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CN-122026003-A - Nanometer silicon coated lithium ion battery diaphragm and preparation method and application thereof

CN122026003ACN 122026003 ACN122026003 ACN 122026003ACN-122026003-A

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a nano-silicon coated lithium ion battery diaphragm and a preparation method and application thereof. The lithium ion battery diaphragm comprises a base film and a nano silicon coating layer coated on one side of the base film, wherein the raw materials of the nano silicon coating layer comprise, by mass, 5-60 parts of nano silicon, 1-10 parts of a binder, 1-5 parts of a dispersing agent, 1-5 parts of a stabilizing agent, 1-10 parts of a conductive polymer monomer, 1-5 parts of an initiator and 20-90 parts of a solvent, and the porosity of the coating layer of the lithium ion battery diaphragm is 0.3-0.8. The invention solves the technical problems of weak diaphragm functionality, influence on rate performance and the like, improves the thermal management capability of the battery, inhibits the occurrence of thermal runaway, ensures excellent rate performance and improves the energy density of the battery.

Inventors

  • GUO YUNTAO
  • LI JIAYI
  • LIU XINYU

Assignees

  • 湖南智电谷能源科技有限公司

Dates

Publication Date
20260512
Application Date
20260325

Claims (10)

  1. 1. The lithium ion battery diaphragm coated with the nano silicon is characterized by comprising a base film and a nano silicon coating layer coated on one side of the base film, wherein the nano silicon coating layer comprises the following raw materials in parts by mass: 5-60 parts of nano silicon; 1-10 parts of a binder; 1-5 parts of a dispersing agent; 1-5 parts of a stabilizer; 1-10 parts of conductive polymer monomer; 1-5 parts of an initiator; 20-90 parts of a solvent; the porosity of the coating layer of the lithium ion battery diaphragm is 0.3-0.8.
  2. 2. The lithium ion battery diaphragm according to claim 1, wherein the thickness of the coating layer of the lithium ion battery diaphragm is 50-500 nm, the material of the base film comprises at least one of polyethylene, polypropylene, polyethylene/polypropylene composite material or polyethylene/polypropylene/polyethylene composite material, and the thickness of the base film is 2-30 μm.
  3. 3. The lithium ion battery separator of claim 1, wherein the nano-silicon morphology comprises at least one of nanospheres, nanowires or nanoplatelets, the nano-silicon particle size is 5-100 nm, and the specific surface area is 10-300 m 2 /g.
  4. 4. The lithium ion battery separator of claim 1, wherein the conductive polymer monomer comprises at least one of pyrrole, thiophene and derivatives thereof, 3-hexylthiophene, 3-octylthiophene, or aniline monomers.
  5. 5. The lithium ion battery separator of claim 1, wherein the binder comprises at least one of polyvinylidene fluoride, styrene-butadiene rubber, sodium carboxymethyl cellulose, polyacrylic acid, polytetrafluoroethylene, polyethylene oxide, alginate, polyvinylidene fluoride-hexafluoropropylene copolymer, vinyl alcohol, polyurethane, or polyacrylate, the dispersant comprises at least one of sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, cetyltrimethylammonium bromide, sodium dodecyl sulfonate, sodium hexametaphosphate, polyacrylic acid, ammonium polyacrylate, or polyvinylpyrrolidone, and the stabilizer comprises at least one of sodium carboxymethyl cellulose, a polysaccharide-based derivative, sodium 2-ethyl hexane sulfosuccinate, nonylphenol polyoxyethylene ether, polyethylene oxide, sorbitan monooleate, sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, fluoroalkyl quaternary ammonium salt, oleic acid, sodium 4-styrene sulfonate, lithium dodecyl benzene sulfonate, lithium dodecyl diphenyl ether disulfonate, or lithium hexadecyl sulfophenoxy benzene sulfonate.
  6. 6. The lithium ion battery separator of claim 1, wherein the initiator comprises at least one of ziegler-natta catalyst, nickel-base, ferric chloride, ammonium persulfate, potassium permanganate, copper chloride, palladium catalyst, bis-phosphine-nickel complex, or potassium t-butoxide initiator, and the solvent comprises at least one of water, ethanol, methanol, acetone, ethyl acetate, methylene chloride, chloroform, N-hexane, benzene, toluene, xylene, diethyl ether, tetrahydrofuran, N-dimethylformamide, dimethyl sulfoxide, acetonitrile, dimethyl carbonate, diethyl carbonate, or ethylene carbonate.
  7. 7. A method for preparing the nano-silicon coated lithium ion battery separator according to any one of claims 1 to 6, comprising the steps of: (1) Uniformly mixing nano silicon with a binder, a dispersing agent, a stabilizing agent, a conductive polymer monomer, an initiator and a solvent to obtain coating slurry; (2) And (3) uniformly coating the coating slurry prepared in the step (2) on one side of the base film, and curing and drying to obtain the nano-silicon coated lithium ion battery diaphragm.
  8. 8. The lithium ion battery separator according to claim 1, wherein the slurry in the step (1) has a viscosity of 50 to 2000 mPa s。
  9. 9. The lithium ion battery separator according to claim 1, wherein the curing process in step (2) comprises at least one of thermal initiation, electron beam initiation, gamma ray initiation, ultraviolet light initiation or in situ initiation curing process, the initiation temperature is 30-100 ℃, and the curing time is 0.5-24 h; the drying temperature is 40-200 ℃, the vacuum degree is 10 Pa-10 4 Pa, and the drying time is 1-24 hours.
  10. 10. Use of a nano-silicon coated lithium ion battery separator according to any of claims 1-6 for assembling a lithium ion battery, wherein the side of the base film coated with the nano-silicon coating layer is in contact with a negative electrode.

