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<p>Temperature substantially alters the deliverable capacity and terminal-voltage response of LiFePO<sub>4</sub> cells, yet the relationship between external capacity variation, accessible electrode states, and kinetic limitations remains insufficiently resolved. This study develops a wide-temperature analytical framework that connects electrode-window accessibility, kinetic-parameter effects, and cross-condition validation. Multi-temperature OCV-SOC curves are decoupled using electrode equilibrium potentials, SOC-to-stoichiometry mapping, and cyclable-lithium conservation to identify accessible electrode stoichiometric windows on a unified internal-state scale. A pseudo-two-dimensional model is then used to distinguish the effects of the solid-phase diffusion coefficient <i>D</i><sub><i>s</i></sub> and interfacial reaction-rate constant <i>k</i>, while local sensitivity and Fisher information are employed to partition their dominance intervals. Results over 0–60&#xa0;°C indicate that intensified transport limitations and interfacial polarization at low temperatures trigger the cutoff voltage prematurely, compressing the accessible windows and reducing delivered capacity. The inferred capacity on the unified cyclable-lithium scale remains within 244.79–250.34 Ah, suggesting that the observed capacity variation primarily reflects changes in window accessibility rather than comparable changes in cyclable-lithium inventory. The parameter <i>k</i> predominantly governs the initial voltage drop and plateau level, whereas <i>D</i><sub><i>s</i></sub> becomes dominant near the end-of-discharge knee. Under baseline 0.5C discharge, the voltage RMSE ranges from 0.0052 to 0.0104&#xa0;V. Independent 0.2C, 1C, and 2C bidirectional charge–discharge tests further confirm the principal capacity-voltage trends, while revealing increased errors during low-temperature charging and high-rate discharge. The framework provides a physically interpretable basis for wide-temperature capacity analysis, parameter identification, and model applicability assessment.</p> Graphical Abstract <p></p>

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Mechanistic characterization of wide-temperature-range capacity and voltage behavior in LiFePO4 batteries via cyclable-lithium-window scale optimization

  • 期刊论文

  • 发表日期：

    2026年7月11日

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  • Liangdong Sun,
  • Shunli Wang,
  • Chunmei Yu,
  • Donglei Liu,
  • Liangwei Cheng,
  • Haotian Shi,
  • Carlos Fernandez

摘要

Temperature substantially alters the deliverable capacity and terminal-voltage response of LiFePO4 cells, yet the relationship between external capacity variation, accessible electrode states, and kinetic limitations remains insufficiently resolved. This study develops a wide-temperature analytical framework that connects electrode-window accessibility, kinetic-parameter effects, and cross-condition validation. Multi-temperature OCV-SOC curves are decoupled using electrode equilibrium potentials, SOC-to-stoichiometry mapping, and cyclable-lithium conservation to identify accessible electrode stoichiometric windows on a unified internal-state scale. A pseudo-two-dimensional model is then used to distinguish the effects of the solid-phase diffusion coefficient Ds and interfacial reaction-rate constant k, while local sensitivity and Fisher information are employed to partition their dominance intervals. Results over 0–60 °C indicate that intensified transport limitations and interfacial polarization at low temperatures trigger the cutoff voltage prematurely, compressing the accessible windows and reducing delivered capacity. The inferred capacity on the unified cyclable-lithium scale remains within 244.79–250.34 Ah, suggesting that the observed capacity variation primarily reflects changes in window accessibility rather than comparable changes in cyclable-lithium inventory. The parameter k predominantly governs the initial voltage drop and plateau level, whereas Ds becomes dominant near the end-of-discharge knee. Under baseline 0.5C discharge, the voltage RMSE ranges from 0.0052 to 0.0104 V. Independent 0.2C, 1C, and 2C bidirectional charge–discharge tests further confirm the principal capacity-voltage trends, while revealing increased errors during low-temperature charging and high-rate discharge. The framework provides a physically interpretable basis for wide-temperature capacity analysis, parameter identification, and model applicability assessment.

Graphical Abstract