Titanium carbide MXene shows an electrochemical anomaly in water-in-salt electrolytes

19 July 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Identifying and understanding charge storage mechanisms is important for advancing energy storage, especially when new materials and electrolytes are explored. Well-separated peaks in cyclic voltammograms (CVs) are considered key indicators of diffusion-controlled electrochemical processes with distinct Faradic 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 water-in-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 new opportunities for the development of high-rate aqueous energy storage devices and electrochemical actuators using safe and inexpensive aqueous electrolytes.


Titanium carbide MXene
water-in-salt electrolytes
desolvation-free cation insertion
abnormal electrochemical behavior

Supplementary materials

SI: Titanium carbide MXene shows an electrochemical anomaly in water-in-salt electrolytes
Supporting figures S1-S18 and supporting tables S1-S2


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