CN-121282568-B - Diaphragm and battery

CN121282568BCN 121282568 BCN121282568 BCN 121282568BCN-121282568-B

Abstract

The invention provides a diaphragm and a battery, the diaphragm comprises a carrier layer and a glue layer positioned on at least one side surface of the carrier layer, the carrier layer comprises a substrate layer and an organic coating positioned on at least one side surface of the substrate layer, the organic coating comprises first particles, the components of the first particles comprise dicyclic organic matters, the molecular structure of the dicyclic organic matters comprises dicyclic structures formed by 2-mercaptoimidazole rings sharing 2 adjacent carbon atoms and benzene rings, the glue layer has a porous continuous phase structure, the glue layer comprises a polymer forming a porous structure and second particles, the diaphragm meets the following relation of 1-15 and B 1 /N 1 , wherein B 1 is Dv50 of the second particles, the unit is [ mu ] m, N 1 is Dv10 of the first particles, and the unit is [ mu ] m. The battery of the invention comprises the separator. The separator can weaken or even eliminate static accumulation phenomenon, has higher binding force and electrolyte wettability, and ensures that the battery has low self-discharge rate and long-cycle stability.

Inventors

ZHANG LIUHAO
CUI HONGYU
CAO XIAODONG
WU ZHIJIE
ZHONG JUNDONG

Assignees

珠海冠宇电池股份有限公司

Dates

Publication Date: 20260512
Application Date: 20251205

Claims (12)

