Titanium Carbide MXene Shows an Electrochemical Anomaly in Water-in-Salt Electrolytes

Identifying and understanding charge storage mechanisms is important for advancing energy storage. Well-separated peaks in cyclic voltammograms (CVs) are considered key indicators of diffusion-controlled electrochemical processes with distinct Faradaic charge transfer. Herein, we report on an electrochemical system with separated CV peaks, accompanied by surface-controlled partial charge transfer, in 2D Ti3C2Tx MXene in waterin-salt electrolytes. The process involves the insertion/ desertion of desolvation-free cations, leading to an abrupt change of the interlayer spacing between MXene sheets. This unusual behavior increases charge storage at positive potentials, thereby increasing the amount of energy stored. This also demonstrates opportunities for the development of highrate aqueous energy storage devices and electrochemical actuators using safe and inexpensive aqueous electrolytes.

Automated summary

The study presents an electrochemical system in 2D Ti3C2Tx MXene in water-in-salt electrolytes, with separated CV peaks and surface-controlled partial charge transfer. This process increases charge storage at positive potentials, offering opportunities for developing high-rate aqueous energy storage devices and electrochemical actuators.