摘要
CONSPECTUS:Frequent safety accidents of lithium-ion batteries(LIBs)originating from the utilization of flammable electrolytes urges the battery community to develop a safe substitute.This safety background is a boom for aqueous batteries(ABs)which employ aqueous electrolytes to address safety concerns.Recently,ABs have experienced a rapid advance because various battery chemistries have been successively developed,e.g.,aqueous Zn batteries(AZBs),aqueous LIBs,aqueous sodium-ion battery,etc.Impeded by the narrow voltage window of aqueous electrolytes,however,the majorities of cathode materials with high operation potential employed in traditional nonaqueous batteries are excluded from the range of ABs cathodes,leading to a low energy density.Directly using metal as an anode is likely to improve the energy density,whereas most of the reported metal anodes,e.g.,lithium,sodium,magnesium,etc.,cannot run in aqueous electrolytes.One exceptional case is the Zn metal anode that permits theoretically high energy density AZBs due to triple merits:(1)the Zn metal anode exhibits a low redox potential(−0.76 V vs standard hydrogen electrode,SHE),taking the best advantage of the limited voltage window of aqueous electrolytes;(2)Zn metal anode with mild protection can easily maintain its chemical stability in aqueous medium;(3)Zn metal anode releases a high specific capacity of 820 mAh g^(−1).AZBs thus exhibit a rapid development,especially in developing high specific capacity cathode materials such as MnO_(2)and V_(2)O_(5),and the corresponding structure modification.Despite these spurring achievements,the overall energy density of the whole AZB device is still unsatisfactory.
基金
The authors acknowledge the financial support by the National Key R&D Program of China under Project 2019YFA0705104 and ITC.
