Solid electrolyte interphases (SEI) plays a vital role in stabilizing lithium (Li) metal anodes for rechargeable batteries. However, forming robust SEI layers is challenging in the state-of-the-art electrolytes. Herein, we report a long-lasting and dual-function additive (potassium nonafluoro-1-butanesulfonate or KPBS) for dual-salt LiFSI-LiTFSI ether electrolyte. Our work suggests that the electrostatic shield effect from potassium ion (K⁺) and the F-rich PBS⁻ anions with a middle lowest unoccupied molecular orbital (LUMO) level together promote the formation of a LiF-rich SEI during the Li plating/striping process, which effectively restricts Li dendrite growth and suppresses electrolyte consumption. As a consequence, the designed electrolyte endows small nucleation overpotential, highly reversible Li plating/stripping, and excellent cycling stability. Specifically, with such an electrolyte, Li–Cu cells can maintain stable cycling during 400 cycles at 1 mA cm⁻² for 1 mA h cm⁻² with a high coulombic efficiency (CE) of 99.1%. Li–LiFePO₄ full cells displayed dramatically improved cycling stability after 100 cycles with high CE of 99.6% under relatively lean electrolyte condition (7.5 μL mA h⁻¹), limited Li supply (N/P = 1.2) and high areal capacity (4.1 mA h cm⁻²).

固态电解质中间相（SEI）在稳定可充电电池的锂（Li）金属阳极方面起着至关重要的作用。然而，在现有技术的电解质中，形成坚固的SEI层是有挑战性的。在此，我们报告了一种用于双盐LiFSI-LiTFSI醚电解质的长效双功能添加剂（九氟-1-丁磺酸钾或KPBS）。我们的工作表明，钾离子（K ⁺）和富F的PBS的静电屏蔽作用^-具有较低的未占据分子轨道（LUMO）最低水平的阴离子共同促进了Li镀层/剥离过程中富LiF的SEI的形成，从而有效地限制了Li树枝状晶体的生长并抑制了电解质的消耗。结果，所设计的电解质具有小的成核超电势，高度可逆的锂镀覆/剥离以及出色的循环稳定性。具体而言，这样的电解质，锂铜细胞可以在400个循环在1mA厘米维持稳定的循环^-2为1毫安高厘米^-2与99.1％的高库仑效率（CE）。Li–LiFePO _{4 4}电池在相对稀薄的电解质条件（7.5μLmA h ^-1）下经过100次循环后，循环稳定性显着提高，CE高达99.6％。），有限的锂供应（N / P = 1.2）和高面容量（4.1 mA h cm ^-2）。