Electrolytes consisting of carbonate solvents and LiPF₆ readily decompose at high operating voltages, causing poor battery performances. In order to meet the needs of high voltage and high specific energy cells, electrolytes with improved electrochemical stabilities are urgently required. Here, we have introduced the lithium bis(fluorosulfonyl)imide (LiFSI) as an electrolyte additive to accomplish this goal. Through the research in this paper, it is found that the electrolyte system with LiFSI can form more stable and uniform solid electrolyte interphase (SEI) film during the cycle, which can be used to suppress the decomposition of carbonate‐based electrolytes. Subsequently, this finding is supported by the density functional calculations and the structural analysis. LiNi_0.5Co_0.2Mn_0.3O₂/graphite full cells with different amounts of LiFSI additive are fabricated to demonstrate the improvement of electrochemical performance. Working at 4.4 V and 1 C, the capacity retention rate of cells with 5 wt.% LiFSI is significantly enhanced compared with non‐LiFSI (52.4 % for none and 85.0 % for 5 wt. % loading at room temperature after 120 cycles; 47.5 % for none and 80.0 % for 5 wt. % loading at 45 °C after 100 cycles).

中文翻译：

---

通过添加双（氟磺酰基）酰亚胺锂作为电解质添加剂来提高工作电压和温度范围

由碳酸盐溶剂和LiPF ₆组成的电解质容易在高工作电压下分解，从而导致电池性能下降。为了满足高压和高比能量电池的需求，迫切需要具有改善的电化学稳定性的电解质。在这里，我们引入了双（氟磺酰基）酰亚胺锂（LiFSI）作为电解质添加剂来实现这一目标。通过本文的研究，发现具有LiFSI的电解质体系可以在循环过程中形成更稳定和均匀的固体电解质相间（SEI）膜，可用于抑制碳酸盐基电解质的分解。随后，该发现得到密度泛函计算和结构分析的支持。LiNi _0.5 Co制备了具有不同量的LiFSI添加剂的_0.2 Mn _0.3 O ₂ /石墨全电池，以证明电化学性能的改善。在4.4 V和1 C下工作时，与非LiFSI相比，具有5 wt。％LiFSI的电池的容量保持率显着提高（120次循环后在室温下无负载时为52.4％，在5 wt。％下为85.0％; 47.5） 100个循环后，在45°C时，无载量为80％，无载量为80.0％）。