Dual-Salt Mixed Electrolyte for High Performance Aqueous Aluminum Batteries

A dual-salt electrolyte with 5 M Al(OTF)₃ and 0.5 M LiOTF is proposed for aqueous aluminum batteries, which can effectively prevent the corrosion caused by the hydrogen evolution reaction. With the addition of LiOTF in the electrolyte, the solvation phenomenon has changed with the coordination mode of Al³⁺ conversion from an all octahedral structure to a mixed octahedral and tetrahedral structure. This change can reduce the hydrogen bond between water molecules, which will minimize the occurrence of hydrogen evolution reactions. Moreover, the new electrolyte improves the cycle life of the battery. With MnO as the cathode, 2.1 V high charging platform and 1.5 V high discharge platform can be obtained. The electrochemical stability window (ESW) has been improved to 3.8 V. The first cycle capacity is up to 437 mAh g^–1, which can be maintained at 103 mAh g^–1 after 100 cycles. This work provides solutions for the future development of electrolyte for aqueous aluminum batteries.