Electrochemical–thermal modelling of high power Li-ion pouch cells

Accurate thermal modelling of large-format lithium-ion cells under high C-rate conditions is critical for electric vehicles, especially during fast charging, but finding parsimonious approaches is a challenge. Here, a simplified physics-based (3+0)D electrochemical and thermal porous-electrode model based on the formulation by Chu et al. (2020) was implemented to capture both electrical characteristics and spatial temperature gradients within high-power LFP/Gr 9 Ah A123 Systems pouch cells. The model was then parametrised using lock-in thermography. Following the method of Lin et al. (2022), data from short square-wave current cycling (ca. ± 5% state of charge swing) centred around fixed initial states of charge were fitted to parametrise a linearised model, whose nonlinear analogue was subsequently validated against full charge/discharge tests ranging from 2C–10C. Surface temperature differences ranged up to 6 °C during 10C discharge. The model closely matched experimental data (within 15 mV voltage and 0.35 °C temperature root-mean-square error for 10C charge on an independent validation dataset), showing that fast diffusion in high-power cells permits model simplification without sacrificing accuracy. Results highlight the need for spatially resolved models for robust battery management under aggressive cycling. • Novel lock-in thermography data for pulse, discharge, charge experiments. • Streamlined (3+0)D electrochemical-thermal model for 9 Ah LFP/Gr Li-ion pouch cell. • Extends existing streamlined (3+0)D model to constant-current full-SOC range. • Power cell permits solid-diffusion-free, accurate, parsimonious model.