Sustainable production of multifunctional hierarchical carbon from weed water hyacinth: Assessment for lithium-ion battery and supercapacitor

Abstract

The proliferation of water hyacinth (WH) can cause significant problems in freshwater; therefore, the effective management and utilization of WH are intensively required. This contribution demonstrates the conversion of WH to nitrogen-doped hierarchical activated carbon (WHAC). The developed treatment process is facile and requires two steps: hydrothermal treatment to fix the inherited nitrogen atoms in the carbon structure and chemical activation to alter physical properties. The resultant WHAC shows a high nitrogen content of 4.17 wt% in its structure and a surface area of 1353 m2 g−1 with a significant degree of micropores of 1076 m2 g−1, making it suitable for energy applications. As an anode material in lithium-ion batteries, the WHAC exhibits a good capacity of 931 mAh g−1 at a current rate of 100 mAh g−1, which is 2.5 times more remarkable than commercial graphite. Moreover, as an electrode material in supercapacitors in a two-electrode system, the WHAC provides a high specific capacitance of 93 F g−1 in 1 M TEABF4 in acrylonitrile at a current rate of 0.5 A g−1, which is 20 % higher than that of commercial activated carbon (YP-50F). This illustration confirms the sustainable strategy for waste-to-materials treatment for engineering implications, e.g., energy storage devices.