Non-conductive ion extraction molds biomass into dual cross-linked structures with defect as both commercial conductor and electrode active material

Porous carbon derived from waste biomass materials is a characteristic active material for fabricating high-performance, economical and environment-friendly carbonaceous energy storage material. Herein, a sort of biomass carbon with an oriented sphere and 2D graphene dual cross-linked structure is synthesized by a safe, novel and universal method using waste corn stalk as raw material. Besides, the non-conductive calcium impurity in biomass is removed by ion liquid-phase extirpation engineering using NH4Cl to obtain pure corn stalk carbon (YM), and of which the property is more remarkable in energy storage applications. As a result, the YM emerges larger superficial acreage (1053.54 m2 g−1) compared with the impurity corn stalk carbon material (CYM), indicating an immediate optimization effect due to impurities removal and structure optimization. Moreover, the electrochemical performance of YM is comparable to that of activated carbon (AC), a comparable storage capacity of 113.4 F g−1 at 1 A g−1 is obtained (AC is 130.7 F g−1). More importantly, YM is also used as a conductor material to increase the conductivity of electrode materials, which is similar to the effect of commercial acetylene black (AB). Anyway, this novel design scheme is conducive to the application of waste biomass and the development of economic and environmentally friendly carbon materials. The calcium impurity in corn stalk biomass is removed by ion liquid-phase extirpation engineering using NH4Cl to obtain carbon spheres and 2D graphene. More importantly, the biochar material as both an active material and conductive agent expresses an optimized surface area (1053.54 m2 g−1), an outstanding mass capacity of 145.1 F g−1, which is superior to the electrode that activated carbon as active material and acetylene black as conductive agent, thus replacing activated carbon and acetylene black as efficient carbon electrodes. [Display omitted] •Removal of inactive calcium impurities by ion extraction with NH4Cl.•Construction of biomass carbon spheres and 2D graphene structure.•Corn stalk biochar replaces activated carbon as an electrode material.•Corn stalk biochar replaces acetylene black as a conductive agent.•Corn stalk biochar concurrently replaces activated carbon and acetylene black.