Rational design of Ti3C2Tx MXene coupled with hierarchical CoS for a flexible supercapattery

Flexible energy storage materials are finding much research interest due to their high demand in the rapidly growing wearable electronics industry. For the fabrication of such devices, the electrode material should possess high flexibility as well as high mechanical stability. Besides having these prerequisites, 2D metal carbides/nitrides/carbonitrides (MXenes) are well-established electrode materials due to their excellent conductivity, high specific surface area, and ion intercalation properties. This work reports on a fabric-based flexible electrode material fabricated by in-situ growth of CoS on carbon cloth fibers (CC) followed by drop-casting of Ti3C2Tx MXene layer. The resulting electrode Ti3C2Tx/CoS@CC, owing to the synergy between hydrophilic and highly conductive Ti3C2Tx and redox-active CoS, shows an excellent augmentation in its supercapattery features (120 Cg(-1) at 1 Ag-1) compared to its individual components (10.4 and 60 Cg(-1) for Ti3C2Tx and CoS, respectively, at 1 Ag-1). The kinetic and charge storage mechanism studies reveal the faradic battery-type character of the electrode, mainly because of the redox nature of CoS, which is reinforced by highly conducting MXene. Furthermore, the fabricated flexible symmetrical device using Ti3C2Tx/CoS@CC electrode shows a maximum energy density of 13.13 Wh.kg(-1) and maximum power density of 1.91 kW.kg(-1) with 93.41% retention in capacity after 10,000 cycles. The superior flexible character of the electrode is confirmed by its unaltered electrochemical performance under varying mechanical stress (stretching, bending, and twisting). The fabrication and electrochemical performance of Ti3C2Tx/CoS@CC electrode open new possibilities for rationally designing efficient electrode materials for next-generation flexible electronic devices.

Automated summary

Flexible energy storage materials with high flexibility and mechanical stability are in high demand for wearable electronics. 2D MXenes are well-established electrode materials due to their excellent conductivity, large specific surface area, and ion intercalation properties. This work reports on a fabric-based flexible electrode material using Ti3C2Tx MXene and CoS, which shows enhanced supercapattery features compared to individual components. The fabricated flexible symmetrical device using Ti3C2Tx/CoS@CC electrode demonstrates high energy density and power density, with excellent electrochemical performance under mechanical stress. These findings open new possibilities for designing efficient electrode materials for flexible electronic devices.