Improved supercapacitive performance of low pore size and highly stable nanostructured NiCo2O4 electrodes

The nanostructured nickel cobaltite has been synthesized by a cost-effective facile hydrothermal method and demonstrated excellent electrochemical capacitive properties. The microstructural properties of as-synthesized nanostructured nickel cobaltite are probed with various analytical techniques, viz. XRD, XPS, BET, SEM, and TEM. A high-intensity (311) orientation along with other characteristic peaks observed in XRD spectrum corresponds to cubic spinel NiCo 2 O 4 (NCO) phase with Fd 3 ¯ m (227) symmetry. The NCO material is comprised of homogenous distribution of cuboid-shaped nanocrystalline particles as observed from TEM analysis. Brunauer-Emmett-Teller (BET) analysis evidenced that the prepared nickel cobaltite material possesses a high specific surface area 138 m 2 g −1 with an average pore radius 4 nm. The high surface area and low average pore size generally offer more electroactive sites for Li-ion adsorption-desorption and avoid the stress upon the structure of the compound which resulted exemplary electrochemical performance. The NCO electrode delivered a superior specific capacitance of 2040 F g −1 at 1 A g −1 and retained 85.5% of its capacitance even after 5000 cycles. The desirable integrated quality such as long calendar life with high capacitance of the newly fabricated electrode enables it to be a promising material for high-performance supercapacitor devices.