Predicting the Pseudocapacitive Windows for MXene Electrodes with Voltage-Dependent Cluster Expansion Models

James M. Goff, Francisco Marques Dos Santos Vieira, Nathan D. Keilbart, Yasuaki Okada, Ismaila Dabo

Research output: Contribution to journalArticlepeer-review

Abstract

MXene transition-metal carbides and nitrides are of growing interest for energy storage applications. These compounds are especially promising for use as pseudocapacitive electrodes due to their ability to convert energy electrochemically at fast rates. Using voltage-dependent cluster expansion models, we predict the charge storage performance of MXene pseudocapacitors for a range of electrode compositions. M3C2O2 electrodes based on group-VI transition metals have up to 80% larger areal energy densities than prototypical titanium-based (e.g., Ti3C2O2) MXene electrodes. We attribute this high pseudocapacitance to the Faradaic voltage windows of group-VI MXene electrodes, which are predicted to be 1.2 to 1.8 times larger than those of titanium-based MXenes. The size of the pseudocapacitive voltage window increases with the range of oxidation states that are accessible to the MXene transition metals. By similar mechanisms, the presence of multiple ions in the solvent (Li+ and H+) leads to sharp changes in the transition-metal oxidation states and can significantly increase the charge capacity of MXene pseudocapacitors.

Original languageEnglish (US)
Pages (from-to)3151-3159
Number of pages9
JournalACS Applied Energy Materials
Volume4
Issue number4
DOIs
StatePublished - Apr 26 2021

All Science Journal Classification (ASJC) codes

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Electrical and Electronic Engineering
  • Materials Chemistry

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