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CN-122000449-A - Composite solid electrolyte membrane, preparation method and solid lithium battery

CN122000449ACN 122000449 ACN122000449 ACN 122000449ACN-122000449-A

Abstract

The application belongs to the technical field of solid electrolyte preparation, and particularly relates to a composite solid electrolyte membrane, a preparation method and a solid lithium battery. The composite solid electrolyte membrane comprises a solid electrolyte three-dimensional composite framework, and crown ether functionalized polymer, lithium salt and additives which are arranged on the surface of the solid electrolyte three-dimensional composite framework, wherein the solid electrolyte three-dimensional composite framework is prepared from polyamide acid PAA and polydopamine PDA modified solid electrolyte. The solid electrolyte of the solid electrolyte three-dimensional composite skeleton membrane is modified by polydopamine PDA, and the surface of the solid electrolyte is composited by crown ether functionalized polymer, lithium salt and combined additive FEC assisted by inorganic filler to form the composite solid electrolyte membrane, so that the synergy of ion conduction efficiency, interface compatibility and structural stability is realized, and the cycle performance and safety performance of the battery are improved and improved.

Inventors

  • LIU CHENGZHE
  • HUANG LING
  • ZHANG JIN

Assignees

  • 中汽新能电池科技有限公司

Dates

Publication Date
20260508
Application Date
20260112

Claims (10)

  1. 1. A composite solid electrolyte membrane is characterized by comprising a solid electrolyte three-dimensional composite skeleton, and crown ether functionalized polymer, lithium salt and additive which are arranged on the surface of the solid electrolyte three-dimensional composite skeleton; the solid electrolyte three-dimensional composite skeleton is prepared from polyamide acid PAA and polydopamine PDA modified solid electrolyte.
  2. 2. The method for preparing the three-dimensional composite skeleton of the solid electrolyte according to claim 1, wherein the method comprises the steps of mixing polyamic acid PAA solution and solid electrolyte powder modified by polydopamine PDA to form electrostatic spinning solution, adopting electrostatic spinning equipment to obtain a fiber membrane, and then carrying out vacuum drying to obtain the three-dimensional composite skeleton of the solid electrolyte; The mass ratio of the polyamide acid PAA to the solid electrolyte modified by the PDA is (5-9): 1-5, and preferably, the mass ratio of the polyamide acid PAA to the solid electrolyte modified by the PDA is 7:3.
  3. 3. The composite solid electrolyte membrane according to claim 2, wherein the polyamic acid PAA is prepared by adding 2,2' -diaminodiphenyl ether ODA to N, N-dimethylacetamide DMAc and adding pyromellitic dianhydride PMDA under nitrogen atmosphere, and stirring and reacting to obtain a polyamic acid PAA solution; preferably, the mass ratio of N, N-dimethylacetamide DMAc to 2,2' -diaminodiphenyl ether ODA to pyromellitic dianhydride PMDA is 15:1:1.
  4. 4. The composite solid electrolyte membrane according to claim 2, wherein the polydopamine PDA modified solid electrolyte comprises a solid electrolyte and a polydopamine layer coated on the surface of the solid electrolyte; Preferably, the solid electrolyte modified by polydopamine PDA is prepared by dissolving aminotrimethylolmethane and dopamine hydrochloride in methanol, adding solid electrolyte powder, continuously stirring, continuously introducing pure oxygen gas into a reaction system, self-polymerizing dopamine, and drying after the reaction is finished to obtain the solid electrolyte modified by polydopamine PDA; Preferably, the solid electrolyte is a ceramic solid electrolyte, preferably LLZTO.
  5. 5. The composite solid electrolyte membrane according to claim 1, wherein the crown ether functionalized polymer is prepared by dissolving a polycarboxy polymer in an organic solvent under nitrogen protection, adding a catalyst and a carboxy activator, and stirring to form a carboxy group as an activated intermediate; slowly adding a mono-alcohol crown ether compound into an activation solution for reaction, and enabling carboxyl-COOH in the multi-carboxyl polymer and hydroxyl-OH in the mono-alcohol crown ether compound to undergo esterification reaction to obtain a crown ether functionalized polymer; preferably, the mass ratio of the polycarboxy polymer to the catalyst to the carboxyl activator to the mono-ol crown ether compound is 50:0.5:11.5:4.5.
  6. 6. The composite solid electrolyte membrane according to claim 5, wherein the monol crown ether compound is one of 2-hydroxymethyl-12-crown-4, 2-hydroxymethyl-18-crown-6 or benzo-12-crown-4-2-methanol; preferably, the polycarboxy polymer is one of polyacrylic acid PAA, polymethacrylic acid PMAA or polymaleic acid PMA; Preferably, the catalyst is a 4-dimethylaminopyridine DMAP carboxyl activator; preferably, the carboxyl activating agent is 1-ethyl- (3-dimethylaminopropyl) carbodiimide hydrochloride EDC.HCl.
  7. 7. The composite solid electrolyte membrane according to claim 1, wherein the crown ether functionalized polymer and lithium salt have a ratio of (1-2): 1, preferably wherein the lithium salt is lithium bis (fluorosulfonyl) imide LiTFSI.
  8. 8. The composite solid electrolyte membrane according to claim 1, wherein the additive is a mixture of an organic additive and an inorganic additive, Preferably, the organic additive accounts for 1-5wt% of the mixed mass of the crown ether functionalized polymer and the lithium salt; Preferably, the inorganic additive accounts for 10-30wt% of the mixed mass of the crown ether functionalized polymer and the lithium salt; preferably, the organic additive is fluoroethylene carbonate FEC; Preferably, the inorganic additive is nano silicon dioxide SiO 2 .
  9. 9. The preparation method of the composite solid electrolyte membrane according to any one of claims 1 to 8, which is characterized by comprising the following steps of pouring crown ether polymer composite electrolyte solution on the surface of a three-dimensional composite skeleton of the solid electrolyte, and carrying out knife coating and curing to obtain the three-dimensional fiber skeleton reinforced support composite solid electrolyte membrane; the crown ether polymer composite electrolyte is prepared by dissolving the crown ether functionalized polymer, the lithium salt and the additive in an organic solvent; the organic solvent is one of N, N-dimethylformamide DMF, N dimethylacetamide or N-methyl-2-pyrrolidone.
  10. 10. A solid lithium battery is characterized by comprising the composite solid electrolyte membrane, the positive electrode and the negative electrode, which are packaged according to any one of claims 1-8, The positive electrode is prepared by mixing a positive electrode active substance, a conductive agent super P, a binder PVDF and an additive LiTFSI with a solvent N-methylpyrrolidone NMP; Preferably, the mass ratio of the positive electrode active material to the conductive agent super P to the binder PVDF to the additive LiTFSI is 80:10:8:2; Preferably, the positive electrode active material comprises one or more of lithium cobalt oxide LCO, lithium iron phosphate LFP and nickel cobalt lithium manganate NCM; The negative electrode adopts one or more of metal lithium and lithium metal alloy negative electrodes.

