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<p>This study introduces a novel three-dimensional electrochemical-thermal model to investigate the performance of a 10 Ah LiFePO<sub>4</sub>/graphite pouch battery under low-temperature stress (−&#xa0;20&#xa0;°C to 25&#xa0;°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 LiPF<sub>6</sub> decomposition, and heat transfer equations, the model quantifies the interplay of ionic mobility, chemical degradation, and thermal dynamics. Key findings reveal that at −&#xa0;20&#xa0;°C, reduced ionic diffusivity leads to significant lithium-ion accumulation (1480&#xa0;mol&#xa0;m⁻<sup>3</sup>, 48% increase) at the separator-cathode interface, while LiPF<sub>6</sub> decomposition generates hydrofluoric acid (HF) at 15.00&#xa0;mM, rising to 30.00&#xa0;mM at 25&#xa0;°C, accelerating cathode corrosion and increasing solid-electrolyte interphase (SEI) resistance (230.0–254.0 Ω cm<sup>2</sup>). Joule heating causes a modest temperature rise (0.90&#xa0;K at −&#xa0;20&#xa0;°C), insufficient to overcome kinetic limitations. Validated with a Root Mean Square Error (RMSE) of 0.041&#xa0;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.</p>

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

  • 期刊论文

  • 发表日期：

    2025年12月27日

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

摘要

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.