Separator and manufacturing method thereof, 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] The present application relates to the field of secondary batteries, and in particular to separators and their manufacturing methods, secondary batteries, battery modules, battery packs and power consuming devices. [Background technology]

[0002] With the development of electric vehicles and large-scale energy storage systems, the market has placed higher demands on the energy density of secondary batteries such as lithium-ion batteries. Here, the use of lithium metal negative electrodes is one of the means for improving the energy density of secondary batteries. However, if lithium metal deposits unevenly on the surface of the lithium metal negative electrode during charging and discharging, it will cause deterioration of the negative electrode and affect the cycle performance of the secondary battery. Summary of the Invention

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

[0004] According to a first aspect of the present application, A porous substrate, and A separator is provided that includes a polymer coating, the polymer coating covering at least one surface of the porous substrate and wherein voids of the porous substrate are not completely filled with the polymer coating, and the polymer coating is capable of conducting lithium ions.

[0005] The separator has a continuous polymer coating on the surface of a porous substrate, the polymer coating having lithium ion conductivity, and the polymer coating does not completely fill the voids in the porous substrate, so as not to affect the infiltration of the electrolyte into the separator. The distribution of the polymer coating on the surface of the separator is uniform. When used in a secondary battery with a lithium metal negative electrode, the separator can improve the uniformity of the negative electrode lithium metal deposition, avoid deterioration of the electrochemical performance of the lithium metal negative electrode, and improve the cycle performance of the secondary battery.

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

[0007] In some of the embodiments, the weight percentage of the matrix polymer in the polymer coating is between 5% and 30%.

[0008] In some of the embodiments, the weight percentage of the plasticizer in the polymer coating is between 40% and 70%.

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

[0010] In some of the embodiments, the weight percentage of the lithium salt in the polymer coating is between 10% and 30%.

[0011] In some embodiments thereof, the matrix polymer is at least one selected from a linear polymer and a crosslinked network polymer.

[0012] In some of the embodiments, the plasticizer comprises at least one of an ester type and a sulfone type.

[0013] In some embodiments thereof, 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 embodiments thereof, the thickener is compatible with the plasticizer.

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

[0016] In some of the embodiments, the weight average molecular weight of the thickener is ≧500,000.

[0017] In some embodiments thereof, 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 difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0018] In some of the embodiments, the polymer coating composition further comprises inorganic particles having a weight percentage of 0-42%.

[0019] In some of the embodiments, the weight percentage of the inorganic particles in the polymer coating is between 20% and 30%.

[0020] In some of the 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] In some of the embodiments, the polymer coating has a thickness of between 3 μm and 20 μm.

[0022] In some of these embodiments, the separator further comprises an inorganic coating; wherein at least one of the inorganic coatings is disposed between the porous substrate and the polymer coating; Alternatively, at least one of the inorganic coatings is provided on a surface of the polymer coating away from the porous substrate, Alternatively, at least one of the inorganic coatings is provided on a surface of the porous substrate remote from the polymeric coating.

[0023] According to a second aspect, the present application further provides a method for producing a separator, the method comprising: mixing raw materials for producing a polymer coating to produce a precursor solution; applying the precursor solution to cover at least one surface of a porous substrate; and polymerizing the precursor solution to produce a polymer coating.

[0024] In some of the embodiments, the manufacturing raw materials include, calculated based on mass percentage, 5% to 30% manufacturing monomer, and / or 40% to 70% plasticizer, and / or 3% to 10% thickener, and / or 10% to 20% lithium salt, and / or 0 to 42% inorganic particles.

[0025] In some embodiments, the product monomers include at least one of a crosslinking monomer and a linear monomer, where the number of polymerization sites of the crosslinking monomer is at least two and the number of polymerization sites of the linear monomer is one.

[0026] In some of these embodiments, the cross-linking monomer is an acrylate monomer.

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

[0028] In some embodiments, the linear monomer is at least one selected from carbonate monomers, sulfate monomers, sulfonate monomers, phosphate monomers, carboxylate monomers, sulfone monomers, amide monomers, nitrile monomers, and ether monomers.

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

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

[0031] In some of the 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 including the separator described above or a separator manufactured by the method for manufacturing the separator described above.

[0033] In some of these embodiments, the secondary battery further includes a lithium metal negative electrode plate, the lithium metal negative electrode plate being disposed on a side of the separator proximate 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 consuming device including at least one selected from the above secondary battery, the above battery module, and the above battery pack.

