A kind of lithium battery composite binder and its application

Abstract

The invention relates to a composite binder for a lithium battery and an application of the composite binder. The composite binder for the lithium battery consists of a flexible binder polytetrafluoroethylene and a rigid binder, wherein the rigid binder is selected from at least one kind of polyacrylate, acrylonitrile multipolymer, carboxymethylcellulose and sodium carboxymethylcellulose; and the mass ratio of the flexible binder polytetrafluoroethylene to the rigid binder is (6-16) to (1-4). By adoption of the compounding of the "flexible" binder PTFE and the "rigid" binder, the complementary property characteristics of the two kinds of binders are utilized, so that the tendency of pulse capability decline at the discharging tail end of a lithium-manganese dioxide battery is relieved; and meanwhile, organic functional groups of the polyacrylate, the acrylonitrile multipolymer, natural cellulose modified materials and the like can be coordinated with Mn atoms, so that reaction sites on the surface of the positive electrode manganese dioxide can be reduced, generation of side reaction caused by manganese dioxide catalysis can be lowered, the internal stability of the lithium-manganese dioxide battery system is improved, and the storage life of a lithium-manganese battery is prolonged.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a lithium battery composite binder and its application. Background technique [0002] For commercial lithium-manganese dioxide primary batteries, the positive electrode is usually composed of active material manganese dioxide and conductive carbon black (acetylene black, graphite, Ketjen black, etc.), binder (polytetrafluoroethylene, and four Copolymers of vinyl fluoride and other fluorinated monomers). This type of binder is easy to form a network structure, wrapping the positive active material and conductive carbon black, forming such as figure 1 structure shown. However, during the discharge process of the battery, as lithium ions are continuously embedded in the positive electrode manganese dioxide, the manganese dioxide lattice continues to expand, which eventually leads to poor contact between the positive electrode active material and the conductive network fo...

AI Technical Summary

Problems solved by technology

However, during the discharge process of the battery, as lithium ions are continuously embedded in the positive electrode manganese dioxide, the manganese dioxide lattice continues to expand, which eventually leads to poor contact between the positive electrode active material and the conductive network formed by the current collector and conductive carbon black; The contact resistance of the battery becomes larger, and the rate of decline of the discharge platform at the end of the battery discharge is faster

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