Construction and electrochemical energy storage performance of free-standing hexagonal Ti3C2 film for flexible supercapacitor

In order to improve the specific capacitance of flexible supercapacitor and solve the specific capacitance attenuation problem of MXene Ti3C2 electrode material caused by stacking of its own lamellae under long cycle charge and discharge, this work innovatively adopts "Lewis acid melting salt method & microwave assisted etching method" to construct hexagonal Ti3AlC2 powder into free-standing hexagonal Ti3C2 film. Compared with free-standing common Ti3C2 film, the microstructure and morphology of hexagonal Ti3C2 film was characterized, and the electrochemical energy storage performance and mechanism was analyzed. It is found that this method can effectively increase the crystal plane spacing of Ti3C2 and inhibit the lamellar stacking. The specific capacitance retention rate of the film is 97.37% after 10,000 cycles of charge and discharge, and the attenuation is small. The charge storage of the film mainly comes from the contribution of surface capacitance. At 100 mV/s, the contribution rate of surface capacitance is 71.42%. This is due to the increase of the surface group -O of Ti atom of hexagonal Ti3C2, which increases the pseudocapacitance. This provides a new idea and theoretical support for the research and development of long cycle stable flexible supercapacitor with high specific capacitance.