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

Xuehang Wang (1) , Tyler Mathis (1) , Yangyunli Sun (2) , Wan-Yu Tsai (3) , Netanel Shpigel (4) , Hui Shao (5) , Danzhen Zhang (6) , Kanit Hantanasirisakul (6) , Fyodor Malchik (4) , Nina Balke (3) , De-En Jiang (2) , Patrice Simon (5) , Yury Gogotsi (6)

1 Drexel University
2 UC Riverside - University of California [Riverside]
3 ORNL - Oak Ridge National Laboratory [Oak Ridge]
4 Bar-Ilan University [Israël]
5 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
6 Department of Physics - Drexel University

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 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 opportunities for the development of high-rate aqueous energy storage devices and electrochemical actuators using safe and inexpensive aqueous electrolytes.

Mots clés: Titanium carbide MXene; water-in-salt electrolytes; desolvation-free cation insertion; abnormal electrochemical behavior; charge storage mechanism; partial charge transfer

Domaines: Matériaux

Xuehang Wang, Tyler Mathis, Yangyunli Sun, Wan-Yu Tsai, Netanel Shpigel, et al.. Titanium Carbide MXene Shows an Electrochemical Anomaly in Water-in-Salt Electrolytes. ACS Nano, 2021, 15 (9), pp.15274-15284. ⟨10.1021/acsnano.1c06027⟩. ⟨hal-03880297⟩