Intercalation effect of mono and divalent metal cations into Ti3C2Tx layers electrode for high performance asymmetric coin cell supercapacitors

Metal cation intercalation is an effective strategy for enhancing the ion transport properties of layered Ti₃C₂Tₓ MXene electrodes. In this study, multilayered Ti₃C₂Tₓ was intercalated with monovalent (K + , Li + , and Na + ) and divalent (Mg 2+ , Zn 2+ , and Fe 2+ ) metal ions via a simple wet-chemical etching and stirring process, followed by the fabrication of coin-cell asymmetric supercapacitors. Structural characterization confirmed successful intercalation and revealed that K + ions induced the large expansion of the Ti₃C₂Tₓ interlayer spacing, as evidenced by the shift of the (002) diffraction peak from 8.47° to 7.05°. The enhanced performance is attributed to the low hydration energy of K + , which facilitates efficient desolvation and rapid ion transport within the MXene galleries. Consequently, the K + -intercalated Ti₃C₂Tₓ electrode exhibited a high specific capacitance of 808.5 F g −1 at 1 A g −1 in a three-electrode configuration. A K + -Ti₃C₂Tₓ//activated carbon coin-cell asymmetric supercapacitor achieved a specific capacitance of 42.5 F g −1 , an energy density of 23.3 Wh kg −1 , and a maximum power density of 1281.9 W kg −1 , while retaining 81.3% of its initial capacitance after 10,000 charge–discharge cycles. These results demonstrate that K + intercalation effectively enhances the electrochemical performance of Ti₃C₂Tₓ and offers a practical approach for developing high-performance MXene-based energy storage devices.