Mechanochemical Pretreated M_n+1AX_n (MAX) Phase to Synthesize 2D-Ti₃C₂T_x MXene Sheets for High-Performance...

Two-dimensional (2D) MXenes sheet-like micro-structures have attracted attention as an effective electrochemical energy storage material due to their efficient electrolyte/cation interfacial charge transports inside the 2D sheets which results in ultrahigh rate capability and high volumetric capacitance. In this article, Ti₃C₂T_x MXene is prepared by a combination of ball milling and chemical etching from Ti₃AlC₂ powder. The effects of ball milling and etching duration on the physiochemical properties are also explored, as well as the electrochemical performance of as-prepared Ti₃C₂ MXene. The electrochemical performances of 6 h mechanochemically treated and 12 h chemically etched MXene (BM-12H) exhibit an electric double layer capacitance behavior with an enhanced specific capacitance of 146.3 F g^-1 compared to 24 and 48 h treated samples. Moreover, 5000-cycle stability tested sample's (BM-12H) charge/discharge show increased specific capacitance due to the termination of the -OH group, intercalation of K⁺ ion and transformation to TiO₂/Ti₃C₂ hybrid structure in a 3 M KOH electrolyte. Interestingly, a symmetric supercapacitor (SSC) device fabricated in a 1 M LiPF₆ electrolyte in order to extend the voltage window up to 3 V shows a pseudocapacitance behavior due to Li on interaction/de-intercalation. In addition, the SSC shows an excellent energy and power density of 138.33 W h kg^-1 and 1500 W kg^-1, respectively. The ball milling pre-treated MXene exhibited an excellent performance and stability due to the increased interlayer distance between the MXene sheets and intercalation and deintercalation of Li⁺ ions.