Cassava- and bamboo-derived carbons with higher degree of graphitization for energy storage

Biomass-derived carbons are among the most promising candidates for large-scale electrochemical-energy-storage devices owing to their low cost, sustainability and widespread resources. Herein, the authors report a simplistic synthesis process for preparing two types of biomass carbons derived from cassava stalks and bamboo consisting of direct pyrolysis of the ground samples at 750°C for 4 h. The electrochemical performances of the prepared biomass carbons are investigated in supercapacitors and lithium-ion battery (LIB) systems. Both the cassava and bamboo samples possess a high graphitization degree and good surface wettability as demonstrated by X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. As a supercapacitor electrode, cassava-derived carbons show the best performance with a maximum specific capacitance of 212 F/g and capacity retention of 95% after 2000 cycles. Moreover, as an electrode material for LIBs, cassava-derived carbons demonstrate the highest charge capacity of 357 mAh/g (at 100 mA/g), which stabilizes at 254 mAh/g. This approach shows great potential to achieve advanced electrode materials from low-cost, green and industrial-grade production of biomass-derived carbon materials by simple synthesis for advanced energy-storage applications in the future compared with conventional approaches.