Lithium-ion storage performance of camphoric carbon wrapped NiS nano/micro-hybrids

Abstract

Camphoric carbon wrapped NiS powders have been profitably exploited to fabricate high surface area electrodes for Li storage. The NiS morphology showed a network of interconnected nanoscale units with rod like profiles which terminated into needle-like apexes spanning diameters of about 50–80 nm. These particles were pyrolyzed using a camphoric solution to form a carbon sheath wrapping. These carbon functionalized NiS powders were processed into high-surface-area cathodes for a fully functional coin cell unit. A detailed study was performed to elucidate the effect of carbon content on the performance of these coin cells. BET surface area analysis revealed that these carbon sheathed NiS could exhibit a high surface area of 32 m² g⁻¹ compared to pristine powders which exhibited surface area values of 20 m² g⁻¹. From the analysis of relevant electrochemical parameters, an intrinsic correlation between the specific capacity, internal resistance and temperature has been deduced. Relative contributions of capacitive and diffusion-controlled processes underlying these thin-film electrodes have been mathematically modeled. These thin-film electrodes exhibited specific capacity values as high as 500 mA h g⁻¹ as determined from charge discharge curves. The present study shows that this functional material can provide the advantages of simple processing technique, low cost, and scalability.