A Conductive and Highly Deformable All‐Pseudocapacitive Composite Paper as Supercapacitor Electrode with Improved Areal and Volumetric Capacitance

Abstract Flexible energy storage electronics have gained increasing attention in recent years, but the simultaneous acquiring of high volumetric and high areal capacities as well as excellent flexibility in order to truly implement wearable and portable electronics in practice remains challenging. Here, a conductive and highly deformable freestanding all‐pseudocapacitive paper electrode (Ti 3 C 2 T x /MnO 2 NWs) is fabricated by solution processing of hybrid inks based on Ti 3 C 2 T x MXene and ultralong MnO 2 nanowires. The resulting Ti 3 C 2 T x /MnO 2 NWs hybrid paper manifests a remarkable areal capacitance of up to 205 mF cm −2 and outstanding volumetric capacitance of 1025 F cm −3 . Both the values are highly comparable with, or in most cases much higher than those of previously reported MXene‐based flexible electrodes. The excellent energy storage performance is well maintained with a capacitance retention of 98.38% during 10 000 charge–discharge cycles. In addition, the flexible supercapacitor demonstrates excellent flexibility and electrochemical stability during repeated mechanical bendings of up to 120°, suggesting great potentials for the applications in future flexible and portable electronics.