a lithium salt, an organic solvent, an additive, and a gel monomer; Gel monomers include at least one of acrylate monomers, epoxy monomers, and amine monomers.

[0039] By adopting the above scheme, the gel monomer is dissolved in the liquid electrolyte, and the gel monomer polymerizes to form a gel electrolyte. This gel electrolyte is in full contact with the active material in the electrode, which effectively alleviates the solid-solid contact problem in the gel electrolyte, thereby providing a sufficient and effective lithium-ion channel.

[0040] In some embodiments of this application, the acrylate monomers include at least one of methacrylates, polyol acrylates, and acrylates containing special functional groups. Exemplarily, methacrylates include, but are not limited to, at least one of methyl methacrylate and butyl methacrylate. Polyol acrylates include, but are not limited to, at least one of pentaerythritol tetraacrylate (PETEA), ethoxylated trimethylolpropane triacrylate (ETPTA), dipentaerythritol hexaacrylate (DPAHA), bis(trimethylolpropane tetraacrylate) (DI-TMPTA), and polyethylene glycol diacrylate (PEGDA). Acrylates containing special functional groups include, but are not limited to, at least one of cyanoacrylate (CA), heptafluoroisopropyl acrylate (HFiPA), methyl 2-fluoroacrylate (M2-FA), hexafluorobutyl acrylate (HFBA), trifluoroethyl acrylate (TFEA), 2-methacryloyloxyethyl phosphate (HEMAP), 2-acryloyloxyethyl borate pinacol ester (2-POEBPE), 1-acryloyloxymethyl-o-carborane (AOMB), di-[acryloyloxyethyl]phenyl phosphate (Bis-[AOE]PP), and di(2-acryloyloxyethyl) phosphate (P Bis-[2-POE]E).

[0041] The CAS number for 2-methacryloyloxyethyl phosphate is 15458-75-0.

[0042] Synthesis of 2-acryloyloxyethylboronic acid pinacol ester: In anhydrous tetrahydrofuran, 2-bromoethanol and n-butyllithium react at a certain temperature to generate the lithium reagent OHCH2CH2Li. The solution is cooled to -78°C, and then isopropanol pinacol ester is added. The mixture is then heated to room temperature. After the reaction is complete, the product is obtained by separation and purification. A suitable amount of 2-hydroxyethylboronic acid pinacol ester and acryloyl chloride are dissolved in dichloroethane, and a suitable amount of alkali and catalyst are added. The mixture is reacted at room temperature for 4-5 hours. After the reaction is complete, the product is obtained by separation and purification, yielding the target product, 2-acryloyloxyethylboronic acid pinacol ester.

[0043] Synthetic method of 1-acryloyloxymethyl-o-carborane: In dry acetonitrile, decaborane was added and refluxed for 4-6 hours to obtain an acetonitrile borane complex. An appropriate amount of propynyl alcohol was added to the solution from the first step, and the reaction was heated for 12 hours. After the reaction was completed, 1-hydroxymethyl-o-carborane was obtained by separation and purification. In anhydrous dichloromethane, an appropriate amount of 1-hydroxymethyl-o-carborane, a base, and a catalyst were added sequentially. Finally, acryloyl chloride was added dropwise at 0°C. After the addition was completed, the mixture was raised to room temperature and reacted for 4-6 hours. After the reaction was completed, the target product 1-acryloyloxymethyl-o-carborane was obtained by separation and purification.

[0044] Synthesis of bis-[acryloyloxyethyl]phenyl phosphate: Dissolve an appropriate amount of phenylphosphine dichloride in anhydrous dichloromethane, then cool the solution to -5°C, and add an appropriate amount of 2-hydroxyethyl acrylate dropwise to the solution. React for 4-6 hours. After the reaction is complete, the target product, di-[acryloyloxyethyl]phenyl phosphate, is obtained by separation and purification.

[0045] In some embodiments of this application, the epoxy monomers include glycidyl ether monomers. Exemplarily, glycidyl ether monomers include, but are not limited to, at least one of ethylene glycol diglycidyl ether (EDGE), 1,4-butanediol diglycidyl ether (Oxirane), glyceryl diglycidyl ether (GDE), neopentyl glycol diglycidyl ether (NPGDE), 2,2'-((oxydi(ethane-2,1-diacyl))di(oxy)di(methylene)di(ethylene oxide) (DEEDGE), 1,6-hexanediol diglycidyl ether (BEPH), 2,2',2''-((propane-1,2,3-triacyltri(oxy))tri(methylene)tri(ethylene oxide) (PTTT), and polyethylene glycol diglycidyl ether (PEG-DGE).

