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 CuSe@C 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 CuSe@C as a positive electrode still retains a discharge capacity of 171.5 mA h g–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.