Gopalan Muralidharan

Binary nanocomposites of Li₂ incorporated β-NiS have been synthesized via hydrothermal technique. XRD results indicate the formation of nanocomposite of Li₂ and rhombohedral β-NiS. A spongy layered morphology could be identified through SEM analysis. The presence of Ni, S and Li₂ could be identified through energy-dispersive X-ray analysis. The charge storage capabilities of Li₂: β-NiS nanocomposites were examined using electroanalytical methods such as cyclic voltammetry, galvanic charge-discharge, and ac impedance analysis. In the three-electrode configuration, the electrodes could provide a specific capacitance of 860 F g^− 1 (CV at 10 mV s^− 1) and 700 F g^− 1 (GCD at 2 mA cm^− 2). The Li₂: β-NiS electrode reveals pseudocapacitive behaviour. The Li₂: β-NiS electrode could provide 90% capacity retention after 3000 continuous charge-discharge cycles at 10 mA cm^− 2. A symmetric device has been fabricated using Li₂: β-NiS as the working electrodes, and its performance has been studied in a window of 1 V with the lower end at 0.5 V. The energy and power density exhibited by the symmetric device is 12 W h kg^− 1 and 500 W kg^− 1. The symmetric device could yield 94% capacity retention even after 5,000 continuous charge-discharge cycles.

A growing quest for supercapacitors capable of quickly transferring energy has led to investigations focusing on developing electrode materials that incorporate noble metals due to their superior electrical conductivity. Here, we report the synthesis and charge storage performance of mesoporous silver molybdate electrodes of cubic β-Ag₂MoO₄ morphology and potatoes-like nanostructures. The electrochemical performance of the mesoporous β-Ag₂MoO₄ electrode has a battery-type behaviour with the transfer of two electrons (Ag⁰ ↔ Ag²⁺) during the redox reaction in 2 M KOH aqueous solution within a potential range of −0.45 to 0.35 V. In addition, the electrodes demonstrate quasi-conversion reaction during the discharge, which is due to the oxidation of unoxidized Ag⁰. Furthermore, the electrodes exhibit a maximum specific capacity of 2610 C g⁻¹ at 1 A g⁻¹ and significant retention of 82% upon 5000 continuous galvanostatic charge/discharge (GCD) cycles. A battery-type asymmetric supercapacitor cell (BASC) was designed using β-Ag₂MoO₄ as the positive electrode, activated carbon as the negative electrode, and polyurethane foam/KOH as the separator-cum-charge reservoir. The fabricated BASCs yielded maximum specific energy of 54 W h kg⁻¹ at a specific power of 194 W kg⁻¹. These appreciable electrochemical features suggest that β-Ag₂MoO₄ can be a viable material for developing supercapacitor electrodes.

This work represents the design of superior supercapacitor electrode that comprised of 3D cloud like silver cobalt oxide/cobalt oxide (AgCoO₂−Co₃O₄) and carbon architecture. AgCoO₂−Co₃O₄/C architecture can be fabricated from Co−Ag nitrate precursors with the addition of carboxymethyl cellulose followed by annealing. Mesoporous 3D cloudy architecture provides higher specific capacitance (575 F g⁻¹ at a scan rate of 2 mV s⁻¹) and rate performance (666 F g⁻¹ at a current density of 1 A g⁻¹). The combined effect of AgCoO₂ embedded Co₃O₄ and carboxymethyl cellulose (carbon) highly favors for outstanding cycle life (around 1 % capacitance degradation even after 5000 cycles). Presence of such porous 3D architecture with carbon backbone delivers admirable energy/power density. Also, an advanced asymmetric supercapacitor with an operating range of 1.2 V is designed by utilizing this porous 3D cloudy architecture as positive electrode and activated carbon as negative electrode. The fabricated design shows a robust energy density of 17 W h kg⁻¹ with a high power density of 166 W kg⁻¹ at a current density of 1 A g⁻¹. The findings of the current study underline the potential of AgCoO₂−Co₃O₄/C electrodes for supercapacitor applications.