High specific capacitance and long cycle stability of few-layered hexagonal Ti3C2 free-standing film constructed with spiral chiral Hexagon Ti3AlC2

Abstract

Two-dimensional Ti3C2 MXene has become a rising star in the field of electrochemical energy storage due to its excellent conductivity and controllable surface functional groups. However, Ti3C2 has the risk of structural collapse caused by stacking of sheets in water-based electrolyte during long cycle charging-discharging. So, hexagon Ti3AlC2, a strong precursor material was synthesized and first visually demonstrated as a spiral chiral shape following a spiral dislocation-driven growth pattern. Then, the few-layered hexagonal Ti3C2 was constructed by “Lewis acid molten salt method first, then microwave assisted etching method” from spiral chiral Hexagon Ti3AlC2 for the first time. Then, it was fabricated into few-layered hexagonal Ti3C2 free-standing film, and the microstructure evolution, electrochemical energy storage properties and mechanism of this film were researched. The results showed that the problem of large attenuation of specific capacitance caused by the lamellar accumulation of Ti3C2 under long cycle was effectively solved. This provides a novel idea for the research and development of energy storage materials for flexible supercapacitors with long period stability and high specific capacitance. This will also lay a structural foundation for the synthesis of single-layered hexagonal MXene materials and the research of magic angle effect of interlayer rotation.