Flexible and wearable electronic devices have attracted growing attention worldwide. However, common energy storage devices fail to meet the demand of high volumetric capacitance combined with good flexibility. In this study, we reported the fabrication and properties of a two-dimensional titanium carbide (MXene1) and polyvinyl alcohol (PVA) composite films, which are both highly flexible and have a large volumetric capacitance. Ti3C2, as a typical MXene, was delaminated into single- and few-layered sheets with a lateral size around 2 m and a thickness around 1-2 nm. The nanosheets can be easily assembled into composite by vacuum filtration, forming Ti3C2/PVA composite films. The Ti3C2/PVA films have sufficient mechanical strength for handling and even folding. The microstructure of films was characterized by scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, and X-ray diffraction. PVA layers were confined between Ti3C2, forming a highly aligned structures. Ti3C2 films exhibit excellent volumetric capacitance, yet the PVA addition allows to confine potassium ions in a gel electrolyte between Ti3C2nanosheets by introducing KOH into the Ti3C2/PVA during filtration. The composite films, being flexible and mechanically strong, offer volumetric capacitances in excess of 500 F/cm3, which is higher than reported for pure Ti3C2 films.
1. M. Naguib, V.N. Mochalin, M.W. Barsoum, Y. Gogotsi, MXenes: A New Family of Two-Dimensional Materials, Advanced Materials, 26, 992-1005 (2014)
2. M. R. Lukatskaya, O. Mashtalir, C. E. Ren, Y. Dall’Agnese, P. Rozier, P. Louis Taberna, M. Naguib, P. Simon, M. W. Barsoum, Y. Gogotsi, Cation Intercalation and High Volumetric Capacitance of Two-dimensional Titanium Carbide,Science, 341, 1502-1505 (2013)