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Revealing the Pseudo‐Intercalation Charge Storage Mechanism of MXenes in Acidic Electrolyte
Author(s) -
Mu Xinpeng,
Wang Dashuai,
Du Fei,
Chen Gang,
Wang Chunzhong,
Wei Yingjin,
Gogotsi Yury,
Gao Yu,
Dall'Agnese Yohan
Publication year - 2019
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201902953
Subject(s) - mxenes , materials science , pseudocapacitance , intercalation (chemistry) , electrolyte , supercapacitor , energy storage , cyclic voltammetry , chemical engineering , electrochemistry , hydrogen storage , electrode , nanotechnology , inorganic chemistry , composite material , chemistry , alloy , thermodynamics , physics , engineering , power (physics)
Since the discovery of Ti 3 C 2 T x in 2011, the family of two‐dimensional transition metal carbides, carbonitrides, and nitrides (collectively known as MXenes) has quickly attracted the attention of those developing energy storage applications such as electrodes for supercapacitors with acidic aqueous electrolytes. The excellent performance of these MXenes is attributed to a pseudocapacitive energy storage mechanism, based on the non‐rectangular shape of cyclic voltammetry curves and changes in the titanium oxidation state detected by in situ X‐ray absorption spectroscopy. However, the pseudocapacitive mechanism is not well understood and no dimensional changes due to proton insertion have been reported. In this work, in situ X‐ray diffraction and density functional theory are used to investigate the charge storage mechanism of Ti 3 C 2 T x in 1 m H 2 SO 4 . Results reveal that a 0.5 Å expansion and shrinkage of the c ‐lattice parameter of Ti 3 C 2 T x occur during cycling in a 0.9 V voltage window, showing that the charge storage mechanism is intercalation pseudocapacitance with implication for MXene use in energy storage and electrochemical actuators.