Investigation of pouch-cell supercapacitors with a high working voltage range of 1.5 V fabricated using Ti3C2Tx-MXene electrodes and an environmentally safe PVA–CH3COONa gel polymer electrolyte

Abstract

MXenes are a novel class of 2D nanomaterials with functional properties that have been extensively studied over the past decade for applications in various industries, including energy storage. Among various MXene types, Ti₃C₂ is a promising supercapacitor material owing to its large surface area, tunable surface chemistry, and high electrical conductivity. This study investigates the interplay between electric double-layer capacitance and pseudocapacitance of MXene-based electrodes, with a focus on their thermal stability, to optimize their energy storage performance. In this study, we investigated supercapacitors that were fabricated using the Ti₃C₂T_x-MXene material combined with an environmentally safe PVA–CH₃COONa gel polymer electrolyte. The novelty of this study lies in investigating the electrochemical response of Ti₃C₂T_x at high temperatures for optimizing its application as an electrode material in symmetric supercapacitors. A three-electrode system was used to investigate the electrochemical ability of independent MXene materials at different breakdown temperatures from ambient conditions to 80 °C, which illustrated the strong stability of Ti₃C₂T_x as a working electrode material. Furthermore, to deeply study the electrochemical response of the Ti₃C₂T_x material, the performance of symmetrical solid-state supercapacitors based on Ti₃C₂T_x-MXene material electrodes and the PVA–CH₃COONa gel polymer electrolyte were investigated at a wide working voltage window of up to 1.5 V, which demonstrated excellent electrochemical adaptability. These devices exhibited a maximum specific capacitance of 91.5 F g⁻¹ at a current density of 0.5 A g⁻¹ with an energy density of 28.6 W h kg⁻¹. Moreover, the supercapacitors exhibited a durability of 87.58% after 2000 charge–discharge cycles at 0.5 A g⁻¹, with a Coulombic efficiency of 99.08%.