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CN-121238173-B - Diaphragm and battery

CN121238173BCN 121238173 BCN121238173 BCN 121238173BCN-121238173-B

Abstract

The invention provides a separator and a battery. The membrane comprises a substrate layer, an organic coating layer positioned on one side or two side surfaces of the substrate layer and a glue layer positioned on at least the surface of the organic coating layer, wherein the organic coating layer comprises a dicyclic organic matter, the molecular structure of the dicyclic organic matter comprises 2-mercaptoimidazole rings and six-membered rings which share 2 adjacent carbon atoms, the six-membered rings are benzene rings or benzene rings substituted by characteristic groups, the glue layer comprises first polymer particles, and the average particle size of the first polymer particles is 0.5-1.5 mu m. The diaphragm provided by the invention can improve the infiltration effect between the diaphragm and the electrode plate interface, and reduce the risk of lithium separation at the interface, so that the rate capability and long-cycle stability of the battery are improved. The battery of the present invention includes the separator of the present invention.

Inventors

  • WU ZHIJIE
  • CAO XIAODONG

Assignees

  • 珠海冠宇电池股份有限公司

Dates

Publication Date
20260512
Application Date
20251203

Claims (11)

  1. 1. A separator, characterized in that the separator comprises a substrate layer, an organic coating layer positioned on one side or two side surfaces of the substrate layer and a glue layer positioned on at least the surface of the organic coating layer, wherein the organic coating layer comprises first particles, the components of the first particles are dicyclic organic matters, the molecular structure of the dicyclic organic matters comprises 2-mercaptoimidazole rings and six-membered rings which share 2 adjacent carbon atoms, the six-membered rings are benzene rings or benzene rings substituted by characteristic groups, the weight ratio of the first particles is 90% -99% based on the total weight of the organic coating layer, the glue layer comprises first polymer particles, and the average particle size of primary particles of the first polymer particles is 0.5 μm-1.5 μm.
  2. 2. The separator of claim 1, wherein the characteristic group is selected from one or more of C1-C6 alkyl, C1-C6 alkoxy, hydroxy, amino, cyano, halogen substituent, sulfonic acid group, carboxyl, and nitro.
  3. 3. The separator according to claim 2, wherein the first particles have a particle diameter satisfying the relationship of 0.5≤Dv90-Dv10)/Dv50≤2.4; and/or, the Dv10 of the first particles is 0.1 μm to 0.5 μm; and/or, the Dv50 of the first particles is 0.2 μm to 1 μm; And/or, the Dv90 of the first particles is 0.5 μm to 2 μm; And/or the separator satisfies the following relation D 1 /D 2 & lt 3.5 & gt, wherein D 1 is the average particle size of primary particles of the first polymer particles, the unit is [ mu ] m, and D 2 is the Dv50 of the first particles, the unit is [ mu ] m.
  4. 4. The separator of claim 1, wherein the subbing layer further comprises second polymer particles having an average primary particle size of 150nm to 250nm; And/or the dicyclo organic matter is selected from at least one of 2-mercaptobenzimidazole and 2-mercaptobenzimidazole derivatives.
  5. 5. The separator of claim 4, wherein the second polymer particles comprise secondary particles polymerized from primary particles, the secondary particles having an average particle size of 3-20 μm; And/or the second polymer particles comprise secondary particles formed by polymerizing primary particles, and the number of the secondary particles with the particle size of more than or equal to 3 mu m is 10-70 in a single SEM image shot at 2500 times of the surface of the adhesive layer; And/or soaking in a test electrolyte at 60 ℃ for 72 hours, wherein the swelling degree of the second polymer particles is less than 60%, the test electrolyte consists of lithium hexafluorophosphate, ethylene carbonate, methyl ethyl carbonate and dimethyl carbonate, the concentration of the lithium hexafluorophosphate is 1mol/L, and the volume ratio of the ethylene carbonate, the methyl ethyl carbonate and the dimethyl carbonate is 1:1:1; and/or the ratio of the weight of the first polymer particles to the weight of the second polymer particles is (0.2-8.5): 1; And/or the components of the second polymer particles comprise at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl fluoride, polyhexafluoropropylene, vinyl fluoride-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polymethyl methacrylate, polyethyl hexyl acrylate, polybutyl acrylate, acrylic monomer-acrylonitrile copolymer, acrylic monomer-acrylonitrile-ethylene copolymer, styrene-acrylic monomer-acrylonitrile copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-N, N-dimethylacrylamide copolymer, ethyl acrylate-2- (diethylamino) ethyl acrylate copolymer, ethyl acrylate-N, N-diethylacrylamide copolymer.
