Ti ₃ C ₂ MXenes have revealed immense potential in energy storage systems.

Solvent-free all-solid-state supercapacitors have recently received attention. Despite their highly specific capacitance, they suffer issues related to the solid–solid interface that degrade their performance during prolonged cycling. Here, we propose a novel strategy for improving the electrode–electrolyte interface by introducing a small amount of polymer into the activated carbon-based electrode. An electrode composition of 80AC:8SA:7AB:5[PEO_0.95 (LiClO₄)_0.05]—where AC, SA, and AB stand for activated carbon, sodium alginate binder, and acetylene black, respectively—is optimized. A composite membrane—viz., PEO-LiClO₄ reinforced with 38 wt% NASICON structured nano crystallites of Li_1.3Al_0.3Ti_1.7(PO₄)₃—is used as a solid electrolyte. Incorporating a small amount of salt-in-polymer (95PEO-5 LiClO₄) in the electrode matrix leads to a smooth interface formation, thereby improving the performance parameters of the all-solid-state supercapacitors (ASSCs). A typical supercapacitor with a polymer-incorporated electrode exhibits a specific capacitance of ~102 Fg⁻¹ at a discharge current of 1.5 Ag⁻¹ and an operating voltage of 2 V near room temperature. These ASSCs also exhibit relatively better galvanostatic charge–discharge cycling, coulombic efficiency, specific energy, and power in comparison to those based on conventional activated carbon.