Description

Nanometer silicon coated lithium ion battery diaphragm and preparation method and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a nano-silicon coated lithium ion battery diaphragm and a preparation method and application thereof. Background Lithium ion batteries have been widely used in the fields of consumer electronics, new energy automobiles, large-scale energy storage, and the like because of their advantages such as high energy density, long cycle life, low self-discharge rate, and the like. However, with the continuous increase of energy density and the increasing severity of application scenes, the safety problem of the battery is more and more remarkable, and particularly, serious accidents such as combustion, explosion and the like caused by thermal runaway have become key bottlenecks for restricting the development of industry. As a key component of the battery, a separator is positioned between the positive electrode and the negative electrode, and has the core function of preventing contact short circuit between the two electrodes and allowing free passage of lithium ions. Although the traditional polyolefin separator (such as PE and PP) has excellent electronic insulation property and chemical stability, the traditional polyolefin separator has the problems of poor thermal safety, extremely poor heat conductivity, insufficient electrolyte wettability and interface stability and the like, and the defects become weak links of battery safety. To improve the thermal stability of conventional separators, it is common in the industry to coat inorganic ceramic particles (e.g., alumina (Al 2O3), silica (SiO 2)) on the surface of the base film to form a ceramic coated separator. Such a separator does improve the high temperature resistance of the separator (can maintain the skeleton structure at high temperature), preventing the risk of short circuit due to thermal shrinkage to some extent. However, there are significant limitations to existing ceramic coated membranes. Firstly, the traditional ceramic coating has a single function, mainly solves the problem of heat shrinkage, but has a limited heat conduction property (for example, al 2O3 has a heat conduction coefficient of about 30W/(m.K)), and has limited contribution to improving the heat management capability of the whole battery system, and cannot effectively inhibit local overheating and heat spreading, secondly, the coating thickness is increased to seek high heat stability and lithium dendrite penetration resistance, the whole porosity of the diaphragm is reduced, the lithium ion transmission distance is increased, and the ion transmission resistance is increased, so that the rate performance of the battery is negatively influenced. Therefore, developing a novel composite diaphragm with excellent thermal safety, high thermal conductivity and good multiplying power performance has great significance for fundamentally improving the safety performance of the lithium ion battery, prolonging the service life and widening the application scene, and is also a technical problem to be solved urgently by the technicians in the field. Disclosure of Invention The invention provides a nano-silicon coated lithium ion battery diaphragm and a preparation method and application thereof, and aims to solve the technical problems of weak diaphragm functionality, influence on rate performance and the like, improve the thermal management capability of a battery, inhibit the occurrence of thermal runaway, ensure excellent rate performance and improve the energy density of the battery. In order to achieve the above purpose, the invention provides a nano-silicon coated lithium ion battery diaphragm, which comprises a base film and a nano-silicon coating layer coated on one side of the base film, wherein the raw materials of the nano-silicon coating layer comprise the following components in parts by mass: 5-60 parts of nano silicon; 1-10 parts of a binder; 1-5 parts of a dispersing agent; 1-5 parts of a stabilizer; 1-10 parts of conductive polymer monomer; 1-5 parts of an initiator; 20-90 parts of a solvent; the porosity of the coating layer of the lithium ion battery diaphragm is 0.3-0.8. The application selects nano silicon as the coating material of the lithium ion battery diaphragm, and compared with the traditional coating material, the nano silicon has the following two characteristics: 1. the nano silicon has high heat conductivity coefficient and strong heat dissipation capacity, can be used as a filler to physically protect the diaphragm, improves the strength of the diaphragm and prevents the short circuit effect caused by heat shrinkage; 2. The nano silicon has higher lithium intercalation capacity, but has large volume expansion, easy deactivation and lower conductivity when intercalating and deintercalating lithium; aiming at the characteristics of nano silicon, the application