Synthesis and characterization of high porous carbon sphere@nickel oxide core-shell nanocomposite for supercapacitor applications

Carbon Sphere(CS) varied with high porous pristine nickel oxide (NiO) (CS@NiO) core shell has been successfully synthesized in different mole ratios of CS:NiO, i.e., 0:1(ncs0), 0.5:1(ncs1), 1:1(ncs2), 1.5:1(ncs3) and 2:1(ncs4) via low temperature water-bath method without further calcination. XRD results confirm that NiO and CS@NiO are in cubic structure. FT-IR studies confirm the complexation of NiO and CS. In TEM, CS appears as distinctly distributed spheres; ncs0 appears as uniformly distributed flakes; ncs3 appears as sphere enshrouded with NiO interlinked to one another. N2 adsorbtion/desorbtion isotherms (BET) have been observed for ncs0 and ncs3; and noted that the ncs3 exhibits uniform pore distribution of 3.7 nm. The electrochemical performance of pure NiO and CS@NiO nanocomposites is studied using Cyclic Voltammetry, Galvanostatic Charge/Discharge and Electrochemical Impedance spectroscopy. The nanocomposite in the ratio 1.5:1 (ncs3) is found to exhibit good specific capacitance of 825 F g−1 at current density of 1 A g−1 which is 50% higher than the pure porous NiO(ncs0). Cyclic stability of the same is tested for continuous 3500 cycles. The enhancement of better specific capacitance and cyclic stability of ncs3 may be attributed to its uniform distribution of mesopores and more electrode/electrolyte interaction.