Device-Scaled Controlled Crumpling of MXene-Based Ultrathin Supercapacitors as Stretchable Power Sources

Abstract

Two-dimensional transition-metal carbide (MXene) Ti3C2Tx possesses advantages of high conductivity and high volumetric capacitance, making it an ideal electrode material for high-performance supercapacitors. However, the high stiffness impedes its direct implementation in stretchable supercapacitors for integrated wearable electronics. Here, we demonstrate a stretchable supercapacitor based on Ti3C2Tx electrodes through a device-scaled controlled crumpling strategy. An ultrathin supercapacitor with a thickness of about 45 μm is assembled with gold foil gilded ultrathin preservative membrane as a current collector, drop cast Ti3C2Tx as an active material, and poly(vinyl alcohol)-H3PO4 as a polymer gel electrolyte. The ultrathin supercapacitor with optimized electrodes exhibits an areal specific capacitance of 10.2 mF cm–2 at 5 mV s–1 with excellent mechanical flexibility. The controlled adhesion of the ultrathin supercapacitor on a prestretched latex substrate and the elastic deformation of the substrate induce local displacements on the ultrathin supercapacitor to create periodic crumples. Stretching the crumpled supercapacitor only causes the amplitude and wavelength changes of the crumples, leading to a high level of stretchability (up to 100%). Also, the crumpled supercapacitor can sustain 1000 stretching cycles at a maximum strain of 100%. Moreover, it can provide sufficient power to drive α-In2Se3 nanoflake-based photodetector at 100% strain. This device-scaled controlled crumpling method provides a facile and effective way to design stretchable energy devices with high stretching durability for stretchable devices.