Can Anions Be Inserted into MXene?

Netanel Shpigel, Arup Chakraborty, Fyodor Malchik, Gil Bergman, Amey Nimkar, Bar Gavriel, Meital Turgeman, Chulgi Nathan Hong, Maria R. Lukatskaya, Mikhael D. Levi, Yury Gogotsi, Dan T. Major, Doron Aurbach

Research output: Contribution to journalArticlepeer-review

59 Scopus citations

Abstract

Despite the continuous progress in the research and development of Ti3C2Tx (MXene) electrodes for high-power batteries and supercapacitor applications, the role of the anions in the electrochemical energy storage and their ability to intercalate between the MXene sheets upon application of positive voltage have not been clarified. A decade after the discovery of MXenes, the information about the possibility of anion insertion into the restacked MXene electrode is still being questioned. Since the positive potential stability range in diluted aqueous electrolytes is severely limited by anodic oxidation of the Ti, the possibility of anion insertion was evaluated in concentrated aqueous electrolyte solutions and aprotic electrolytes as well. To address this issue, we have conducted in situ gravimetric electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) measurements in highly concentrated LiCl and LiBr electrolytes, which enable a significant extension of the operation range of the MXene electrodes toward positive potentials. Also, halogens are among the smallest anions and should be easier to intercalate between MXene layers, in comparison to multiatomic anions. On the basis of mass change variations in the positive voltage range and complementary density functional theory calculations, it was demonstrated that insertion of anionic species into MXene, within the range of potentials of interest for capacitive energy storage, is not likely to occur. This can be explained by the strong negative charge on Ti3C2Tx sheets terminated by functional groups.

Original languageEnglish
Pages (from-to)12552-12559
Number of pages8
JournalJournal of the American Chemical Society
Volume143
Issue number32
DOIs
StatePublished - 18 Aug 2021

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