Dynamic Simulation for LFP pouch batteries Coupled mechanics-electrics-thermodynamics under mechanical abuse 2020-01-1332
The safety design of batteries, an important part in passive safety development of electric vehicle, is difficult in practical project application because of complex structure inside and multi-physical reactions coupled mechanics-electrics-thermodynamics under mechanical abuse. An efficient computational model of batteries that can be attached to model of vehicle used for collision simulation is needed. In this work, four types of multi-physical battery models (detailed computational model, simplified representative-sandwich model, composite layered model and simplified layered model) of pouch cell with LiFePO4 system are established in a commercial finite element software LS-DYNA○R(usually used for vehicle collision simulation) and their difficulty of modeling, calculating time, accuracy of result (respectively in mechanics, electrics and thermodynamics) are compared. In detail, based on quasi-static mechanical experiments of positive and negative current collector, positive and negative current collector with active material, separator and aluminum casing, the component materials are established and validated. The mechanical properties of the detailed computational model constituted of all components of battery are validated by dynamic indentation condition on cell. The mechanical simulation predicts the deformation of battery cell. All component materials are without failure criteria in the four types of models, therefore, we use the deformation of achieved from the dynamic indentation experiment as the criteria for short-circuit. The electromagnetism and thermal simulation predicts resistive heating problems after short-circuit onset and conduction of heat in the whole cell. Results show that these models can describe battery behavior from deformation to thermal runaway onset under dynamic mechanical abuse, and the simplified layered model is most efficient, and accurate enough for further development in engineering application.