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Multiple Anionic Transition-Metal Oxycarbide for Better Lithium Storage and Facilitated Multielectron Reactions
journal contribution
posted on 2019-09-16, 13:40 authored by Jing Cuan, You Zhou, Jian Zhang, Tengfei Zhou, Gemeng Liang, Sean Li, Xuebin Yu, Wei Kong Pang, