Wood‐Derived Monolithic Ultrathick Porous Carbon Electrodes Filled with Reduced Graphene Oxide for High‐Performance Supercapacitors with Ultrahigh Areal Capacitances

High performance supercapacitors deploying cube-templated tracheid cavities of wood-derived carbon

Wood-derived carbon, with its strong tracheid array structure, is an ideal material for use as a self-supporting electrode in supercapacitors. By leveraging the inherent through pore structure and surface affinity found in wood tracheids, we successfully engineered a highly spatially efficient cube-templated porous carbon framework inside carbonized wood tracheid cavities through precise control over precursor crystallization temperatures. This innovative cubic channel architecture effectively maximizes up to (79 ± 1)% of the cavity volume in wood-derived carbon while demonstrating exceptional hydrophilicity and high conductivity properties, facilitating the development of supercapacitors with enhanced areal/volumetric capacitances (2.65F cm-2/53.0F cm-3 at 5.0 mA cm-2) as well as superior areal/volumetric energy densities (0.37 mWh cm-2/7.36 mWh cm-3 at 2.5 mW cm-2). The fabrication of these cube-templated channels with high cube filling content is not only simple and precisely controllable, but also environmentally friendly. The proposed method eliminates the conventional acid-base treatment process for pore formation, facilitating the rapid development and practical implementation of thick electrodes with superior performance in supercapacitors. Moreover, it offers a universal research approach for the commercialization of wood-derived thick electrodes.

Supercapacitor Performance of Sulfonyldibenzene Derivative-Functionalized Graphene Aerogel

3D aerogels incorporating functionalized reduced graphene oxide (SUL/rGO) were prepared as a hydrothermal method utilizing graphene oxide (GO) and a sulfonyldibenzene derivative (SUL) as raw materials. The aromatic compound SUL, which contains hydroxyl and sulfonyl groups, was bonded to reduced graphene oxide (rGO) through π-π connections. The obtained composite material exhibited porosity within its structure with improved hydrophilicity, along with excellent electrochemical characteristics. This improvement was ascribed to the specific rGO structure, as well as the pseudocapacitance inherent in SUL, both of which synergistically contribute to improvement in the characteristics of the prepared electrode materials. Also, an analysis was performed employing density functional theory from which the density of states and adsorption energy of SUL on the surface of rGO were computed to further investigate the charge storage process within the prepared composite. The prepared SUL/rGO-2 electrode exhibited the highest specific capacitance value of 388 F/g at a current density equal to 1 A/g. The constructed symmetrical supercapacitor, SUL/rGO-2//SUL/rGO-2, attained an energy density value of 14.55 Wh/kg at a power density equal to 350 W/kg with an exceptional galvanostatic charge-discharge (GCD) cyclic stability equal to 91% following 10 000 cycles. Therefore, this review presents a novel functionalized graphene-based material incorporating hydroxyl and sulfonyl groups, which holds promise in future energy storage applications.

Hydrothermal regulation of MnO2 on a wood-based RGO composite for achieving wide voltage windows and high energy density supercapacitors

The increasing need for improved energy storage devices renders it particularly important that inexpensive electrodes with high capacitance, excellent cycling stability, and environment-friendly characteristics are developed. In this study, a wood-derived carbon@reduced graphene (WRG) conductive precursor with an average conductivity of 15.38 S/m was firstly synthesized. The binder-free WRG-MnO2 electrode was successfully constructed by growing MnO2 onto a WRG under hydrothermal conditions. The asymmetric supercapacitor assembled with the WRG-20MnO2 cathode exhibited excellent electrochemical capacitive behavior with a voltage window of 0-2 V, maximum energy density of 52.3 Wh kg-1, and maximum power density of 1642.7 W kg-1, which is mainly due to the distinctive icicle-shaped structure of the MnO2. Thus, a facile strategy for developing high-performance hierarchical porous carbon electrodes that can be used in supercapacitors was developed herein, which may provide new opportunities to improve the high added value of poplar wood.

A 3D stacked corrugated pore structure composed of CoNiO2 and polyaniline within the tracheids of wood-derived carbon for high-performance asymmetric supercapacitors

A novel 3D stacked corrugated pore structure of polyaniline (PANI)/CoNiO₂@activated wood-derived carbon (AWC) has been successfully constructed to prepare high-performance electrode materials for supercapacitors. AWC functions as a supporting framework that provides ample attachment sites for the loaded active materials. The CoNiO₂ nanowire substrate, consisting of 3D stacked pores, not only serves as a template for subsequent PANI loading, but also acts as an effective buffer to mitigate the volume expansion of the PANI during ionic intercalation. The distinctive corrugated pore structure of PANI/CoNiO₂@AWC facilitates electrolyte contact and significantly enhances the electrode material properties. The PANI/CoNiO₂@AWC composite materials exhibit excellent performance (14.31F cm^-2 at 5 mA cm^-2) and superior capacitance retention (80% from 5 to 30 mA cm^-2), owing to the synergistic effect among their components. Finally, PANI/CoNiO₂@ AWC//reduced graphene oxide (rGO)@AWC asymmetric supercapacitor is assembled, which has a wide operating voltage (0 ∼ 1.8 V), high energy density (4.95 mWh cm^-3 at 26.44 mW cm^-3) and cycling stability (90.96% after 7000 cycles).