Mesoporous Nanoplates Consisting of Seamless Graphene Frameworks

Electric double-layer capacitors (EDLCs) have attracted significant attention in the field of energy storage due to their high specific power, superior safety, and long cycle life. However, commercially available electrode materials, such as activated carbons, are still facing the challenge of low energy density. Graphene mesosponge (GMS) has shown promise as an electrode material for EDLCs due to its mesoporous structure, large specific surface area, and edge-free properties that allow operation under wide potential windows. Nevertheless, GMS materials reported so far consist of large micro-particles above 30 μm, which is unfavorable in terms of the long ion-diffusion path within the particles. In this study, a novel nanoplate GMS (np-GMS) is synthesized via a template carbonization approach, where chemical vapor deposition is performed onto a nanoplate MgO. The np-GMS exhibits a nanoplate structure with a lateral nanoplate size of approximately 1 μm and a nanoplate thickness of less than 100 nm. When employed as an electrode for EDLCs, the np-GMS shows a specific capacitance of 132 F g–1 in the potential window of –0.5 V to 1.5 V vs. Ag/AgClO4. Moreover, the np-GMS-included EDLCs demonstrate a specific energy of 59 Wh kg–1 under a voltage window of 3.5 V, which outperforms the counterpart GMS with a larger particle size and commercialized activated carbon. The introduction of np-GMS is believed to open up new possibilities for improving the performance and industrial feasibility of GMS in EDLCs.