Method for screening self-discharge performance of lithium-ion power battery

Abstract

The invention relates to a method for screening the self-discharge performance of a lithium-ion power battery. The method comprises the following steps: firstly, performing charging and discharging preprocessing on a battery after capacity division to a set voltage value; after the battery to be tested is stewed at a set temperature and set humidity for a certain period of time in a magnetic field, measuring the internal resistance and an open circuit voltage of the battery; then after the battery to be tested is stewed at the set temperature and the set humidity for a certain period of timein the magnetic field, prompting the battery to perform self-discharge; then performing demagnetization on the battery, and measuring the internal resistance and the open circuit voltage of the battery; calculating a voltage drop and a resistance change value of the battery to be tested according to the internal resistance and the open circuit voltage; and judging the battery with qualified self-discharge performance according to the screened voltage drop and the resistance change value. The screening of the abnormality of the self-discharge performance of the lithium-ion power batteries in alithium iron phosphate system is more accurate via a battery voltage difference method, the consistency and reliability of the entire batch of batteries are effectively improved, the self-discharge detection time of the batteries is greatly shortened, and the production efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of lithium-ion batteries, in particular to a screening method for the self-discharge performance of lithium-ion power batteries. Background technique [0002] As a new generation of green high-energy rechargeable batteries, lithium-ion batteries have outstanding advantages such as high voltage, high energy density, good cycle performance, small self-discharge, and no memory effect. Advantages occupy a dominant position in the field of mobile electronic terminal equipment such as notebook computers, mobile phones, camcorders, and weapons and equipment in countries around the world. It is considered to be a high-tech industry that is of great significance to the national economy and people's lives in the 21st century. Lithium iron phosphate system lithium-ion power batteries are widely used in commercial production due to their excellent safety performance and low price. [0003] At present, the use of power ...

AI Technical Summary

Problems solved by technology

[0004] At present, the method of testing the charge retention capacity of lithium-ion batteries for electric vehicles is: put the battery under test at 20±5°C for 28 days. This method takes a long time to test in actual production and takes up a lot of space, material resources and financial resources. , low production efficiency

For example, in the Chinese patent application publication number CN104316877A, entitled "A self-discharge detection method for lithium iron phosphate battery", it uses the voltage difference method to eliminate polarization by standing at different temperatures, and test the voltage for battery screening. , but it does not introduce changes in internal resistance, magnetic field, humidity, etc., and its charge and discharge times are many, the time is long, and the reliability of the test results is not high