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CN-116656278-B - Preparation method of high-wettability high-adhesion lithium battery diaphragm

CN116656278BCN 116656278 BCN116656278 BCN 116656278BCN-116656278-B

Abstract

The invention discloses a preparation method of a high-wettability high-adhesion lithium battery diaphragm, which comprises the following steps of polyethylene wax powder, alumina, an adhesive, a dispersing agent and isopropanol, wherein the surface of the diaphragm is modified by mixing the polyethylene wax powder and the alumina, so that the diaphragm has good heat resistance; the polyethylene wax powder of the polyethylene wax powder solution is coated on the surface of the aluminum oxide and permeates into pores among the aluminum oxide, so that cohesion is weakened, the aluminum oxide is easier to open under the action of external shearing force, the combined coating powder is easier to wet by electrolyte, liquid absorption of a diaphragm is increased, the circulation rate of the lithium battery diaphragm is increased, meanwhile, the high-wettability high-adhesion coating slurry prepared from the polyethylene wax powder is more uniformly coated, the viscosity of the slurry can be reduced, the surface tension of the slurry is better, the material adsorptivity is good, and the adhesion between the diaphragm and a pole piece can be increased.

Inventors

  • YUAN HAICHAO
  • XU FENG
  • WANG JIANHUA
  • Su bihai
  • TIAN HAILONG
  • LI WEI

Assignees

  • 河北金力新能源科技股份有限公司

Dates

Publication Date
20260505
Application Date
20230530

Claims (9)

  1. 1. The high-wettability high-adhesion lithium battery diaphragm is characterized by comprising a base film and a coating layer covered on one surface or two surfaces of the base film, wherein the coating layer is formed by coating high-wettability high-adhesion coating slurry, the high-wettability high-adhesion coating slurry comprises polyethylene wax powder, aluminum oxide, an adhesive, a dispersing agent and isopropanol, and the ratio of the polyethylene wax powder, the aluminum oxide, the adhesive, the dispersing agent and the isopropanol is (1-2) in (7-10) in (5-8) in (0.1-0.5) in (74-92), and the polyethylene wax powder is coated on the surface of the aluminum oxide and permeates into pores among the aluminum oxides; The preparation method of the high-wettability high-adhesion coating slurry comprises the following steps of adding isopropanol into first isopropanol and second isopropanol twice, mixing a dispersing agent, the first isopropanol and aluminum oxide, stirring, performing ultrasonic treatment to obtain a solution A, adding a polyethylene wax powder solution and an adhesive into the solution A, and simultaneously dispersing at a high speed in a vacuum environment with an ultrasonic vibration function to obtain the high-wettability high-adhesion coating slurry, wherein the polyethylene wax powder solution is obtained by mixing polyethylene wax powder and the second isopropanol and stirring.
  2. 2. The high wettability high adhesion lithium battery separator of claim 1, wherein the adhesive is an acrylate copolymer solution and the dispersant is a polyacrylate ammonium salt.
  3. 3. The high-wettability high-adhesion lithium battery separator according to claim 2, wherein the ratio of the first isopropyl alcohol to the second isopropyl alcohol is (1-2): 5-10 by mass.
  4. 4. The high-wettability high-adhesion lithium battery diaphragm according to claim 3, wherein the frequency of the ultrasonic wave is 5-8 khz, and the pressure of the vacuum environment is 0.06-0.08 kpa.
  5. 5. The high-wettability high-adhesion lithium battery separator according to claim 4, wherein the polyethylene wax powder and the second isopropyl alcohol are mixed and stirred at a rotation speed of 1000 to 1500rpm and a revolution speed of 20 to 50rpm for 10 to 20 minutes; Mixing the dispersing agent, the first isopropanol and the alumina, and stirring for 10-20 min at a rotation speed of 1500-3100 rpm and a revolution speed of 20-50 rpm.
  6. 6. The high wettability high adhesion lithium ion battery separator of claim 5, wherein the dispersing agent, the first isopropyl alcohol and the alumina are mixed and stirred, and the ultrasonic wave is applied at a frequency of 10 to 50khz for 10 to 20 minutes.
  7. 7. The high wettability high-adhesion lithium ion battery separator according to claim 6, wherein the polyethylene wax powder solution and the adhesive are added to the solution a while dispersing at a rotation speed of 1000 to 3800rpm and a revolution speed of 20 to 40rpm for 10 to 20 minutes.
  8. 8. The high-wettability high-adhesion lithium battery separator according to claim 1, wherein the particle size of the high-wettability high-adhesion coating paste is 0.583-0.869 microns and 1.449-2.078 microns.
  9. 9. The high-wettability high-adhesion lithium ion battery separator according to claim 1, wherein the preparation method of the high-wettability high-adhesion lithium ion battery separator comprises the following steps: step1, coating high-wettability high-adhesion coating slurry on a base film to obtain a coating on the base film; And 2, drying to obtain the lithium battery diaphragm with high wettability and high binding power.