[0037] The details of one or more embodiments of the application are set forth in the drawings and description which follow, and other features, objects and advantages of the application will become apparent from the description, drawings, and claims. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application. [Diagram 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Diagram 3] FIG. 1 is a schematic diagram of a battery module according to an embodiment of the present application. [Figure 4] FIG. 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Diagram 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of a power consuming device powered by a secondary battery according to an embodiment of the present application;

[0039] To better describe and explain the embodiments and / or examples of those inventions disclosed herein, reference may be made to one or more drawings, in which additional details or examples for describing the drawings should not be considered as limiting the scope of the disclosed inventions, either of the presently described embodiments and / or examples, or the best modes of those inventions as currently understood. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In order to facilitate the understanding of the present application, the following will more fully describe the present application with reference to the accompanying drawings. The drawings show preferred embodiments of the present application. However, the present application may be embodied in many different forms and is not limited to the embodiments set forth herein. Rather, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and complete.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms used herein are for the purpose of describing specific examples only and are not intended to be limiting of this application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0042] The use of lithium metal negative electrode plates is one of the means for improving the energy density of secondary batteries. However, if the lithium metal on the surface of the lithium metal negative electrode plate is unevenly deposited during charging and discharging, it will cause the deterioration of the negative electrode plate and affect the cycle performance of the secondary battery. Conventional separators in secondary batteries generally have a polymer layer distributed in an island shape on their surface, and in the manufacturing process of the battery core, the polymer layer can provide adhesion, and the electrode plate and the separator are bonded together without misalignment. The polymer layer in the conventional separator has very poor ionic conductivity, so it is necessary to distribute it in an island shape to avoid an increase in the internal resistance of the secondary battery.

[0043] The inventors have found through research that when conventional separators are used in secondary batteries with lithium metal negative electrodes, the surface uniformity of the island-shaped polymer layer is relatively low, which affects the lithium metal deposition during the charge and discharge process, resulting in poor uniformity of the lithium metal deposition on the lithium metal negative electrode plate, and affecting the cycle performance of the secondary battery.

[0044] The present application provides a separator and a manufacturing method thereof, as well as a secondary battery, a battery module, a battery pack, and a power consuming device using the separator. Such a secondary battery is applied to various power consuming devices using batteries, such as mobile phones, portable devices, notebook computers, battery-powered vehicles, electric toys, electric tools, electric automobiles, ships, and spacecraft, and the like, such as airplanes, rockets, space shuttles, and spacecraft.

[0045] One embodiment of the present application provides a separator comprising a porous substrate and a polymer coating, the polymer coating covering at least one surface of the porous substrate and the voids of the porous substrate not completely filled by the polymer coating, the polymer coating having lithium ion conducting capability.

[0046] The separator has a continuous polymer coating on the surface of a porous substrate, the polymer coating having lithium ion conductivity, and the polymer coating does not completely fill the voids in the porous substrate, so as not to affect the infiltration of the electrolyte into the separator. The distribution of the polymer coating on the surface of the separator is uniform. When used in a secondary battery with a lithium metal negative electrode, the separator can improve the uniformity of the negative electrode lithium metal deposition, avoid deterioration of the electrochemical performance of the lithium metal negative electrode, and improve the cycle performance of the secondary battery.

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

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

[0049] The matrix polymer may be a skeletal structure in the polymer coating. In some embodiments, the mass percentage of the matrix polymer in the polymer coating is 5% to 30%. Optionally, 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%. In this ratio range, the matrix polymer can improve a good skeletal function, and as the ratio increases, the degree of crosslinking increases, which strengthens the binding ability for the electrolyte and affects the conductivity.

[0050] In the polymer coating, the plasticizer can improve the compatibility between the polymer coating components. In some embodiments, the mass percentage of the plasticizer in the polymer coating is 40% to 70%. Optionally, the mass percentage of the plasticizer in the polymer coating is 40%, 45%, 50%, 55%, 60%, 65% or 70%. Furthermore, the mass percentage of the plasticizer in the polymer coating is 50% to 60%. If the proportion of the plasticizer is too low, the ion transport of the coating is hindered, affecting the ion conductivity, and if the proportion of the plasticizer is too high, it is difficult to completely fix the polymer coating. Within the preferred range, the coating can maintain a good ion conduction rate, satisfying the improvement effect and at the same time not affecting the rate performance of the battery.

[0051] The thickener can increase the viscosity of the polymer coating, avoiding the voids of the porous substrate from being completely filled by the thickener in the manufacturing process, and reducing the electrolyte wettability of the separator. In some embodiments, the weight percentage of the thickener in the polymer coating is 3% to 15%. Alternatively, the weight percentage of the thickener in the polymer coating is 3%, 4%, 5%, 6%, 8%, 10%, 12%, or 15%. Furthermore, the weight percentage of the thickener in the polymer coating is 3% to 10%.

