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CN-115020805-B - Composite solid electrolyte membrane, preparation method thereof and solid lithium battery

CN115020805BCN 115020805 BCN115020805 BCN 115020805BCN-115020805-B

Abstract

The invention discloses a composite solid electrolyte membrane and a preparation method thereof, and a solid lithium battery, wherein the composite solid electrolyte membrane comprises a porous membrane matrix and a solid polymer electrolyte body, the solid polymer electrolyte body comprises alcoholysis matters of vinyl ester-acrylic ester segmented copolymer, polyethylene oxide, epoxy-terminated polyethylene oxide, amino-terminated polyoxyalkylene and lithium salt, and the solid polymer electrolyte body is arranged on the upper surface and the lower surface of the porous membrane matrix, and at least part of the solid polymer electrolyte body is embedded into pores of the porous membrane matrix. The composite solid electrolyte membrane has higher lithium ion migration number, conductivity and mechanical strength.

Inventors

  • XU JIAN
  • AN MAN
  • CHANG DA
  • CHEN TONGHONG
  • CHENG ZHIXIU
  • ZHAO YILI

Assignees

  • 中国乐凯集团有限公司

Dates

Publication Date
20260512
Application Date
20220607

Claims (8)

  1. 1. A composite solid electrolyte membrane comprising: A porous membrane matrix; A solid polymer electrolyte body including an alcoholate of a vinyl ester-acrylate block copolymer, polyethylene oxide, epoxy-terminated polyethylene oxide, amino-terminated polyethylene oxide, and a lithium salt, the solid polymer electrolyte body being provided on upper and lower surfaces of the porous membrane substrate and at least a portion of the solid polymer electrolyte body being embedded in pores of the porous membrane substrate; the solid polymer electrolyte body comprises 10-70 parts by weight of polyethylene oxide, 1-20 parts by weight of epoxy-terminated polyethylene oxide, 2-30 parts by weight of amino-terminated polyalkylene oxide, 3-55 parts by weight of alcoholysis product of vinyl ester-acrylic ester block copolymer and 10-50 parts by weight of lithium salt; The alcoholysis degree of the alcoholysis product of the vinyl ester-acrylic ester segmented copolymer is 65% -100%; The molar ratio of vinyl ester to acrylic ester in the alcoholysis product of the vinyl ester-acrylic ester block copolymer is 1:5-4:1.
  2. 2. The composite solid electrolyte membrane of claim 1 wherein the acrylate comprises at least one of methyl acrylate, methyl methacrylate, ethyl acrylate, butyl acrylate, ethyl methacrylate, and butyl methacrylate.
  3. 3. The composite solid electrolyte membrane of claim 1 wherein the epoxy-terminated polyethylene oxide comprises at least one of cyclohexanedimethanol diglycidyl ether, monoglycidyl ethers of C12-C14 alcohols, butanediol diglycidyl ether, tert-butylphenol monoglycidyl ether, trimethylolpropane triglycidyl ether, polypropylene glycol diglycidyl ether, and 1, 6-hexanediol diglycidyl ether; Optionally, the epoxy equivalent of the epoxy-terminated polyethylene oxide is 150-700 g/Eq.
  4. 4. The composite solid electrolyte membrane of claim 1 wherein the amino-terminated polyoxyalkylene comprises at least one of D-205, D-400, D-230, EDR-148, T-430, SD-401, ED-900, and T-5000; Optionally, the average AHEW of the amino-terminated polyoxyalkylene is 120 to 800g/Eq.
  5. 5. The composite solid electrolyte membrane according to claim 1, wherein the polyethylene oxide has a molecular weight of 35 to 80 tens of thousands; Optionally, the thickness of the porous film matrix is 6-16 mu m, and the gram weight is 10-100 g/m 2 ; Optionally, the porous membrane matrix comprises at least one of polyethylene terephthalate, polypropylene, polyethylene, polyvinylidene fluoride, aramid, nylon-10, and nylon-66.
  6. 6. A method of preparing the composite solid electrolyte membrane of any one of claims 1 to 5, comprising: (1) Mixing an alcoholysis product of a vinyl ester-acrylate block copolymer, polyethylene oxide and a solvent to obtain a first mixed solution; (2) Mixing the first mixed solution with epoxy-terminated polyethylene oxide, amino-terminated polyethylene oxide and lithium salt to obtain a solid polymer electrolyte slurry; (3) Coating the solid polymer electrolyte slurry on the upper and lower surfaces of the porous membrane matrix, then placing the porous membrane matrix into a heating device for step heating, and drying at constant temperature to obtain the composite solid electrolyte membrane.
  7. 7. The method for producing a composite solid electrolyte membrane according to claim 6, wherein in step (3), the stepwise temperature increase includes a solvent evaporation stage, a first polymerization stage and a second polymerization stage, The temperature of the solvent volatilization section is 30-60 ℃, the temperature of the first polymerization stage is 50-70 ℃, the temperature of the second polymerization stage is 60-90 ℃, and the total temperature holding time of each stage of step heating is 30 min-2 h.
  8. 8. A solid lithium battery comprising a positive electrode, a negative electrode and a solid electrolyte membrane, wherein the solid electrolyte membrane is the composite solid electrolyte membrane according to any one of claims 1 to 5 or the composite solid electrolyte membrane obtained by the method according to claim 6 or 7.

