Hierarchical porous microspheres of activated carbon with a high surface area from spores for electrochemical double-layer capacitors

Owing to the advantages of high surface area, good conductivity, sustainability, and chemical stability, biomass-based activated carbon materials have been one of the research hotspots in the field of supercapacitors. Yet common techniques to synthesize nanostructured electrodes of activated carbon only offer limited control on their morphology and structure. In this work, three-dimensional porous hollow microspheres of activated carbon are fabricated by utilizing various spores (Lycopodium clavatum, Ganodorma lucidum and Lycopodium annotinum spores) as carbon precursors and self-templates through a facile, green and low-cost route. The abundant and easily available carbon sources of spores allow for mass production of activated carbon microspheres (ACMs), which almost ideally inherit the distinctive nano-architectures of spores, presenting a superhigh specific surface area (up to 3053 m2 g(-1)) and hierarchical porous structure. Such ACM electrodes show remarkable electrical double-layer storage performances, such as high specific capacitance (308 F g(-1) in organic electrolytes), ultrafast rate capability (retaining 263 F g(-1) at a very high current density of 20 A g(-1)) and good cycling stability (93.8% retention after 10 000 charge-discharge cycles), thus leading to a high energy density (57 W h kg(-1)) and superior power density (17 kW kg(-1)).