Polyindole-Stabilized Nanocellulose-Wrapped Ti3C2TX (MXene) Nanocomposite for Asymmetric Supercapacitor Devices

Abstract

Nanocellulose fiber-based composites have been studied as supercapacitor electrodes due to their mechanical and chemical stability. The non-conductivity of nanocellulose has been tuned by MXene, a 2D nanomaterial, and its composites, for use as electrode materials for energy storage applications. This work reports the synthesis of polyindole-stabilized nanocellulose-wrapped MXene nanocomposite-based electrodes for supercapacitors. Nanocellulose, extracted from various renewable biowastes, is wrapped around MXene nanosheets to prevent the restacking of Ti3C2Tx layers with the structure being stabilized with polyindole. The morphology, structure, and chemical composition were confirmed with field-emission scanning electron microscopy (FESEM), Xray diffraction, and X-ray photoelectron spectroscopy, respectively. Morphological analysis, by FESEM and transmission electron microscopy, confirmed successful synthesis of the ternary nanocomposites. The concentration of Ti3C2Tx and nanocellulose was optimized to get best possible electrochemical performance of the electrodes. The best electrochemical performance was achieved with an MXene-grass cellulose-polyindole-1:1 composite [MPC(G)-1:1] with a specific capacitance of 858 F g-1 at 1 A g-1, in a three-electrode setup. An asymmetric device fabricated with developed nanocomposites as the cathode delivered a specific capacitance of 90 F g-1 and an energy density of 40.5 W h kg-1 at 1 A g-1 with 94.1% capacitance retention after 10,000 cycles. This study established the conversion of biowaste to efficient supercapacitor electrodes via a facile low-cost process.