A kind of all-solid composite electrolyte and its preparation method and application

Abstract

The invention discloses an all-solid composite electrolyte, a preparation method thereof and an application in a solid-state secondary lithium battery. The all-solid composite electrolyte includes sulfur-containing copolymers, inorganic fillers and lithium salts; the sulfur-containing copolymers are selected from at least one of the copolymers containing polysulfide segments, the copolymers containing polysulfoxide segments, and the copolymers containing polysulfone segments A sort of. The preparation method includes: uniformly mixing sulfur-containing copolymer, lithium salt, inorganic filler and organic solvent to obtain a uniform polymer solution, then casting in a mold to form a film, and preparing an all-solid composite electrolyte after vacuum drying. The all-solid composite electrolyte provided by the invention has high ionic conductivity, mechanical strength and oxidation resistance, can inhibit the formation of lithium dendrites, and can improve the cycle stability of the battery at the same time, and can be applied to the solid-state secondary electrolyte of high-voltage positive electrode materials. Lithium battery field.

Description

technical field [0001] The invention relates to the technical field of new energy, in particular to an all-solid-state composite electrolyte and a preparation method and application thereof. Background technique [0002] In recent years, due to the shortage of earth resources and environmental pollution, the rapid development of new industrial technologies such as electric vehicles and large-scale energy storage equipment, the demand for high-performance, high-energy-density rechargeable batteries has become more and more urgent. [0003] Existing rechargeable batteries often use organic liquid electrolytes, but the properties of their easily leaking, volatile, flammable and corrosive electrodes greatly affect the life of the battery and bring serious safety hazards. [0004] Compared with traditional batteries using organic liquid electrolytes, solid-state secondary lithium batteries can suppress the formation of lithium metal dendrites due to their high safety, high energy...

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Problems solved by technology

[0006] Inorganic solid electrolytes have high room temperature ionic conductivity and wide electrochemical window, but their poor processability makes it difficult to prepare large areas. At the same time, their solid-solid interface with electrodes is poor, which seriously restricts Practical Applications of Inorganic Solid Electrolytes

[0007] Solid polymer electrolytes are low in cost, high in safety, good in film formation, and excellent in molding and processing properties, and can be mass-produced industrially. However, in the existing technologies, the key problem of solid polymer electrolytes is the low room temperature ionic conductivity. , the electrochemical window is narrow, and it is difficult to adapt to high-voltage positive electrode active materials

For example, polyethylene oxide is currently one of the most researched and promising polymer electrolyte matrix materials, but polyethylene oxide is easy to crystallize at room temperature, and the coordination between ether oxygen bonds and lithium ions is strong, resulting in lithium The mobility of the ions is low and their room temperature ionic conductivity is low

Another disadvantage is that its electrochemical stability window is narrow, which is difficult to match with high-voltage cathode materials

From the perspective of mechanism, the key factors limiting the improvement of its electrochemical stability window are still unclear

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