[0046] In some embodiments of this application, the amine monomers include alkylamines or arylamines.

[0047] For example, alkylamines include, but are not limited to, at least one of 1,3-diaminopropane (DAP), 2-methyl-1,3-propanediamine, and 2-methyl-1,3-propanediamine (MPDA); arylamines include, but are not limited to, at least one of 4,4-diaminodiphenyl ether (DADPE), 4,4'-diaminodiphenyl sulfone (DADPS), bis(3-amino-4-hydroxyphenyl)sulfone (DADHDPS), 1,3-bis(3-aminophenoxy)benzene (DAPOB), and 4,4'-oxybis[3-(trifluoromethyl)aniline] (4-BZDF).

[0048] In some embodiments of this application, the gel electrolyte may further include an initiator, which is an azo initiator. Exemplarily, azo initiators include, but are not limited to, at least one of bis(azobisisobutyronitrile), azobisisovalerate, azobisisoheptanenitrile, diethyl azodicarbonate, di-2-methoxyethyl azodicarbonate, di-tert-butyl azodicarbonate, diisopropyl azodicarbonate, and dimethyl azobisisobutyrate.

[0049] In some embodiments of this application, the gel electrolyte is prepared using the following method: The precursor was prepared by mixing lithium salt, organic solvent, additives and gel monomer; The precursor is injected into the battery cell, left to stand, and then heated to solidify, resulting in a gel electrolyte.

[0050] By adopting the above scheme, a precursor is made by adding a gel monomer to a common liquid electrolyte. The gel monomer dissolves in the precursor. During the liquid injection stage, the precursor is wetted, and the gel monomer can be fully wetted in the pores of the electrode. Under heating, the gel monomer solidifies in situ to form a gel electrolyte.

[0051] In some embodiments of this application, the organic solvent in the precursor is 30% to 80% by mass. Exemplarily, the organic solvent in the precursor is 30%, 40%, 50%, 60%, 70%, 80%, or any value between two adjacent values.

[0052] In some embodiments of this application, the mass percentage of lithium salt in the precursor is 5% to 20%. Exemplarily, the mass percentage of lithium salt in the precursor is 5%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, and any value between two adjacent values.

[0053] In some embodiments of this application, the mass percentage of the additive in the precursor is 2% to 20%. Exemplarily, the mass percentage of the additive in the precursor can be 2%, 5%, 8%, 12%, 15%, 18%, 20%, or any value between two adjacent values.

[0054] In some embodiments of this application, the mass percentage of the gel monomer in the precursor is 2% to 34%. Exemplarily, the mass percentage of the gel monomer in the precursor can be 2%, 5%, 10%, 15%, 20%, 25%, 30%, 34%, or any value between two adjacent values.

[0055] In some embodiments of this application, the electrode may include a positive electrode, which may include at least one of lithium nickel manganese cobalt oxide, lithium cobalt oxide, and lithium iron phosphate. The separator of the embodiments of this application can be adapted to the above-mentioned different positive electrode material systems.

[0056] In some embodiments of this application, the electrode includes a negative electrode, which comprises at least one of graphite and silicon-based negative electrode materials. The separator of the embodiments of this application can be adapted to the different negative electrode material systems described above.

[0057] In some embodiments of this application, the peel force between the electrode and the separator is greater than or equal to 0.3N. Further, the peel force between the electrode and the separator is greater than or equal to 0.5N. Exemplarily, the peel force between the electrode and the separator can be 0.5N, 0.8N, 1.0N, 1.2N, 1.5N, 1.8N, 2.0N, or any value between two adjacent values ​​mentioned above.

[0058] By adopting the above scheme, the greater the peeling force, the better it is to mitigate the negative impact on the battery caused by the volume change of the electrode during cycling.

[0059] In some embodiments of this application, the battery pass rate in the hot box test is 30 / 50 or higher. Further, the battery pass rate in the hot box test is 41 / 50 or higher. Exemplarily, the battery pass rate in the hot box test is any one of 41 / 50, 42 / 50, 43 / 50, 44 / 50, 45 / 50, 46 / 50, 47 / 50, 48 / 50, 49 / 50, and 50 / 50.