[0052] The lithium salt, as an electrolyte salt, can improve the ion conductivity of the polymer coating in the polymer coating. In some embodiments, the mass percentage of the lithium salt in the polymer coating is 10% to 30%. Optionally, the mass percentage of the lithium salt in the polymer coating is 10%, 12%, 15%, 16%, 18%, 20%, 24%, 25%, 28% or 30%. Furthermore, the mass percentage of the lithium salt in the polymer coating is 10% to 20%. The lithium salt mainly improves the ion transport capacity of the coating system and improves the lithium metal deposition behavior. The content of the lithium salt is high, and the effect of improving the ion transport capacity is high, but the increase in cost is relatively large. Furthermore, the ratio of the lithium salt to the plasticizer is 20% to 30%, which can effectively improve the ion transport capacity and has a relatively low cost.

[0053] In some embodiments, the matrix polymer is at least one selected from a linear polymer and a crosslinked network polymer. The linear polymer or the crosslinked network polymer may be used as the matrix polymer to form the backbone of the polymer coating, and components such as plasticizers, thickeners, and lithium salts are fixed to the backbone structure, so that the uniformity and compatibility of the polymer coating are relatively high. Furthermore, the matrix polymer includes a linear polymer and a crosslinked network polymer.

[0054] In some of the embodiments, the plasticizer comprises at least one of an ester and a sulfone. The ester has better overall performance as a plasticizer. Preferably, the plasticizer comprises an ester. Optionally, 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 the embodiments, the thickener is compatible with the plasticizer. In some of the embodiments, the thickener has a weight average molecular weight of ≧500,000. In some of the 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, polymethyl acrylate, polymethyl methacrylate, polyacrylamide (PAM), and polyvinylpyrrolidone (PVP).

[0056] In some embodiments thereof, the lithium salt comprises at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonate), lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0057] In some embodiments, the polymer coating composition further comprises inorganic particles having a weight percentage of 0-42%. The inorganic particles may be used as a filler in the polymer coating and may improve the strength of the polymer coating. Optionally, the weight percentage of the inorganic particles in the polymer coating is 0, 5, 10, 15, 20, 25, 30, 35, 40 or 42%. Additionally, the weight percentage of the inorganic particles in the polymer coating is 20%-30%.

[0058] In some embodiments thereof, 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 embodiments, the thickness of the polymer coating is 3 μm to 20 μm. By controlling the thickness of the polymer coating within the above range, it is possible to provide a more suitable adhesive force between the separator and the electrode plate, and the influence on the internal resistance of the separator is relatively small. Optionally, the thickness of the polymer coating is 3 μm, 5 μm, 10 μm, 15 μm, or 20 μm.

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

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

[0062] Specifically, in some embodiments, the separator includes a porous substrate, an inorganic coating, and a polymer coating, the inorganic coating being provided on at least one surface of the porous substrate, and the polymer coating being provided on one surface of the inorganic coating that is remote from the porous substrate. As can be understood, when the number of inorganic coatings is two, the compositions of the inorganic coatings may be the same or different. By providing in this manner, the inorganic coating in the separator can further improve the electrolyte wettability, and the surface of one of the inorganic coatings is covered with a polymer coating, which is used to bond with a lithium metal negative electrode plate, and can improve the uniformity of lithium metal deposition on the negative electrode plate.

[0063] In some of these embodiments, at least one inorganic coating is applied to a surface of the polymer coating away from the porous substrate.

[0064] Specifically, in some embodiments, the separator comprises a porous substrate, an inorganic coating, and a polymeric coating. One side of the porous substrate comprises an inorganic coating and a polymeric coating, which are layered in sequence, and the other side of the porous substrate comprises a polymeric coating and an inorganic coating, which are layered in sequence. As can be appreciated, the compositions of the inorganic coatings can be the same or different, and the compositions of the polymeric coatings can be the same or different.

[0065] In some embodiments, at least one inorganic coating is applied to a surface of the porous substrate remote from the polymeric coating. Specifically, in some embodiments, the separator includes a porous substrate, an inorganic coating, and a polymeric coating. The polymeric coating is applied to one surface of the porous substrate, and the inorganic coating is applied to the other surface of the porous substrate.

[0066] Another embodiment of the present application further provides a method for producing the above separator, which includes the following steps S1 to S3.

[0067] Step S1: The raw materials for producing the polymer coating are mixed to produce a precursor solution.

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

[0069] Step S3: The precursor solution is polymerized to produce a polymer coating.

[0070] In some of the embodiments, the manufacturing raw materials include, calculated based on mass percentage, 5% to 30% manufacturing monomer, and / or 40% to 70% plasticizer, and / or 3% to 10% thickener, and / or 10% to 20% lithium salt, and / or 0 to 42% inorganic particles.

