Separator and its manufacturing method, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides a separator including a porous substrate and a polymer coating, wherein the polymer coating covers at least one surface of the porous substrate and the voids of the porous substrate are not completely filled by the polymer coating, and the polymer coating has lithium ion conducting capability.

Description

[Technical Field]

[0001] This application relates to the field of secondary batteries, and more specifically to separators and methods for manufacturing the same, secondary batteries, battery modules, battery packs, and power consumption devices. [Background technology]

[0002] With the development of electric vehicles and large-scale energy storage systems, the market is demanding higher energy density from secondary batteries such as lithium-ion batteries. Using lithium metal negative electrodes is one way to improve the energy density of secondary batteries. However, if lithium metal deposits unevenly on the surface of the lithium metal negative electrode during the charge-discharge process, it can lead to degradation of the negative electrode and affect the cycle performance of the secondary battery. [Overview of the project]

[0003] Based on the above problems, this application provides a separator used in a lithium metal negative electrode secondary battery, which can improve the uniformity of lithium metal deposition on the negative electrode plate surface and improve the cycle performance of the secondary battery, as well as a secondary battery, a battery module, a battery pack, and a power consumption device.

[0004] According to the first aspect of this application, Porous substrate, and A separator is provided comprising a polymer coating, wherein the polymer coating covers at least one surface of the porous substrate, and the voids of the porous substrate are not completely filled with the polymer coating, and the polymer coating has lithium ion conductivity.

[0005] The above-described separator has a continuous polymer coating with lithium ion conductivity covering the surface of a porous substrate. The polymer coating does not completely fill the voids in the porous substrate and therefore does not affect the electrolyte penetration of the separator. The distribution of the polymer coating on the separator surface is uniform, and it can be used in lithium metal anode secondary batteries to improve the uniformity of lithium metal deposition in the anode, avoid degradation of the electrochemical performance of the lithium metal anode, and improve the cycle performance of the secondary battery.

[0006] In some of these examples, the components of the polymer coating include a matrix polymer, a plasticizer, a thickener, and a lithium salt.

[0007] In some of these embodiments, the mass percentage of the matrix polymer in the polymer coating is 5% to 30%.

[0008] In some of these embodiments, the mass percentage of the plasticizer in the polymer coating is 40% to 70%.

[0009] In some of these embodiments, the mass percentage of the thickener in the polymer coating is 3% to 15%.

[0010] In some of these embodiments, the mass percentage of the lithium salt in the polymer coating is 10% to 30%.

[0011] In some of these embodiments, the matrix polymer is at least one selected from chain polymers and crosslinked network polymers.

[0012] In some of these embodiments, the plasticizer comprises at least one of ester-based and sulfone-based plasticizers.

[0013] In some of these embodiments, the plasticizer comprises at least one selected from ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0014] In some of these embodiments, the thickening agent is compatible with the plasticizer.

[0015] In some of these embodiments, the thickening agent comprises at least one selected from polyvinyl formal, polyvinylidene fluoride and its copolymer, polydifluoroethylene, polyvinylidene fluoride, trichloroethylene, polytetrafluoroethylene, acrylic rubber, epoxy resin, polyoxyethylene, polyacrylonitrile, sodium carboxymethylcellulose, styrene-butadiene rubber, methyl polyacrylate, polymethyl methacrylate, polyacrylamide, and polyvinylpyrrolidone.

[0016] In some of these examples, the weight-average molecular weight of the thickener is ≥ 500,000.

[0017] In some of these embodiments, the lithium salt comprises at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorophosphate, lithium difluorodioxalathrate, and lithium tetrafluorooxalathrate.

[0018] In some of these embodiments, the components of the polymer coating further include inorganic particles with a mass percentage of 0 to 42%.

[0019] In some of these embodiments, in the polymer coating, the mass percentage of the inorganic particles is 20% to 30%.

[0020] In some of these embodiments, the inorganic particles are at least one selected from aluminum oxide, boehmite, zirconia, aluminum nitride, titanium dioxide, magnesium oxide, silicon carbide, calcium carbonate, and diatomaceous earth.

[0021] <00​​​​​​​​​​​​​​​​​​​​​​​​In some of these embodiments, the manufacturing raw materials, calculated on a mass percentage basis, consist of 5% to 30% manufacturing monomers and / or 40% to 70% plasticizers and / or 3% to 10% thickeners and / or 10% to 20% lithium salts and / or 0% to 42% inorganic particles.

[0025] In some of these embodiments, the manufactured monomer comprises at least one of a crosslinked monomer and a linear monomer, wherein the number of polymerization sites of the crosslinked monomer is at least two, and the number of polymerization sites of the linear monomer is one.

[0026] In some of these embodiments, the crosslinked monomer is an acrylate monomer.

[0027] In some of these embodiments, the mass percentage of the crosslinked monomer in the manufacturing raw material is 0 to 30%.

[0028] In some of these embodiments, the linear monomer is at least one selected from carbonate monomers, sulfate ester monomers, sulfonic acid ester monomers, phosphate ester monomers, carboxylic acid ester monomers, sulfone monomers, amide monomers, nitrile monomers, and ether monomers.

[0029] In some of these embodiments, the mass percentage of the linear monomer in the manufacturing raw material is 0 to 30%.

[0030] In some of these embodiments, in the step of polymerizing the precursor solution, the polymerization initiation method is selected from electron beam initiation, ultraviolet light initiation, and thermal initiation.

[0031] In some of these embodiments, the viscosity of the precursor solution is between 300 mPa·s and 1000 mPa·s.

[0032] According to a third aspect, the present application further provides a secondary battery comprising the above-mentioned separator or a separator manufactured by the above-mentioned method for manufacturing the separator.

[0033] In some of these embodiments, the secondary battery further includes a lithium metal negative electrode plate, the lithium metal negative electrode plate being located on the side of the separator closer to the polymer coating.

