Free-standing LiMn2O4/CNT electrodes for improved low-temperature electrochemical performance

초록

Low-temperature operation significantly deteriorates the electrochemical performance of lithium-ion batteries because of reduced electrolyte ionic conductivity, sluggish lithium-ion diffusion, and increased interfacial resistance. In conventional slurry-cast electrodes, insulating polymer binders further hinder electron transport and increase internal resistance by interrupting conductive pathways and introducing additional interfacial contacts. These effects become more critical under low-temperature conditions, where electrochemical reaction kinetics are already suppressed. In this study, the low-temperature electrochemical performance of a binder-free free-standing LiMn2O4 (LMO) electrode (LMO-F) and a conventional slurry-cast LMO electrode (LMO-S) is comparatively evaluated. During cycling at 0.5C with decreasing temperature from room temperature to −20 °C, the discharge capacity of LMO-F decreases from 92.26 to 77.84 mAh g−1, whereas that of LMO-S decreases from 82.78 to 52.39 mAh g−1. In addition, LMO-F exhibits higher discharge capacities than LMO-S over the entire C-rate range during rate tests at −20 °C. Electrochemical impedance spectroscopy shows that LMO-F has a lower charge-transfer resistance at −20 °C (129.2 Ω) than LMO-S (301.5 Ω), and lithium-ion diffusion analysis also indicates better diffusion behavior for LMO-F under low-temperature conditions. These results suggest that the binder-free free-standing structure is beneficial for improving the low-temperature electrochemical performance of LMO electrodes. © 2026 Elsevier Inc.

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