Understanding the MXene Pseudocapacitance
Top Cited Papers
- 20 February 2018
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Physical Chemistry Letters
- Vol. 9 (6), 1223-1228
- https://doi.org/10.1021/acs.jpclett.8b00200
Abstract
MXenes have attracted great attention as next-generation capacitive energy-storage materials, but the mechanisms underlying their pseudocapacitive behavior are not well understood. Here we provide a theoretical description of the surface redox process of Ti3C2Tx (T=O, OH), a prototypical MXene, in 1M H2SO4 electrolyte, based on joint density functional theory with an implicit solvation model and the analysis of Gibbs free energy under a constant-electrode potential. From the dependence of the O/OH ratio (or the surface H coverage) and the surface charge on the applied potential, we obtain a complete picture of the capacitive energy-storage mechanism of Ti3C2Tx that shows good agreement with previous experimental findings in terms of the integral capacitance and Ti valence change. We find a voltage-dependent redox/double-layer co-charging behavior: the capacitive mechanism is dominated by the redox process but the electric double layer charge works against the redox process. This new insight may be useful in improving the capacitance of MXenes.Keywords
Funding Information
- Basic Energy Sciences
This publication has 38 references indexed in Scilit:
- MXene-based materials for electrochemical energy storageJournal of Energy Chemistry, 2018
- Electrochemical and in-situ X-ray diffraction studies of Ti 3 C 2 T x MXene in ionic liquid electrolyteElectrochemistry Communications, 2016
- Two-Dimensional Molybdenum Carbide (MXene) as an Efficient Electrocatalyst for Hydrogen EvolutionACS Energy Letters, 2016
- Effect of Postetch Annealing Gas Composition on the Structural and Electrochemical Properties of Ti2CTx MXene Electrodes for Supercapacitor ApplicationsChemistry of Materials, 2015
- Sulfur Cathodes Based on Conductive MXene Nanosheets for High‐Performance Lithium–Sulfur BatteriesAngewandte Chemie, 2015
- Ion Intercalation into Two-Dimensional Transition-Metal Carbides: Global Screening for New High-Capacity Battery MaterialsJournal of the American Chemical Society, 2014
- Role of Surface Structure on Li-Ion Energy Storage Capacity of Two-Dimensional Transition-Metal CarbidesJournal of the American Chemical Society, 2014
- Cation Intercalation and High Volumetric Capacitance of Two-Dimensional Titanium CarbideScience, 2013
- Are MXenes Promising Anode Materials for Li Ion Batteries? Computational Studies on Electronic Properties and Li Storage Capability of Ti3C2 and Ti3C2X2 (X = F, OH) MonolayerJournal of the American Chemical Society, 2012
- MXene: a promising transition metal carbide anode for lithium-ion batteriesElectrochemistry Communications, 2012