[0034] According to a fourth aspect, the present application further provides a battery module including the above-mentioned secondary battery.

[0035] According to a fifth aspect, the present application further provides a battery pack including the above-mentioned battery module.

[0036] According to a sixth aspect, the present application further provides a power consumption device comprising at least one selected from the secondary battery, the battery module, and the battery pack described above.

[0037] Details of one or more embodiments of this application are shown in the following drawings and description, and other features, purposes and advantages of this application will become apparent in the specification, drawings and claims. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic diagram of a secondary battery according to one embodiment of the present application. [Figure 2] Figure 1 is an exploded view of a secondary battery according to one embodiment of this application. [Figure 3] This is a schematic diagram of a battery module according to one embodiment of the present application. [Figure 4] This is a schematic diagram of a battery pack according to one embodiment of the present application. [Figure 5] Figure 4 is an exploded view of a battery pack according to one embodiment of this application. [Figure 6] This is a schematic diagram of a power consumption device powered by a secondary battery according to one embodiment of the present application.

[0039] To better describe and illustrate the embodiments and / or examples of the inventions disclosed herein, one or more drawings may be referenced. Any additional details or examples used to illustrate the drawings should not be considered to limit the scope of the disclosed inventions, the embodiments and / or examples described herein, or the best current understanding of these inventions. [Modes for carrying out the invention]

[0040] To facilitate understanding of this application, the following provides a more complete description with reference to the relevant drawings. The drawings illustrate preferred embodiments of this application. However, this application may be realized in many different forms and is not limited to the embodiments described herein. Rather, the purpose of providing these embodiments is to provide a clearer and more complete understanding of the disclosures of this application.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art. The terms used herein are for the sole purpose of describing specific embodiments and are not intended to limit this application. The terms “and / or” as used herein include any and all combinations of one or more related enumerated items.

[0042] Using lithium metal negative electrodes is one way to improve the energy density of secondary batteries. However, if lithium metal deposits unevenly on the surface of the lithium metal negative electrode during the charge-discharge process, it can cause degradation of the negative electrode and affect the cycle performance of the secondary battery. Conventional separators in secondary batteries generally have polymer layers distributed in an island-like pattern on their surface. During the manufacturing process of the battery core, the polymer layer provides adhesive force, bonding the electrode plate and the separator together and preventing misalignment. Because the polymer layer in conventional separators has extremely poor ionic conductivity, it is necessary to distribute it in an island-like pattern to avoid increasing the internal resistance of the secondary battery.

[0043] Through research, the inventors discovered that when conventional separators are used in lithium metal anode secondary batteries, the surface uniformity of the island-like polymer layer is relatively low, which affects lithium metal deposition during the charge-discharge process. This leads to poor uniformity of lithium metal deposition on the lithium metal anode plate, affecting the cycle performance of the secondary battery.

[0044] This application provides a separator, a method for manufacturing the same, and a secondary battery, battery module, battery pack, and power consumption device using the separator. Such secondary batteries are applied to various power consumption devices that use batteries, such as mobile phones, portable devices, laptop computers, battery-powered cars, electric toys, power tools, electric automobiles, ships, and aerospace vehicles. For example, aerospace vehicles are used in airplanes, rockets, space shuttles, and spacecraft.

[0045] One embodiment of this application provides a separator comprising a porous substrate and a polymer coating. The polymer coating covers at least one surface of the porous substrate, and the voids of the porous substrate are not completely filled by the polymer coating, and the polymer coating has lithium ion conductivity.

[0046] The above-described separator has a continuous polymer coating with lithium ion conductivity covering the surface of a porous substrate. The polymer coating does not completely fill the voids in the porous substrate and therefore does not affect the electrolyte penetration of the separator. The distribution of the polymer coating on the separator surface is uniform, and it can be used in lithium metal anode secondary batteries to improve the uniformity of lithium metal deposition in the anode, avoid degradation of the electrochemical performance of the lithium metal anode, and improve the cycle performance of the secondary battery.

[0047] Specifically, in the embodiments of this application, when the cross-section of the separator is observed with a scanning electron microscope, it can be seen that the voids in the porous substrate are not completely filled by the polymer coating, and the abundant void structure of the porous substrate can be observed.

[0048] In some of these examples, the polymer coating components include a matrix polymer, a plasticizer, a thickener, and a lithium salt.

[0049] The matrix polymer may serve as the skeletal structure in the polymer coating. In some embodiments, the mass percentage of the matrix polymer in the polymer coating is 5% to 30%. Selectively, the mass percentage of the matrix polymer in the polymer coating is 5%, 10%, 15%, 20%, 25%, or 30%. Furthermore, the mass percentage of the matrix polymer in the polymer coating is 5% to 20%. Within this ratio range, the matrix polymer can improve the skeletal function, and as the percentage increases, the degree of crosslinking increases, the ability to restrain the electrolyte strengthens, and the conductivity is affected.

[0050] In polymer coatings, plasticizers can improve the compatibility between polymer coating components. In some embodiments, the mass percentage of plasticizer in the polymer coating is 40% to 70%. Selectively, the mass percentage of plasticizer in the polymer coating is 40%, 45%, 50%, 55%, 60%, 65%, or 70%. Furthermore, the mass percentage of plasticizer in the polymer coating is 50% to 60%. If the proportion of plasticizer is too low, ion transport in the coating is inhibited, affecting the ionic conductivity, and if the proportion of plasticizer is too high, it becomes difficult to completely fix the polymer coating. Within the preferred range, the coating can maintain a good ionic conductivity, satisfying the improvement effect without affecting the battery's rate performance.

