Synthesis of Hierarchically Porous Sandwich-Like Carbon Materials for High-Performance Supercapacitors

For the first time, hierarchically porous carbon materials with a sandwich-like structure are synthesized through a facile and efficient tri-template approach. The hierarchically porous microstructures consist of abundant macropores and numerous micropores embedded into the crosslinked mesoporous walls. As a result, the obtained carbon material with a unique sandwich-like structure has a relatively high specific surface (1235 m²  g^-1 ), large pore volume (1.30 cm³  g^-1 ), and appropriate pore size distribution. These merits lead to a comparably high specific capacitance of 274.8 F g^-1 at 0.2 A g^-1 and satisfying rate performance (87.7 % retention from 1 to 20 A g^-1 ). More importantly, the symmetric supercapacitor with two identical as-prepared carbon samples shows a superior energy density of 18.47 Wh kg^-1 at a power density of 179.9 W kg^-1 . The asymmetric supercapacitor based on as-obtained carbon sample and its composite with manganese dioxide (MnO₂ ) can reach up to an energy density of 25.93 Wh kg^-1 at a power density of 199.9 W kg^-1 . Therefore, these unique carbon material open a promising prospect for future development and utilization in the field of energy storage.