Polyindole-Stabilized Nanocellulose-Wrapped Ti₃C₂T_x (MXene) Nanocomposite for Asymmetric Supercapacitor Devices

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 Ti 3 C 2 T x layers with the structure being stabilized with polyindole. The morphology, structure, and chemical composition were confirmed with field-emission scanning electron microscopy (FESEM), X-ray 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 Ti 3 C 2 T x 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.