High-capacitance activated bio-carbons with controlled pore size distribution for sustainable energy storage

Depletion of fossil-fuel energy resources creates a demand for sustainable energy technologies and therefore necessitates the development of sustainable energy storage devices with sustainable materials, eco-efficient synthetic methods, and robust cycle life. Electric double layer capacitors are potential candidates for sustainable energy storage because they usually employ carbon-based electrode materials with semi-permanent lifetimes and high powers. Although various carbon materials are commercially available, new methods are needed to produce eco-efficient synthesized carbon materials with high performances. Herein, we introduce an effective strategy that uses biomaterials as carbon sources and adopts a reusable KOH solution soaking method for the activation process to reduce KOH consumption, which includes a pore-size control process to enhance electrochemical performances. The obtained bio-carbons exhibit specific capacitances (160.6 and 151.2 F g(-1) in aqueous and organic electrolytes, respectively) superior to that of commercially available activated carbon (similar to 80 F g(-1)), which is attributed to the synergetic effect between the pore-size-controlled activated carbon for efficient ion transport and the well-matched electrolyte. Our strategy provides a versatile method for the scalable fabrication of sustainable energy storage materials and is promising for the development of high-performance supercapacitors.