Porous α‐MnSe Microsphere Cathode Material for High‐Performance Aluminum Batteries

Abstract Aluminum batteries (ABs) have been considered as a viable candidate for new‐generation energy‐storage devices due to its low cost and high theoretical volumetric capacity. Despite these advantages, the large‐scale application of ABs is constrained by scarce options of suitable cathode materials. Herein, three‐dimensional nanostructured α‐MnSe microspheres with porous properties are reported as a cathode for ABs. The nanosized and porous structure of α‐MnSe could offer numerous open channels and the short ionic transport path, which would efficiently mitigate volume changes and enhance electrochemical reaction kinetics. Moreover, the pseudocapacitive characteristic of Al 3+ storage in α‐MnSe contributes to the fast kinetics of the cathode. It is demonstrated that the reversible Al 3+ insertion/extraction occurs in the α‐MnSe cathode during the cycling process. The resulting aluminum battery based on the α‐MnSe cathode, AlCl 3 /[EMIm]Cl ionic liquid electrolyte, and aluminum anode exhibits an ultrahigh reversible capacity of 408 mA h g −1 at 0.2 A g −1 . Even for a current density at 1 A g −1 , a discharge capacity of 131 mA h g −1 could be retained with a Coulombic efficiency of 97 % over 150 cycles. This strategy has referential significance in aspects of the selection of compatible cathode for ABs.