98 / 2021-09-29 11:49:41

WOOD-DERIVED MATERIALS FOR ADVANCED ELECTROCHEMICAL ENERGY STORAGE DEVICES

Wood; Wood-based materials; Energy storage devices

The ever-growing smart electronics and electric vehicles (EVs) urgently require advanced energy storage technologies (e.g., supercapacitors and rechargeable batteries) toward higher energy/power densities, longer cycling life and better safety^[1,2]. Herein, a facile, low-cost, and efficient strategy by surface engineering to synthetic ultrathick electrodes of all-solid-state symmetric supercapacitor (SSC) based on activated wood-carbon (AWC) monoliths is presented (Fig.1). The AWC as a freestanding ultrathick electrode shows an impressive areal capacitance of 6.85 F cm^-2 at 1 mA cm^-2 and 4.55 F cm^-2 at 20 mA cm^-2. Furthermore, an all-solid-state SSC assembled by the two identical AWC monoliths delivers an encouraging energy density of 0.23 mWh cm^-2 (4.59 Wh Kg^-1 and 0.77 Wh L^-1) at a power density of 500 mW cm^-2 (9.9 mW Kg^-1 and 2500 W L^-1) while keeping a capacitance retention of 86% after 10 000 continuous charge-discharge cycles. The remarkable electrochemical performance is attributed mainly to the preservation of structural integrity from natural wood, the introduction of oxygen-containing functional groups and ultrathick electrode design, which significantly improves electroactive material loading and device integration.