[0071] In some embodiments thereof, the product monomers include at least one of a crosslinking monomer and a linear monomer, where the number of polymerization sites of the crosslinking monomer is at least two and the number of polymerization sites of the linear monomer is one.

[0072] In some of the embodiments, the crosslinking monomer is an acrylate monomer. The acrylate monomer may be selected from the group consisting of 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, 2-carboxyethyl acrylate, butyl ... 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,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)isocyanuric acid triacrylate, bis(trimethylolpropane)tetraacrylate, pentaerythritol tetraacrylate, 4(ethoxy)pentaerythritol tetraacrylate, and dipentaerythritol hexaacrylate. ,

[0073] Additionally, the cross-linking 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 embodiments, the weight percentage of the crosslinking monomer in the monomer mixture is 0-30%. Optionally, the weight percentage of the crosslinking monomer in the monomer mixture is 0, 5, 10, 15, 20, 25, or 30%.

[0075] In some embodiments thereof, the linear monomer is at least one selected from carbonate monomers, sulfate monomers, sulfonate monomers, phosphate monomers, carboxylate monomers, sulfone monomers, amide monomers, nitrile monomers, and ether monomers.

[0076] In some embodiments thereof, the carbonate monomer comprises at least one selected from vinylene carbonate (VC), ethylene carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, and chloroethylene carbonate.

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

[0078] In some embodiments thereof, the sulfonate monomer comprises at least one selected from 1,3-propene sultone, 1,3-propane sultone, 1,4-butane sultone, and methylenemethane disulfonate.

[0079] In some embodiments thereof, the phosphate monomer includes at least one selected from dimethylvinyl phosphate, diethylvinyl phosphate, diethylpropenyl phosphate, diethylbutenyl phosphate, diethyl 1-buten-2-ylphosphonate, diethylethynyl phosphate, vinyl trifluoromethyl phosphate, vinyl-1-trifluoroethyl phosphate, diethylfluorovinyl phosphate, and 1-trifluoropropenylethyl phosphate.

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

[0081] In some embodiments thereof, the sulfone-based monomer comprises at least one selected from methyl vinyl sulfone, ethyl vinyl sulfone, cyclobutene sulfone, sulfolane, and cycloethylene sulfoxide.

[0082] In some of the embodiments, the amide monomer comprises acrylamide.

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

[0084] In some embodiments thereof, the ether monomer comprises 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] Additionally, the linear monomer may be selected from at least one of vinylene carbonate (VC), 4-methyl vinyl sulfate, methylenemethane disulfonate, diethylpropenyl phosphate, vinyl acetate, ethyl vinyl sulfone, acrylamide, acrylonitrile, and 1,3-dioxane.

[0086] In some embodiments, the weight percentage of linear monomer in the raw material is 0-30%. Optionally, the weight percentage of linear monomer in the raw material is 0, 5%, 10%, 15%, 20%, 25% or 30%.

[0087] In addition, the manufacturing monomers include linear monomers and crosslinking monomers, and in the manufacturing raw materials, the mass percentage of the linear monomers is 10%-25%, and the mass percentage of the crosslinking monomers is 5%-15%. Through the rational selection and mixing ratio of the manufacturing monomers, the uniformity of lithium metal deposition in the secondary battery can be further improved.

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

[0089] In some embodiments, the thermal initiation temperature is between 50°C and 80°C.

[0090] In some embodiments, in step S3, the polymerization of the monomer is initiated by an initiator. Specifically, the initiator is optionally at least one of a peroxide initiator and an azo initiator. 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 the embodiments, the viscosity of the precursor solution is 300 mPa·s to 1000 mPa·s. By controlling the viscosity of the precursor solution within the above 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 treatment time of steps S2 and S3 does not exceed 1 hour, thereby further avoiding the precursor solution from penetrating into the pores of the porous substrate.

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

[0094] In one embodiment of the present application, a secondary battery is provided.

[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 shuttle between the positive electrode plate and the negative electrode plate to be absorbed and desorbed. The electrolyte serves to conduct ions between the positive electrode plate and the negative electrode plate. The separator is provided between the positive electrode plate and the negative electrode plate, and serves mainly to prevent short-circuiting of the positive and negative electrodes, while allowing ions to pass through.

[0096] Separator In the embodiment of the present application, the separator used is the separator according to the first embodiment.

[0097] In some embodiments, the material of the porous substrate may be at least one selected from glass fiber, nonwoven fabric, polyethylene (PE), polypropylene (PP), polyimide (PI) and polyvinylidene fluoride. The porous substrate may be a single layer film or a multi-layer composite film, and there is no particular limitation. When the porous substrate is a multi-layer composite film, the materials of each layer may be the same or different, and there is no particular limitation.

