High-energy-density lithium-metal batteries face the challenge of developing functional electrolytes enabling both the stabilization of the lithium-metal negative electrode and high-voltage positive electrodes (> 4 V versus Li⁺/Li). Herein, a low-volatility and non-flammable ionic liquid electrolyte (ILE) incorporating two anions, bis(fluorosulfonyl) imide (FSI) and bis(trifluoromethanesulfonyl)imide (TFSI), is successfully applied to overcome this challenge, employing the high-energy, low-Co, and Ni-rich positive-electrode material, LiNi_0.88Co_0.09Mn_0.03O₂ (NCM88), in Li-metal batteries. With this specific electrolyte, the cathode exhibits remarkable electrochemical performance, achieving an initial specific capacity of 214 mAh g⁻¹ and outstanding capacity retention of 88% over 1,000 cycles. More importantly, this electrolyte enables an average Coulombic efficiency of 99.94%. The excellent compatibility of the dual-anion ILE with both the lithium metal (50 μm) and the high-voltage positive-electrode material enables the realization of Li-metal cells achieving specific energies of more than 560 Wh kg⁻¹ based on their combined active material masses.

高能量密度锂金属电池面临着开发功能性电解质的挑战，该电解质能够稳定锂金属负极和高压正极（> 4 V vs Li ⁺ /Li）。在此，一种低挥发性且不可燃的离子液体电解质 (ILE) 包含两种阴离子，双（氟磺酰基）酰亚胺（FSI）和双（三氟甲磺酰基）酰亚胺（TFSI），成功应用于克服这一挑战，采用高能量、低钴、富镍正极材料，LiNi _0.88 Co _0.09 Mn _0.03 O ₂(NCM88)，在锂金属电池中。使用这种特殊电解质，正极表现出卓越的电化学性能，初始比容量为 214 mAh g ^-1，1,000次循环后容量保持率高达 88%。更重要的是，这种电解质能够实现 99.94% 的平均库仑效率。双阴离子 ILE 与锂金属 (50 μm) 和高压正极材料的出色兼容性使锂金属电池能够实现超过 560 Wh kg ^-1的比能量，基于它们的组合活性物质质量。