[0051] Thickening agents can improve the viscosity of polymer coatings, prevent penetration beneath the polymer coating during the manufacturing process and complete filling of voids in the porous substrate, and reduce the electrolyte wettability of the separator. In some of these embodiments, the mass percentage of the thickening agent in the polymer coating is 3% to 15%. Selectively, the mass percentage of the thickening agent in the polymer coating is 3%, 4%, 5%, 6%, 8%, 10%, 12%, or 15%. Furthermore, the mass percentage of the thickening agent in the polymer coating is 3% to 10%.

[0052] Lithium salts, as electrolyte salts, can improve the ionic conductivity of polymer coatings. In some examples, the mass percentage of lithium salt in the polymer coating is 10% to 30%. Selectively, the mass percentage of lithium salt in the polymer coating is 10%, 12%, 15%, 16%, 18%, 20%, 24%, 25%, 28%, or 30%. Furthermore, the mass percentage of lithium salt in the polymer coating is 10% to 20%. Lithium salts primarily improve the ion transport capacity of the coating system and improve the lithium metal deposition behavior. Higher lithium salt content results in a greater improvement in ion transport capacity, but also a relatively large increase in cost. Furthermore, a ratio of 20% to 30% lithium salt to plasticizer effectively improves ion transport capacity while remaining relatively costly.

[0053] In some of these embodiments, the matrix polymer is at least one selected from chain polymers and crosslinked network polymers. Chain polymers or crosslinked network polymers may be used as the matrix polymer, forming the backbone of the polymer coating. Components such as plasticizers, thickeners, and lithium salts are immobilized in the backbone structure, resulting in relatively high uniformity and compatibility of the polymer coating. Furthermore, the matrix polymer may include chain polymers and crosslinked network polymers.

[0054] In some of these embodiments, the plasticizer comprises at least one of ester-based and sulfone-based plasticizers. Ester-based plasticizers have better overall performance. Preferably, the plasticizer comprises ester-based plasticizers. Selectively, the plasticizer comprises at least one selected from ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate (EC), methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0055] In some of these embodiments, the thickener is compatible with the plasticizer. In some of these embodiments, the weight-average molecular weight of the thickener is ≥ 500,000. In some of these embodiments, the thickener comprises at least one selected from polyvinyl formal, polyvinylidene fluoride (PVDF) and its copolymers, polydifluoroethylene, polyvinylidene fluoride, trichloroethylene, polytetrafluoroethylene, acrylic rubber, epoxy resin, polyoxyethylene (PEO), polyacrylonitrile, sodium carboxymethylcellulose, styrene-butadiene rubber, methyl polyacrylate, polymethyl methacrylate, polyacrylamide (PAM), and polyvinylpyrrolidone (PVP).

[0056] In some of these examples, the lithium salt comprises at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorodioxalatrate, and lithium tetrafluorooxalatrate.

[0057] In some of these embodiments, the polymer coating further comprises inorganic particles in a mass percentage of 0-42%. The inorganic particles may also be used as fillers in the polymer coating to improve its strength. Selectively, the mass percentage of inorganic particles in the polymer coating is 0, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, or 42%. Furthermore, the mass percentage of inorganic particles in the polymer coating is 20-30%.

[0058] In some of these embodiments, the inorganic particles are at least one selected from aluminum oxide, boehmite, zirconia, aluminum nitride, titanium dioxide, magnesium oxide, silicon carbide, calcium carbonate, and diatomaceous earth.

[0059] In some of these embodiments, the polymer coating thickness is 3 μm to 20 μm. By controlling the polymer coating thickness within this range, a more appropriate adhesive force can be achieved between the separator and the electrode plate, while minimizing the impact on the internal resistance of the separator. Selectively, the polymer coating thickness is 3 μm, 5 μm, 10 μm, 15 μm, or 20 μm.

[0060] In some of these embodiments, the separator further includes an inorganic coating. The inorganic coating can further improve the electrolyte wetting performance of the separator.

[0061] In some of these embodiments, at least one inorganic coating is provided between the porous substrate and the polymer coating.

[0062] Specifically, in some embodiments, the separator comprises a porous substrate, an inorganic coating, and a polymer coating, wherein the inorganic coating is provided on at least one surface of the porous substrate, and the polymer coating covers one surface of the inorganic coating that is away from the porous substrate. As can be understood, if there are two inorganic coatings, the compositions of the multiple inorganic coatings may be the same or different. By providing the separator in this manner, the inorganic coatings in the separator can further improve the electrolyte wetting properties, and one of the inorganic coatings can be covered with a polymer coating, which is used to bond with a lithium metal negative electrode plate, thereby improving the uniformity of lithium metal deposition on the negative electrode plate.

[0063] In some of these embodiments, at least one inorganic coating is provided on one side of the polymer coating that is away from the porous substrate.

[0064] Specifically, in some embodiments, the separator includes a porous substrate, an inorganic coating, and a polymer coating. The porous substrate includes an inorganic coating and a polymer coating, laminated sequentially on one side, and a polymer coating and an inorganic coating, laminated sequentially on the other side. As can be understood, the compositions of the multiple inorganic coatings may be the same or different, and the compositions of the multiple polymer coatings may be the same or different.

[0065] In some of these embodiments, at least one inorganic coating is provided on the surface of the porous substrate, away from the polymer coating. Specifically, in some embodiments, the separator includes a porous substrate, an inorganic coating, and a polymer coating. The polymer coating covers one side of the porous substrate, and the inorganic coating is provided on the other side of the porous substrate.

[0066] Another embodiment of this application further provides a method for manufacturing the separator described above, comprising the following steps S1 to S3.

[0067] Step S1: Mix the raw materials for the polymer coating to produce a precursor solution.

[0068] Step S2: The precursor solution is applied to and covers at least one surface of the porous substrate.

[0069] Step S3: Polymerize the precursor solution to produce a polymer coating.

