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 (LiPO 2 F 2 ) additive and dominant carbonate solvents with low melting point and high boiling point. The addition of LiPO 2 F 2 into this novel dual‐salt electrolyte dramatically improves cycleability and rate capability of a LiNi 0.5 Mn 0.3 Co 0.2 O 2 /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.