Pivotal factors of wood-derived electrode for supercapacitor: Component striping, specific surface area and functional group at surface

Abstract

Wood has been identified as a renewable and biodegradable biomass energy in the domain of electrochemical energy storage material. Nevertheless, since wood owns an anisotropic hierarchical multi-scale structure and is formed by embedding several components into each other in terms of chemical composition, effectively component stripping and anchoring its specific electrochemical mechanism at the molecular level for corresponding chemical modification and structural regulation is a necessary means to achieve efficient application of wood in energy storage. Therefore, six wood (Balsa, P. sylvestris var. mongolica, Basswood, Maple, Sapele and Fraxinus mandshurica)-derived carbon electrode materials with hierarchical porous structure are designed for supercapacitor. The capacitance behavior is systematically studied in allusion to the correlation of composition, structure and properties of wood-derived porous carbon. The effective molecule stripping of lignin, specific surface area and the surface functional group C–O bond promote the capacitance improvement. And the wood-derived electrode capacitance contribution is mainly controlled by the surface and less by the diffusion. In addition, the Balsa-derived electrode possesses the highest specific capacity of 252.1 F g−1. All the wood-derived electrodes show attractive cycling performance (more than 85% capacity retention after10,000 cycles). This study analyzed the mechanism of effective molecular stripping, rational regulation of micropores and directional design of surface functional groups on the electrochemical properties. This also provides technical support for high-capacitance composite wood-derived material.