High‐Performance Flexible and Symmetric Supercapacitors Based on Micro‐Flower‐Like MnSe@Ti ₃ C ₂ T x Heterostructure

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Flexible supercapacitors, renowned for their exceptional power density and cycling stability, are a focus in the field of energy storage. Ti₃C₂Tx 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@Ti₃C₂Tx heterostructure is developed to enhance the electrochemical performance of Ti₃C₂Tx-based electrode materials. With the solvothermal synthesis method, MnSe nanosheets are in situ grown on Ti₃C₂Tx surface to form micro-flower-like MnSe@Ti₃C₂Tx heterostructures by adjusting the ratio of ethanolamine solvent and the amount of Ti₃C₂Tx. The specific capacitance of the optimized heterostructure (E₃/MnSe@Ti₃C₂Tx-45) is as high as 721.4 F g⁻¹ at 1 A g⁻¹, approximately ten times higher than that of pure Ti₃C₂Tx. The MnSe@Ti₃C₂Tx flexible symmetric supercapacitor (MT-FSC) based on E₃/MnSe@Ti₃C₂Tx-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 Ti₃C₂Tx-based flexible supercapacitors but also offers a robust energy supply for flexible wearable electronic devices.