Dynamic Simulation for LFP Pouch Batteries Coupled Mechanics-Electrics-Thermodynamics under Mechanical Abuse

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-physics 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-physics 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 (usually used for vehicle collision simulation). And the difficulties of modeling, resource demanded for calculation, accuracy of results (in mechanics, electrics and thermodynamics) in the four models are compared. In detail, based on quasi-static mechanical experiments of positive and negative current collectors, current collectors with active materials and separators, the corresponding constitutive models and material cards are established. And a one-way coupling methodology is adopted for the Multi-physics simulation. We use the thickness deformation of separators and distance between positive and negative current collectors in one circuit achieved from the dynamic indentation experiment as the criteria for short-circuit. The mechanical simulation predicts the deformation of battery cell. The electrical and thermal simulation predicts resistive heating problems after short-circuit onset and propagation of heat in the whole cell. Results show that these models can describe battery behavior from deformation to thermal propagation under dynamic mechanical abuse well. And an efficient method to simplify models of battery cell for engineer application of battery-package or vehicle simulation is present in the end