A three-dimensional hybrid conductive binder for lithium batteries and batteries containing the binder

Abstract

A three-dimensional mixed conductive adhesive for lithium batteries and a battery containing the adhesive. The binder includes: carbon nanotubes, graphene, and polymers with chemical bonds between carbon nanotubes and graphene. The carbon nanotubes and graphene in the binder are mixed in a certain ratio to form a three-dimensional conductive network, and the polymer groups and the groups on the graphene carbon nanotubes can be effectively combined to improve the strength of the composite, and in the preparation of the electrode slurry can be well dispersed. During the charge and discharge process, the three-dimensional composite conductive binder can better restrain the expansion and contraction of the active material of the electrode sheet, and effectively improve the cycle stability and rate performance of high capacity and high volume change electrode materials, such as, Silicon-based negative electrode materials, tin-based negative electrodes, and high volume change electrode materials that can be expanded to new battery systems in the future.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and relates to a three-dimensional mixed conductive adhesive for lithium batteries and a battery containing the adhesive. Background technique: [0002] Lithium-ion batteries have outstanding advantages such as high specific energy, small self-discharge, long service life, green and pollution-free, and have been widely used in portable electronic products and electric vehicles. With the development and progress of society, the further application of lithium-ion batteries urgently needs to increase the energy density, and the development of electrode materials with high specific capacity is one of the effective ways. Among the negative electrode materials, carbon materials are mainly commercialized at present, and their theoretical specific capacity is relatively low, about 372 mA h g-1. Silicon has attracted more and more attention because of its high theoretical specific capacity (about 357...

AI Technical Summary

Problems solved by technology

PVDF has poor adhesion and flexibility, and the effect of inhibiting the expansion of the pole piece is also very limited. It is difficult to improve the capacity and rate characteristics of the battery. In addition, the price of PVDF and its solvent is relatively high, which increases the cost of lithium-ion batteries.

SBR / CMC water-based binder is widely used in the market, but due to its own reasons, it is difficult to apply it to the preparation of positive electrode sheets. It has a relatively mature application in traditional graphite systems, but it is not suitable for high capacity, especially high volume change. The electrode material still shows poor effect of inhibiting expansion

On the other hand, in order to increase the energy density of the battery, the amount of conductive additives is also controlled within 5%, and it is difficult to realize the high capacity and high rate performance of the material.

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