1. A separator is characterized in that the separator comprises a carrier layer and a glue layer positioned on at least one side surface of the carrier layer, the carrier layer comprises a substrate layer and an organic coating positioned on at least one side surface of the substrate layer, the organic coating comprises first particles, the components of the first particles are dicyclic organic matters, the molecular structure of the dicyclic organic matters comprises a dicyclic structure formed by 2-mercaptoimidazole rings sharing 2 adjacent carbon atoms and benzene rings, the glue layer has a porous structure, the glue layer comprises a polymer forming the porous structure and second particles, and the separator meets the following relation of 1-B 1 /N 1 -15, wherein B 1 is Dv50 of the second particles, the unit is Dv10 of the first particles, the unit is [ mu ] m, the Dv10 of the first particles is 0.05-1 [ mu ] m, and/or the Dv50 of the second particles is 0.1-1.2 [ mu ] m.
2. The separator of claim 1, wherein substituents are present or absent on the benzene rings in the bicyclic structure, the substituents selected from one or more of C1-C6 alkyl, C1-C6 alkoxy, hydroxy, amino, cyano, halogen substituents, sulfonic acid groups, carboxyl, and nitro; And/or the ratio of the weight of the polymer to the weight of the second particles is (3-19): 7-1; and/or the glue layer is continuously coated or discontinuously coated.
3. The separator of claim 1, wherein the bicyclic organic is 2-mercaptobenzimidazole or a 2-mercaptobenzimidazole derivative; And/or the polymer comprises one or more of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, polyhexafluoropropylene, vinyl fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, poly-paraphenylene terephthalamide, poly-m-phenylene isophthalamide, phenolic resin and polyimide; and/or the weight ratio of the first particles in the organic coating is 75% -99%; and/or the organic coating further comprises a first binder, wherein the weight ratio of the first binder in the organic coating is 1-25%; and/or the thickness of the organic coating is 0.2 μm to 5 μm; and/or the thickness of the adhesive layer on one side is 0.5-5 μm; and/or the adhesive layers are positioned on the two side surfaces of the carrier layer, and the thicknesses of the adhesive layers positioned on the two side surfaces of the carrier layer are the same or different.
4. A separator as claimed in claim 3, wherein the weight ratio of the first particles in the organic coating is 90-98%; And/or the weight ratio of the first binder in the organic coating layer is 2-10%; And/or the 2-mercaptobenzimidazole derivative comprises one or more of 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-5-ethoxybenzimidazole, 2-mercapto-5-hydroxybenzimidazole, 2-mercapto-5-aminobenzimidazole, 2-mercapto-5-chlorobenzimidazole, 2-mercapto-5-sulfobenzimidazole, 2-mercapto-5-carboxybenzimidazole, 2-mercapto-5-nitrobenzimidazole, 2-mercaptobenzimidazole lithium salt, 2-mercaptobenzimidazole sodium salt, 2-mercaptobenzimidazole potassium salt, 2-mercaptobenzimidazole calcium salt, 2-mercaptobenzimidazole magnesium salt, 2-mercaptobenzimidazole aluminum salt and 2-mercaptobenzimidazole ammonium salt; And/or the first binder comprises one or more of polyvinyl alcohol, styrene-butadiene rubber, ethylene-vinyl acetate copolymer, sodium carboxymethylcellulose, polyvinylpyrrolidone, styrene-acrylic latex, polyacrylonitrile, polyacrylic acid, polyvinyl acetate, acrylic acid-based binder, polyurethane, polyvinylidene fluoride-hexafluoropropylene or a copolymer system derived from the above polymers; And/or the organic coating is positioned on the surface of one side of the substrate layer, the adhesive layer is positioned on the surface of the organic coating and the surface of the other side of the substrate layer, the adhesive layer positioned on the surface of the organic coating is a first adhesive layer, the adhesive layer positioned on the surface of the other side of the substrate layer is a second adhesive layer, and the thickness of the first adhesive layer is smaller than that of the second adhesive layer.
5. The separator of claim 1, wherein the composition of the second particles comprises one or more of 2-mercaptobenzimidazole, 2-mercaptobenzimidazole derivatives, melamine cyanurate, melamine thiocyanate, melamine polyphosphate, uracil, cytosine, guanine, 4-amino-2, 6-dihydroxypyrimidine, alumina, boehmite, barium sulfate, silica, tin dioxide, titanium oxide, barium titanate, magnesium oxide, boron nitride, and magnesium hydroxide.
6. The separator of claim 5, wherein the weight ratio of the first particles in the organic coating is 90% -98%; And/or the 2-mercaptobenzimidazole derivative comprises one or more of 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-5-ethoxybenzimidazole, 2-mercapto-5-hydroxybenzimidazole, 2-mercapto-5-aminobenzimidazole, 2-mercapto-5-chlorobenzimidazole, 2-mercapto-5-sulfobenzimidazole, 2-mercapto-5-carboxybenzimidazole, 2-mercapto-5-nitrobenzimidazole, 2-mercaptobenzimidazole lithium salt, 2-mercaptobenzimidazole sodium salt, 2-mercaptobenzimidazole potassium salt, 2-mercaptobenzimidazole calcium salt, 2-mercaptobenzimidazole magnesium salt, 2-mercaptobenzimidazole aluminum salt and 2-mercaptobenzimidazole ammonium salt; And/or the organic coating is positioned on the surface of one side of the substrate layer, the adhesive layer is positioned on the surface of the organic coating and the surface of the other side of the substrate layer, the adhesive layer positioned on the surface of the organic coating is a first adhesive layer, the adhesive layer positioned on the surface of the other side of the substrate layer is a second adhesive layer, and the thickness of the first adhesive layer is smaller than that of the second adhesive layer.
7. The separator of claim 4, wherein the difference between the thickness of the second glue layer and the thickness of the first glue layer is 0.1-0.8 μm.
8. The separator of claim 1, wherein in the porous structure of the gel layer, the porous structure comprises pores, polymer fibers are present between edges of the pores and adjacent the pores, the polymer fibers having a diameter of 0.1-0.3 μm; And/or the number of holes with a diameter greater than 1 μm is 80-1500 in an area of arbitrarily selected 100 μm×100 μm on the surface of the glue layer.
9. The separator of any of claims 1-8, wherein the first particles have a solubility of less than or equal to 5% in a polar solvent selected from one or more of N-methylpyrrolidone, N-dimethylacetamide; and/or the puncture strength of the substrate layer is 200gf-500gf; and/or the porosity of the substrate layer is 30% -60%; and/or the aperture of the substrate layer is 20nm-75nm; and/or the average pore diameter of the substrate layer is 30nm-50nm; and/or the thickness of the substrate layer is 3 μm to 16 μm; And/or the components of the substrate layer comprise polyolefin, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyethylene terephthalate, polybutylene terephthalate, poly (p-phenylene terephthalamide), poly (m-phenylene isophthalamide) or one or more of the above polymer derivatives.
10. A battery comprising a positive electrode sheet, a negative electrode sheet, and the separator of any one of claims 1-9, the separator being located between the positive electrode sheet and the negative electrode sheet.
11. The battery according to claim 10, wherein in the separator, the organic coating layer is located on a surface of one side of the substrate layer, the adhesive layer is located on a surface of the organic coating layer and a surface of the other side of the substrate layer, wherein the adhesive layer located on the one side of the organic coating layer is a first adhesive layer, the adhesive layer located on the one side of the substrate layer is a second adhesive layer, the positive electrode sheet corresponds to the side of the separator where the organic coating layer is present, the negative electrode sheet corresponds to the other side of the separator, and a thickness of the first adhesive layer is smaller than a thickness of the second adhesive layer; and/or the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer positioned on one side or two side surfaces of the negative electrode current collector, wherein the negative electrode active layer comprises a silicon-based material, and the silicon-based material comprises one or more of a simple substance silicon material, a silicon-oxygen material, a silicon-carbon material, a silicon-nitrogen composite material and a silicon alloy material.
12. The battery of claim 11, wherein the difference between the thickness of the second glue layer and the thickness of the first glue layer is 0.1-0.8 μιη; and/or the negative electrode sheet comprises a negative electrode current collector and a negative electrode active layer positioned on one side or two side surfaces of the negative electrode current collector, wherein the negative electrode active layer comprises a silicon carbon material, and the average grain diameter of the silicon carbon material is 5-12 mu m.

