Lithium ion battery consistency screening method

Abstract

The present invention provides a lithium ion battery consistency screening method. The screening method at least comprises: testing the AC resistance of a battery after a liquid injection process, then performing a capacity grading test to obtain the capacity of the battery, and testing the AC internal resistance after the capacity grading; performing a self-discharge process on the battery afterthe capacity grading for still standing, and performing charging and discharging to obtain a discharge capacity of the battery; according to the AC resistance of the battery after the liquid injectionprocess, the capacity obtained by the capacity grading test, the AC internal resistance after the capacity grading, and the discharge capacity obtained by the charging and discharging, calculating acycle state value of the battery; and finally grouping the batteries according to the cycle state values to implement battery consistency screening. According to the method provided by the present invention, the capacity and the AC internal resistance of the lithium ion battery are obtained, and the cycle state value can be calculated through the formula, so that batteries with a similar cycle life can be screened out; and the method is simple in operation, the cycle life of the screened batteries has good consistency, and there is no damage to the battery.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a consistency screening method for lithium-ion batteries. Background technique [0002] Lithium-ion batteries have high energy density, good rate performance, and long service life, and have been widely used, especially in the fields of energy storage and electric vehicles, where a huge amount of lithium-ion battery cells are used. According to reports, an electric vehicle with a range of 440km uses more than 7,000 lithium-ion battery cells. For many lithium-ion battery cells, consistency is of great significance for lithium-ion battery packs, and one battery can affect the experience of the entire vehicle. [0003] The cycle life is an important indicator to measure the performance of lithium-ion batteries. It refers to the fact that lithium-ion batteries are charged and discharged according to the specified system. When the discharge capacity of the b...

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Problems solved by technology

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a lithium-ion battery consistency screening method for solving the problems in the prior art that the battery cycle life consistency screening period is long and the consistency is poor

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