Development of Penroseite (Ni,Co)Se2 and Ti‐MXene Inks for Maximizing the Energy Density of Screen‐Printed Flexible Microsupercapacitor

Abstract The push towards reducing the size of portable/wearable electronics, wireless sensors, and the Internet of Things (IoT's) needs a critical requirement of miniaturized energy storage solutions. Typically, micro‐supercapacitors (MSC's) are the main key factors of electrochemical energy storage systems for those miniaturized device applications. Herein, a scalable screen printable flexible microsupercapcitor with highly flexible architecture is developed using a Prussian blue derived 3D‐penroseite (Ni,Co)Se 2 nanocubes as the positive electrode and Ti 3 C 2 T x MXene as the negative electrode. As a result, the printed flexible device delivers an enhanced active electrochemical site and a high areal capacitance of 63 mF cm −2 with a broad working potential range of 1.0 V. Furthermore, the (Ni,Co)Se 2 || Ti 3 C 2 T x based flexible MSC (FMSC) offers a remarkable energy density of 8.75 µWh cm −2 at a power density of 0.5 mW cm −2 , making it an excellent microscale energy storage system for small, portable, and wireless applications.