Hexagonal Composite CuSe@C as a Positive Electrode for High-Performance Aluminum Batteries

As an energy-storage and conversion device, rechargeable aluminum batteries are considered to be a very potential secondary battery system. However, the lack of a suitable positive electrode material with high capacity, good rate capability, and excellent cycling performance hinders the further development of aluminum batteries. In this work, a carbon-coated hexagonal sheet-like CuSepC composite was studied in rechargeable aluminum batteries, which exhibits a high initial discharge specific capacity of 668.7 mA h g(-1) with a current density of 500 mA g(-1). The aluminum battery with CuSepC as a positive electrode still retains a discharge capacity of 171.5 mA hg(-1) at 1.5 A g(-1).( )Furthermore, the energy-storage mechanism was studied by electrochemical and X-ray photoelectron spectroscopy characterization methods, which reveal that the [AlCl4](-) anions are intercalated/deintercalated into CuSe@C positive electrode materials during charging/discharging. In addition, the valence behaviors of Se and Cu were also studied, and the intercalation/deintercalation of the [AlCl4](-) anions caused the reversible redox of Cu and Se.