A Ti3C2Tx 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 Ti3C2Tx–LiCl current collector and a Ti3C2Tx–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 Ti3C2Tx MXene cathode and a redox-active electrolyte was used to power a Ti3C2Tx 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.