Wood-structured, hydrophilic, low-tortuosity thick electrode enables high-performance supercapacitor

Abstract

It is a natural ingenuity to ignite the aspiration of wood-structured biomaterials with largely-distributed porosity, mechanical integrity, and tunable functionalities in energy engineering. As a hierarchically architectured carbon scaffold with well-aligned channels and high active-mass loading, free-standing wood thick electrode expedites the electron/ion transfer kinetics to heighten storage capacitance. Herein, we have facilely designed a holey wood-structured bulk electrode (a thickness of ∼1 mm) with the depositing of MoS2 and NiS2 clusters by a tandem hydrothermal and pyrolysis strategy for the efficient supercapacitors. In the perpendicular direction, artificial small holes (∼ 0.5 mm diameter) are drilled across the 3D-wood thick electrode to perforate the growth channels, hence ameliorating ion migration as well as reducing diffused impedance. Benefitting from the vertical low-tortuosity channels, high charge conductivities, superhydrophilic interface, reversible redox behavior, and excellent mechanical stability, the superior areal capacitance (7806–8538 mF cm−2 at a current density of 10 mA cm−2) and long-term cycling lifespan (∼ 100 % retention over 10,000 cycles even at 100 mA cm−2) of wood thick electrodes (energy densities of 0.287 −0.423 mWh cm−2 in the asymmetric supercapacitors) are achieved without the structural deformation. The wood-structured, self-supporting thick electrode sketch a promising blueprint of high-performance biocompatible supercapacitors with maximum active-substance loading and monolithic low-tortuosity design that also can be popularized to rechargeable batteries.