Description

Composite solid electrolyte membrane, preparation method and solid lithium battery Technical Field The invention belongs to the technical field of solid electrolyte preparation, and particularly relates to a composite solid electrolyte membrane, a preparation method and a solid lithium battery. Background The lithium ion battery has the advantages of high energy density, long cycle life, strong designability and the like, and is widely applied to the fields of consumer electronics, electric automobiles, distributed energy storage and the like. However, the conventional liquid lithium ion battery adopts a liquid electrolyte, and lithium metal is easy to generate dendrites in the circulation process and has side reactions with the electrolyte, so that the safety problems of unstable solid electrolyte interface film (SEI), penetration of lithium dendrites through a diaphragm, short circuit, even thermal runaway and the like are caused. In addition, the liquid electrolyte has the characteristics of inflammability, easy leakage and the like, and further aggravates the safety risk of the lithium metal battery under the condition of high energy density. To solve the above problems, solid electrolytes are considered as effective approaches to replace liquid electrolytes and to improve the safety of lithium metal batteries because they have excellent thermal stability and mechanical strength, are capable of effectively suppressing dendrite formation and avoiding electrolyte leakage. The existing solid electrolyte mainly comprises three major categories of inorganic solid electrolyte, organic polymer solid electrolyte and organic-inorganic composite solid electrolyte. The inorganic solid electrolyte has the advantages of higher ionic conductivity, excellent mechanical property, high brittleness, poor interface contact, complex processing and higher cost, and the polymer solid electrolyte has the advantages of good flexibility, good interface contact with an electrode, low cost molding, low ionic conductivity, insufficient mechanical strength, limited high-voltage resistance and the like, and is difficult to meet the long-term stable operation requirement of the lithium metal battery with high energy density. To overcome the above-mentioned drawbacks, researchers have proposed to introduce an inorganic reinforcing phase into a polymer electrolyte to prepare a composite solid electrolyte, i.e., an organic-inorganic composite solid electrolyte, which is the main stream of research. However, the existing composite solid electrolyte has the defects that on one hand, the interface compatibility between the inorganic solid electrolyte and the organic polymer matrix is poor, the interface impedance is easy to generate, the ion conduction efficiency is reduced, and on the other hand, the mechanical supporting capability of the composite electrolyte is limited, the composite electrolyte is easy to deform in the charging and discharging process of a battery, the penetration of lithium dendrites cannot be effectively inhibited, and the safety risk still exists. The three-dimensional fiber skeleton material is widely used for enhancing the supporting performance of the composite solid electrolyte due to the unique porous structure, high specific surface area and excellent mechanical strength, and can form a continuous ion transmission network in a polymer matrix, thereby being beneficial to realizing high-efficiency ion migration and improving the overall mechanical property and thermal stability of the system. Although the conventional composite solid electrolyte has improved ionic conductivity, mechanical properties and the like, the problems of poor interface contact, low ion migration number, insufficient structural stability and the like are common, and long cycle and high safety are difficult to realize in a high-voltage lithium metal battery. Therefore, how to design a composite solid electrolyte with high ionic conductivity, excellent interface stability and mechanical strength is a key technical problem to be solved in the current lithium metal battery field. Disclosure of Invention The invention provides a composite solid electrolyte membrane, a preparation method and a solid lithium battery, which solve the problems of low ionic conductivity, poor interface stability, insufficient mechanical strength and the like in the prior art. The ceramic solid electrolyte particles and polyimide are compounded to construct a three-dimensional skeleton high ion conduction region, the crown ether polymer lithium salt precursor permeates the three-dimensional skeleton to be solidified to form a continuous interface ion transmission path, the lithium ion migration rate is improved, nano silicon dioxide is used as an inorganic filler to remarkably improve the electrolyte conductivity and ion migration number, and the method is suitable for producing high-energy density lithium metal batteries and all-solid-state lithium batteries and m