High specific power/energy, ultralong life supercapacitors enabled by cross-cutting bamboo-derived porous carbons

The advantages of carbon-based supercapacitors are high specific power and long life, but their specific energy is low. It is difficult to increase the specific energy and specific power of carbon-based supercapacitors simultaneously. In this work, bamboos are cross-cut into thin flakes, which are carbonized and KOH-treated to obtain porous carbons for supercapacitors. The specific capacitance, specific energy and the rate performance of the carbons from cross-cutting bamboo are significantly improved. More interestingly, the symmetric supercapacitor in 1 M Na2SO4 electrolyte based on cross-cutting bamboo carbons provide a high specific energy of 10.4 Wh kg−1 in 0.47 s at a relatively high specific power of 80,000 W kg−1, and no capacitance loss is found after 30,000 cycles at 50 A g−1. These features are explained for the improvement of the effective specific surface area and the shortened ion diffusion distance in carbon electrode due to cross-cutting of the long natural pore tunnels of bamboo and the enhancement of hydrophilicity of carbon surface. The results reveal that such a simple strategy of cross-cutting biomass is an efficient way to prepare promising porous carbons for supercapacitors with good performance.