Description

Diaphragm and battery Technical Field The invention relates to the technical field of batteries, in particular to a diaphragm and a battery comprising the diaphragm. Background Compared with other secondary batteries, the lithium ion battery has the advantages of high energy density, long cycle life, small self-discharge, no memory effect and the like, and has been widely accepted and applied to the market since the advent of the prior art. The lithium ion battery is generally composed of anode and cathode materials, a diaphragm and electrolyte, wherein the diaphragm is used as a barrier material between the anode and cathode materials, and the main function of the diaphragm is to prevent the anode and the cathode from being directly contacted and the electron transmission between the anode and the cathode, and meanwhile, ions in the electrolyte can reach the anode and the cathode through the diaphragm. Currently, the main stream commercial separator is mostly made of high polymer materials (such as Polyethylene (PE), polypropylene (PP), polyimide and aramid fiber), and the materials have excellent electrochemical stability and mechanical strength. However, high molecular materials, particularly polyolefin materials, have extremely high resistivity and are prone to develop and accumulate large amounts of static charge due to friction during production and processing. This phenomenon of static accumulation causes a series of serious technical difficulties. Firstly, the charged diaphragm can strongly adsorb tiny particles such as dust, metal fragments and the like in the environment, and the impurities are introduced into the battery core in the subsequent battery assembly process, so that the diaphragm is extremely easy to puncture, internal short circuit is caused, the self-discharge rate of the battery is increased, and the cycle life is reduced. In addition, in the high-speed winding or lamination process, the diaphragm can be adhered and misplaced with the pole piece due to electrostatic adsorption, so that the winding is uneven, the lamination precision is reduced, the production efficiency and the product yield are seriously restricted, meanwhile, the strong static electricity can generate electrostatic discharge in the production process, and the precise battery manufacturing equipment is interfered or damaged, so that the processing capability of the battery is seriously reduced. Therefore, it is important to invent a battery including a separator that can reduce or even eliminate static electricity accumulation. Disclosure of Invention In the prior art, in order to eliminate static charges of high polymer materials, particularly polyolefin materials, the surface of the diaphragm is generally modified or coated with an antistatic coating, but the problems of weak coating adhesion, influence on the diaphragm pore structure, poor compatibility with electrolyte and the like often exist, so that the wettability or ionic conductivity of the diaphragm can be reduced, the interface performance between the diaphragm and a pole piece is reduced, and the long-cycle performance of a battery is influenced. In order to simultaneously solve the problems that in the prior art, the separator is easy to accumulate static electricity and the adhesiveness of the separator coating and the wettability of electrolyte are reduced after the separator is modified or coated with an antistatic coating, the invention provides a separator and a battery comprising the separator. The membrane can weaken or even eliminate the phenomenon of static accumulation, reduce or even avoid the adsorption of impurities by the membrane, reduce or even prevent the risk of internal short circuit caused by the puncture of the membrane, thereby effectively reducing the self-discharge rate of the battery, improving the long-cycle stability and safety of the battery, simultaneously, the membrane also has higher binding force and electrolyte wettability, ensures the structural integrity and good ionic conductivity of the membrane, improves the interface performance between the membrane and a pole piece, and improves the long-cycle performance of the battery. In order to achieve the above object, a first aspect of the present invention provides a separator comprising a support layer and a gel layer on at least one side surface of the support layer, the support layer comprising a substrate layer and an organic coating layer on at least one side surface of the substrate layer, the organic coating layer comprising first particles whose composition comprises a bicyclic organic substance whose molecular structure comprises a bicyclic structure formed of 2-mercaptoimidazole rings sharing 2 adjacent carbon atoms and benzene rings, the gel layer having a porous structure, the gel layer comprising a polymer forming the porous structure and second particles, the separator satisfying the following relationship 1≤B 1/N1≤15, wherein B 1 is Dv50 of the second part