[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, and the positive electrode active material layer includes a positive electrode active material.

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

[0100] In some of the embodiments, the positive electrode current collector may be a metal foil sheet or a composite current collector. For example, an aluminum foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer 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 substrate. Here, the polymer substrate may be a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0101] In some of the embodiments, the positive electrode active material may be a positive electrode active material for batteries known in the art. For example, the positive electrode active material may include at least one of the following materials: a lithium-containing phosphate with an olivine structure, a lithium transition metal oxide, and a respective modified compound. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery may be used. These positive electrode active materials may be used alone or in combination of two or more. Here, examples of the lithium transition metal oxide include lithium cobalt oxide (e.g., LiCoO 2 ), lithium nickel oxide (e.g. LiNiO 2 ), lithium manganese oxide (such as LiMnO 2 , LiMn 2 O 4 ), 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 O 2 (NCM 333 (may be abbreviated as LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM 523 (may be abbreviated as LiNi0.5 Co 0.25 Mn 0.25 O 2 (NCM 211 (may be abbreviated as LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622 (may be abbreviated as LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811 Lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O 2 ) and modified compounds thereof. Examples of lithium-containing phosphates having an olivine structure include lithium iron phosphate (e.g., LiFePO 4 (which may be abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO 4 ), a composite of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite of lithium iron manganese phosphate and carbon.

[0102] In some of the embodiments, the positive electrode active material layer further optionally 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 the embodiments, the positive electrode active material layer may further include 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 the embodiments, the positive electrode plate may be manufactured in the following manner: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[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, and the negative electrode active material layer includes a negative electrode active material.

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

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

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

[0109] In some of the embodiments, the negative electrode active material layer further optionally includes an adhesive, which 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 the embodiments, the negative electrode active material layer further optionally includes a conductive agent, which 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 the embodiments, the negative electrode active material layer optionally further includes other auxiliary agents, such as a thickener (eg, sodium carboxymethylcellulose (CMC-Na)).

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

[0113] In some of these embodiments, the negative electrode plate is a lithium metal negative electrode plate, which is disposed on the side of the separator adjacent to the polymer coating.

[0114] In some of the embodiments, during the production of a secondary battery, the porous substrate coated with the precursor solution of the second aspect is laminated with a lithium metal negative electrode plate, the precursor solution is brought into contact with the lithium metal negative electrode plate, and the precursor solution is then polymerized to produce a polymer coating, thereby intimately bonding the separator to the lithium metal negative electrode plate.

[0115] electrolyte The electrolyte serves to conduct ions between the positive and negative electrodes. The present application is not specifically limited to the type of electrolyte, and may be selected according to need. For example, the electrolyte may be liquid, gel, or all solid.

[0116] In some of the embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0117] In some embodiments thereof, 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(trifluoromethanesulfonate), lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluoro(oxalato)borate, lithium bis(oxalato)borate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0118] In some embodiments thereof, 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 the embodiments, the electrolyte solution further includes optional 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 performance of the battery, such as an additive that improves the battery overcharge performance, an additive that improves the battery's high temperature or low temperature performance, etc.

[0120] In some embodiments, the positive electrode plate, the negative electrode plate and the separator may be fabricated into an electrode assembly by a winding process or a stacking process.

[0121] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0122] In some of the embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The material of the pouch may be plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0123] The present application does not particularly limit the shape of the secondary battery, which may be cylindrical, rectangular, or any other shape. Fig. 1 shows a secondary battery 5 having a rectangular structure as an example.

[0124] In some embodiments, referring to FIG. 2, the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected on the bottom plate, and the bottom plate and the side plate surround and form a receiving cavity. The case 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be installed on the opening to seal the receiving cavity. The positive electrode plate, the negative electrode plate and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is infiltrated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art may select according to specific actual needs.

[0125] In some 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 according to the application and capacity of the battery module.

[0126] Fig. 3 shows an example of a battery module 4. Referring to Fig. 3, the battery module 4 may have a plurality of secondary batteries 5 arranged in order along the longitudinal direction of the battery module 4. Of course, the batteries may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0127] Optionally, the battery module 4 may further include a housing having an accommodating space, and the multiple secondary batteries 5 are accommodated in the accommodating space.

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

[0129] 4 and 5 show an example of a battery pack 1. Referring to FIG. 4 and FIG. 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, and the upper housing 2 may be provided as a cover for the lower housing 3, forming a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0130] The present application further provides a power consuming device, the power consuming device including at least one of the secondary battery, the battery module, or the battery pack according to the present application. The secondary battery, the battery module, or the battery pack may be used as a power source for the power consuming device, or may be used as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, a mobile device, an electric vehicle, an electric train, a ship and a satellite, an energy storage system, etc. Here, the mobile device may be, for example, a mobile phone, a laptop, etc., and the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but is not limited to these.