Description

Preparation method of high-wettability high-adhesion lithium battery diaphragm Technical Field The invention belongs to the technical field of batteries, and particularly relates to a preparation method of a lithium battery separator with high wettability and high binding power. Background With the rapid development of modern society and the improvement of living standard, the requirements of people on lithium batteries are also higher and higher, especially on the aspects of rapid charging performance, cycle performance and safety performance of lithium ion batteries. According to the working principle of the lithium battery, li+ in the electrolyte passes through the diaphragm to reciprocate between the anode and the cathode under the action of electrode potential to finish one-time charge and discharge, under the condition that the quantity of the electrolyte is too small, the infiltration condition of the anode and the diaphragm can be seriously influenced, the process that Li+ is separated from the anode and passes through the diaphragm to reach the cathode is very slow, the quick charge performance and the circulation performance of the battery are finally influenced, the internal temperature of the battery is excessively high under the condition of overcharging and overdischarging of the lithium ion battery, at the moment, the diaphragm playing a role of a barrier can contract transversely and longitudinally, at the moment, the anode and the cathode are contacted, short circuit occurs, a large amount of heat is released by reaction, the electrolyte is decomposed in a large quantity, the internal air pressure of the battery is rapidly increased, and the battery is finally invalid and exploded. Meanwhile, the lithium ion battery is a bare cell assembled by a positive electrode plate and a negative electrode plate through winding or lamination and the like, in the traditional coating method, a single adhesive polymer coating can not simultaneously keep enough adhesive force with the positive electrode and the negative electrode, and after being soaked by electrolyte, the adhesive membrane and the negative electrode plate have almost no adhesive property, so that the cycle life of the lithium battery is influenced, and serious short circuit possibly occurs, and safety accidents are caused. Therefore, the improvement of the liquid absorption of the lithium battery and the improvement of the bonding force of the diaphragm to the pole piece are of great significance for the exertion and the safety of the electrical performance of the lithium ion battery. Disclosure of Invention Aiming at the defects of the prior art, the invention aims to provide the coating slurry with high wettability and high binding power. Another object of the present invention is to provide a method for preparing the above-mentioned high-wettability high-adhesion coating paste. The invention further aims to provide the lithium battery separator with high wettability and high binding power. The invention further aims to provide a preparation method of the high-wettability high-adhesion lithium battery separator. The aim of the invention is achieved by the following technical scheme. The high-wettability high-adhesion coating slurry comprises, by mass, polyethylene wax powder, aluminum oxide, an adhesive, a dispersing agent and isopropanol, wherein the ratio of the polyethylene wax powder to the aluminum oxide to the adhesive to the dispersing agent to the isopropanol is (1-2): (7-10): (5-8): (0.1-0.5): (74-92). In the technical scheme, the adhesive is an acrylic ester copolymer solution, and the dispersing agent is a polyacrylic acid ammonium salt. The preparation method of the high-wettability high-adhesion coating slurry comprises the following steps of adding isopropanol into first isopropanol and second isopropanol twice, mixing a dispersing agent, the first isopropanol and alumina, stirring, carrying out ultrasonic treatment to obtain a solution A, adding a polyethylene wax powder solution and an adhesive into the solution A, and simultaneously dispersing at a high speed in a vacuum environment with an ultrasonic vibration function to obtain the high-wettability high-adhesion coating slurry, wherein the polyethylene wax powder solution is obtained by mixing polyethylene wax powder and the second isopropanol and stirring. In the technical scheme, the ratio of the first isopropyl alcohol to the second isopropyl alcohol is (1-2) (5-10) in parts by weight. According to the technical scheme, after the polyethylene wax powder and the second isopropanol are mixed, stirring is carried out for 10-20 min at a rotation speed of 1000-1500 rpm and a revolution speed of 20-50 rpm. In the technical scheme, the dispersing agent, the first isopropyl alcohol and the alumina are mixed, and stirred for 10-20 min at the rotation speed of 1500-3100 rpm and the revolution speed of 20-50 rpm. In the technical scheme, the dispersing agent, the first isopro