Method for determining thermal stress and temperature in lithium ion battery discharging process based on thermal-mechanical coupling model

Abstract

The invention discloses a method for determining thermal stress and temperature in the discharge process of a lithium ion battery based on a thermal-mechanical coupling model, and relates to the fieldof lithium ion battery thermal expansion and stress calculation. The method is used for establishing a thermal expansion model according to the three-dimensional geometrical scale of the lithium ionbattery, and comprises the following specific steps: (1) selecting a single battery cell, and acquiring three-dimensional geometrical parameters and mechanical and thermodynamic initial parameters ofthe single battery cell; (2) establishing a three-dimensional cell scale thermal-mechanical coupling model according to the thermal expansion coefficient, the temperature difference and a coupling mechanism of a stress-strain relationship; (3) measuring the temperature of the battery and the temperature of the tab through experiments, and verifying the effectiveness of the model; and (4) obtainingtemperature distribution of the battery and expansion displacement and stress along x, y and z directions. The method is an expansion model on the macroscopic scale of the battery cell, and can provide a certain guidance basis for the prediction of the expansion behavior and fracture of the battery cell in the charging and discharging process.

Description

technical field [0001] The invention belongs to the field of thermal expansion and stress calculation of lithium-ion batteries, and in particular relates to a method for determining thermal stress and temperature during the discharge process of lithium-ion batteries based on a thermal-mechanical coupling model. Background technique [0002] Lithium-ion batteries are widely used in electronic equipment, electric vehicles and energy storage power stations due to their excellent performance, but there have also been many safety accidents. During the charging and discharging process of lithium-ion batteries, especially in the high-rate charging and discharging process, there will be local high temperature phenomenon, and high temperature will cause thermal expansion, which will lead to thermal stress. When the generated stress is large, it will Accompanied by the cracking and falling off of the electrode material, and the poor contact of each part of the battery cell due to the ...

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Problems solved by technology

[0003] At present, the traditional experimental method is difficult to observe the expansion behavior of the battery cell during the charging and discharging process and predict the stress, and the thermal expansion model on the macro scale of the battery cell is difficult to verify the validity of the model and difficult to establish the model. less

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