[0131] As the power consuming device, a secondary battery, a battery module or a battery pack may be selected according to the usage needs.

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

[0133] Another example of the device may be a mobile phone, a tablet computer, a notebook computer, etc. These devices are generally required to be thin and lightweight, and may employ a secondary battery as a power source.

[0134] Working Example The following describes the examples of the present application. The examples described below are illustrative and are used only to interpret the present application, and should not be understood as limitations on the present application. If no specific techniques or conditions are specified in the examples, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified, the reagents or equipment used are all commercially available ordinary products.

[0135] Positive electrode plate manufacturing NCM811, acetylene black as a conductive agent, and polyvinylidene fluoride (PVDF) as an adhesive are mixed in a weight ratio of 94:3:3 in N-methylpyrrolidone (NMP) solvent system by thorough stirring to make a homogeneous mixture, then coated on both sides of aluminum foil, dried, and cold pressed to obtain a positive electrode plate, which is then cut to the corresponding size for use.

[0136] Negative plate manufacturing: A 50μm thick lithium foil is attached to the surface of the copper foil and cold pressed to produce a lithium metal anode. The composite lithium metal copper foil and bare copper foil are cut to size 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 and discharge process, lithium metal is deposited on the lithium-free anode plate.

[0137] Separator manufacturing: Prepare a precursor solution based on the formulations in Tables 1 to 5, and control the viscosity of the precursor solution to 300 mPa·s to 1000 mPa·s. Apply the precursor solution to one side of the surface of the separator (porous substrate or porous substrate with initial coating) to a coating thickness of 5 μm. Then, immediately bond it to a negative electrode plate and expose it to ultraviolet light (2 W / cm 2 The precursor solution is cured for 10 minutes, and the separator is bonded to the negative electrode plate after curing. In Tables 1 to 5, the porous substrate is a PE, PP, or PI film having a thickness of 12 μm and a porosity of about 36%, and the polymer coating in the produced separator does not completely fill the voids in the porous substrate.

[0138] The manufacturing method of 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 by slit coating. This is further applied to the opposite side of the coating side to obtain a separator with double-sided inorganic ceramic layers. A slurry (PVDF (5 wt%) is dissolved in NMP) is produced on the surface of the inorganic ceramic layer of the separator by a spin coating process, and after drying, a polymer layer distributed in an island shape can be obtained.

[0139] Test method for porosity of porous substrate: Use true density method to test porosity, place the sample cup containing the sample on the true density tester, seal the test system, introduce helium gas according to the procedure, detect the pressure of the gas in the sample chamber and the expansion chamber, and then calculate the true volume V2 according to Bore's law (PV=nRT). Use a spiral micrometer and a vernier caliper to measure the apparent volume V1 of the sample according to the volume calculation formula (V=S*h). The porosity of the sample is Porosity=(V1-V2) / V1*100%, where V1 is the apparent volume of the sample, and V2 is the true volume of the sample.

[0140] Test method for precursor solution viscosity: Use DV-2TLV instrument to perform viscosity test, the measurement range is related to the rotor and rotation speed, 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 rough range of the sample viscosity, select Multi Point data collection mode, start automatic detection, and read the viscosity data.

[0141] Observation of the separator coating: The separator containing the prepared polymer coating was placed in liquid nitrogen and cooled for 30 minutes, after which a cross-sectional sample was prepared and the cross-sectional morphology of the separator was observed by SEM. As can be seen, the coating in this example is mainly distributed on the surface of the separator substrate, and the polymer is not dispersed inside the separator substrate, and the morphology is still porous. The polymer coating in the separator thus prepared does not completely fill the voids in the porous substrate.

[0142] Secondary battery assembly: The double-sided coated positive electrode plate, the bonded separator, and the negative electrode plate are stacked to assemble into a laminated battery core, and a bare cell is assembled in the order of negative electrode plate, separator, positive electrode plate, separator, and negative electrode plate, the separator is placed between the positive and negative electrodes, and the bare cell is placed in an outer casing to obtain a dry battery core. The electrolyte solvent is EC:EMC:DMC=1:1:1 (volume ratio), the lithium salt is LiFSI, and the concentration is 1M / L. 0.3g is injected into each battery core, and after injection, the battery core is vacuum sealed and left to stand to allow infiltration.

