Composite binder for solid-state lithium battery as well as preparation method and application of composite binder

Abstract

The invention discloses a preparation method and application of a composite binder for a solid-state battery, and the composite binder is formed by compounding polyvinylidene fluoride (PVDF), polyoxyethylene (PEO) and a cross-linking agent, wherein the cross-linking agent is one or more of poly (ethylene glycol) methacrylate, polyethylene glycol diglycidyl ether, polyether ammonia and the like. A conventional solid binder PVDF is supplemented, PEO and the cross-linking agent are added into PVDF to prepare the composite binder, PEO provides lithium ion transmission sites, and the cross-linking agent enhances the compatibility of PVDF and PEO through special functional groups of the cross-linking agent. In addition, the cohesiveness of the composite binder is not affected by adding a small amount of the cross-linking agent, and the complete structure of the electrode can still be maintained after circulation. According to the composite binder, a continuous conduction lithium ion transmission channel is constructed in a three-dimensional porous positive electrode, the solid-solid contact resistance of a solid-state battery is effectively reduced, the preparation process is simple, the raw materials are cheap, and the composite binder has a great application prospect.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a composite binder for solid lithium batteries and a preparation method and application thereof. Background technique [0002] With the demand for high energy density storage systems in portable electronic devices and electric vehicles, lithium metal due to its extremely high theoretical capacity (3060mAh / g 1 ), the lowest redox potential (-3.04V vs. SHE) and lower density (0.59g / cm 3 ), which is regarded as the most ideal anode in lithium batteries. However, due to the decomposition of the liquid electrolyte and the uncontrollable growth of lithium dendrites, the battery is short-circuited or even thermally runaway, which leads to serious safety issues, making the traditional electrolyte unsuitable for lithium metal anodes. Therefore, replacing liquid electrolytes with solid electrolytes is considered to be the most promising method to fundamentally eliminate safety ...

AI Technical Summary

Problems solved by technology

However, PEO has poor mechanical properties at high temperatures, and it is difficult to adapt to the volume change of the positive electrode due to ion deintercalation, which leads to irreversible attenuation of battery capacity.

Although the use of polymer solid electrolyte as a binder has achieved certain results, the preparation cost is too high, the preparation process is relatively complicated, the practicability is poor, and there is still a certain distance from industrial application

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