A hierarchically porous rice husk-based activated carbon, which had been prepared by a combined method (carbonization, NaOH-leaching and KOH activation), has a high specific capacitance and power density as a supercapacitor electrode in aqueous or organic electrolytes. It was subjected to a simple thermal treatment at 800 °C for 1 h to modify its microstructure and electrochemical performance. Results indicate that its original hierarchical pore structure is retained and the number of oxygen-containing functional groups is reduced after this modification. Mesopores developed and the volume ratio of mesopores to total pores increased from 25.62 to 33.62%. The modified activated carbon showed a higher specific capacitance of 147 F g⁻¹ than the unmodified one (116 F g⁻¹) at a current density of 0.5 A g⁻¹. The voltage of the modified activated carbon was 84.5% of its initial value after self-discharge for 24 h, which is higher than that (75.2%) of the unmodified one. The capacitance retention of the modified carbon was 92% while that of the unmodified one was 85% after 10 000 galvanostatic charge/discharge cycles at 1 A g⁻¹, indicating the better cycling stability of the former.

通过组合方法（碳化，NaOH浸出和KOH活化）制备的分层多孔的稻壳基活性炭具有高比电容和功率密度，可作为水性或有机电解质中的超级电容器电极。在800°C下对其进行简单的热处理1 h，以改变其微观结构和电化学性能。结果表明，经过这种修饰后，其原始的分层孔结构得以保留，含氧官能团的数量减少了。产生了中孔，中孔与总孔的体积比从25.62％增加到33.62％。改性的活性炭比未改性的活性炭具有更高的比电容147 F g ^-1（116 F g ^-1）在0.5 A g ^-1的电流密度下。自放电24小时后，改性活性炭的电压为其初始值的84.5％，高于未改性活性炭的电压（75.2％）。在1 A g ^-1下进行10000次恒电流充电/放电循环后，改性碳的电容保持率为92％，而未改性碳的电容保持率为85％，表明前者具有更好的循环稳定性。