A Ti₃C₂T_x MXene cathode and redox-active electrolyte based flexible Zn-ion microsupercapacitor for integrated pressure sensing application

Frequently used aqueous electrolytes in MXene-based Zn-ion hybrid microsupercapacitors (MSCs) limit their cycling and rate stability. The use of metal and nonmetal additives in electrolytes for the performance improvement of Zn-ion MSCs is considered a valid method. Herein, we propose an additive assisted Zn(CF₃SO₃)₂ electrolyte as a redox-active electrolyte to prepare a flexible MXene-based Zn-ion hybrid MSC by a facile spraying method, and it consists of a conductive Ti₃C₂T_x-LiCl current collector and a Ti₃C₂T_x-DMSO cathode. In the process of the current density change (from 5 A cm⁻³ to 30 A cm⁻³ and then to 5 A cm⁻³), the capacity retention of the as-fabricated MSC with K₃Co(CN)₆ additive is over 99.0%, which is higher than 96.7% for the MSC with CKNSe additive and 82.3% for the MSC without an additive. Moreover, the designed MSC with the redox-active K₃Co(CN)₆ electrolyte exhibits a maximal capacitance retention of 70% after 5000 cycles. Furthermore, the flexible Zn-ion MSC with the Ti₃C₂T_x MXene cathode and a redox-active electrolyte was used to power a Ti₃C₂T_x based pressure sensor; the excellent press response of the integrated system not only provides insights into the development of large capacity and long-period stable energy storage devices, but also paves a new way for the development of capacitor-sensor integrated systems.