NixCo1-x(OH)2 nanosheets on carbon nanofoam paper as high areal capacity electrodes for hybrid supercapacitors

This work reports the charge storage ability of NixCo1-x(OH)2 nanosheet-carbon nanofoam paper (CNFP) composites prepared by electrodeposition for high areal capacity supercapacitor electrodes. The NixCo1-x(OH)2 film grew through instantaneous nucleation, uniformly covered CNFP, and displayed a porous morphology composed of a nanosheet percolation network. The electrochemical response of the NixCo1-x(OH)2 films was tuned by varying the Co to Ni ratios. The optimized NixCo1-x(OH)2 stoichiometry resulted in Ni0.33Co0.67(OH)2-CNFP electrodes displaying areal capacity/capacitance values of 1.52 C cm−2/2.03 F cm−2 at 2.1 mA cm−2, resulting from the contribution of the double layer capacity of CNFP with the redox capacity of NixCo1-x(OH)2. A two electrode cell composed of CNFP as negative electrode and NixCo1-x(OH)2-CNFP as positive electrode presented a high areal capacity value of 0.73 C cm−2 at 7.2 mA cm−2.