With a higher demand towards the energy density of power batteries for electric vehicles, the Li-metal batteries (LMBs) have staged a comeback in recent years. However, the low cycle efficiency and safety issues associated with Li dendrite growth and electrolyte combustion severely limit their practical applications. Here we prepare a highly concentrated TFSI-FSI dual-anion electrolyte (HCDE) based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), N-ethyl-N-methyl-pyrrolidinium bis(fluorosulfonyl)imide ([C₂mpyr][FSI]), and dimethyl carbonate (DMC). The co-solvent of [C₂mpyr][FSI] and DMC exhibits promoted ionic conductivity, low viscosity and non-flammability. In HCDE, the TFSI-FSI dual-anion is preferentially decomposed to obtain a robust inorganic solid electrolyte interphase (SEI), which induces a dense and uniform Li deposition on the Li-metal surface and effectively suppresses Li dendrite growth. Meanwhile, it also enables good suppression of Al current collector corrosion and stable cycling performance at high-voltage owing to the high salt-to-solvent ratio. The LFP (LiFePO₄)/Li cells steadily deliver a long-term cycle life and obtain ∼80% capacity retention with an extremely high CE (∼99.9%) after 500 cycles, and the NCM523 (LiNi_0.5Co_0.2Mn_0.3O₂)/Li cells retain ∼95% of their original capacity after 100 cycles at a high cut-off voltage of 4.5 V. According to X-ray photoelectron spectroscopy (XPS) and molecular dynamic (MD)-density functional theory (DFT) simulations, the forming mechanism of SEI layer is suggested.

随着对电动汽车动力电池能量密度的更高要求，锂金属电池（LMB）近年来已卷土重来。然而，与锂枝晶生长和电解质燃烧相关的低循环效率和安全性问题严重限制了它们的实际应用。在这里，我们基于双（三氟甲磺酰基）酰亚胺锂（LiTFSI），N-乙基-N-甲基-吡咯烷鎓双（氟磺酰基）酰亚胺（[C ₂ mpyr] [FSI ]）和碳酸二甲酯（DMC）。[C ₂的助溶剂mpyr] [FSI]和DMC表现出增强的离子导电性，低粘度和不燃性。在HCDE中，TFSI-FSI双阴离子被优先分解以获得坚固的无机固体电解质中间相（SEI），该相可在Li-金属表面上诱导致密且均匀的Li沉积并有效地抑制Li树枝状晶体的生长。同时，由于高的盐溶剂比，它还能够很好地抑制Al集电器的腐蚀，并在高压下具有稳定的循环性能。LFP（LiFePO ₄）/ Li电池稳定地提供长期的循环寿命，并在500次循环后获得极高的CE（〜99.9％）的〜80％容量保持率，以及NCM523（LiNi _0.5 Co _0.2 Mn _0.3 O _2））/ Li电池在4.5 V的高截止电压下经过100次循环后，仍可保留约95％的原始容量。根据X射线光电子能谱（XPS）和分子动力学（MD）-密度泛函理论（DFT）模拟提出了SEI层的形成机理。