Capacitance-Enhanced Microsupercapacitors with a Redox Electrolyte Additive for an All-MXene-Based Flexible Self-Powered Integrated Photodetecting System

Although much effort has been devoted to improving the electrochemical performances of MXene-based metal-ion hybrid microsupercapacitors (MSCs), few works focus on the electrolyte. Therefore, we proposed K₄Fe(CN)₆ as the redox additive to alter the properties of the Zn(CF₃SO₃)₂ gel electrolyte used in Ti₃C₂T_x-DMAC MXene-based interdigital Zn-ion hybrid MSCs. The electron transfers between Fe²⁺ and Fe³⁺ in K₄Fe(CN)₆ can provide an additional Faraday pseudocapacitance, resulting in the high volumetric capacitance (2107.4 F cm^-3 at a scan rate of 5 mV s^-1) of the MSCs and excellent cycling stability with 88.64% of the original capacity retention after 5000 cycles of charge and discharge. Such a superior performance of MSCs can provide a potential of 0.9 V for the integrated Ti₃C₂T_x-DCTES MXene-based photodetector, which endows the detector with a stable response to 808 nm wavelength laser, providing a strong support for flexible self-powered integrated sensing systems.