Glycine-assisted hydrothermal synthesis of NiCo2S4 as an active electrode material for supercapacitors

Abstract

Nickel cobalt sulfide (NCS) was synthesized from nickel and cobalt nitrate (NCS-1) by a hydrothermal method. In another method, nickel cobalt sulfide (NCS-2) was also synthesized from hydrothermally synthesized nickel cobalt oxide (NCO). The syntheses of NCS-1 and NCO were conducted in the presence of glycine as a templating agent. The NCS and NCO samples were thoroughly characterized by different techniques. XRD studies showed that both NCO and NCS consisted of the cubic crystal phases. Cyclic voltammetry of NCO and NCS revealed that, with an increasing scan rate within the range of 10–100 mV s−1, the specific capacitance of the samples reduced. The specific capacitance of NCS-2, measured by galvanostatic charge–discharge, was found to be 675 F g−1, which is higher than those of NCO (313 F g−1) and NCS-1 (500 F g−1). The specific capacitance retention of NCS-2 was 88% over 1000 cycles, indicating the good cyclic stability of the material. Keywords: Nickel cobaltite, Nickel cobalt sulfide, Glycine, Pseudocapacitor, Supercapacitor