Polymer-based composite solid electrolyte as well as preparation method and application thereof

Abstract

The invention discloses a polymer-based composite solid electrolyte as well as a preparation method and application thereof. The preparation method comprises the following steps of: applying a mixed solution containing an inorganic electrolyte, a polymer and an organic solvent to a substrate, carrying out freeze casting, and carrying out phase inversion on a cured membrane to prepare a composite structure basement membrane of a pore channel structure; and making the composite structure basement membrane in contact with an organic electrolyte solution containing a lithium salt, a plasticizer, a cross-linking agent and an interface stabilizing additive, enabling the organic electrolyte to enter the pore channel of the composite structure substrate membrane, and performing cross-linking curing on the cross-linking agent under ultraviolet light to obtain the polymer-based composite solid electrolyte. The polymer-based composite solid electrolyte has high conductivity at room temperature, the lithium ion transference number t<Li+> is greater than 0.68, and the polymer-based composite solid electrolyte has relatively long cycle life and relatively low overpotential. A lithium metal total battery based on the composite solid electrolyte is good in cycling stability, and has relatively high average coulombic efficiency and specific capacity and more excellent rate capability.

Description

technical field [0001] The invention relates to the preparation of a solid electrolyte, in particular to a polymer-based composite solid electrolyte and its preparation method, and its application in lithium batteries, belonging to the technical field of electrochemical energy. Background technique [0002] Since the advent of commercial lithium-ion batteries in 1991, people's demand for high-energy-density energy storage devices has been increasing. Traditional lithium-ion batteries with graphite as negative electrodes (volume energy density 765Wh L -1 ) can no longer meet the energy needs of emerging electronics and smart grids. Lithium metal has high energy density, low reduction potential and low density, and is generally considered to be the best choice for next-generation high-performance secondary battery anode materials. However, lithium metal still has many problems such as uncontrollable growth of dendrites, which brings safety hazards; high reactivity, continuous...

AI Technical Summary

Problems solved by technology

[0005] Although composite solid electrolytes have better overall performance than single-component solid electrolytes, they still have the disadvantage of lower electrical conductivity compared to traditional liquid electrolytes, because composite solid electrolytes based on polymers usually dope inorganic solid electrolyte particles in the polymer However, in this method, the inorganic solid electrolyte can only conduct lithium ions when the content of inorganic particles is high enough, and excessive doping will lead to a decrease in mechanical properties. Therefore, optimizing the geometry of ceramic fillers is crucial It is very important to further improve the comprehensive performance of the composite solid electrolyte. The vertically arranged structure is equivalent to a fast channel for ion transmission, and is considered to be the optimal structure for improving the conductivity of the composite electrolyte.

Moreover, the polymer is usually in a crystalline state at room temperature, and its chain segments are frozen, so it is difficult to conduct lithium ions, resulting in low conductivity of the composite solid electrolyte, and the battery can only be cycled at a higher temperature or a lower rate.

Secondly, due to the solid-solid contact between the electrode and the electrolyte during the preparation process, the large contact resistance and the growth of lithium dendrites also hinder the further improvement of the performance of the composite solid electrolyte.

Images