Fabrication of Robust, Highly Conductive, and Elastic Hybrid Carbon Foam Platform for High-Performance Compressible Asymmetry Supercapacitors.

Highly conductive and elastic three-dimensional (3D) porous carbon materials are ideal platforms to fabricate electrodes for high-performance compressible supercapacitors. Herein, a robust, highly conductive, and elastic carbon foam (CF) hybrid material is reported, which is fabricated by integrating cellulose nanofiber/multiwalled carbon nanotube (CNF/MWCNT) aerogel sheets with a melamine sponge (MS), followed by carbonization. The carbonized CNF/MWCNT aerogel sheets contribute to the high conductivity and specific surface area of the CF, and the 3D network-like skeleton derived from the carbonization of the MS enhances the elasticity and stability of the CF. More importantly, the CF possesses good scalability, allowing the introduction of electroactive materials such as polypyrrole (PPy) and Fe3O4 to fabricate high-performance compressible PPy-CF and Fe3O4-CF electrodes. Moreover, an assembled PPy-CF//Fe3O4-CF device shows reversible charging-discharging at a voltage of 1.6 V and demonstrates a high specific capacitance (172.5 F/g) and an outstanding energy density (59.9 W h/kg). The device exhibits capacitance retention rates reaching 98.3% and stable energy storage characteristics even under different degrees of compressive deformation. This study offers a scalable strategy for fabricating high-performance compressible supercapacitors, thereby providing a new means of satisfying the energy storage needs of portable electronic devices that are prone to deformation.

Three-dimensional "skin-framework" hybrid network as electroactive material platform for high-performance solid-state asymmetric supercapacitor.

Three-dimensional (3D) electrode materials are ideal candidates for use in fabricating high-performance supercapacitors (SCs), owing to their unique network structure and excellent electrochemical properties. In this study, an aerogel film produced by the freeze-drying self-aggregation of multiwall carbon nanotubes (MWCNTs) and cellulose nanofibers (CNFs) served as the "skin", and an inter-connected 3D network of nickel foam (NF) as the "framework", for the fabrication of an MWCNT/CNF-NF (called MCN) hybrid material with a distinct "skin-framework" architecture. Considering the metrics of excellent conductivity, high wettability, binder-free and unique 3D "skin-framework" structure, the MCN hybrid material has great potential as an electroactive material platform in constructing state-of-the-art asymmetric supercapacitor (ASC) electrodes. By incorporating MCN with electroactive manganese dioxide (MnO2) and active carbon (AC), MnO2-MCN and AC-MCN composite electrodes with respective high areal capacitances of 1784.8 (equal to 469.7 F g-1) and 868.8 mF cm-2 (equal to 126.3 F g-1) at 5 mA cm-2 were successfully prepared. Further, both kinds of electrodes exhibited high charge/discharge ability rates and good cycle performance. Moreover, an optimally assembled MnO2-MCN//AC-MCN solid-state ASC was reversibly charged/discharged at voltages as high as 1.8 V and possessed a remarkable volumetric capacity of 9.83 F cm-3 and an energy density of 4.25 mW h cm-3, as well as good cycle stability.