Description

Composite solid electrolyte membrane, preparation method thereof and solid lithium battery Technical Field The invention belongs to the field of lithium ion batteries, and particularly relates to a composite solid electrolyte membrane, a preparation method thereof and a solid lithium battery. Background At present, along with the urgent global demand for new energy materials, in recent years, the lithium ion battery has the advantages of high voltage, high energy density, long cycle life, wide electrochemical window and the like, and is rapidly applied and developed. However, the conventional lithium battery inevitably has potential safety hazards due to the adoption of liquid electrolyte, so that the problem can be fundamentally solved by developing a solid-state lithium ion battery. The structure of the all-solid-state lithium ion battery comprises a positive electrode, a solid electrolyte and a negative electrode. The solid electrolyte plays a role of a diaphragm and can prevent electron transmission while conducting lithium ions. Compared with the traditional lithium battery, the solid-state lithium battery has the advantages that firstly, the risk of spontaneous combustion or explosion of the solid-state battery is remarkably reduced, and the safety is high. And secondly, the anode and cathode materials are optimized, inactive ingredients are reduced, and the energy density is improved. Thirdly, the electrolyte does not generate the problem of dry up when the solid electrolyte circulates for a long time, and the circulating life is long. In view of the advantages and prospects of solid-state lithium ion batteries, the solid-state lithium ion batteries are favored by research institutions, large-scale electronics and automobile manufacturing companies in various countries. The governments of various countries are continuously sending policies for encouraging the research, development and industrialization of solid-state batteries, and in the process, solid-state electrolytes are emerging in various types of materials such as inorganic materials, polymers, organic/inorganic composite materials and the like, wherein if a polymer system can break through a series of technical bottlenecks such as electrical property improvement and the like, the polymer system is put into practical industrial application. Among the solid polymer electrolytes, polyether, polyamine, polyester, etc., are classified according to the molecular structure of the polymer matrix, and these polymer electrolytes form materials having ion-conducting properties by complexation and decomplexing with Li +. Among polyether-based polymer electrolytes, polyethylene oxide (PEO) has been widely used as a host of polymer electrolytes in the past several decades because of its high dielectric constant, facilitating dissociation of lithium salts. In polymer PEO, li + conduction relies primarily on Li + complexing with anions on the PEO segment, while this conduction occurs primarily in the amorphous region. At normal temperature, PEO crystallinity is very strong, and therefore, the polymer electrolyte ion conductivity of the conventional PEO-Li + system is low (10 -7～10-6S cm-1, 25 ℃). Furthermore, PEO is low in strength and cannot inhibit lithium dendrite growth, which further hinders its application. Accordingly, the existing solid electrolyte membrane is to be improved. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a composite solid electrolyte membrane having a high lithium ion migration number, conductivity and mechanical strength, which can remarkably improve the specific discharge capacity, the cycle capacity retention rate and the service life thereof, and a method for preparing the same, and a solid lithium battery. In one aspect thereof, the present invention provides a composite solid electrolyte membrane comprising a porous membrane substrate and a solid polymer electrolyte body comprising an alcoholate of a vinyl ester-acrylate block copolymer, polyethylene oxide, epoxy-terminated polyethylene oxide, amino-terminated polyalkylene oxide, and a lithium salt, and the solid polymer electrolyte body being disposed on upper and lower surfaces of the porous membrane substrate and at least a portion of the solid polymer electrolyte body being embedded in pores of the porous membrane substrate, according to an embodiment of the present invention. The solid polymer electrolyte body is formed on the upper surface and the lower surface of a porous membrane matrix and at least part of the solid polymer electrolyte body is embedded into pores of the porous membrane matrix to obtain the composite solid electrolyte membrane, wherein the alcoholysis of the vinyl ester-acrylic ester segmented copolymer can reduce the crystallinity of a polyethylene oxide polymer system at normal temperature, so that the li