[0070] In some of these embodiments, the manufacturing raw materials, calculated on a mass percentage basis, consist of 5% to 30% manufacturing monomers, and / or 40% to 70% plasticizers, and / or 3% to 10% thickeners, and / or 10% to 20% lithium salts, and / or 0% to 42% inorganic particles.

[0071] In some of these embodiments, the manufactured monomer comprises at least one of a crosslinked monomer and a linear monomer, wherein the number of polymerization sites of the crosslinked monomer is at least two, and the number of polymerization sites of the linear monomer is one.

[0072] In some of these embodiments, the crosslinked monomer is an acrylate monomer. Furthermore, the acrylate monomers include acrylic acid, methacrylic acid, methyl methacrylate, butyl methacrylate, methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, butyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, isobornyl acrylate, isobornyl methacrylate, ethoxyethoxyethyl acrylate, cyanoacrylate, caprolactone acrylate, 2-phenoxyethyl acrylate, tetrahydrofuryl acrylate, ethoxylated tetrahydrofuran acrylate, cyclotrimethylolpropane acrylate, and 2-carboxy Diethyl acrylate, cyclohexyl acrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, propylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol diacrylate, 1,It comprises at least one selected from 6-hexanediol dimethacrylate, dipropylene glycol diacrylate, dipropylene glycol dimethacrylate, tripropylene glycol diacrylate, tripropylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 2(propoxy)neopentyl glycol diacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, polycyclohexyl acrylate, methoxypolyethylene glycol acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, methoxypolyethylene glycol methacrylate, pentaerythritol triacrylate, propoxylated glycerin triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, bis(trimethylolpropane)tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy)pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. ,

[0073] Furthermore, the crosslinked monomer may be selected from at least one of polyethylene glycol diacrylate (PEGDA), glycerol propoxylated triacrylate (GPTA), and ethoxylated trimethylolpropane triacrylate (ETPTA).

[0074] In some of these examples, the mass percentage of the crosslinked monomer in the manufactured monomer is 0-30%. Selectively, the mass percentage of the crosslinked monomer in the manufactured monomer is 0%, 5%, 10%, 15%, 20%, 25%, or 30%.

[0075] In some of these embodiments, the linear monomer is at least one selected from carbonate monomers, sulfate ester monomers, sulfonic acid ester monomers, phosphate ester monomers, carboxylic acid ester monomers, sulfone monomers, amide monomers, nitrile monomers, and ether monomers.

[0076] In some of these examples, the carbonate monomer includes at least one selected from vinylene carbonate (VC), ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and chloroethylene carbonate.

[0077] In some of these embodiments, the sulfate ester monomer comprises at least one selected from vinyl vinylsulfite, vinyl sulfite, 4-methyl vinyl sulfate, and 4-ethyl vinyl sulfate.

[0078] In some of these examples, the sulfonic acid ester monomer comprises at least one selected from 1,3-propensultone, 1,3-propanesultone, 1,4-butanesultone, and methylenemethanedisulfonate.

[0079] In some of these embodiments, the phosphate ester monomer includes at least one selected from dimethyl vinyl phosphate, diethyl vinyl phosphate, diethyl propenyl phosphate, diethyl butenyl phosphate, diethyl 1-buten-2-yl phosphonate, diethylethynyl phosphate, vinyl trifluoromethyl phosphate, vinyl-1-trifluoroethyl phosphate, diethyl fluorovinyl phosphate, and 1-trifluoropropenylethyl phosphate.

[0080] In some of these examples, the carboxylic acid ester monomer includes vinyl acetate.

[0081] In some of these examples, the sulfone monomer includes at least one selected from methyl vinyl sulfone, ethyl vinyl sulfone, cyclobutene sulfone, sulfolane, and cycloethylene sulfoxide.

[0082] In some of these examples, the amide monomer includes acrylamide.

[0083] In some of these embodiments, the nitrile monomer comprises at least one selected from acrylonitrile, succinonitrile, glutalonitrile, and adiponitrile.

[0084] In some of these examples, the ether monomer includes at least one selected from 1,3-dioxane, ethylene oxide, 1,2-propylene oxide, 4-methyl-1,3-dioxane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, ethylene glycol dimethyl ether, ethylene glycol diglycidyl ether, and triethylene glycol divinyl ether.

[0085] Furthermore, the linear monomer may be selected from at least one of vinylene carbonate (VC), 4-methyl vinyl sulfate, methylene methane disulfonate, diethylpropenyl phosphate, vinyl acetate, ethyl vinyl sulfone, acrylamide, acrylonitrile, and 1,3-dioxane.

[0086] In some of these examples, the mass percentage of linear monomer in the manufactured monomer is 0-30%. Selectively, the mass percentage of linear monomer in the raw material is 0%, 5%, 10%, 15%, 20%, 25%, or 30%.

[0087] Furthermore, the manufactured monomers include linear monomers and crosslinked monomers, with the mass percentage of linear monomers being 10% to 25% and the mass percentage of crosslinked monomers being 5% to 15% in the manufacturing raw materials. By rationally selecting and blending the manufactured monomers, the uniformity of lithium metal deposition in secondary batteries can be further improved.

[0088] In some of these embodiments, in step S3, the polymerization initiation method is selected from electron beam initiation, ultraviolet light initiation, and thermal initiation.

[0089] In some of these embodiments, the temperature at which heat is initiated is between 50°C and 80°C.

[0090] In some of these embodiments, the polymerization of the monomer is initiated in step S3 by an initiator. Specifically, the initiator is selectively at least one of peroxide initiators and azo initiators. For example, the initiator may be selected from acyl peroxides (e.g., benzoyl peroxide, lauroyl peroxide), persulfates (e.g., ammonium persulfate), and azo initiators (e.g., azobisisobutyronitrile, azobisisoheptanonitrile).