  6. 6. The separator of claim 1, wherein the coverage of the glue layer is 10% -70%; And/or the bicyclic organic is selected from one or more of 2-mercapto benzimidazole, 2-mercapto-5-methylbenzimidazole, 2-mercapto-5-ethylbenzimidazole, 2-mercapto-5-propylbenzimidazole, 2-mercapto-5-methoxybenzimidazole, 2-mercapto-5-ethoxybenzimidazole, 2-mercapto-5-hydroxy benzimidazole, 2-mercapto-5-aminobenzimidazole, 2-mercapto-5-chlorobenzimidazole, 2-mercapto-5-bromobenzimidazole, 2-mercapto-5-sulfobenzimidazole, 2-mercapto-5-carboxybenzimidazole, 2-mercapto-5-nitrobenzimidazole, 2-mercapto-5-fluorobenzimidazole, 2-mercapto-5, 6-dichlorobenzimidazole, 2-mercapto-5-cyanobenzimidazole; And/or the components of the first polymer particles comprise one or more of polymethyl methacrylate, polyethyl hexyl acrylate, polybutyl acrylate, acrylic ester monomer-acrylonitrile copolymer, acrylic ester monomer-acrylonitrile-ethylene copolymer, styrene-acrylic ester monomer-acrylonitrile copolymer, ethylhexyl acrylate-methyl methacrylate copolymer, butyl acrylate-methyl methacrylate copolymer, methyl acrylate-acrylic acid-N, N-dimethylacrylamide copolymer, ethyl acrylate-acrylic acid-2- (diethylamino) ethyl acrylate copolymer, ethyl acrylate-acrylic acid-N, N-diethylacrylamide copolymer; And/or the glass transition temperature of the first polymer particles is 45 ℃ to 95 ℃; And/or soaking in a test electrolyte at 60 ℃ for 72 hours, wherein the swelling degree of the first polymer particles is greater than 100%, the test electrolyte consists of lithium hexafluorophosphate, ethylene carbonate, methyl ethyl carbonate and dimethyl carbonate, the concentration of the lithium hexafluorophosphate is 1mol/L, and the volume ratio of the ethylene carbonate, the methyl ethyl carbonate and the dimethyl carbonate is 1:1:1.
  7. 7. The separator of any of claims 1-6, wherein the ratio of the number of first polymer particles having a particle size of less than or equal to 0.4 μιη at the surface of the gum layer to the total number of first polymer particles is 0.5-10%; And/or soaking in a test electrolyte at 60 ℃ for 72 hours, wherein the swelling degree of the first polymer particles is 120-300%, the test electrolyte consists of lithium hexafluorophosphate, ethylene carbonate, methyl ethyl carbonate and dimethyl carbonate, the concentration of the lithium hexafluorophosphate is 1mol/L, and the volume ratio of the ethylene carbonate, the methyl ethyl carbonate and the dimethyl carbonate is 1:1:1; And/or the adhesive layer is positioned at two sides of the substrate layer, and the components of the first polymer particles in the adhesive layer positioned at two sides of the substrate layer are the same or different; And/or the organic coating further comprises a first binder, wherein the weight ratio of the first binder is 1-10%.
  8. 8. The separator of any of claims 1-6, wherein the glue layer is located on both sides of the substrate layer, wherein the glue layer on one side of the substrate layer comprises second polymer particles and the glue layer on the other side of the substrate layer does not comprise second polymer particles.
  9. 9. The separator of any of claims 1-6, wherein the thickness of the organic coating is 0.3-4 μιη; And/or the thickness of the adhesive layer is 0.5-5 μm; and/or the thickness of the substrate layer is 3 μm to 16 μm; and/or the porosity of the substrate layer is 30% -70%; and/or the average pore diameter of the substrate layer is 30nm-50nm; And/or the substrate layer has a permeability of 50s/100cc to 180s/100cc; 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. 10. A battery comprising a negative electrode sheet, a positive electrode sheet, an electrolyte, and the separator of any one of claims 1-9 between the negative electrode sheet and the positive electrode sheet.
  11. 11. The battery according to claim 10, wherein one side of the separator where the organic coating is present corresponds to the positive electrode sheet, and the other side corresponds to the negative electrode sheet; And/or the adhesive layers in the diaphragm are positioned at two sides of the substrate layer, the adhesive layer corresponding to the positive electrode plate is a first adhesive layer, the adhesive layer corresponding to the negative electrode plate is a second adhesive layer, the first adhesive layer comprises second polymer particles, and the second adhesive layer does not comprise second polymer particles; 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 silicon carbon particles, the battery satisfies the following relation that D 1 /D 3 is more than or equal to 0.05 and less than or equal to 0.15, wherein D 1 is the average particle size of primary particles of the first polymer particles, the unit is mu m, and D 3 is the average