All-solid-state flexible microsupercapacitor based on two-dimensional titanium carbide

MXenes, serving as a novel family of two-dimensional (2D) metal carbides, have attracted great research interest as one of the promising electrode materials due to the unique properties. However, to our best knowledge, the 2D titanium carbide (one kind of MXene) used in constructing microsupercapacitors (MSCs) has not yet been reported to date. To this end, we firstly produce the MXene films on various kinds of substrates including polyethylene terephthalate (PET), silicon oxide film and titanium plate through vacuum-filtrating and subsequent controlled transferring. On this basis, flexible all-solid-state symmetric MSCs on PET substrate based on MXene films are fabricated by micro-fabrication process using polyvinyl alcohol (PVA)/H₂SO₄ as gel electrolyte. The results show that the as-made MSC has an ultrahigh rate performance with the scan rate of up to 1000 V s^-1 as well as an ultrafast frequency response (τ₀=0.5 ms). In addition, the MSC delivers a large volumetric capacitance of 1.44 F cm^-3, a high volumetric energy density (0.2 mWh cm^-3) at the current density of 0.288 A cm^-3 and a good cycling stability. Our research results presented here may pave the way for a new potential application of MXene in micro-power suppliers and micro-energy storage devices.