Advanced materials and technologies for supercapacitors used in energy conversion and storage: a review

Abstract

Supercapacitors are increasingly used for energy conversion and storage systems in sustainable nanotechnologies. Graphite is a conventional electrode utilized in Li-ion-based batteries, yet its specific capacitance of 372 mA h g −1 is not adequate for supercapacitor applications. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period and longer lifetime. This review compares the following materials used to fabricate supercapacitors: spinel ferrites, e.g., MFe 2 O 4 , MMoO 4 and MCo 2 O 4 where M denotes a transition metal ion; perovskite oxides; transition metals sulfides; carbon materials; and conducting polymers. The application window of perovskite can be controlled by cations in sublattice sites. Cations increase the specific capacitance because cations possess large orbital valence electrons which grow the oxygen vacancies. Electrodes made of transition metal sulfides, e.g., ZnCo 2 S 4 , display a high specific capacitance of 1269 F g −1 , which is four times higher than those of transition metals oxides, e.g., Zn-Co ferrite, of 296 F g −1. This is explained by the low charge-transfer resistance and the high ion diffusion rate of transition metals sulfides. Composites made of magnetic oxides or transition metal sulfides with conducting polymers or carbon materials have the highest capacitance activity and cyclic stability. This is attributed to oxygen and sulfur active sites which foster electrolyte penetration during cycling, and, in turn, create new active sites.

Recent advances in carbon capture storage and utilisation technologies: a review

“…Graphene Graphene is a unique category of carbonaceous substances with superior adsorption potential and lately got extensive consideration (Abdel Maksoud et al 2020). Various investigations applied different strategies to qualify the surface of graphene and introduce an extraordinary surface area and acceptable pore volume (Kumar and Xavior 2014).…”

Industrial biochar systems for atmospheric carbon removal: a review

“…For example, for agronomic applications, a high electrical conductivity value indicates the presence of salts, where a high biochar application rate may have negative effects on salt-sensitive plants (Singh et al 2017). However, a high electrical conductivity value would be favourable for other applications such as supercapacitors for energy storage (Gabhi et al 2020;Abdel Maksoud et al 2020). Similar to pH, the type of feedstock and the processing conditions are determinants for the electrical conductivity values measured in the resulting biochar.…”

Nanostructured ZnFe2O4: An Exotic Energy Material

“…Regardless of the environmental pressure to reduce energy consumption, global power demand is growing—and one of the ways to solve this “looming energy crisis” is through the exploration of novel earth-abundant energy materials [ 1 , 2 , 3 , 4 ]. Further, the pace of technological change is getting faster, thus the miniaturization of electronic devices is also key [ 5 , 6 , 7 ].…”

“…These demands can be met by realizing an efficient oxide energy material at the nanoscale by controlling their complex crystal structure with many degrees of freedom (i.e., charge, spin, and orbital) [ 8 ]. Oxide materials usually possess high density, display robust physical properties, and show great flexibility to tune their optical, electrical, and magnetic properties, with subtle changes such as elemental substitutions, defect, and strain engineering [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Among the oxides, earth-abundant Zn-ferrite can be the potential alternative energy material.…”