Coordination interaction boosts energy storage in rechargeable Al battery with a positive electrode material of CuSe

Transition metal selenides (TMSs) are promising candidates for positive electrodes of rechargeable Al batteries (RABs) owing to their appealing merits of high specific capacity and relatively low-cost. However, TMSs suffer from fast capacity fading. To tackle the dramatic capacity loss in TMS positive electrode, herein, we design a coordination adsorption strategy into RABs using CuSe as a conversion-type positive electrode material, with significantly enhanced cycling stability and rate capability. Ex situ X-ray photoelectron spectroscopy and electron microscopy measurements unveil that both Cu and Se species experience reversible redox reaction during the charge/discharge processes and the fast capacity-deterioration is due to the dissolution of electroactive Cu and Se species into the electrolyte. Theoretical calculations reveal that the suppressed shuttle effects can be attributed to the presence of strong coordination interaction between nitrogen-doped reduced graphene oxide and the soluble active Cu and Se species. Consequently, such delicately engineered RABs exhibit an excellent cycling stability of 216.1 mA h g-1 after 500 cycles at 500 mA g-1 with an outstanding rate performance. This study offers an alternative approach to restrain the shuttle effects of active species for achieving advanced RAB system, with the potential importance far beyond the battery chemistry.

Automated summary

In this study, a coordination adsorption strategy was employed using CuSe as a positive electrode material to enhance cycling stability and rate capability. Ex situ X-ray photoelectron spectroscopy revealed reversible redox reactions of Cu and Se species, while electron microscopy measurements showed capacity deterioration due to the dissolution of active Cu and Se species. Theoretical calculations identified strong coordination interaction between nitrogen-doped reduced graphene oxide and active species as key in suppressing shuttle effects and achieving excellent cycling stability.