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

[0144] [Table 1]

[0145] [Table 2]

[0146] [Table 3]

[0147] [Table 4]

[0148] [Table 5]

[0149] [Table 6]

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

[0151] The separator of Comparative Example 2 was the same as that of Comparative Example 1 except that a 3 μm ceramic layer and an island polymer layer were added to both sides of the separator.

[0152] The separator of Comparative Example 3 was the separator of Comparative Example 1 with the addition of a 3 μm ceramic layer applied on both sides.

[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 to 7 and Example 1 is the composition of the polymer coating. The composition of the negative electrode system and the separator in the secondary batteries of Comparative Examples 5 to 7 is recorded in Table 7. Here, PVDF is not added to the polymer coating in Comparative Example 6, and the polymer coating is filled into the pores of the porous substrate during the manufacturing process.

[0155] [Table 7]

[0156] Test part: Cycle life test: The secondary battery manufactured above is subjected to a life test in a constant temperature environment of 25°C, and the flow is as follows: leave it for 5 min, discharge it at 0.5C (72mA) to 2.8V, leave it for 5 min, charge it at 1 / 3C to 4.25V, then charge it at a constant voltage of 4.25V to a current ≦0.05mA, leave it for 5 min, and then discharge it at 1 / 3C to 2.8V, and the discharge capacity at this time is the initial discharge capacity and is recorded as D0. Next, according to the above flow, a cycle test is performed within the range of 2.8 to 4.25V, and the capacity value Dn (n=1, 2, 3...) is recorded for each cycle, and if the capacity value Dn<=80%*D0, the number of cycles n is recorded as the cycle life.

[0157] Ionic Conductivity Test: According to the formulations in Tables 1 to 5, the slurry was prepared and applied to the surface of the aluminum foil. The thickness of the coating was about 5 μm. Then, the slurry was cured by ultraviolet light at 2 W / cm. 2 The cured polymer layer was punched into a small disk with a diameter of 16 mm, and the thickness d of the polymer layer was measured and recorded. The punched small disk was packaged into a button cell and tested using the electrochemical AC impedance method of a Solartron 1470E CellTest multi-channel electrochemical workstation, the test temperature was 25°C, the test voltage was 10 mV, and the test frequency was 0.1 Hz to 100 KHz. A Nyquist diagram was prepared, and the obtained Nyquist diagram was analyzed using the equivalent circuit curve fitting method using Zview software, and the intersection point between the straight line and the horizontal axis was noted as R. The ionic conductivity (λ represents ionic conductivity, d represents thickness, and R represents ionic resistance) was calculated using the formula λ=d / RS.

[0158] The test data is recorded in Table 8.

[0159] [Table 8]

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

[0161] Specifically, in Examples 5 and 8, the polymer coating contains 5-20wt% linear monomer, 5-10wt% crosslinking monomer, 50-60wt% plasticizer, 5wt% thickener and 20wt% lithium salt, in which the ratio of lithium salt and plasticizer is between 20-30%, and the matrix polymer is formed by polymerizing linear monomer and crosslinking monomer in an appropriate ratio, and has a more appropriate binding force. Therefore, the polymer coating of Examples 5 and 8 has better ion conduction performance, and the cycle life is 95 and 98 cycles, respectively, and has better cycle performance.

[0162] The matrix polymer in the polymer coating in Examples 1 and 18 is obtained by polymerizing linear monomers, and the matrix polymer is a chain polymer, which has a relatively weak binding force to other components of the polymer coating. However, the matrix polymer in Examples 17, 19, and 20 is obtained by polymerizing crosslinking 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 slightly lower than that of the other Examples.

[0163] Each of the technical features of the embodiments described above can be combined in any combination. For the sake of brevity, not all possible combinations of each of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, any combination should be considered within the scope of the present specification.

[0164] The above examples only show some embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the invention patent. It should be noted that those skilled in the art can make some modifications and improvements without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application patent shall be subject to the scope of the attached claims. [Explanation of symbols]

[0165] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: secondary battery, 51: case, 52: electrode assembly, 53: cover plate, 6: power consumption device

Claims

1. A separator, A porous substrate, and 1. A separator comprising: a polymer coating, the polymer coating covering at least one surface of the porous substrate, the voids of the porous substrate being incompletely filled with the polymer coating, and the polymer coating having lithium ion conducting capability.

2. 10. The separator of claim 1, wherein components of the polymer coating include a matrix polymer, a plasticizer, a thickener, and a lithium salt.

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

4. The separator according to claim 2 or 3, wherein the mass percentage of the plasticizer in the polymer coating is 40% to 70%.

5. The separator according to any one of claims 2 to 4, characterized in that in the polymer coating, the mass percentage of the thickener is 3% to 15%.

6. The separator according to any one of claims 2 to 5, wherein the mass percentage of the lithium salt in the polymer coating is 10% to 30%.

