High energy density biomass-derived activated carbon materials for sustainable energy storage

Biomass-derived activated carbons are promising materials for sustainable energy storage systems such as aqueous supercapacitors and Zn-ion capacitors due to their abundance, low cost, tunable porosity, and heteroatom-rich structures. Herein, we report biomass derived carbon materials fabrication via a two-step activation method. The activated carbons possess well-tuned pore structures and high heteroatom content, resulting in remarkable surface area, ultrahigh micropore volume, and good wettability. The symmetrical supercapacitors and aqueous Zn-ion capacitors were assembled using the produced activated carbons. The 2PA-6-800 supercapacitor delivers an ultrahigh rate capability (up to 10,000 mV s−1) and promising cycle life, retaining 66.3 % of its initial performance after 33,000 galvanostatic charge–discharge cycles. The assembled 2PA-6-800-based ZIC delivers a superior specific capacitance of 785.0 F g−1, a maximum energy density of 352.5 Wh kg−1, and a remarkable power density of 60.3 kW kg−1. The outstanding performance is attributed to the two-step activation method, high heteroatom content, and the structural integrity of the biomass derived AC to the ZIC device architecture. This work contributes to the design and development of high-performance, safe, and sustainable energy storage systems.