Stamping of Flexible, Coplanar Micro‐Supercapacitors Using MXene Inks

Abstract The fast growth of portable smart electronics and internet of things have greatly stimulated the demand for miniaturized energy storage devices. Micro‐supercapacitors (MSCs), which can provide high power density and a long lifetime, are ideal stand‐alone power sources for smart microelectronics. However, relatively few MSCs exhibit both high areal and volumetric capacitance. Here rapid production of flexible MSCs is demonstrated through a scalable, low‐cost stamping strategy. Combining 3D‐printed stamps with arbitrary shapes and 2D titanium carbide or carbonitride inks (Ti 3 C 2 T x and Ti 3 CNT x , respectively, known as MXenes), flexible all‐MXene MSCs with controlled architectures are produced. The interdigitated Ti 3 C 2 T x MSC exhibits high areal capacitance: 61 mF cm −2 at 25 µA cm −2 and 50 mF cm −2 as the current density increases by 32 fold. The Ti 3 C 2 T x MSCs also showcase capacitive charge storage properties, good cycling lifetime, high energy and power densities, etc. The production of such high‐performance Ti 3 C 2 T x MSCs can be easily scaled up by designing pad or cylindrical stamps, followed by a cold rolling process. Collectively, the rapid, efficient production of flexible all‐MXene MSCs with state‐of‐the‐art performance opens new exciting opportunities for future applications in wearable and portable electronics.