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Solving the Capacitive Paradox of 2D MXene using Electrochemical Quartz‐Crystal Admittance and In Situ Electronic Conductance Measurements
Author(s) -
Levi Mikhael D.,
Lukatskaya Maria R.,
Sigalov Sergey,
Beidaghi Majid,
Shpigel Netanel,
Daikhin Leonid,
Aurbach Doron,
Barsoum Michel W.,
Gogotsi Yury
Publication year - 2015
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201400815
Subject(s) - materials science , quartz crystal microbalance , intercalation (chemistry) , ion , electrochemistry , electrode , capacitance , chemical physics , supercapacitor , conductance , capacitive sensing , crystal (programming language) , adsorption , chemical engineering , nanotechnology , analytical chemistry (journal) , inorganic chemistry , chemistry , condensed matter physics , organic chemistry , physics , computer science , engineering , programming language , operating system
Fast ion adsorption processes in supercapacitors enable quick storage/delivery of significant amounts of energy, while ion intercalation in battery materials leads to even larger amounts of energy stored, but at substantially lower rates due to diffusional limitations. Intercalation of ions into the recently discovered 2D Ti 3 C 2 T x (MXene) occurs with a very high rate and leads to high capacitance, posing a paradox. Herein, by characterizing the mechanical deformations of MXene electrode materials at various states‐of‐charge with a variety of cations (Li, Na, K, Cs, Mg, Ca, Ba, and three tetraalkylammonium cations) during cycling by electrochemical quartz‐crystal admittance (EQCA, quartz‐crystal microbalance with dissipation monitoring) combined with in situ electronic conductance and electrochemical impedance, light is shone on this paradox. Based on this work, it appears that the capacitive paradox stems from cationic insertion, accompanied by significant deformation of the MXene particles, that occurs so rapidly so as to resemble 2D ion adsorption at solid‐liquid interfaces. The latter is greatly facilitated by the presence of water molecules between the MXene sheets.