Strategy to enhance the electrochemical characteristics of lanthanum sulfide nanorods for supercapacitor applications

The exploration of electrode functional materials for supercapacitors may bring a revolution to energy storage devices to boost the portable industry. Herein, lanthanum sulfide nanorods and reduced graphene oxide (rGO)–templated lanthanum sulfide nanorods have been synthesized using the hydrothermal process. Structural, morphological, and compositional analyses were conducted using X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The specific surface area has been measured using the Brunauer–Emmett–Teller technique. Individual lanthanum sulfide and rGO-templated lanthanum sulfide showed the morphology of nanorods. Cyclic voltammetry tests predicted the pseudocapacitive nature of the lanthanum sulfides for supercapacitor applications. The rGO effectively improved the electrochemical characteristics of the lanthanum sulfide, which might be due to the facilitation of charge carriers through nanorods, as the rGO-templated lanthanum sulfide nanorod showed a specific capacitance of 75.17 F/g at a scan rate of 30 mV/s evidenced by cyclic voltammetry (CV) curves. The rGO significantly increased the discharge time from 60 to 188 s, specific capacitance from 20.32 to 34.12 F/g, and energy density from 572 to 1185 mW/kg compared to individual lanthanum sulfide nanorods as seen by the galvanostatic charge/discharge profile. The rGO-templated lanthanum sulfide nanorods showed a power density of 255.20 W/kg at a high current density of 0.2 A/g and a specific capacitance retention up to 91.60% for 2000 cycles at scan rate of 20 mV/s. Symmetric cell exhibited the specific capacitance of 94.45 F/g, energy density of 6.43 Wh/kg at the current density of 0.05 A/g, and power density of 351.25 W/kg at the current density of 0.2 A/g. The test results indicate that the use of rGO is effective in improving the electrochemical characteristics of lanthanum sulfide nanorods for supercapacitor applications.