Nickel-Doped h-MoO3 Cathodes: A High-Performance Material for Aluminum-Ion Batteries

This study introduces a novel method for the effective doping of hexagonal molybdenum trioxide (h-MoO₃) microstructures with different contents of nickel, significantly enhancing its electrochemical performance in aluminum-ion batteries (AIBs). Ni doping does not alter the high crystallinity and phase purity of the pristine oxide but modifies its defective structure and electronic properties. Electrochemical tests, including cyclic voltammograms and charge–discharge cycling, showed improvements in capacity and stability for Ni-doped samples as compared with undoped ones. Moreover, the incorporation of Ni was found to enhance the structural integrity and electrochemical stability of h-MoO₃, preventing the formation of intermediate phases during cycling and reducing resistance at the electrode–electrolyte interface. The existence of an optimal Ni doping of about 1 at% is evidenced. Samples with this Ni content attain a stabilized specific capacity of 230 mAh g⁻¹ over 100 cycles, doubling that reported in previous works for h-MoO₃ composites with carbon nanotubes. Nickel-doped h-MoO₃ shows exciting potential for advanced AIB applications, paving the way for further energy storage technology advancements.