[0091] In some of these embodiments, the viscosity of the precursor solution is between 300 mPa·s and 1000 mPa·s. By controlling the viscosity of the precursor solution within this range, it is possible to prevent the precursor solution from penetrating into the voids of the porous substrate. Specifically, the viscosity of the precursor solution is selectively 300 mPa·s, 400 mPa·s, 500 mPa·s, 600 mPa·s, 700 mPa·s, 800 mPa·s, 900 mPa·s, or 1000 mPa·s.

[0092] In some of these embodiments, the processing time for steps S2 and S3 does not exceed one hour, thereby further preventing the precursor solution from penetrating into the voids of the porous substrate.

[0093] Furthermore, the secondary battery, battery module, battery pack, and power consumption device of this application will be described below with appropriate reference to the drawings.

[0094] One embodiment of this application provides a secondary battery.

[0095] Generally, a secondary battery includes a positive electrode plate, a negative electrode plate, an electrolyte, and a separator. During charging and discharging of the battery, active ions intermittently

[0096] Separator In the embodiment of this application, the separator is the separator according to the first embodiment described above.

[0097] In some of these embodiments, the material of the porous substrate may be selected from at least one of glass fiber, nonwoven fabric, polyethylene (PE), polypropylene (PP), polyimide (PI), and polyvinylidene fluoride. The porous substrate may be a single-layer film or a multilayer composite film, and is not particularly limited. When the porous substrate is a multilayer composite film, the materials of each layer may be the same or different, and are not particularly limited.

[0098] positive electrode plate The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, the positive electrode active material layer containing a positive electrode active material.

[0099] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode active material layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0100] In some of these embodiments, the positive electrode current collector can employ a metal foil sheet or a composite current collector. For example, as the metal foil sheet, aluminum foil may be employed. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be formed by forming a metal material such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy on a polymer material substrate. Here, the polymer material substrate is, for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE).

[0101] In some of these embodiments, the positive electrode active material may employ a positive electrode active material for batteries known in the art. As an example, the positive electrode active material may include at least one of materials such as lithium-containing phosphates having an olivine structure, lithium transition metal oxides, and their respective modified compounds. 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. Here, examples of lithium transition metal oxides are lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which may be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which may be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which may be abbreviated as NCM 211 ), LiNi 0.6 Co0.2 Mn 0.2 O2(NCM 622 (It can also be abbreviated as LiNi) 0.8 Co 0.1 Mn 0.1 O2(NCM 811 (This can also be abbreviated as LiNi)), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 It may include, but is not limited to, at least one of O2) and its modified compounds. Examples of lithium-containing phosphates with an olivine structure include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which may be abbreviated as LFP)), composite materials of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), composite materials of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and composite materials of lithium iron manganese phosphate and carbon.

[0102] In some of these embodiments, the positive electrode active material layer further selectively includes an adhesive. For example, the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic ester resin.

[0103] In some of these embodiments, the positive electrode active material layer further selectively includes a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0104] In some of these embodiments, the positive electrode plate may be manufactured by the following method: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is then applied onto a positive electrode current collector, and after processes such as drying and cold pressing, the positive electrode plate is obtained.

[0105] Negative electrode plate The negative electrode plate includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, the negative electrode active material layer containing a negative electrode active material.

[0106] For example, the negative electrode current collector has two opposing surfaces in the thickness direction of itself, and the negative electrode active material layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0107] In some of these embodiments, the negative electrode current collector may be a metal foil sheet or a composite current collector. For example, copper foil may be used as the metal foil sheet. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy on the polymer material substrate. Here, the polymer material substrate may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0108] In some of these embodiments, the negative electrode active material may be a negative electrode active material for batteries known in the art. For example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon acid compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may be selected from at least one of elemental tin, tin acid compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as battery negative electrode active materials may be used. These negative electrode active materials may be used individually or in combination of two or more.

[0109] In some of these embodiments, the negative electrode active material layer further selectively includes an adhesive. The adhesive may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0110] In some of these embodiments, the negative electrode active material layer further selectively includes a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0111] In some of these embodiments, the negative electrode active material layer selectively further comprises other auxiliary agents, such as thickeners (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0112] In some of these embodiments, the negative electrode plate may be manufactured by the following method: The above components for manufacturing the negative electrode plate, such as a negative electrode active material, a conductive agent, an adhesive, and any other component, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry. The negative electrode slurry is then applied onto a negative electrode current collector, and after processes such as drying and cold pressing, the negative electrode plate is obtained.

[0113] In some of these embodiments, a lithium metal negative electrode plate is used, and the lithium metal negative electrode plate is provided on the side of the separator closest to the polymer coating.

[0114] In some of these embodiments, during the manufacturing process of a secondary battery, a porous substrate coated with the precursor solution described in the second embodiment is bonded to a lithium metal anode plate, the precursor solution is brought into contact with the lithium metal anode plate and bonded together, the precursor solution is then polymerized to produce a polymer coating, thereby tightly bonding the separator to the lithium metal anode plate.

[0115] electrolyte The electrolyte plays a role in conducting ions between the positive and negative electrodes. This application does not specifically limit the type of electrolyte, which may be selected according to the requirements. For example, the electrolyte may be a liquid, a gel, or an all-solid.

[0116] In some of these embodiments, an electrolyte solution is used as the electrolyte. The electrolyte solution contains an electrolyte salt and a solvent.

[0117] In some of these examples, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorodioxalatrate, and lithium tetrafluorooxalatrate.

[0118] In some of these examples, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, ethyl methyl sulfone, and diethyl sulfone.

[0119] In some of these embodiments, the electrolyte further selectively includes additives. For example, the additives may include a negative electrode film-forming additive and a positive electrode film-forming additive, and may further include additives that can improve some of the battery's performance characteristics, such as additives that improve the battery's overcharge performance, or additives that improve the battery's high-temperature or low-temperature performance.

