Porous Carbon Hollow Rod for Supercapacitors with High Energy Density

In this work, we demonstrate a novel strategy for producing a porous carbon hollow rod (PCHR) via simple carbonization of magnesium gluconate. The mass ratios of PCHR/KOH are a key factor in directly determining the PCHR shape, specific surface areas, and pore structures. The obtained PCHR-4 exhibits an ultra-high specific surface area (1980 m 2 g –1 ), high density micropores (0.7–2 nm), a hollow rod shape structure, a hierarchical pore structure, and rich O-doping (8.8 wt %). PCHR-4-based supercapacitors in ionic liquid exhibit an ultrahigh specific capacitance of up to 225 F g –1 . More importantly, the PCHR-4 symmetrical supercapacitor can deliver a maximum energy density of 70.4 W h kg –1, which is superior to those recently reported carbon-based symmetric supercapacitors in ionic liquid.