Two dimensional layered nickel cobaltite nanosheets as an efficient electrode material for high-performance hybrid supercapacitor

Nickel cobalt oxide (NCO) is considered an auspicious electrode candidate for the reinforcement of energy-storage devices. Currently, an immense interest is devoted to modifying the morphological aspects of the NCO to boost their surface texture and electrochemical performances, which is feasible for the development of high energy density and durable devices. Herein, we report the synthesis of layered NCO nanosheets via solvothermal reaction by tuning the solvent volume ratio (water/N,N-Dimethylformamide [DMF]) for supercapacitor electrode material. The nickel cobalt oxide is prepared utilizing a 1:2 (DMF:water) ratio of solvent (NCO1) displays a controlled growth of 2D nanosheets with excellent surface texture. Moreover, NCO1 demonstrates the battery type charge storage properties with a maximum specific capacitance (C_sp) of 731 F g⁻¹, which is far better than NCO2 (623 F g⁻¹) and NCO3 (556 F g⁻¹) prepared in other solvent proportions. Besides, the constructed hybrid supercapacitor utilizing activated carbon (AC) and NCO1 as the negative and positive electrodes, respectively, exhibits the C_sp of 120 F g⁻¹, and maximum specific energy 37.33 W h kg⁻¹ for the specific power 691.31 W kg⁻¹ and demonstrates excellent stability ~80.56% for 20 000 cycles.