[0060] In some embodiments of this application, the battery passes the nail penetration test with a pass rate of 30 / 50 or higher. Further, the battery passes the nail penetration test with a pass rate of 39 / 50 or higher. Exemplarily, the battery passes the nail penetration test with any one of the following pass rates: 39 / 50, 40 / 50, 41 / 50, 42 / 50, 43 / 50, 44 / 50, 45 / 50, 46 / 50, 47 / 50, 48 / 50, 49 / 50, and 50 / 50.

[0061] By adopting the above-mentioned solution, the battery in this application embodiment has a high pass rate in both hot box testing and nail penetration testing, and has excellent safety.

[0062] In some embodiments of this application, the battery retains more than 99% of its discharge capacity at 1C rate, more than 90% at 3C rate, more than 85% at 5C rate, more than 75% at 7C rate, and more than 65% at 10C rate in discharge tests at different rates.

[0063] In some embodiments of this application, the battery retains 100% of its discharge capacity at 1C rate, 100% at 3C rate, over 99% at 5C rate, over 97% at 7C rate, and over 92% at 10C rate in discharge tests at different discharge rates.

[0064] In some embodiments of this application, the battery requires at least 450 cycles to reach 80% of its initial capacity at a 1C charge / discharge rate.

[0065] The present application will be specifically described below through specific embodiments. These embodiments are only some embodiments of the present application and are not intended to limit the present application. Unless otherwise specified, the raw materials used in the following embodiments are all commercially available products.

[0066] Example 1 A battery is prepared using the following method: (1) A slurry was prepared by mixing graphite, acetylene black, sodium carboxymethyl cellulose and styrene-butadiene rubber as negative electrode materials in a mass ratio of 97:1:0.5:1.5 and coated onto a copper foil current collector. The slurry was then dried under vacuum to obtain a negative electrode sheet. (2) The cathode material NCM9055 (LiNi) 0.9 Co 0.05 Mn 0.05 A slurry was prepared by mixing conductive agent acetylene black and binder polyvinylidene fluoride in a mass ratio of 96:2:2. The slurry was coated onto an aluminum foil current collector and dried to obtain a positive electrode sheet. (3) The ceramic material Al2O3 was modified by KH570 coupling agent, and then the ceramic material Al2O3 modified by KH570 coupling agent was coated on both sides of the PE base film to form a ceramic layer. The thickness of the diaphragm was 12μm. The PE base film had a first through hole with an average pore size of 55nm. The porosity of the PE base film was 65%. The puncture strength of the diaphragm was ≥500Kgf and the tensile strength of the diaphragm was greater than or equal to 1200MPa. (4) Under an argon atmosphere, lithium salt, organic solvent, additives, initiator and gel monomer are prepared in proportion, thoroughly mixed to obtain a precursor, then injected into the battery cell, vacuum sealed, and left to stand. First, it is heated to 70°C. oHeating at C for 24 hours to cure, then heating at 60°C o Heating and curing at C for 24 hours, followed by formation, molding, and capacity testing, yields a lithium-ion battery. The lithium salt is 12.6% lithium hexafluorophosphate, the organic solvent is a mixed solvent (EC / EMC / EP = 1:1:1 vol%) of 66%, the additives are 1.5% VC and 1.5% PS, the initiator is 0.4% azobisisovalerate, and the gel monomer accounts for 18% of the electrolyte, of which dipentaerythritol hexaacrylate accounts for 20%, polyethylene glycol diacrylate accounts for 45%, and cyanoacrylate accounts for 35%. In this embodiment, the peel force between the electrode and the separator is approximately 0.5 N.

[0067] Example 2 The difference from Example 1 is that the average pore size of the first through-hole is 45 nm and the porosity of the base film is 65%, while the remaining steps are the same as in Example 1.

[0068] Example 3 The difference from Example 1 is that the average pore size of the first through-hole is 75 nm and the porosity of the base film is 65%, while the remaining steps are the same as in Example 1.

[0069] Example 4 The difference from Example 1 is that the average pore size of the first through-hole is 90 nm and the porosity of the base film is 65%, while the remaining steps are the same as in Example 1.

