Salt-templated two-step activation synthesis of poplar-derived hierarchical porous carbon for high-performance supercapacitor electrodes

This study aims to develop a sustainable carbon electrode material derived from renewable biomass. Poplar wood, an inexpensive and easily accessible fast-growing wood, was utilized as a carbon precursor for the synthesis of poplar-based carbon material (CW-3.5Y2) through hydrothermal pre-carbonization (hydrothermal reaction at 200 °C for 10 h) and template activation processes (800 °C carbonization 2 h, heating rate 5 °C min⁻¹, N₂ atmosphere). The resulting material exhibits a distinctive hierarchically porous structure with abundant hierarchical pores and high mesoporous porosity (up to 62.92 % mesopore volume proportion). The environmentally friendly salts LiCl/ZnCl 2 as template were incorporated into the poplar precursor to help finely regulate the internal pore structure of the carbon material so that pore collapse can be minimized during reaction. Furthermore, high-temperature carbonization and activation enhance the porosity of the carbon material and effectively improves its specific capacitance. At a current density of 0.25 mA g −1 , the CW-3.5Y2 electrode demonstrates a remarkable specific capacitance of 101.41 F g −1 . After undergoing 10,000 charge/discharge cycles, it retains 96.7 % of its initial capacitance, which indicates excellent cyclic stability and overall electrochemical performance of the CW-3.5Y2 electrode material. This study presents an efficient and straightforward method for preparing biomass-derived porous carbon materials and demonstrates their potential application in supercapacitors. • The salt template assisted two-step method can effectively transform wood into high-performance energy storage materials. • Poplar carbon-based materials with hierarchical porous structure were synthesized. • The mesoporous pore volume ratio of the synthetic poplar-based carbon material was as high as 62.92 %. • After 10000 charge-discharge cycles, the super capacitor shows a capacitance retention of 96.7 %.