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

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 Al³⁺ storage in α-MnSe contributes to the fast kinetics of the cathode. It is demonstrated that the reversible Al³⁺ insertion/extraction occurs in the α-MnSe cathode during the cycling process. The resulting aluminum battery based on the α-MnSe cathode, AlCl₃/[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.