Non-Monotonic Capacitance Change of Layered Ti3C2Tx MXene Film Structures under Increasing Compressive Stress

作者：Zhang, Qing^*; Ning, Ran; Cao, Jinxin; Song, Qingrui; Ye, Jiaxin; Wei, Bingqing^*

来源：Advanced Functional Materials, 2023, 33(8).

DOI：10.1002/adfm.202211791

• functionality dissociation
• layered structures
• MXenes
• pressure effects
• supercapacitors

The progress in advanced electronic devices has imposed a great demand for developing flexible electrochemical power devices, which requires a comprehensive understanding of the mechanical-electrochemical coupling behavior of various energy storage materials. Unlike a monotonic capacitance increase of carbon-based double-layer supercapacitors, MXene-based flexible supercapacitors demonstrate a non-monotonic, i.e., "increase-then-decrease" capacitance behavior under the pressure range of 8488 kPa. This non-monotonic capacitance response to pressure is intrinsic to the MXene film as its charge storage is primarily determined by the surface activity, which can be readily affected by pressure-induced dissociation of functionalities, as well as the charge transporting kinetics as limited by the inherent layered structure. The findings described in this study not only expand the knowledge of mechanical-electrochemical coupling to layered MXenes under pressure, but also give a vital design guideline for flexible/stretchable MXene-based energy storage devices or other electronics.