Journal article
Role of surface structure on Li-ion energy storage capacity of two-dimensional transition-metal carbides
Journal of the American Chemical Society, v 136(17), pp 6385-6394
30 Apr 2014
PMID: 24678996
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
A combination of density functional theory (DFT) calculations and experiments is used to shed light on the relation between surface structure and Li-ion storage capacities of the following functionalized two-dimensional (2D) transition-metal carbides or MXenes: Sc2C, Ti2C, Ti3C2, V2C, Cr2C, and Nb2C. The Li-ion storage capacities are found to strongly depend on the nature of the surface functional groups, with O groups exhibiting the highest theoretical Li-ion storage capacities. MXene surfaces can be initially covered with OH groups, removable by high-temperature treatment or by reactions in the first lithiation cycle. This was verified by annealing f-Nb2C and f-Ti3C2 at 673 and 773 K in vacuum for 40 h and in situ X-ray adsorption spectroscopy (XAS) and Li capacity measurements for the first lithiation/delithiation cycle of f-Ti3C2. The high-temperature removal of water and OH was confirmed using X-ray diffraction and inelastic neutron scattering. The voltage profile and X-ray adsorption near edge structure of f-Ti3C2 revealed surface reactions in the first lithiation cycle. Moreover, lithiated oxygen terminated MXenes surfaces are able to adsorb additional Li beyond a monolayer, providing a mechanism to substantially increase capacity, as observed mainly in delaminated MXenes and confirmed by DFT calculations and XAS. The calculated Li diffusion barriers are low, indicative of the measured high-rate performance. We predict the not yet synthesized Cr2C to possess high Li capacity due to the low activation energy of water formation at high temperature, while the not yet synthesized Sc2C is predicted to potentially display low Li capacity due to higher reaction barriers for OH removal.
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Details
- Title
- Role of surface structure on Li-ion energy storage capacity of two-dimensional transition-metal carbides
- Creators
- Yu Xie - Center for Nanophase Materials Sciences, §Chemical and Engineering Materials Division, and ∥Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United StatesMichael NaguibVadym N MochalinMichel W BarsoumYury GogotsiXiqian YuKyung-Wan NamXiao-Qing YangAlexander I KolesnikovPaul R C Kent
- Publication Details
- Journal of the American Chemical Society, v 136(17), pp 6385-6394
- Publisher
- American Chemical Society; Washington, DC
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Materials Science and Engineering
- Web of Science ID
- WOS:000335369200042
- Scopus ID
- 2-s2.0-84899722454
- Other Identifier
- 991014877687704721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Chemistry, Multidisciplinary