Hierarchical porous carbon microspheres derived from porous starch for use in high-rate electrochemical double-layer capacitors

Porous starch was used as a precursor for hierarchical porous carbon microspheres. The preparation consisted of stabilisation, carbonisation and KOH activation, and the resultant hierarchical porous carbon microspheres had a large BET surface area of 3251 m2 g−1. Due to the large surface area and the hierarchical pore structure, electrodes made of the hierarchical porous carbon microsphere materials had high specific capacitances of 304 F g−1 at a current density of 0.05 A g−1 and 197 F g−1 at a current density of 180 A g−1 when used in a symmetric capacitor with 6 M KOH as the electrolyte. After 10,000 cycles, the capacitor still exhibited a stable performance with a capacitance retention of 98%. These results indicate that porous starch is an excellent precursor to prepare high performance electrode materials for EDLCs.