[0070] Example 5 The difference from Example 1 is that the average pore size of the first through-hole is 100 nm and the porosity of the base film is 65%, while the remaining steps are the same as in Example 1.

[0071] Example 6 The difference from Example 1 is that the average pore diameter of the first through-hole is 55 nm and the porosity of the base film is 40%, while the remaining steps are the same as in Example 1.

[0072] Example 7 The difference from Example 1 is that the average pore size of the first through-hole is 55 nm and the porosity of the base film is 80%, while the remaining steps are the same as in Example 1.

[0073] Example 8 The difference from Example 1 is that the average pore size of the first through-hole is 55 nm and the porosity of the base film is 90%, while the remaining steps are the same as in Example 1.

[0074] The average pore size of the first through-hole and the porosity of the base film in Examples 1-8 are shown in Table 1. Table 1

[0075] Examples 9 to 17 Except for adjusting the coupling agent, ceramic material and gel monomer according to Table 2, everything else remains the same as in Example 1.

[0076] Table 2

[0077] Example 18 A battery is prepared using the following method: (1) A slurry was prepared by mixing graphite, acetylene black, sodium carboxymethyl cellulose and styrene-butadiene rubber as negative electrode materials in a mass ratio of 97:1:0.5:1.5 and coated onto a copper foil current collector. The slurry was then dried under vacuum to obtain a negative electrode sheet. (2) The cathode material NCM9055 (LiNi) 0.9 Co 0.05 Mn 0.05 A slurry was prepared by mixing conductive agent acetylene black and binder polyvinylidene fluoride in a mass ratio of 96:2:2. The slurry was coated onto an aluminum foil current collector and dried to obtain a positive electrode sheet. (3) The ceramic material Al2O3 was modified by KH560 coupling agent, and then the ceramic material Al2O3 modified by KH560 coupling agent was coated on both sides of the PE base film to form a ceramic layer. The thickness of the diaphragm was 12μm. The PE base film had a first through hole with an average pore size of 55nm. The porosity of the PE base film was 65%. The puncture strength of the diaphragm was ≥500Kgf and the tensile strength of the diaphragm was greater than or equal to 1200MPa. (4) Under an argon atmosphere, lithium salt, organic solvent, additives, initiator and gel monomer are prepared in proportion, thoroughly mixed to obtain a precursor, then injected into the battery cell, vacuum sealed, and left to stand. First, it is heated to 70°C. o Heating at C for 24 hours to cure, then heating at 60°C o Heating and curing at C for 24 hours, followed by formation, molding, and capacity testing, yields a lithium-ion battery. The lithium salt is 13% lithium hexafluorophosphate, the organic solvent is a mixed solvent of 66% (EC / EMC / EP=1:1:1 vol%), the additives are 1.5% VC and 1.5% PS, and the proportion of gel monomer in the electrolyte is 18%, of which ethylene glycol diglycidyl ether (EDGE) accounts for 33% and 4,4'-diaminodiphenyl sulfone (DADPS) accounts for 67%.

[0078] Examples 19-27 Except for adjusting the coupling agent, ceramic material and gel monomer according to Table 3, the rest remains unchanged from Example 18.

[0079] Table 3

[0080] Comparative Example 1 The difference from Example 1 is that the average pore size of the first through-hole is 20 nm and the porosity of the base film is 20%, while the remaining steps are the same as in Example 1.

[0081] Comparative Example 2 The difference from Example 1 is that the average pore size of the first through-hole is 60 nm and the porosity of the base film is 10%, while the remaining steps are the same as in Example 1.

[0082] Comparative Example 3 The difference from Example 1 is that the ceramic layer uses a ceramic material without coupling agent modification, and the diaphragm is prepared using the following steps: After mixing PE and fiber, the mixture is fed into the machine and undergoes processes such as extrusion, simultaneous biaxial stretching, extraction, transverse stretching, heat setting, coating, drying, and winding. The coating process uses ceramic material that has not been modified by coupling agent to obtain the diaphragm.

