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 K 4 Fe(CN) 6 as the redox additive to alter the properties of the Zn(CF 3 SO 3 ) 2 gel electrolyte used in Ti 3 C 2 T x -DMAC MXene-based interdigital Zn-ion hybrid MSCs. The electron transfers between Fe 2+ and Fe 3+ in K 4 Fe(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 Ti 3 C 2 T 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.