Composite coated diaphragm for high-nickel ternary lithium-ion battery and preparation method thereof

Abstract

The invention discloses a composite coated diaphragm for a high-nickel ternary lithium-ion battery and a preparation method thereof. According to the composite coated diaphragm provided by the invention, a ceramic coating at one side of a negative electrode contains inorganic oxide so that the ceramic coating has relatively good heat-resisting property and mechanical strength and the thermal safety stability of the high-nickel ternary lithium-ion battery can be effectively improved; a sulfonic acid group on a carbon coating at one side of a positive electrode can be used for inhibiting the decomposition of electrolyte to a certain extent so that the interface stability between a material and the electrolyte is enhanced, the circulating performance of the battery is improved and the rate performance of the battery is effectively improved; the two types of coatings are complementary to each other due to respective excellent performance, so that the circulating performance, the rate performance and the safety performance of the high-nickel ternary lithium-ion battery are improved and large-scale application of a system is promoted; the composite coated diaphragm for the high-nickel ternary lithium-ion battery is high in practicability and equipment is easy to popularize and apply.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a composite coated separator for high-nickel ternary lithium ion batteries and a preparation method thereof. Background technique [0002] With the continuous development of new energy vehicles in my country, the requirements for battery energy density are getting higher and higher. As the current mainstream battery system, lithium-ion batteries have been widely used in power batteries due to their advantages such as high energy density, good cycle performance, and no memory effect. However, the energy density of lithium-ion batteries in my country can only reach 260Wh / kg, which is still a long way from the 2020 target of 300Wh / kg. In order to vigorously develop new energy vehicles, it is imperative to increase the energy density of lithium-ion batteries. [0003] At present, the main way to increase the energy density of lithium-ion batteries is to use high-nic...

AI Technical Summary

Problems solved by technology

[0003] At present, the main way to increase the energy density of lithium-ion batteries is to use high-nickel ternary positive electrodes (NCM / NCA, the molar fraction of nickel ≥ 0.6) with silicon-carbon negative electrode materials. As the content increases, the stability of the material will gradually decrease, especially the stability of the material / electrolyte interface will decrease accordingly, leading to the occurrence of side reactions and affecting the cycle stability of the material

In addition, due to the rich layered structure of the high-nickel ternary cathode material, its charge-discharge rate performance is poor, and it has obvious shortcomings in high-rate charge-discharge, and under the condition of overcharge, it is easy to cause polarization to cause the oxidative decomposition of the electrolyte. A large amount of heat is released, which increases the internal pressure and temperature of the battery, posing a safety hazard

These defects of high-nickel ternary lithium-ion batteries limit its development and application to a certain extent. In order to solve these problems, people usually add various additives to the electrolyte to improve the interface stability of the material and the rate charge and discharge performance of the battery. And use a ceramic separator to improve the safety performance of the battery, but the overall improvement effect is limited

Images