High-voltage rechargeable lithium-metal batteries (LMBs) require electrolytes that are compatible with both the Li metal anode (LMA) and the metal-oxide cathode. Herein, by imitating the fluorosulfonyl imide group from a well-known LMA-compatible salt, lithium bis(fluorosulfonyl) imide (LiFSI), we come up with an organic solvent dimethylsulfamoyl fluoride (FSO₂NC₂H₆), a fluorosulfonamide (FSA) with two methyl substituents, to develop a new “full fluorosulfonyl” (FFS) electrolyte. Remarkably, it enables a highly reversible LMA with an excellent initial coulombic efficiency (CE) ∼91%, and rapidly approaching 99% within only 10 cycles, with average CE outperforming the well-known LMA-compatible fluoroethylene carbonate (FEC)-based electrolyte. Furthermore, benefitting from its high anodic stability against the oxidative LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) and LiMn₂O₄ (LMO) surfaces, the Li‖NMC622 cell retains 89% of its original capacity after 200 cycles using a limited Li excess anode. This electrolyte design strategy opens a new avenue for exploring new medium-concentration organic electrolytes for 4 V class lithium-metal batteries (LMBs).

中文翻译：

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受FSI启发的溶剂和“全氟磺酰基”电解液，用于4 V级锂金属电池

高压可充电锂金属电池（LMB）需要与锂金属阳极（LMA）和金属氧化物阴极兼容的电解质。在此，通过从众所周知的LMA兼容盐双（氟磺酰基）酰亚胺锂（LiFSI）中模仿氟磺酰亚胺基团，我们提出了一种有机溶剂二甲基氨磺酰氟（FSO ₂ NC ₂ H ₆），具有两个甲基取代基的氟磺酰胺（FSA），以开发新的“全氟磺酰基”（FFS）电解质。值得注意的是，它可实现高度可逆的LMA，具有优异的初始库仑效率（CE）〜91％，并且仅在10个循环内即可迅速达到99％，平均CE优于知名的LMA兼容的碳酸氟亚乙酯（FEC）基电解质。此外，得益于其对氧化LiNi _0.6 Mn _0.2 Co _0.2 O ₂（NMC622）和LiMn ₂ O _4的高阳极稳定性（LMO）表面，Li'NMC622电池在使用有限的过量Li阳极200次循环后仍保持其原始容量的89％。这种电解质设计策略为探索用于4 V级锂金属电池（LMB）的新型中等浓度有机电解质开辟了一条新途径。