7. 7. The separator according to claim 2, wherein the matrix polymer is at least one selected from a linear polymer and a crosslinked network polymer.

8. 8. The separator according to claim 2, wherein the plasticizer includes at least one of an ester-based plasticizer and a sulfone-based plasticizer.

9. The separator according to any one of claims 2 to 8, characterized in that the plasticizer includes 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.

10. The separator according to claim 2 , wherein the thickener is compatible with the plasticizer.

11. 11. The separator according to claim 2, wherein the thickener comprises at least one selected from polyvinyl formal, polyvinylidene fluoride and its copolymers, polydifluoroethylene, polyvinylidene fluoride, trichloroethylene, polytetrafluoroethylene, acrylic rubber, epoxy resin, polyoxyethylene, polyacrylonitrile, sodium carboxymethylcellulose, styrene butadiene rubber, polymethyl acrylate, polymethyl methacrylate, polyacrylamide, and polyvinylpyrrolidone.

12. The separator according to any one of claims 2 to 11, wherein the thickener has a weight average molecular weight of 500,000 or more.

13. The separator according to any one of claims 2 to 12, characterized in that the lithium salt includes 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 difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

14. The separator according to any one of claims 2 to 13, characterized in that the polymer coating components further comprise inorganic particles having a mass percentage of 0 to 42%.

15. The separator according to claim 14, wherein the mass percentage of the inorganic particles in the polymer coating is 20% to 30%.

16. 16. The separator according to claim 14, wherein the inorganic particles are at least one selected from the group consisting of aluminum oxide, boehmite, zirconia, aluminum nitride, titanium dioxide, magnesium oxide, silicon carbide, calcium carbonate, and diatomaceous earth.

17. The separator according to any one of claims 1 to 16, wherein the polymer coating has a thickness of 3 μm to 20 μm.

18. the separator further comprises an inorganic coating; wherein at least one of the inorganic coatings is disposed between the porous substrate and the polymer coating; Alternatively, at least one of the inorganic coatings is provided on a surface of the polymer coating away from the porous substrate, Alternatively, at least one of the inorganic coatings is provided on a surface of the porous substrate remote from the polymeric coating.

19. A method for producing a separator, comprising the steps of: mixing raw materials for producing a polymer coating to produce a precursor solution; applying the precursor solution to cover at least one surface of a porous substrate; and polymerizing the precursor solution to produce a polymer coating.

20. 20. The method for producing a separator according to claim 19, characterized in that, calculated based on mass percentage, the production raw materials include 5% to 30% of production monomers, and / or 40% to 70% of plasticizers, and / or 3% to 10% of thickeners, and / or 10% to 20% of lithium salts, and / or 0 to 42% of inorganic particles.

21. 21. The method for producing a separator according to claim 20, wherein the production monomers include at least one of a cross-linking monomer and a linear monomer, wherein the number of polymerization sites of the cross-linking monomer is at least two, and the number of polymerization sites of the linear monomer is one.

22. The method for producing a separator according to claim 21 , wherein the cross-linking monomer is an acrylate monomer.

23. 23. The method for producing a separator according to claim 21, wherein the mass percentage of the cross-linking monomer in the raw material is 0 to 30%.

24. 24. The method for producing a separator according to claim 21, wherein the linear monomer is at least one selected from the group consisting of carbonate-based monomers, sulfate-based monomers, sulfonate-based monomers, phosphate-based monomers, carboxylate-based monomers, sulfone-based monomers, amide-based monomers, nitrile-based monomers, and ether-based monomers.

25. 25. The method for producing a separator according to claim 21, wherein the mass percentage of the linear monomer in the raw material is 0 to 30%.

26. 26. The method for manufacturing a separator according to claim 19, wherein in the step of polymerizing the precursor solution, the initiation of the polymerization is one selected from the group consisting of electron beam initiation, ultraviolet initiation, and thermal initiation.

27. 27. The method for producing a separator according to claim 19, wherein the precursor solution has a viscosity of 300 mPa·s to 1000 mPa·s.

28. A secondary battery, comprising the separator according to any one of claims 1 to 18 or the separator produced by the method for producing a separator according to any one of claims 19 to 27.

29. 30. The secondary battery of claim 28, further comprising a lithium metal negative electrode plate, the lithium metal negative electrode plate being disposed on a side of the separator proximate to the polymer coating.

30. A battery module comprising the secondary battery according to claim 28 or 29.

31. A battery pack comprising the battery module according to claim 30.

32. 32. A power consuming device comprising at least one selected from the group consisting of the secondary battery according to claim 28 or 29, the battery module according to claim 30, and the battery pack according to claim 31.

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