Electrostatic binding water-based binder and its application in lithium-ion batteries

Abstract

The invention discloses an electrostatic binding type water-based binder, which is mainly composed of a compound containing a phosphoric acid group and a compound containing an amino group according to a mass ratio of 0.5:1-2:1. When the two are respectively prepared into solutions and mixed for use, It can be combined by electrostatic adsorption to form a binder with high cohesive force and strong cohesive performance, which can be used as a water-based binder. The electrostatic binding water-based binder provided by the present invention has significant cohesive force, and the introduction of phosphoric acid groups can effectively improve the ion conductivity, so that when applied to the assembly of lithium-ion batteries, it is beneficial to improve the cycle performance and large-scale performance of lithium-ion battery electrodes. Rate charge and discharge performance. The electrostatic binding water-based binder provided by the invention can be applied to the preparation of lithium-ion battery electrodes, and the prepared electrodes have better electrode structural integrity and stability, and good cycle stability.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an electrostatic binding water-based binder and its application in preparing lithium ion battery electrodes. Background technique [0002] Lithium-sulfur batteries have many advantages such as high theoretical energy density, low cost of sulfur cathode materials, wide sources, and non-toxicity. However, the following problems that have not been well resolved in lithium-sulfur batteries have greatly hindered the practical application and industrial development of lithium-sulfur batteries: (1) the "shuttle effect" of lithium polysulfides during the charging and discharging of lithium-sulfur batteries; ( 2) Due to the elemental sulfur and its discharge products (Li 2 S 2 and Li 2 S) are both electronic and ionic insulators (5×10 -30 S / cm, 25°C), resulting in low active material utilization and poor rate performance when used as a cathode material; (3) t...

AI Technical Summary

Problems solved by technology

But on the one hand, the PVDF excessive swelling electrolyte will gel and form a viscous liquid, so that the active material will be separated from the conductive network, increase the impedance, and cause capacity loss; on the other hand, the PVDF dissolution process requires the use of an organic solvent N-methylpyrrolidone ( NMP), although NMP has good solubility, but its high boiling point (203°C) makes the electrode drying conditions more harsh (drying temperature 120°C), which will cause damage to the electrode structure. At the same time, NMP has certain toxicity and will be harmful to the human body. The reproductive system is harmful, and an NMP recovery device needs to be installed in the battery production process, which will lead to an increase in cost

[0005] Chinese patent application CN111430716A discloses a water-based soybean protein-based supramolecular sulfur cathode binder and its preparation method and application. Excellent lithium ion conductivity, strong lithium polysulfide adsorption, but its preparation method is complicated, and the bonding force of the binder still needs to be improved