Mixed-Biomass Wastes Derived Hierarchically Porous Carbons for High-Performance Electrochemical Energy Storage

A cost-effective route is developed to fabricate hierarchically porous carbons (HPCs) from renewable mixed-biomass wastes of crab shells and rice husks by hydrothermal carbonization followed by KOH activation. Benefiting from the inorganic collaboration between crab shells and rice husks, the resultant HPCs deliver well-developed hierarchical porosity and large specific surface area. used as electrode materials for supercapacitors, the as-prepared HPCs exhibit a high capacitance of 474 F g–1 and remarkable cyclic stability with capacitance retention of 95.6% over 20 000 charge/discharge cycles employing 6 M KOH as electrolyte. Moreover, the HPC-based symmetric supercapacitor displays a high energy density of 30.5 W h kg–1 using 1.0 M Na2SO4 as electrolyte. Additionally, the HPCs-based anode for lithium-ion battery presents a high specific capacity of 541 mA h g–1 and still retains 266 mA h g–1 after 800 cycles (1 A g–1). The attractive electrochemical performances of HPCs indicate that this work provides new opportunities to convert wasted biomass into highly valued carbon micro-/nanomaterials for electrochemical energy storage and conversion.