Composite solid electrolyte membrane and preparation method thereof

Abstract

The invention discloses a composite solid electrolyte material and a preparation method thereof. The electrolyte material comprises a non-oxygen-containing polymer matrix, an oxide electrolyte, a fluorine-containing organic lithium salt, a nitrile compound and an inorganic lithium salt, wherein the content of the non-oxygen-containing polymer matrix is 40-60%, the content of the oxide electrolyteis 5-25%, the content of the fluorine-containing organic lithium salt is 5-30%, the content of the nitrile compound is 10-30%, and the content of the inorganic lithium salt is 2-10%. The preparation method comprises the following steps of sequentially adding the raw materials into a nitrogen-containing organic solvent, mixing and stirring to obtain a uniform suspension glue solution, casting intoa polytetrafluoroethylene mold by using a tape casting method for molding, and carrying out vacuum drying to obtain the composite solid electrolyte material. The room-temperature conductivity and theelectrochemical window of the solid electrolyte are improved, the electrochemical performance is more stable, the solid electrolyte can be matched with high-voltage positive electrode materials such as lithium cobalt oxide, nickel cobalt lithium manganate, lithium manganate and a lithium-rich manganese base for use, and meanwhile, the mechanical property of the composite solid electrolyte membraneis improved.

Description

technical field [0001] The invention relates to a solid electrolyte material, in particular to a composite solid electrolyte membrane with high room temperature ion conductivity and wide electrochemical window and a preparation method thereof. Background technique [0002] A solid-state battery is an energy storage device that uses solid positive and negative electrodes and a solid electrolyte, does not contain any liquid, and all materials are composed of solid materials. Compared with liquid lithium batteries, solid-state batteries have the advantages of good safety, high energy density, and environmental friendliness. It is a new, efficient, and practical energy storage device that meets the requirements for battery development in the fields of digital, power, and energy storage , is a direction for the development of lithium battery technology in the future. [0003] One of the core components of a solid-state battery is a solid-state electrolyte, which can be mainly di...

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Problems solved by technology

Sulfide electrolyte has excellent conductivity and good processing performance, but it will react with moisture in the air in the atmosphere to generate highly toxic gas, so the production process needs to be carried out in a protective atmosphere, which increases production costs; oxide solid electrolyte Although the ion conductivity is high and the voltage window is wide, it has high brittleness and insufficient processability; the polymer electrolyte has good processability and relatively low interface impedance, but the polymer electrolyte has poor ion conductivity, narrow voltage window, and poor mechanical properties. Low and difficult to inhibit lithium dendrite growth

The most important point is that common polymer electrolytes use chain segment motion to conduct lithium conduction, which leads to very low ionic conductivity

For example, polyethylene oxide (PEO) as a solid electrolyte has an ionic conductivity of only 10 at room temperature. -6 S / cm, due to the relatively high crystallinity of PEO at lower temperatures, the dissociation ability and chain segment movement of lithium salts are poor, and the voltage exceeding 4V will cause the decomposition of PEO, which cannot be combined with lithium cobalt oxide, nickel cobalt manganese Lithium oxide, lithium manganese oxide, lithium-rich manganese-based and other high-voltage cathode materials

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