Co/Al layered double hydroxides nanostructures: A binderless electrode for electrochemical capacitor

•Hierarchical nanostructures of Co/Al-LDH were grown directly on current collector.•These arrays can be used as binderless electrodes for electrochemical capacitor.•These Co/Al-LDH arrays showed excellent pseudocapacitor properties.•Capacitance was found to increase with the content of Al in the nanostructures.•High capacitance of 0.510 F/cm2 was achieved for Co/Al-LDH array with 12% Al content.

We present here a study of Co/Al layered double hydroxides (LDH) nanoflakes supported on Co nanowires as a binderless electrode for electrochemical capacitor. This nanostructured array was prepared easily via electrodeposition of Co in anodic alumina (AAO) template followed by alkaline treatment. This is the first report AAO template is used as a source of Al3+ to form the LDH directly. Capacitance was found to increase with the amount of Co/Al-LDH, as indicated by the Al content from EDX analysis. This content is controllable by varying the duration of alkaline treatment. High capacitance of 0.510 F/cm2 was achieved for sample containing 12% Al measured at current density 2.5 mA/cm2 in 1 M KOH. The electrodes also exhibited good stability, maintaining more than 90% of their original capacitance after 3000 continuous charge–discharge cycles.