High-Performance Flexible and Symmetric Supercapacitors Based on Micro-Flower-Like MnSe@Ti₃C₂T_x Heterostructure

Flexible supercapacitors, renowned for their exceptional power density and cycling stability, are a focus in the field of energy storage. Ti₃C₂T_x MXene is a promising electrode material for supercapacitors owing to its excellent metallic conductivity. However, its stacking layered structure limits device performance on specific capacitance, operating voltage, and energy density. Herein, a MnSe@Ti₃C₂T_x heterostructure is developed to enhance the electrochemical performance of Ti₃C₂T_x-based electrode materials. With the solvothermal synthesis method, MnSe nanosheets are in situ grown on Ti₃C₂T_x surface to form micro-flower-like MnSe@Ti₃C₂T_x heterostructures by adjusting the ratio of ethanolamine solvent and the amount of Ti₃C₂T_x. The specific capacitance of the optimized heterostructure (E₃/MnSe@Ti₃C₂T_x-45) is as high as 721.4 F g^-1 at 1 A g^-1, approximately ten times higher than that of pure Ti₃C₂T_x. The MnSe@Ti₃C₂T_x flexible symmetric supercapacitor (MT-FSC) based on E₃/MnSe@Ti₃C₂T_x-45 exhibits a wide working voltage window of 1.2 V and a large energy density of 28.68 Wh kg^-1 at 308.23 W kg^-1. The capacitance retention rate keeps 90.77% after 4000 charge-discharge cycles. Furthermore, MT-FSC can power LEDs even under large-angle (90°) bending. This heterostructure electrode material not only improves the electrochemical performance of Ti₃C₂T_x-based flexible supercapacitors but also offers a robust energy supply for flexible wearable electronic devices.