[0083] Performance testing: (1) Loop test: At room temperature, charge at a rate of 1C with constant current and constant voltage to the upper limit of the cutoff voltage, with a cutoff current of 0.02C. Then let it stand for 5 minutes. Then discharge at a rate of 1C with constant current and constant voltage to the lower limit of the cutoff voltage, with a cutoff current of 0.02C. Repeat the above steps until the capacity decays to 80% of the initial capacity and stop the cycle test. Record the number of cycles (e.g., for NCM9500 / graphite material system cells, the upper limit of the cutoff voltage is 4.2V and the lower limit is 3.0V). (2) Hot box test: At room temperature, charge the battery cell at a rate of 1C with constant current and constant voltage until the upper limit of the cutoff voltage is reached and the cutoff current is 0.02C. Let it stand for 3 hours, and then place the battery cell in a 140℃ hot box for 30 minutes. The condition for passing the test is that the battery cell does not catch fire or explode. (3) Needle prick test: At room temperature, the battery cell is charged at a rate of 1C with constant current and constant voltage until the upper limit of the cutoff voltage is reached and the cutoff current is 0.02C. After standing for 3 hours, the battery cell is then punctured with a 3mm steel needle at a speed of 25mm / s. The condition for passing the test is that the battery cell does not catch fire or explode. (4) Ratio performance: At room temperature, the capacitor was charged at a rate of 1C with constant current and constant voltage until the upper limit of the cutoff voltage was reached, with a cutoff current of 0.02C. After resting for 10 minutes, the capacitor was discharged at rates of 1C, 3C, 5C, 7C, and 10C until the lower limit of the cutoff voltage was reached, with a cutoff current of 0.02C. The discharge capacity was recorded. Finally, the ratio (percentage) of the discharge capacity at different rates to the discharge capacity at the 1C rate was calculated.

[0084] The battery test results are shown in Tables 4 and 5. Table 4. Test results of battery performance

[0085] In the table, 45 / 50 for the hot box test means that 45 out of 50 samples passed; 44 / 50 for the needle penetration test means that 44 out of 50 samples passed.

[0086] Table 5. Test results of battery rate discharge performance

[0087] Compared to Examples 1-8 and Comparative Examples 1-3, Examples 1-8 simultaneously employ high porosity and large average pore size, and the ceramic layer uses a coupling agent to modify the ceramic material. Comparative Examples 1-2, however, do not simultaneously satisfy both high porosity and large pore size, and the ceramic layer in Comparative Example 3 uses unmodified ceramic material. As shown in Tables 4-5, the membranes in Examples 1-8 have larger average pore size and higher porosity, which allows the molecular chains of the gel electrolyte to more easily form more interpenetrating structures with the membrane, providing more lithium-ion transport channels and facilitating lithium-ion movement within the gel electrolyte. Simultaneously, during the formation of the gel electrolyte, some monomers can react with residual groups in the coupling agent, effectively improving the composite effect between the membrane, gel electrolyte, and electrode, which helps suppress electrode expansion during cycling, thus ensuring battery performance in subsequent applications. Furthermore, porosity contributes more to lithium-ion transport than average pore size, as can be seen from high-rate discharge. However, an increase in average pore size and porosity can have certain negative effects. The larger the average pore size and porosity, the lower the strength of the separator and the more prone it is to thermal shrinkage, which can lead to a deterioration in the safety performance of the battery cell.

[0088] Figure 1 This is a SEM image of the base film portion of the diaphragm in Example 1, magnified 5000 times. Figure 1 It can be seen that the base film of Example 1 has a high porosity and a large average pore size.

[0089] Figure 2 This is a schematic diagram of the cycle performance of the battery provided in Example 1. Figure 2 It can be seen that the battery of Example 1 requires 410 cycles to reach 95% of its initial capacity at a 1C charge / discharge rate, and at least 450 cycles to reach 80% of its initial capacity at a 1C charge / discharge rate. Therefore, it can be seen that the battery of Example 1 has excellent cycle performance.

