Currently, graphene and its 2D layered analogue materials, particularly hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2), are attracting high research interest due to their exceptional functional properties for energy storage applications. Graphene reveals high electric conductivity and surface area, besides excellent mechanical, chemical and electrochemical stability. These properties are key for the development of advanced supercapacitor and battery devices. On the other hand, despite its low electric conductivity, h-BN exhibits outstanding chemical stability and charge storage capacity, showing high potential for secondary batteries. As well, semiconducting MoS2 displays remarkable capabilities for energy storage when combined with conducting polymers and graphene.
Several fabrication routes as chemical vapour deposition, hydro/solvothermal synthesis, wet chemical methods, liquid exfoliation, soft colloidal template approaches, mechanical exfoliation, epitaxial growth, sputtering, or laser-based techniques, are being employed to synthesize high quality materials and integrate them in efficient devices with special attention to scalability. Of significant importance is also the exploration of innovative growth approaches for fine tuning of the materials properties, with the aim of optimizing their functional properties. Thereby, different strategies as chemical doping, intercalation of different types of atoms and molecules, or combination with other nanostructures forming hybrid composites, are being constantly developed.
Regardless of the great advancements reached so far, the commercial exploitation of graphene, h-BN and MoS2 materials in real-world energy storage devices requires the previous resolution of challenges related to morphological optimization of the porous materials, electrochemical interferences, low internal conductivity, and low working potential. These issues, which are being addressed, hamper the great potential of these materials in terms of energy storage capacity and charge-discharge cycling life. This review describes the research strategies deployed for overcoming such drawbacks.
A review on synthesis of graphene, h-BN and MoS2 for energy storage applications: recent progress and perspectives
Rajesh Kumar, Sumanta Sahoo, Ednan Joanni, Rajesh Kumar Singh, Ram Manohar Yadav, Rajiv Kumar Verma, Dinesh Pratap Singh, Wai Kian Tan, Angel Pérez del Pino, Stanislav A. Moshkalev, Atsunori Matsuda
Nano Research 12(11): 2655–2694, 2019
Figure: (a) Scheme of graphene, MoS2 and h-BN for clean energy related applications, particularly, supercapacitors and batteries. (b) SEM image of carbon nanosheets obtained by CVD. (c) HRTEM images of hydrothermally synthesized MoS2 nanosheets. (d) Atomic-scale image of an h-BN film (scale bar = 2 nm).