[0120] In some of these embodiments, the positive electrode plate, negative electrode plate, and separator may be manufactured as an electrode assembly by a winding process or a lamination process.

[0121] In some of these embodiments, the secondary battery may include an outer casing. This casing may be used to package the electrode assembly and electrolyte.

[0122] In some of these embodiments, the casing of the secondary battery may be a rigid case, such as a rigid plastic case, an aluminum case, or a steel case. The casing of the secondary battery may also be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0123] This application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. Figure 1 shows a rectangular secondary battery 5 as an example.

[0124] In some of these embodiments, referring to Figure 2, the casing may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates enclose and form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 can be fitted over the opening to seal the housing cavity. The positive electrode plate, negative electrode plate and separator may form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is packaged within the housing cavity. The electrolyte is impregnated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and a person skilled in the art can select according to the specific actual needs.

[0125] In some of these embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art depending on the application and capacity of the battery module.

[0126] Figure 3 shows an example of a battery module 4. Referring to Figure 3, multiple secondary batteries 5 may be installed in the battery module 4 in a sequential arrangement along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 5 may be fixed in place by fasteners.

[0127] Selectively, the battery module 4 may further include a housing having a housing space, in which a plurality of secondary batteries 5 are housed.

[0128] In some of these embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack may be one or more, and the specific number may be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0129] Figures 4 and 5 show an example of a battery pack 1. Referring to Figures 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, the upper housing 2 can be provided as a lid for the lower housing 3, and forms a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0130] Furthermore, this application provides a power consumption device comprising at least one of a secondary battery, battery module, or battery pack according to this application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage unit for the power consumption device. The power consumption device may include, but is not limited to, mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc. Here, mobile devices may be, for example, mobile phones, laptop computers, etc., and electric vehicles may be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but is not limited to these.

[0131] As a power consumption device, a secondary battery, battery module, or battery pack may be selected depending on the usage needs.

[0132] Figure 6 shows an example of a power consumption device 6. This power consumption device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the demand for higher output and higher energy density of the secondary battery of this power consumption device, a battery pack or battery module may be used.

[0133] Other examples of devices may include mobile phones, tablet computers, and laptop computers. These devices generally require to be thin and lightweight, and may use rechargeable batteries as a power source.

[0134] Examples Examples of the present application are described below. The examples described below are illustrative and are used solely for the purpose of interpreting this application and should not be understood as limitations thereon. Unless specific techniques or conditions are specified in the examples, they shall be carried out in accordance with the techniques or conditions described in the literature in the art or in accordance with the product description. Unless the manufacturer is specified, the reagents or equipment used are all commercially available and commonly used products.

[0135] Manufacturing of positive electrode plates NCM811, acetylene black (a conductive agent), and polyvinylidene fluoride (PVDF) (an adhesive) are thoroughly mixed in an N-methylpyrrolidone (NMP) solvent system in a weight ratio of 94:3:3 until uniform. Both sides are then coated onto aluminum foil, dried, and cold-pressed to obtain a positive electrode plate, which is then cut to the corresponding size for use.

[0136] Manufacturing of negative electrode plates: A lithium metal anode is manufactured by attaching a 50 μm thick lithium foil to the surface of a copper foil and cold pressing it. The composite lithium metal copper foil and bare copper foil are cut to size in preparation for use. The composite lithium metal copper foil is used as the lithium metal anode plate, and the bare copper foil is used as the lithium-free anode plate. During the charge-discharge process, lithium metal is deposited on the lithium-free anode plate.

[0137] Separator manufacturing: Precursor solutions are prepared based on the formulations in Tables 1 to 5, and the viscosity of the precursor solution is controlled to 300 mPa·s to 1000 mPa·s. The precursor solution is applied to one side of the surface of a separator (porous substrate or porous substrate with an initial coating) with a coating thickness of 5 μm, and then immediately bonded to the negative electrode plate and subjected to ultraviolet irradiation (2 W / cm²). 2 The precursor solution is cured for 10 minutes, and after curing, the separator is bonded to the negative electrode plate. In Tables 1 to 5, a 12 μm thick PE, PP, or PI film with a porosity of approximately 36% was selected as the porous substrate, and the polymer coating on the manufactured separator did not completely fill the voids of the porous substrate.

[0138] The method for manufacturing the porous substrate, including the initial coating used in the examples, is as follows: Aluminum oxide and adhesive (PVDF) are dissolved in NMP in a mass ratio of 95:5, and a 3 μm separator inorganic ceramic layer is manufactured using slit coating. This layer is then coated once more on the opposing side of the coating to obtain a double-sided inorganic ceramic separator. A slurry (PVDF (5 wt%) dissolved in NMP) is then applied to the surface of the inorganic ceramic layer of the separator using a spin coating process, and after drying, a polymer layer distributed in an island-like manner can be obtained.

[0139] Test method for porosity of porous substrates: The porosity is tested using the true density method. A sample cup containing the sample is placed in a true density tester, the test system is sealed, helium gas is introduced according to the procedure, and the gas pressure in the sample chamber and expansion chamber is detected. The true volume V2 is then calculated based on Bore's law (PV=nRT). The apparent volume V1 of the sample is measured using a spiral micrometer and calipers according to the volume calculation formula (V=S*h). The porosity of the sample is calculated as Porosity=(V1-V2) / V1*100%, where V1 is the apparent volume of the sample and V2 is the true volume of the sample.

[0140] Method for testing the viscosity of the precursor solution: The viscosity test is performed using the DV-2TLV instrument. The measurement range is related to the rotor and rotation speed, and the calculation formula is FSR = TK * SMC * 10000 / RPM. Pour the sample into the dedicated sample cup, select the corresponding rotor rotation speed based on the approximate range of sample viscosity, select the Multi Point data acquisition mode, start automatic detection, and read the viscosity data.