particle size of the silicon carbon particles, and the unit is 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 The lithium ion battery is used as a high-efficiency energy storage carrier and is widely applied to the fields of consumer electronics, electric automobiles, large-scale energy storage and the like. With the increasing energy density demands of batteries, solving the rate capability and long cycle life of batteries has become a technical problem. Currently, electrochemical performance and safety of lithium ion batteries are highly dependent on effective impregnation of the internal materials. The pores between the positive and negative plates and the diaphragm are required to be fully filled with electrolyte so as to ensure efficient and uniform migration of lithium ions. However, the existing pole piece (especially thick electrode) and the diaphragm have the problems of insufficient electrolyte infiltration and uneven distribution, thereby obviously increasing ion migration impedance, leading to increased internal resistance and aggravated polarization of the battery, rapidly attenuating capacity during high-current charge and discharge, deteriorating rate performance, and simultaneously accelerating lithium precipitation at the interface between the diaphragm and the pole piece in the long-cycle use process, and seriously affecting the long cycle life of the battery. Therefore, the battery capable of improving the wettability of the electrolyte between the diaphragm and the pole piece is very important to improve the multiplying power performance and the long-cycle stability of the battery. Disclosure of Invention In order to solve the technical problems of reduced rate performance and deteriorated interfacial lithium precipitation caused by poor infiltration effect between the separator and the electrode plate interface, the invention provides a separator and a battery comprising the separator. In the diaphragm and the battery, the interface between the diaphragm and the pole piece has good electrolyte infiltration effect, the serious lithium separation risk of the interface between the diaphragm and the pole piece is reduced, and the rate capability and the long-cycle stability of the battery can be effectively improved. In order to achieve the above object, a first aspect of the present invention provides a separator comprising a substrate layer, an organic coating layer located on one or both side surfaces of the substrate layer, and a gel layer located at least on the surface of the organic coating layer, the organic coating layer comprising a bicyclic organic substance having a molecular structure including a 2-mercaptoimidazole ring sharing 2 adjacent carbon atoms and a six-membered ring which is a benzene ring or a benzene ring substituted with a characteristic group, the gel layer comprising first polymer particles having an average particle diameter of primary particles of 0.5 μm to 1.5 μm. A second aspect of the invention provides a battery comprising a negative electrode sheet, a positive electrode sheet, an electrolyte, and a separator provided in the first aspect of the invention, the separator being located between the negative electrode sheet and the positive electrode sheet. Through the technical scheme, compared with the prior art, the invention has at least the following advantages: The membrane comprises an organic coating containing a dicyclic organic matter, wherein the dicyclic organic matter comprises polar groups of sulfhydryl (-SH), secondary amino (N-H) and pyridine nitrogen atoms (N=), the polar groups enable the membrane to have good electrolyte wettability, so that the organic coating containing the dicyclic compound has good electrolyte wettability, electrolyte is fully infiltrated and uniformly distributed between the membrane and a pole piece, the rate capability of a battery is improved, the risk of serious lithium precipitation between the membrane and the pole piece interface is reduced, meanwhile, the adhesive layer on the surface of the organic coating comprises first polymer particles, the first polymer particles enable the membrane to have good adhesion, the interface adhesion between the membrane and the pole piece can be enhanced, the average particle size of the first polymer particles in the adhesive layer is controlled, the problem of insufficient membrane adhesion caused by excessively small particles of the first polymer particles can be improved, the risk of swelling and blocking holes of the first polymer particles due to excessively large particles can be improved or even avoided, the membrane is ensured to have good adhesion and pores, the rate of the membrane is further improved, the lithium precipitation rate and the lithium precipitation rate of the membrane is improved under the conditions of high cooperation with the high rate of the membrane and the pole piece interface is a