Secondary battery

Abstract

The invention relates to the field of energy storage materials, in particular to a secondary battery which comprises an anode piece, a cathode piece, a diaphragm and electrolyte. The diaphragm comprises diaphragm matrixes and coatings, the coatings are arranged on the surfaces of the diaphragm matrixes and comprise polymer micro-spheres, and the softening temperatures of the polymer micro-spheres are 50-120 DEG C; the electrolyte comprises additives, and the decomposition voltages of the additives are 4.4V-4.8V. The secondary battery has the advantages that sufficient hole closing of the diaphragm can be synergistically promoted by the diaphragm with the polymer micro-sphere coatings and the additives, the polymer micro-spheres with the low softening temperatures are coated on the surfaces of the diaphragm, and accordingly the hole closing temperature of the diaphragm can be lowered; the voltages can be increased, accordingly, the reactive additives can be triggered, self-reaction can be quickly carried out at over-charge initial phases to generate heat, and melting of the polymer micro-spheres and large-area hole closing of the diaphragm can be promoted.

Description

technical field [0001] The present application relates to the field of energy storage materials, in particular, to a secondary battery. Background technique [0002] As the safety requirements of lithium-ion batteries increase, the requirement for the separator to have a shutdown function also increases. The closed cell temperature of the diaphragm is an important parameter reflecting the safety characteristics of the diaphragm. When the internal temperature of the battery rises to the closed cell temperature of the diaphragm under abnormal conditions, the micropores of the diaphragm are automatically closed to prevent the conduction of ions and cut off the charging current, thereby preventing the battery from thermal runaway. This feature can provide some safety protection for lithium-ion batteries. At present, the closed cell temperature of the commonly used PE separator is about 130°C, and the closed cell temperature of the PP separator is about 150°C. Usually, at such ...

AI Technical Summary

Problems solved by technology

At present, the closed cell temperature of the commonly used PE separator is about 130°C, and the closed cell temperature of the PP separator is about 150°C. Usually, at such a high temperature, a violent chemical reaction has occurred inside the battery and caused thermal runaway, so that Does not provide the safety protection of a heat-sealed diaphragm

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