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<p>Lithium-ion batteries (LIBs) are often subjected to non-uniform temperature conditions, significantly influencing their thermal runaway propagation (TRP) characteristics at the cell level. To elucidate the coupling between temperature gradient (TG) and cathode chemistry, this study develops a three-dimensional electrochemical–thermal model with a four-step reaction mechanism and employs the BatteryFOAM solver to investigate the TRP of LMO and NCA pouch cells under longitudinal TGs of 10–100&#xa0;K/m. An idealized linear TG and a localized hotspot are established to analyze spatiotemporal thermophysical field evolution, while a Gaussian kernel density estimation method is introduced to quantify propagation speed distributions. Results reveal the dominant role of cathode chemistry. The NCA cell exhibits stable propagation under moderate TGs (17.5–23&#xa0;mm/s) with low variance (0.21–0.53 m<sup>2</sup>/s<sup>2</sup>) and near-zero skewness, indicating symmetric and uniform propagation, but becomes highly heterogeneous at 100&#xa0;K/m (variance 7.3 m<sup>2</sup>/s<sup>2</sup>, skewness 5.1). In contrast, the LMO cell shows strong TG sensitivity, with propagation speed increasing from 7.5&#xa0;mm/s to 19.3&#xa0;mm/s, accompanied by high variance (4.2–14.1 m<sup>2</sup>/s<sup>2</sup>) and negative skewness (− 0.12 to − 0.97), reflecting inherent heterogeneity and asymmetry toward slower regions. KDE analysis further reveals a bimodal-to-unimodal transition in LMO speed distribution above 60&#xa0;K/m. This work quantitatively clarifies distinct TRP behaviors under non-uniform thermal fields, offering theoretical guidance for cathode-oriented thermal safety design.</p>

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Effect of Cathode Chemistry on In-Cell Thermal Runaway Propagation Under Non-Uniform Battery Temperatures

  • 期刊论文

  • 发表日期：

    2026年6月22日

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  • Yan Ding,
  • Li Lu,
  • Huangwei Zhang

摘要

Lithium-ion batteries (LIBs) are often subjected to non-uniform temperature conditions, significantly influencing their thermal runaway propagation (TRP) characteristics at the cell level. To elucidate the coupling between temperature gradient (TG) and cathode chemistry, this study develops a three-dimensional electrochemical–thermal model with a four-step reaction mechanism and employs the BatteryFOAM solver to investigate the TRP of LMO and NCA pouch cells under longitudinal TGs of 10–100 K/m. An idealized linear TG and a localized hotspot are established to analyze spatiotemporal thermophysical field evolution, while a Gaussian kernel density estimation method is introduced to quantify propagation speed distributions. Results reveal the dominant role of cathode chemistry. The NCA cell exhibits stable propagation under moderate TGs (17.5–23 mm/s) with low variance (0.21–0.53 m2/s2) and near-zero skewness, indicating symmetric and uniform propagation, but becomes highly heterogeneous at 100 K/m (variance 7.3 m2/s2, skewness 5.1). In contrast, the LMO cell shows strong TG sensitivity, with propagation speed increasing from 7.5 mm/s to 19.3 mm/s, accompanied by high variance (4.2–14.1 m2/s2) and negative skewness (− 0.12 to − 0.97), reflecting inherent heterogeneity and asymmetry toward slower regions. KDE analysis further reveals a bimodal-to-unimodal transition in LMO speed distribution above 60 K/m. This work quantitatively clarifies distinct TRP behaviors under non-uniform thermal fields, offering theoretical guidance for cathode-oriented thermal safety design.