Ordered multimodal porous carbon with hierarchical nanostructure as high performance electrode material for supercapacitors

Ordered multimodal porous carbon (OMPC) with hierarchical nanostructure is successfully synthesized by using a hard template method. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analyses are employed to characterize the as-synthesized OMPC sample. Based on the characterization results, it is confirmed that the as-prepared sample has multimodal porous structure with unique structural characteristics, such as high surface area (1161 m² g^-1) and well-developed three-dimensional (3D) interconnected ordered macropore framework with open mesopores embedded in the macropore walls, which enable the OMPC to effectively store and release large amounts of electrical charge. The electrochemical performance reveals that the combined hierachical meso- and macroporosity of OMPC electrode plays an important role in improving cycle stability and rate performance of the electrode. The OMPC electrode exhibits a highest specific capacitance of 257 F g^-1 at low current density of 0.5 A g^-1 and 152 F g^-1 at high current density of 10 A g^-1 in aqueous electrolyte of 1.0 M H ₂SO₄. This hierarchical nanostructure of OMPC can deliver energy density of 8.4 W h kg^-1 at a power density of 5.0 kW kg ^-1. The specific capacitance of about 90% is preserved after 1200 cycles, revealing excellent cycling stability of OMPC. Such excellent performance is attributed to the unique hierarchical nanostructure of the OMPC, which facilitates fast mass transport along with large surface area for high electrical charge storage compared to commonly used electrode material such as activated carbon (AC).