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Efficient thermal management is crucial for preventing temperature-induced degradation in LiFePO₄/graphite batteries operating at high discharge rates. This study examines how the chemical composition of phase change materials (PCMs) influences thermal regulation, solid electrolyte interphase (SEI) growth, and electrolyte stability using a fully coupled electrochemical–thermal–chemical multiphysics model validated against experimental data (RMSE = 0.07 V). Five PCMs (paraffin, graphene-doped paraffin, salt hydrate, SrCl₂-enhanced salt hydrate, and an organic–inorganic Al₂O₃-based composite) were evaluated under 0.5C–3 C discharge. Results show that PCM molecular design strongly affects thermal conductivity, latent heat utilization, and phase-transition kinetics, which collectively determine degradation suppression. The organic–inorganic PCM exhibited the best performance, lowering peak temperature from 66.7 °C to 44.6 °C at 3 C, reducing temperature gradients by 46%, achieving 70% latent-heat utilization, and decreasing SEI growth rate by ~50%. Graphene-doped paraffin and SrCl₂-stabilized salt hydrate provided moderate improvements (45–47% SEI reduction), while pure paraffin showed limited effectiveness. These results establish a clear link between PCM chemical composition and temperature-driven degradation mitigation in LiFePO₄/graphite pouch cells under constant-current discharge (0.5C–3 C). Accordingly, the proposed materials-focused framework is applicable to the comparative design and screening of high-performance PCMs for LiFePO₄-based pouch cells operating under similar thermal and electrochemical conditions, while extension to other chemistries, cell formats, or dynamic duty cycles requires further investigation. While the electrochemical model is validated against experimental voltage data (RMSE = 0.07 V), the reported temperature reduction, latent heat utilization, and SEI suppression are obtained from coupled multiphysics simulations and should be interpreted as model-based trends rather than direct measurements.
Mohammad et al. (Sun,) studied this question.