Determination method for stress between electrode particles during lithium ion battery discharge process based on electrochemical-mechanical coupling model

Abstract

The invention discloses a determination method for stress between electrode particles during a lithium ion battery discharge process based on an electrochemical-mechanical coupling model, and relatesto the field of computation of the lithium ion battery stress. The method builds a three-dimensional model on a lithium ion battery electrode particle scale, and specifically comprises the following steps of: 1, selecting positive and genitive electrode materials, acquiring electrochemical and mechanical initial parameters, and building the electrochemical-mechanical coupling model on a three-dimensional particle scale; 2, computing a solid phase lithium concentration according to the electrochemical reaction of a battery and the Fick law; and 3, coupling the lithium concentration computed inthe step 2 into a stress model, wherein the expansion rate of the electrode particles is a function of the solid phase lithium concentration, and then computing the stress of the negative electrode particles. According to the determination method provided by the invention, the stress suffered by the electrode particles of the lithium battery during the discharge process can be computed, and then the certain guidance basis is provided for cracking and crushing of the electrode material.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery electrode stress calculation, and in particular relates to a method for determining the stress between electrode particles in a lithium-ion battery discharge process based on an electrochemical-force coupling model. Background technique [0002] In recent years, as an excellent energy storage carrier, lithium-ion batteries have been widely used in portable electronic devices such as mobile phones and computers, as well as in the field of electric vehicles. However, as the number of charge-discharge cycles increases, lithium ions are continuously deintercalated in the positive and negative electrodes, which will cause the expansion and contraction of the electrode particles, resulting in stress inside and between the particles. The generation of stress has the following three factors: (1) the deintercalation of external lithium ions, resulting in particle expansion, and the stress generated by th...

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Problems solved by technology

Excessive stress will lead to cracking, crushing, and delamination of electrode materials, which will lead to reduced contact of various components in the battery, increased internal resistance, capacity attenuation, and reduced cycle performance, eventually leading to battery failure

Previous studies have found that during the charging and discharging process, the volume deformation rate of negative electrode graphite particles can reach 10%, especially for high-capacity negative electrode silicon, its volume deformation rate can reach 400%, and the generation of huge stress will cause rapid capacity decay.

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