Although significant progress has been made on the cycle life of silicon (Si)-based lithium (Li)-ion batteries (LIBs), their calendar life is still far less than those required for electrical vehicle applications. Here, the fundamental mechanisms behind the limited calendar life of Si-LIBs were systematically investigated. It is found that fluoroethylene carbonate (FEC) additive typically used in the electrolyte to enhance the room temperature cycling stability of Si-LIBs is responsible for the rapid impedance increase of Si-LIBs during storage at 55 °C. An FEC-free localized high-concentration electrolyte (lithium bis(fluorosulfonyl)imide:ethyl propionate:ethylene carbonate:1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (1:2.8:0.2:1 by mol.) with 1 wt % lithium difluorophosphate) promotes stable interphase layers formed on electrodes that can effectively block the crosstalk between cathode and anode and minimize the impedance increase of Si||LiNi_0.6Mn_0.2Co_0.2O₂(NMC622) batteries during storage at 55 °C, therefore largely improving their calendar life. Si||NMC622 batteries using this electrolyte demonstrated a high-capacity retention of 92.4% after 500 cycles at 45 °C with a well-preserved electrode structure. The failure mechanism revealed in this work and the approach used to improve the stability of Si-LIBs can also be used to improve the calendar life of other rechargeable batteries.

中文翻译：

---

通过局部高浓度电解质延长硅基锂离子电池的日历寿命

尽管硅（Si）基锂（Li）离子电池（LIB）的循环寿命已取得重大进展，但其日历寿命仍远低于电动汽车应用所需的寿命。在这里，系统地研究了 Si-LIB 有限日历寿命背后的基本机制。研究发现，电解液中通常使用的氟代碳酸亚乙酯（FEC）添加剂可增强 Si-LIB 的室温循环稳定性，这是 Si-LIB 在 55 °C 储存期间阻抗快速增加的原因。不含FEC的局部高浓度电解液（双(氟磺酰基)亚胺锂:丙酸乙酯:碳酸亚乙酯:1,1,2,2-四氟乙基-2,2,3,3-四氟丙醚(1:2.8:0.2: 1摩尔）与1重量％二氟磷酸锂）促进电极上形成稳定的中间相层，可以有效阻止正极和负极之间的串扰，并最大限度地减少Si||LiNi _0.6 Mn _0.2 Co _0.2 O ₂ (NMC622)电池的阻抗增加在 55°C 下储存期间，因此大大提高了其日历寿命。使用该电解质的 Si||NMC622 电池在 45 °C 下循环 500 次后显示出 92.4% 的高容量保持率，且电极结构保存完好。这项工作中揭示的失效机制以及用于提高 Si-LIB 稳定性的方法也可用于提高其他可充电电池的日历寿命。