Lithium ion battery and positive plate thereof

Abstract

The invention discloses a lithium ion battery positive plate, comprising a positive current collector as well as a positive membrane and a terminal which are distributed on the positive current collector; wherein the surface of the positive current collector uncovered by the positive membrane and terminal is distributed with an insulation protective layer capable of improving the surface resistance of the positive current collector. The lithium ion battery positive plate of the invention protects the positive current collector uncovered by the positive membrane and terminal by virtue of the insulation protective layer, the ohmic resistance when the positive current collector is contacted with negative membrane can be improved, and security feature of lithium ion battery can be improved. Besides, the invention also discloses a lithium ion battery applying the lithium ion battery positive plate.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to a lithium ion battery with good safety performance and its positive electrode sheet. Background technique [0002] With the development of modern electronic technology, various portable devices such as video cameras, digital cameras, notebook computers, MP4, portable DVD, etc. have been widely used. As a battery with high energy density and environmental friendliness, lithium-ion batteries are gradually favored by people because of their advantages such as light weight, large energy storage, high power, long life, small self-discharge coefficient, and wide temperature range. Used in various portable devices. [0003] Lithium-ion batteries have a special electrochemical system. Generally, carbonates are used as electrolyte solvents. The flammability of carbonates makes lithium-ion batteries bring convenience to people but also bring certain safety hazards. Overcharge and internal short c...

AI Technical Summary

Problems solved by technology

[0003] Lithium-ion batteries have a special electrochemical system. Generally, carbonates are used as electrolyte solvents. The flammability of carbonates makes lithium-ion batteries bring convenience to people while also bringing certain safety hazards.

Overcharge and internal short circuit are two main problems that threaten the safety performance of lithium-ion batteries. The overcharge safety problem of lithium-ion batteries can be solved to a large extent by using external protection circuits and anti-overcharge electrolyte additives. However, due to internal short-circuit undetectability, which remains an important issue threatening the safety of Li-ion batteries

[0004] In order to facilitate the manufacturing process, the positive electrode sheet of the lithium-ion battery usually retains a part of the positive electrode collector not covered by the positive electrode film and the terminal. When the lithium-ion battery is used improperly, such as being squeezed, hit or pierced by sharp objects When wearing and other mechanical damage, it is very easy to cause the exposed positive electrode collector to contact with the negative electrode diaphragm and cause a short circuit

At this time, the short-circuit resistance formed by the short-circuit is small, the short-circuit current is large, and the temperature of the short-circuit point rises suddenly in a short period of time, which may cause the thermal runaway of the battery and easily cause safety problems.

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