Method for predicting cycle life of lithium ion battery based on pole piece expansion degree

Abstract

The invention discloses a method for predicting the cycle life of a lithium ion battery based on the pole piece expansion degree, and belongs to the technical field of lithium ion battery cycle life testing. The method comprises the following steps of: increasing the cycle number of lithium batteries in the same batch at a fixed gradient, and establishing a relation curve between the cycle numberand the capacity retention ratio; carrying out discharging treatment on the tested lithium ion batteries and then disassembling the lithium ion batteries; carrying out cyclic test on each lithium ionbattery, and carrying out shooting calculation on the pole piece expansion degree; establishing a relation curve between the capacity retention ratio and the pole piece expansion degree; disassemblinga lithium ion battery to be predicted after circulation for a certain number of circles, and calculating the pole piece expansion degree and the capacity retention ratio; and calculating the cycle life of the lithium ion battery. According to the method for predicting the cycle life of a lithium ion battery based on the pole piece expansion degree, based on the change of the expansion degree of the pole piece in the battery cycle process, the service life of the battery is predicted through fitting calculation of measured data after short-term cycle, better consistency with an actual test result is achieved, and the method is simple and easy to implement.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery cycle life testing, in particular to a method for predicting the cycle life of lithium-ion batteries based on the expansion degree of pole pieces. Background technique [0002] Cycle life is an important indicator that limits the practical application of lithium-ion batteries. In the field of power batteries, it is generally believed that when the battery capacity drops to 80% of the rated capacity, it will no longer be used in electric vehicles. However, the conventional lithium-ion battery cycle life test method takes a long time and will take up a lot of manpower and material costs. Therefore, it is necessary to find a method that can quickly predict battery life. [0003] Chinese patent (Notice No. CN107144790A) provides a method for predicting the cycle life of lithium-ion batteries. By measuring the impedance spectra of different cells, comparing the shape of the graphs, the rel...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for predicting the cycle life of a lithium-ion battery based on the degree of expansion of the pole piece to solve the existing method for predicting the life of a lithium-ion battery. The process is complicated, takes a long time, and is affected by many factors , resulting in the inability to objectively predict the cycle life of lithium-ion batteries

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