Facile fabrication of cobalt oxalate nanostructures with superior specific capacitance and super-long cycling stability

• We fabricate cobalt oxalate-anchored cobalt foil electrode through anodization.
• The hybrid electrode presents superior specific capacitance of 1269 F g−1.
• The hybrid electrode retains 91.9% after super-long cycling of 100,000 cycles.
• The present electrode has excellent flexibility and good mechanical properties.
• The asymmetric CoC2O4//AC supercapacitor shows high energy and power density.

Transition metal oxalate materials have shown huge competitive advantages for applications in supercapacitors. Herein, nanostructured cobalt oxalate supported on cobalt foils has been facilely fabricated by anodization, and could directly serve as additive/binder-free electrodes for supercapacitors. The as-prepared cobalt oxalate electrodes present superior specific capacitance of 1269 F g−1 at the current density of 6 A g−1 in the galvanostatic charge/discharge test. Moreover, the retained capacitance is as high as 87.2% as the current density increases from 6 A g−1 to 30 A g−1. More importantly, the specific capacitance of cobalt oxalate retains 91.9% even after super-long cycling of 100,000 cycles. In addition, an asymmetric supercapacitor assembled with cobalt oxalate (positive electrode) and activated carbon (negative electrode) demonstrates excellent capacitive performance with high energy density and power density.

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