Blended‐salt electrolytes showing synergistic effects have been formulated by simply mixing several lithium salts in an electrolyte. In the burgeoning field of next‐generation lithium batteries, blended‐salt electrolytes have enabled great progress to be made. In this Review, the development of such blended‐salt electrolytes is examined in detail. The reasons for formulating blended‐salt electrolytes for lithium batteries include improvement of thermal stability (safety), inhibition of aluminum‐foil corrosion of the cathode current collector, enhancement of performance over a wide temperature range (or at a high or low temperature), formation of favorable interfacial layers on both electrodes, protection of the lithium metal anode, and attainment of high ionic conductivity. Herein, we highlight key scientific issues related to the formulation of blended‐salt electrolytes for lithium batteries.

plating/stripping. [7][8][9][10][11][12][13][14][15] As a result, LMB always suffer from rapid capacity deterioration and high safety risk, especially at high charge/discharge rates and over a wide temperature range (from subzero temperatures to high temperatures). Encouragingly, varied strategies have been devoted to explore the Li-dendrite growth mechanism and Li-metal protection. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Wherein, one of the most effective and feasible strategy in protecting Li metal is electrolyte optimization, such as developing ionic liquids, [16] dual-salt electrolytes with additives, [20] gel polymer electrolyte, [18,27,28] concentrated electrolytes, [9,[24][25][26]29,30] etc.Undoubtedly, wide temperature range high-energy LMBs are urgently demanded for special applications, such as carrying out special missions in polar areas, desert areas, snowy mountains region, and outer space. [31] However, the operation of LMBs over a wide temperature range is seldom reported because of the fact that it is a huge challenge to find a compromise between subzero temperature performances and high temperature performances. [31][32][33] At subzero temperatures, due to the significantly reduced Li + conductivity (increased viscosity) of electrolyte and simultaneously increased charge transfer resistances, the severe growth of Li dendrites will become more uncontrolled. [31,34] At high temperatures, the bottlenecks are thermal instability of conventional LiPF 6 salt, severe solid electrolyte interphase (SEI) layer destruction-reformation accompanied by severe gas evolution, and accelerated transition metal dissolution-migration-deposition. [31] Significantly, formulating an electrolyte will play a dominant role in enabling the wide temperature operation of LMBs.Dual-salt electrolyte systems adopting two thermally stable main lithium salts have been proposed to significantly enhance the performances of both LIBs and LMBs. [20,[33][34][35][36][37][38][39][40][41][42] For the wide temperature operation of LIBs, thermally stable lithium borates (such as lithium tetrafluoroborate (LiBF 4 ), lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalate)borate (LiDFOB), etc.) dissolved in low melting point and high boiling point carbonatebased solvents (such as propylene carbonate (PC, T m = −48.8 °C, T b = 242 °C), ethyl methyl carbonate (EMC, T m = −53 °C, T b = 110 °C), etc.), have been investigated. [33][34][35][36][37][38] Recently, we have reviewed the potential application of functional lithium-borate salts in high performance lithium batteries, [43] and have successfully synthesized a bulky anion lithium trifluoro(perfluoro-tert-butyloxyl)borate (Li[(CF 3 ) 3 COBF 3 ], LiTFPFB), which exhibits high Li + conductivity and oxidation stability, as well as noncorrosivity to 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 contain...