Bamboo-based hierarchical porous carbon for high-performance supercapacitors: the role of different components

Abstract

Bamboo shavings hierarchical porous carbon (BPC) possesses excellent prospects for applications in supercapacitors. Herein, the formation mechanism of the hierarchical porous structure of BPC is systematically investigated in an attempt to clarify the role of three components (cellulose, hemicellulose, and lignin) in bamboo shavings on the pore structure and electrochemical properties of BPC. An efficient three-component separation method of bamboo shavings is proposed. We adopt a green activation strategy of CO2-catalyzed induction of small doses of K2CO3 to prepare bamboo shavings and their different components into honeycomb-like hierarchical porous carbons with excellent supercapacitor performance. The findings demonstrate that cellulose and hemicellulose mainly provide the microporous structure for BPC. Lignin provides not only a large number of mesopores but also abundant micropores. Compared with porous carbon derived from other components, lignin-derived porous carbon exhibits the optimal specific capacitance (273 Fg−1 at 0.5 Ag−1) and rate performance (capacity retention of 82.6% at 20 Ag−1) attributed to the largest specific surface area (1985 m2g−1) and micro-mesopore volume, indicating that lignin provides an important guarantee for the excellent specific capacitance and rate performance of BPC. The cellulose-derived porous carbon demonstrates superior cycling stability (98.2% capacitance retention over 15,000 cycles) due to its extraordinary electrical conductivity and stable carbon backbone, which means that cellulose is essential to the outstanding cycling stability of the BPC. Furthermore, the existence of hemicellulose also promotes the electrochemical performance of BPC to some extent. With the combined action of lignin, cellulose and hemicellulose, the BPC demonstrates excellent electrochemical properties. This work provides a promising ideas for the subsequent adjustment of pore structure and optimization of electrochemical properties of biomass-derived carbon by adjusting the content of each component in biomass.