[0141] Observation of the separator coating: After cooling the separator containing the manufactured polymer coating in liquid nitrogen for 30 minutes, a cross-sectional sample was prepared, and the cross-sectional morphology of the separator was observed using SEM. As can be observed, the coating in this embodiment is mainly distributed on the surface of the separator substrate, and the polymer is not dispersed inside the separator substrate, remaining in a porous state. The polymer coating in the separator manufactured in this way does not completely fill the voids of the porous substrate.

[0142] Assembly of rechargeable batteries: A positive electrode plate coated on both sides, a bonded separator, and a negative electrode plate are stacked and assembled into a laminated battery core. A bare cell is assembled in the order of negative electrode plate, separator, positive electrode plate, separator, and negative electrode plate, with the separator positioned between the positive and negative electrodes. The bare cell is then placed in an outer casing to obtain a dry battery core. The solvent for the electrolyte is EC:EMC:DMC = 1:1:1 (volume ratio), the lithium salt is LiFSI, and the concentration is 1 M / L. 0.3 g of the electrolyte is injected into each battery core, which is then vacuum-sealed and left to stand to allow for immersion.

[0143] In Tables 1-7 below, VC represents vinylene carbonate, PEGDA represents polyethylene glycol diacrylate, GPTA represents glycerol propoxylated triacrylate, and ETPTA represents ethoxylated trimethylolpropane triacrylate.

[0144] [Table 1]

[0145] [Table 2]

[0146] [Table 3]

[0147] [Table 4]

[0148] [Table 5]

[0149] [Table 6]

[0150] The separator in Comparative Example 1 is a PE film with a thickness of 12 μm and a porosity of approximately 36%.

[0151] The separator in Comparative Example 2 was modified by adding a 3 μm ceramic layer and an island-shaped polymer layer, both coated on both sides, to the separator in Comparative Example 1.

[0152] The separator in Comparative Example 3 was modified by adding a 3 μm ceramic layer coated on both sides to the separator in Comparative Example 1.

[0153] The difference between Comparative Example 4 and Comparative Example 2 is that the negative electrode system is a lithium-free negative electrode.

[0154] The difference between Comparative Examples 5-7 and Example 1 lies in the composition of the polymer coating. The composition of the negative electrode system and separator in the secondary batteries of Comparative Examples 5-7 is recorded in Table 7. In Comparative Example 6, PVDF was not added to the polymer coating, and during the manufacturing process, the polymer coating was filled into the voids of the porous substrate.

[0155] [Table 7]

[0156] Exam section: Cycle life test: The rechargeable batteries manufactured as described above are subjected to a life test in a constant temperature environment of 25°C, with the following flow: Allow to stand for 5 minutes, discharge to 2.8V at 0.5C (72mA), allow to stand for 5 minutes, charge to 4.25V at 1 / 3C, then charge at a constant voltage of 4.25V to current ≤0.05mA, allow to stand for 5 minutes, then discharge to 2.8V at 1 / 3C. The discharge capacity at this time is the initial discharge capacity and is denoted as D0. Subsequently, a cycle test is performed in the range of 2.8~4.25V according to the above flow, and the capacity value Dn (n=1, 2, 3...) is recorded for each cycle. If the capacity value Dn <= 80% * D0, the number of cycles n is recorded as the cycle life.

[0157] Ionic conductivity test: Prepare the slurry according to the formulations in Tables 1-5, apply it to the surface of the aluminum foil to a thickness of approximately 5 μm, and then cure it using the UV method at 2 W / cm². 2 The polymer layer was then irradiated for 10 minutes. The cured polymer layer was punched out into small discs with a diameter of 16 mm, and the thickness d of the polymer layer was measured and recorded. The punched-out discs were packaged into button batteries, and tested using the electrochemical AC impedance method on a Solartron 1470E CellTest multi-channel electrochemical workstation. The test temperature was 25°C, the test voltage may be 10 mV, and the test frequency may be 0.1 Hz to 100 kHz. A Nyquist diagram was created, and the Nyquist diagram obtained using the equivalent circuit curve fitting method with Zview software was analyzed, with the intersection of the line and the horizontal axis denoted as R. The ionic conductivity (where λ represents ionic conductivity, d represents thickness, and R represents ionic resistance) was calculated using the formula λ = d / RS.

[0158] Record the test data in Table 8.

[0159] [Table 8]

[0160] As can be seen from the data in Table 8, the cycle life of the secondary batteries in Comparative Examples 1 to 7 was 12 to 49 cycles, and the ionic conductivity of the polymer coating in Comparative Examples 5 to 7 was 0.08 mS / cm to 6.0 mS / cm. In the secondary batteries of Examples 1 to 20, the ionic conductivity of the polymer coating was 1.8 mS / cm to 5.4 mS / cm, and the cycle life was 47 to 98 cycles. The secondary batteries of Examples 1 to 20 can effectively improve the uniformity of lithium metal deposition on the negative electrode plate in the lithium metal negative electrode system by using a polymer coating having a specific structure, thereby improving the cycle life of the secondary battery.

[0161] Specifically, in Examples 5 and 8, the polymer coating contains 5-20 wt% linear monomer, 5-10 wt% crosslinked monomer, 50-60 wt% plasticizer, 5 wt% thickener, and 20 wt% lithium salt, with the ratio of lithium salt to plasticizer being between 20-30%, and the matrix polymer being formed by polymerizing appropriate proportions of linear monomer and crosslinked monomer, resulting in a more appropriate restraining force. Therefore, the polymer coatings of Examples 5 and 8 have superior ion conductivity and superior cycle life, with cycle lives of 95 and 98 cycles, respectively.

