Recent Advances on the Application of Graphene Quantum Dots in Energy Storage

As an emerging carbon nanomaterial, graphene quantum dots (GQDs) have shown great potential application in new energy storage devices due to their unique small size effect and abundant edge active sites. This work introduces the main synthesis strategies of GQDs, which includes top-down and bottom-up methods; the application examples of GQDs and GQDs-based composites in energy storage are reviewed, and more, the unique advantages of GQDs are used in supercapacitors, Lithium-ion batteries (LIBs) and Lithium-sulfur batteries (Li-S batteries) are highlighted. The problems and development prospects in this growing area are also discussed.We conducted a detailed search of "the application of GQDs in energy storage devices" in the published papers and the public patents based on Web of Science database in the period from 2014 to 2020. The corresponding literature was carefully evaluated and analyzed.Sixty papers and twenty-eight recent patents were included in this mini-review. The significant advances in the recent years are summarized with comparative and balanced discussion. Thanks to the unique properties of large specific surface area, high conductivity and abundant active sites, GQDs have unparalleled potential application for new energy storage, especially improving the specific capacity and cycle stability of supercapacitors, LIBs and Li-S batteries.The findings of this mini-review confirm the importance of GQDs, show the enhanced electrochemical performance in supercapacitors, LIBs and Li-S batteries, and also provide a helpful guide to design and fabricate highefficiency electrode materials.