High-Temperature Supercapacitors Based on MXene with Ultrahigh Volumetric Capacitance

Currently, MXene-based supercapacitors (MSCs) have been widely studied due to their good flexibility and excellent electrochemical performance. At present, the application of supercapacitors is more and more extensive, which requires them to face various complex environments. However, MSCs applied under high-temperature conditions have not been reported. In this paper, the MXene–V₂O₅–polyaniline (MVP) ternary composite material is used as the electrode material, and sulfonated polybenzimidazole (SPBI) is used as the solid electrolyte to design high-temperature MSCs for the first time. The preparation of MVP is achieved by introducing V₂O₅ into the MXene layer and loading polyaniline (PANI) on its surface, which not only greatly improves the capacitance performance of the electrode but also ensures its stability at a high temperature. The capacitance value of the MVP electrode was as high as 3180 mF cm^–3 (880 F g^–1), with excellent mechanical properties and increased flexibility at the same time. Furthermore, the assembled supercapacitor has a high energy density of 79.2 Wh L^–1 (22.1 Wh kg^–1). Moreover, its capacitance value can reach 985.3 mF cm^–3 (276 F g^–1) at 120 °C. This work provides an efficient design of an energy storage device that can be used for high-temperature applications.