Hierarchical porous carbon composite derived from corn stalk/sodium alginate for high performance supercapacitor

Biomass-derived carbon has been widely used as active material in supercapacitor. However, two or more kinds of biomass-derived carbon composite is still not distinctly aware and seldom used. In this work, the carbon composite is brought forward by taking corn stalk (CS) and sodium alginate (SA) as source examples, which owns hierarchical porous structure and thus a higher specific surface area (SSA) (2658.97 m 2  g −1 ) and specific pore volumes (0.98 cm 3  g −1 ) than those single component carbon from pure CSC (1698.67 m 2  g −1 ) or SAC (2564.06 m 2  g −1 ). The optimized carbon composite of CSSAC-5 exhibits a high specific capacitance of 435 F g −1 at the current density of 0.5 A g −1 and a high retention up to 97.8 % after 10,000 repeated charge-discharge cycles. Moreover, symmetric supercapacitor (SSC) of CSSAC-5//CSSAC-5 delivers an energy density of 18.96 Wh kg −1 at 250 W kg −1 and 14.58 Wh kg −1 at 5000 W kg −1 , as well as a retention of 83.7 % after 10,000 cycles. The strategy of carbon composite will efficiently expand the carbon sources of active materials and push the exploitation of the high performance supercapacitor.