[0162] In Examples 1 and 18, the matrix polymer in the polymer coating is formed by polymerizing linear monomers, and the matrix polymer is a chain-like polymer, which has a relatively weak binding force to other components of the polymer coating. However, in Examples 17, 19, and 20, the matrix polymer is formed by polymerizing crosslinked monomers, and the matrix polymer is a crosslinked network polymer, which has a relatively strong binding force. In particular, the content of the crosslinked network matrix polymer in Example 19 is relatively high, so the ionic conductivity of the polymer coating is somewhat lower compared to the other examples.

[0163] Each of the technical features of the embodiments described above can be combined in any way, and for the sake of brevity, not all possible combinations of each technical feature in the embodiments described above are described; however, as long as there is no contradiction in these combinations of technical features, they should all be considered to fall within the scope described herein.

[0164] The above embodiments illustrate only a few embodiments of this application, and while the descriptions are more specific and detailed, they should not be understood as limiting the scope of the invention patent. It should be noted that a person skilled in the art can make several further modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this patent application shall be in accordance with the attached claims. [Explanation of Symbols]

[0165] 1: Battery pack, 2: Upper casing, 3: Lower casing, 4: Battery module, 5: Rechargeable battery, 51: Case, 52: Electrode assembly, 53: Cover plate, 6: Power consumption device

Claims

1. A separator for a lithium metal anode secondary battery, Porous substrate, and Including polymer coating, The components of the polymer coating include a matrix polymer, a plasticizer, and polyvinylidene fluoride and lithium salt, which are thickeners. The mass percentage of polyvinylidene fluoride in the polymer coating is 3% to 5%. The mass percentage of the lithium salt in the polymer coating is 10% to 30%. The mass percentage of the plasticizer in the polymer coating is 40% to 60%. A separator characterized in that the polymer coating covers at least one surface of the porous substrate, and the voids of the porous substrate are not completely filled with the polymer coating, and the polymer coating has lithium ion conductivity.

2. The separator according to claim 1, characterized in that the mass percentage of the matrix polymer in the polymer coating is 5% to 30%.

3. The separator according to claim 1, characterized in that the matrix polymer is at least one selected from chain polymers and crosslinked network polymers.

4. The separator according to claim 1, characterized in that the plasticizer comprises at least one of ester-based and sulfone-based plasticizers.

5. The separator according to claim 1, characterized in that the plasticizer comprises at least one selected from ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, ethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

6. The separator according to claim 1, characterized in that the thickening agent is compatible with the plasticizer.

7. The separator according to claim 1, characterized in that the weight-average molecular weight of the thickening agent is ≥ 500,000.

8. The separator according to claim 1, characterized in that the lithium salt comprises at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorophosphate, lithium difluorodioxalathrate, and lithium tetrafluorooxalathrate.

9. The separator according to claim 1, characterized in that the polymer coating further comprises inorganic particles in a mass percentage of 0 to 42%.

10. The separator according to claim 9, characterized in that the inorganic particles are at least one selected from aluminum oxide, boehmite, zirconia, aluminum nitride, titanium dioxide, magnesium oxide, silicon carbide, calcium carbonate, and diatomaceous earth.

11. The separator according to claim 1, characterized in that the thickness of the polymer coating is 3 μm to 20 μm.

12. The separator further comprises an inorganic coating, Here, at least one of the inorganic coatings is provided between the porous substrate and the polymer coating, Alternatively, at least one of the inorganic coatings is provided on one surface of the polymer coating that is away from the porous substrate, Alternatively, the separator according to claim 1, wherein at least one of the inorganic coatings is provided on the surface of the porous substrate, away from the polymer coating.

13. A method for manufacturing a separator for a lithium metal anode secondary battery, A step of mixing raw materials for polymer coating production, which, when calculated based on mass percentage, contain 5% to 30% of the production monomer, 40% to 60% of the plasticizer, 3% to 5% of the thickening agent polyvinylidene fluoride, 10% to 30% of the lithium salt, and 0% to 42% of the inorganic particles, to produce a precursor solution. The steps include: applying and covering at least one surface of a porous substrate with the precursor solution; A method for producing a separator, characterized by comprising the step of polymerizing the precursor solution to produce a polymer coating.

14. The method for producing a separator according to claim 13, characterized in that the manufactured monomer comprises at least one of a crosslinked monomer and a linear monomer, wherein the number of polymerization sites of the crosslinked monomer is at least two, and the number of polymerization sites of the linear monomer is one.

15. The method for producing a separator according to claim 14, characterized in that the crosslinked monomer is an acrylate monomer.

16. The method for producing a separator according to claim 14, characterized in that the mass percentage of the crosslinked monomer in the raw materials for production is 0 to 30%.

17. The method for producing a separator according to claim 14, characterized in that the linear monomer is at least one selected from carbonate monomers, sulfate ester monomers, sulfonic acid ester monomers, phosphate ester monomers, carboxylic acid ester monomers, sulfone monomers, amide monomers, nitrile monomers, and ether monomers.

18. The method for producing a separator according to claim 14, characterized in that the mass percentage of the linear monomer in the raw materials for production is 0 to 30%.

19. The method for producing a separator according to claim 13, characterized in that, in the step of polymerizing the precursor solution, the method for initiating the polymerization is one selected from electron beam initiation, ultraviolet light initiation, and thermal initiation.

20. The method for producing a separator according to claim 13, characterized in that the viscosity of the precursor solution is 300 mPa·s to 1000 mPa·s.

21. A secondary battery, characterized by comprising a separator as described in any one of claims 1 to 12.

22. The secondary battery according to claim 21, further comprising a lithium metal negative electrode plate, wherein the lithium metal negative electrode plate is provided on the side of the separator closest to the polymer coating.

23. A battery module characterized by including the secondary battery described in claim 21.

24. A battery pack, characterized by including the battery module described in claim 23.

25. A power consumption device characterized by including the secondary battery described in claim 21.

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