Degradation characterization and thermal management of LTO||LFP-based lithium-ion batteries for wide-range operating temperature applications

In subzero temperature environments, the charge-discharge performance of lithium-ion batteries declines significantly due to cell degradation. This degradation is primarily attributed to sluggish charge-transfer kinetics, which affect the reversibility of electrochemical reactions, leading to low electrolyte conductivity. Moreover, low operating temperatures contribute to further electrolyte degradation, leading to increased internal resistance and insufficient ionic conductivity. This study addresses these challenges by proposing feasible, practical solutions that focus on enhancing the battery's inert components rather than its active materials. A thin-film heater was integrated with the pouch cell to enable controlled internal heating, while a lightweight polymer-based insulation case was developed to minimize heat loss under cold conditions.Comparative analysis of capacity retention revealed that the bare pouch cell retained only 2 % of its capacity at −60 °C, whereas the heated and insulated pouch cells retained 50 % and 81 %, respectively. Coulombic efficiency results further indicated that the bare cell exhibited greater electrochemical irreversibility compared to the heated and insulated cells. Post-cycling characterization of the cathodes further verified that the effect of the subzero environment was effectively mitigated, resulting in improved cell capacity and stability. • Thermal management strategy prevents battery degradation in extreme cold. • Thin-film heater improves battery capacity retention to 50 % at −60 °C. • PEEK insulation casing increases capacity retention to 81 % under subzero conditions. • Heated cells exhibit lower charge-transfer resistance compared to bare and insulated cells. • XRD and XPS confirm reduced cathode degradation in heated and insulated LFP cells.