A lignin dissolution-precipitation strategy for porous biomass carbon materials derived from cherry stones with excellent capacitance

Abstract Bio-carbon derived from agricultural waste is promising as electrode material of supercapacitor. However, it is still challenging to obtain excellent capacitance from raw biomass with an inherently dense and hard structure. In this work, a facile and scalable route is developed to fabricate N-doped hierarchical porous bio-carbon from cherry stones (CSs). Through the pretreatment of lignin dissolution-reprecipitation, the dense CSs were successfully transformed into porous precursor. With the promotion of mass transfer inside the material, the as-obtained carbon can be well-manipulated by N-doping and molten salt activation. A hierarchical and porous structure was formed in the bio-carbon with a specific surface area of up to 1681 m2 g−1. The material possessed an excellent specific capacitance of 370.5 F g−1 in 6 M KOH at a current density of 0.5 A g−1 and a prominent rate performance with a capacitance remaining 225.1 F g−1 at 20.0 A g−1. After 5000 cycles, an initial capacitance of 99.1% was maintained. All the results ensured that the bio-carbon derived from CSs could serve as renewable, low-cost and high-performance electrode materials for supercapacitors, and the proposed pretreatment method could effectively enhance energy storage capability of biomass-derived activated carbon.