Low temperature has been a major challenge for lithium‐ion batteries (LIBs) to maintain satisfied electrochemical performance, and the main reason is the deactivation of electrolyte with the decreasing temperature. To address this point, in present work, we develop a low‐temperature resistant electrolyte which includes ethyl acetate (EA) and fluoroethylene carbonate (FEC) as solvent and lithium difluoro(oxalato)borate (LiDFOB) as the primary lithium salt. Due to the preferential decomposition of LiDFOB and FEC, a solid electrolyte interface rich in LiF is formed on the lithium metal anodes (LMAs) and lithium cobalt oxide (LCO) cathodes, contributing to higher stability and rapid desolvation of Li+ ions. The batteries with the optimized electrolyte can undergo cycling tests at ‐40 °C, with a capacity retention of 83.9 % after 200 cycles. Furthermore, the optimized electrolyte exhibits excellent compatibility with both LCO cathodes and graphite (Gr) anodes, enabling a Gr/LCO battery to maintain a capacity retention of 90.3 % after multiple cycles at ‐25 °C. This work proposes a cost‐effective electrolyte that can activate potential LIBs in practical scenarios, especially in low‐temperature environments.

中文翻译：

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低温锂离子电池羧酸酯电解液的浓度控制


低温一直是锂离子电池（LIB）保持满意的电化学性能的主要挑战，其主要原因是电解质随着温度的降低而失活。为了解决这一点，在目前的工作中，我们开发了一种耐低温电解质，其中包括乙酸乙酯（EA）和氟代碳酸亚乙酯（FEC）作为溶剂以及二氟（草酸）硼酸锂（LiDFOB）作为主要锂盐。由于LiDFOB和FEC的优先分解，在锂金属阳极（LMA）和钴酸锂（LCO）阴极上形成富含LiF的固体电解质界面，有助于提高Li+离子的稳定性和快速去溶剂化。采用优化电解液的电池可在‐40℃下进行循环测试，200次循环后容量保持率为83.9%。此外，优化后的电解质与 LCO 正极和石墨 (Gr) 负极表现出优异的兼容性，使 Gr/LCO 电池在 ‐25 °C 下多次循环后仍能保持 90.3% 的容量保持率。这项工作提出了一种经济有效的电解质，可以在实际场景中激活潜在的锂离子电池，特别是在低温环境下。