One-step molten salt-assisted preparation of crab shell-based hierarchical porous carbon for capacitive energy storage

Carbon-based materials have become the most commonly used electrode materials for supercapacitors due to their simple production and low preparation cost. The preparation of hierarchical porous carbon materials with excellent properties using biomass materials is a very valuable study. Therefore, we used crab shells as carbon precursors to prepare crab shell-based carbon materials by using the self-templating method (CaCO 3 ) combined with low-temperature eutectic molten salt. When the composition of the eutectic salt was CaCl 2 /KCl (molar ratio of 43:57) and the mass ratio of crab shells to eutectic salt was 1:5, the prepared crab-shell-based carbon material (CC-CaK-5) exhibited excellent physical and electrochemical properties with high specific surface area (1193.7 m 2 g −1 ), rich heteroatom doping (O (7.83 %) and N (6.71 %)), and high specific capacitance (290 Fg −1 at 0.5 Ag −1 ).The CC-CaK-5//CC-CaK-5 devices assembled with CC-CaK-5 as the electrode material exhibited excellent electrochemical performance. At a current density of 1 Ag −1 , the capacitance value of the device remained at 93.11 % of the initial capacitance value after 5000 cycles. The energy density reached 6.95 Whkg −1 at a power density of 302.09 Wkg −1 and remained at 4.71 Whkg −1 at a power density of 13,037.54 Wkg −1 .