Additive‐Assisted Novel Dual‐Salt Electrolyte Addresses Wide Temperature Operation of Lithium–Metal Batteries

Abstract

In this study, self-synthesized lithium trifluoro(perfluoro-tert-butyloxyl)borate (LiTFPFB) is combined with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to formulate a novel 1 m dual-salt electrolyte, which contains lithium difluorophosphate (LiPO₂ F₂ ) additive and dominant carbonate solvents with low melting point and high boiling point. The addition of LiPO₂ F₂ into this novel dual-salt electrolyte dramatically improves cycleability and rate capability of a LiNi_0.5 Mn_0.3 Co_0.2 O₂ /Li (NMC/Li) battery, ranging from -40 to 90 °C. The NMC/Li batteries adopt a Li-metal anode with low thickness of 100 µm (even 50 µm) and a moderately high cathode mass loading level of 10 mg cm^-2 . For the first time, this paper provides valuable perspectives for developing practical lithium-metal batteries over a wide temperature range.