Fabrication of porous carbon spheres for high-performance electrochemical capacitors

Abstract

Porous carbon spheres (PCS) with meso/microporous structure are designed and fabricated through a facile hydrothermal method by employing glucose as a carbon precursor and sodium molybdate (Na₂MoO₄) as a porogen, structure-direct agent and catalyst. With the assistance of Na₂MoO₄, the porous structure of the carbon sphere is significantly enhanced. In addition, the meso/microporous structure can be modulated by adjusting the proportion of the reactants. In optimal conditions, the PCS exhibit a high specific surface area (SSA, 757.3 m² g⁻¹) and pore volume (0.24 cm³ g⁻¹). When evaluated as an electrode for electrochemical capacitors, the PCS exhibits a high specific capacitance of 260 F g⁻¹ with remarkable high-rate performance and long-term cycling stability. The excellent electrochemical performances are exclusively attributed to the micro/mesoporous structure, which maximize the ion accumulation on the electrode surface and facilitate fast ion transportation. The well-defined porous nanostructure plus easy strategy make current study provide new opportunities for hydrothermal carbonization of biomass as electrode materials for energy storage.