Supercapacitor featuring Ti3C2Tx MXene electrode: Nanoarchitectonics and electrochemical performances in aqueous and non-aqueous electrolytes

Abstract

Ti₃C₂Tx MXenes, synthesized via HCl+LiF etching, show promise as pseudocapacitive electrodes for electrochemical energy storage, addressing the low voltage limitation of aqueous supercapacitors (SCs). This study explores Ti₃C₂Tx MXene electrodes in aqueous and gel electrolytes, specifically H₂SO₄ and H₃PO₄. Electrochemical testing, based on Dunn's approach, confirms supercapacitor-like performance, with specific capacitances of 299 F/g in 1 M aqueous H₃PO₄ and 212 F/g in H₂SO₄ at a 5 mV/s scan rate. Remarkably, in symmetric SCs with 1 M H₃PO₄, Ti₃C₂Tx MXene retains 95% capacitance at 1 V after 25,000 cycles, demonstrating excellent stability. Additionally, Ti₃C₂Tx in a 1 M gel H₃PO₄ electrolyte achieves a higher energy density of 72 Wh/kg within a 1.6 V window than with gel H₂SO₄, highlighting the impact of electrolyte choice. These findings underscore MXenes' potential as stable, high-rate electrodes for sustainable supercapacitors.