[0090] In Examples 9-17, the gel electrolyte uses a free radical polymerized acrylate system, requiring the addition of an initiator. In contrast, in Examples 18-27, the gel electrolyte uses an epoxy-amine system, eliminating the need for an initiator. As shown in Tables 4-5, the surface content of hydroxyl and carboxyl groups in LLTO, silica, and boehmite facilitates greater deposition of the coupling agent on the material particle surface, forming a denser polysiloxane layer. This allows the gel monomer to react with the coupling agent residues, forming multiple radial polymer chains centered on the ceramic material particles. These polymer chains serve as lithium-ion transport channels; the more radial polymer chains present, the stronger the adhesion between the gel electrolyte and the ceramic material, promoting a tighter bond between the ceramic layer, gel, and electrode. This provides more lithium-ion channels with shorter pathways and mitigates the negative stress effects caused by electrode volume changes during cycling. Meanwhile, in the gel formulation, the gel spatial structure involving multiple branches (three, four, six branches, etc.) has more microporous spatial structures, a larger specific surface area, and more and shorter lithium-ion transport paths; the monomers in the formulation have special groups, which can participate in the construction of SEI / CEI, and can improve the thermal stability, lithium-ion penetration performance and electronic insulation performance of SEI / CEI.

[0091] The above provides a detailed description of a separator and battery provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A diaphragm, characterized in that, It is configured for use with gel electrolytes; The diaphragm includes a base membrane and a ceramic layer, wherein the ceramic layer is disposed on at least one side of the base membrane; The base film has a first through-pore, the average pore diameter of the first through-pore is greater than or equal to 25 nm, and the porosity of the base film is greater than or equal to 15%. The ceramic layer comprises a ceramic material modified with a coupling agent.

2. The diaphragm according to claim 1, characterized in that, The average aperture of the first through-hole is greater than or equal to 25 nm and less than or equal to 90 nm; and / or The porosity of the base membrane is greater than or equal to 15% and less than or equal to 85%.

3. The diaphragm according to claim 2, characterized in that, The average aperture of the first through hole is greater than or equal to 45 nm and less than or equal to 90 nm; The porosity of the base membrane is greater than or equal to 40% and less than or equal to 80%.

4. The diaphragm according to claim 1, characterized in that, The ceramic material includes at least one of alumina, boehmite, silicon dioxide, titanium dioxide, lithium titanium aluminum phosphate, and lithium lanthanum titanium oxide; and / or The coupling agent includes a silane coupling agent; Preferably, the silane coupling agent includes at least one of KH-550, KH-560, KH-570, KH-792, GR-SI151, GR-SI171, and GR-SI172.

5. The diaphragm according to any one of claims 1 to 4, characterized in that, The diaphragm must satisfy at least one of the following conditions: The thickness of the diaphragm is 3 μm to 35 μm; preferably, the thickness of the diaphragm is 7 μm to 20 μm. The tensile strength of the diaphragm is greater than or equal to 700 MPa; The puncture strength of the diaphragm is greater than or equal to 300 kgf; preferably, the puncture strength of the diaphragm is greater than or equal to 500 kgf.

6. A battery, characterized in that, The battery includes electrodes, a separator as described in any one of claims 1 to 5, and a gel electrolyte.

7. The battery according to claim 6, characterized in that, The gel electrolyte is formed by polymerization of a precursor; the precursor includes lithium salt, organic solvent, additives and gel monomer; The gel monomer includes at least one of acrylate monomers, epoxy monomers, and amine monomers; Preferably, the acrylate monomers include at least one of methacrylates, polyol acrylates, and acrylates containing special functional groups; and / or The epoxy monomers include glycidyl ether monomers; and / or The amine monomers include alkylamines or arylamines.

8. The battery according to claim 6, characterized in that, The gel electrolyte is prepared using the following method: The precursor was prepared by mixing lithium salt, organic solvent, additives and gel monomer; The precursor is injected into the battery cell, left to stand, and then heated to solidify, thus obtaining the gel electrolyte.

9. The battery according to claim 6, characterized in that, The electrode includes a positive electrode, which comprises at least one of lithium nickel manganese cobalt oxide, lithium cobalt oxide, and lithium iron phosphate; and / or The electrode includes a negative electrode, which includes at least one of graphite and silicon-based negative electrode materials.

10. The battery according to claim 6, characterized in that, The peel force between the electrode and the diaphragm is greater than or equal to 0.3 N; and / or The battery achieved a pass rate of 30 / 50 or higher in the hot chamber test; and / or The battery has a pass rate of 30 / 50 or higher in the nail penetration test; and / or In discharge tests at different rates, the battery maintained a capacity retention rate of over 99% at 1C, over 90% at 3C, over 85% at 5C, over 75% at 7C, and over 65% at 10C; and / or The battery requires at least 450 cycles to reach 80% of its initial capacity at a 1C charge / discharge rate.

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