Morphology engineering of biomass-derived porous carbon from 3D to 2D towards boosting capacitive charge storage capability

Abstract

Carbon morphology significantly affects the capacitive performance of porous carbons. Biomass-derived porous carbons are usually restricted by inferior capacitive performance owing to their inherently three-dimensional (3D) blocked morphologies. Fabricating two-dimensional (2D) sheet-like morphology is expected to expose more inner space for better electrochemical performance, however, it needs to overcome the self-aggregation of biomass. The comprehensive understanding of how 2D morphology boosts capacitive performance remains challenging. Herein, we provide a morphology-regulating strategy to prepare 2D and 3D porous carbons and investigate the morphology effect on charge storage capability via both experimental data and theoretical simulations. 2D carbon exhibits better capacitance than 3D carbon in both electric double-layer capacitors (254 versus 211F g−1) and zinc-ion hybrid supercapacitors (320 versus 232F g−1), because the 2D carbon morphology not only improves the pore accessibility for higher double-layer capacitance, but also facilitates the exposure of active functional groups for more pseudocapacitance. Moreover, 2D morphology shortens pore length, leading to better anti-self-discharge capability. This study is beneficial to understanding the relationship between carbon morphology and capacitive performance and provides a facile strategy to upgrade biomass-derived porous carbons via morphology engineering.