ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Electrochemical and chemical dynamics of LiFePO₄ pouch cells at low temperatures through 3D modeling

Fadhil Faez Sead, Vicky Jain, Suhas Ballal, Abhayveer Singh, Sofia Gupta, Girish Chandra Sharma, Pushpa Negi Bhakuni, and Amirali Nikpendar

Department of Dentistry, College of Dentistry, The Islamic University, Najaf, Iraq

E-mail: amiralinikpendaracademic@gmail.com

Received: 30 June 2025  Accepted: 2 December 2025

Abstract:

This study introduces a novel three-dimensional electrochemical-thermal model to investigate the performance of a 10 Ah LiFePO₄/graphite pouch battery under low-temperature stress (− 20 °C to 25 °C) at 1C discharge, offering new insights into electrolyte chemistry for cold-climate applications. Uniquely integrating the Nernst-Planck equation for lithium-ion transport, Arrhenius kinetics for LiPF₆ decomposition, and heat transfer equations, the model quantifies the interplay of ionic mobility, chemical degradation, and thermal dynamics. Key findings reveal that at − 20 °C, reduced ionic diffusivity leads to significant lithium-ion accumulation (1480 mol m⁻³, 48% increase) at the separator-cathode interface, while LiPF₆ decomposition generates hydrofluoric acid (HF) at 15.00 mM, rising to 30.00 mM at 25 °C, accelerating cathode corrosion and increasing solid-electrolyte interphase (SEI) resistance (230.0–254.0 Ω cm²). Joule heating causes a modest temperature rise (0.90 K at − 20 °C), insufficient to overcome kinetic limitations. Validated with a Root Mean Square Error (RMSE) of 0.041 V, this model highlights the critical role of electrolyte stability in low-temperature performance degradation. The study’s novelty lies in its detailed spatial analysis of HF-induced degradation and its actionable recommendations for electrolyte optimization, including low-viscosity solvents (e.g., dimethyl carbonate, ethyl methyl carbonate) and stable salts (e.g., LiFSI), to enhance ionic conductivity and mitigate degradation, advancing the design of robust LiFePO₄ batteries for electric vehicles and stationary storage in cold environments.

Keywords: Electrolyte decomposition; Hydrofluoric acid; LiFePO4 pouch cell solid-electrolyte interphase; COMSOL multiphysics; Modeling

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04576-6

Chemical Papers 80 (3) 3137–3151 (2026)