The Recovery Strategies Exploration for Irreversible Degradation toward LiCoO ₂ /Graphite Batteries at −20 °C

At present, lithium-ion batteries face two major challenges in low-temperature applications: mitigating capacity degradation caused by low-temperature operation to enhance overall performance and suppressing the formation of lithium dendrites on the negative electrode to improve safety. A comprehensive understanding of the battery degradation mechanisms under low-temperature conditions is essential for enhancing safety, and developing effective strategies for capacity recovery. This study, through differential voltage analysis, incremental capacity curves, and postcycling disassembly, reveals that the desolvation energy of lithium ions determines whether they intercalate into active materials or deposit as dendrites. After aging at −20 °C, capacity attenuation is primarily due to interfacial degradation, while the electrode bulk structure remains largely intact, indicating recoverable capacity. A key recovery strategy is proposed: implementing low-current charging during the voltage plateau phase. This approach effectively activates electrodes and reconstructs a stable interface film, thereby repairing aging damage and restoring battery capacity. Concurrently, the number and length of lithium dendrites on the anode are significantly reduced, effectively preventing separator penetration and internal short circuits, substantially enhancing subsequent operational safety. Therefore, this study proposes a viable strategy for restoring the capacity of batteries following low-temperature aging, while simultaneously improving the safety of subsequent operation.