Lithium ion cathode material with high security and lithium ion battery employing same

Abstract

The invention discloses a lithium ion cathode material with high security and a lithium ion battery employing the same. The lithium ion cathode material with high security comprises primary particles of a lithium ion metal oxide and a PTC high-molecular polymer having good conductivity. Secondary ions uniformly doped by the lithium ion metal oxide and the PTC high-molecular polymer by pretreatment of the lithium ion metal oxide and the PTC high-molecular polymer. The PTC high-molecular polymer of the lithium ion cathode material with high security is uniformly distributed in the positive electrode lithium ion metal oxide, has no influence on the conductivity of the positive electrode at a normal temperature. However, when the temperature of the battery raises to 80 DEG C or higher, the size of the doped PTC high-molecular polymer expands to cut off connection between the positive electrode particles, and at the same time, self-resistance of the doped PTC high-molecular polymer increases rapidly to cut off current, so that the security of the lithium ion battery can be effectively guaranteed.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a positive electrode material with high safety and a lithium ion battery using the positive electrode material. Background technique [0002] Due to the high energy density and power density of lithium-ion batteries, it has become the most potential power source for power and energy storage. In practical applications, due to the complexity of the environment, lithium-ion batteries often have safety problems such as fire and explosion. Therefore, the safety of large-capacity, high-specific-energy lithium-ion batteries has become a key factor restricting the development of lithium-ion batteries. [0003] The safety issues of lithium-ion batteries can be divided into two aspects: battery design and battery materials. The battery design mainly includes the type and proportion of positive and negative electrodes, the type of binder, the type of diaphragm, the type of tabs, the we...

AI Technical Summary

Problems solved by technology

[0005] At present, the method of improving battery safety is as in the patent CN1606183A: when preparing the electrode, that is, in the process of homogenizing, the PTC material is mixed with the positive electrode metal oxide, conductive agent, and binder, which will cause a positive temperature coefficient. (PTC) materials are unevenly distributed on the pole piece, resulting in a large battery resistance or when a safety problem occurs in the battery, local overheating on the pole piece will cause thermal runaway, which cannot ensure the safety of the battery

In the patent CN 102376939 A, a positive electrode material with a core-shell structure is used, and the PTC material is coated on the surface of the positive electrode material, which can greatly improve the safety of the battery, but due to the particle characteristics of the positive electrode material used, it will cause The PTC material coated on the surface is uneven, which affects the capacity and conductivity of the positive electrode material and affects the performance of the battery