Designing transition metal-based porous architectures for supercapacitor electrodes: a review

Abstract

This review summarizes the typical synthesis strategies and conversion mechanisms of porous transition metal-based electrode materials and discusses their energy storage characteristics and challenges in supercapacitors in a categorical manner.

Nano-Nest Type Porous NiCo2S4@polyindole Core–Shell Array: Efficient Energy Storage Supercapacitor Device

“…Fast consumption of fossil energy sources and consequent anticipated crises have been acknowledged globally, and serious efforts are being made to switch to alternate power sources by exploring new and efficient energy conversion and storage devices. − (Super-) capacitors have their practical applicability due to their high power density, fast charge–discharge, easy synthesis, high capacitance retention, high mechanical strength, and better ecological coexistence. − Nevertheless, the low energy density of supercapacitors always restricts their practical applications due to the small operational potential window. , To increase the energy density, asymmetric supercapacitors are fabricated with positive electrodes as high-specific capacitance material to increase the power density and negative electrodes (negatrodes) as carbonaceous material (usually activated carbon) to increase the energy density of the device. , In addition to these carbon materials, transition metal sulfides have emerged as promising positive electrode materials for supercapacitors − owing to the advantages of ultrahigh theoretical specific capacitance, excellent cyclic stability, and fast ion diffusion rate. Among them, NiS x and CoS x are the most reported metal sulfide supercapacitors; however, their specific capacitance is always higher than that of their corresponding metal oxides under the same experimental conditions, which is attributed to their high electrical conductivity. − The specific capacitance can further be improved if dual metal sulfides such as NiCo 2 S 4 (NCS) and CuCo 2 S 4 are used due to their strong redox reactions and high theoretical specific capacitance.…”