Manipulating the Interlayer Spacing of 3D MXenes with Improved Stability and Zinc-Ion Storage Capability

2D transition metal carbides/nitrides (MXenes) have excellent physical-chemical properties, which makes them promising for electrochemical energy storage devices. However, because of their inherent self-stacking and narrow interlayer spacing, it is rarely used in multivalent ion energy storage systems. In this study, fatty diamines and aromatic diamines with different molecular sizes are inserted between MXene interlayers as pillars through a one-step amination process to inhibit the self-stacking and obtain different expanded interlayer spacings with improved antioxidant stability. X-ray diffraction results show that interlayer spacing of MXene increases from 1.23 to 1.40 nm. The p-phenylenediamine-intercalated MXene (PDA-MXene) exhibits better matching interlayer spacing (1.38 nm) and pore structure for improved electrolyte-accessible surface area, enhanced charge-transport properties, and promoted Zn2+ ions storage. Therefore, zinc-ion hybrid supercapacitor (ZHSC) using PDA-MXene as cathode exhibits higher specific capacitance (124.4 F g(-1) at 0.2 A g(-1)) in 2 m ZnSO4 electrolyte together with outstanding cycling stability (85% capacity retention after 10 000 cycles at 1 A g(-1)). This study provides a route for precise control of MXene interlayer spacing by small organic molecules, which can be used to observe efficient charge storage in MXene-based electrochemical energy storage devices by optimizing interlayer spacing.

Automated summary

2D transition metal carbides/nitrides (MXenes) show great potential for electrochemical energy storage devices, but their self-stacking and narrow interlayer spacing limit their application in multivalent ion energy storage systems. This study successfully inserted fatty diamines and aromatic diamines between MXene interlayers to inhibit self-stacking and achieve expanded interlayer spacings, leading to improved antioxidant stability. The intercalation of small organic molecules provides a route for precise control of MXene interlayer spacing, enabling efficient charge storage in MXene-based electrochemical energy storage devices.