Nanomaterial-based energy conversion and energy storage devices: a comprehensive review

Abstract

For energy-related applications such as solar cells, catalysts, thermo-electrics, lithium-ion batteries, graphene-based materials, supercapacitors, and hydrogen storage systems, nanostructured materials have been extensively studied because of their advantages of high surface to volume ratios, favorable transport properties, tunable physical properties, and confinement effects resulting from their nanoscale dimensions. Due to their high energy and power densities, supercapacitors are potential power storage technologies. In this case, carbon nanomaterials, in particular carbon nanotubes, graphene, mesoporous carbon, and their hybrids, have received extensive research interest as effective electrode materials for supercapacitors because of their distinctive hierarchical structure, excellent electrical and mechanical properties, and large specific surface area. Lithium-ion batteries (LIBs) have been receiving extensive attention because of their high specific energy density. In LIBs, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. Recently, nanowire/graphene hybrids have been developed for the enhancement of the LIB performance; therefore, we present a new approach of hydrothermally growing uniform nanowires on a graphene aerogel to further improve the performance. This nanowire/graphene aerogel hybrid not only exhibited the large surface area of graphene aerogels but also increased the specific surface area for electrode–electrolyte interaction. Therefore, this new nanowire/graphene aerogel hybrid anode material can enhance the specific capacity and charge–discharge rate. There is enormous interest in the use of graphene-based materials for energy storage. Graphene-based materials have great potential for application in supercapacitors owing to their unique two-dimensional structure and inherent physical properties, such as excellent electrical conductivity and large specific surface area. In recent years, the development of different organic and inorganic nanostructured materials such as nanocarbons, metal oxides (W₁₈O₄₉ and Co₃O₄), metal sulphides (MoS₂ and WS₂), graphene nanosheets, and conducting polymers has enabled the fabrication of high-performance devices. MoS₂, a typical layered transition-metal dichalcogenide material, has attracted significant attention for application in heterogeneous catalysis, lithium ion batteries and electrochemical energy storage systems considering its unique layered structure and electronic properties. Thus, transition metal dichalcogenide nanomaterials have shown important research progress in the field of energy conversion and storage.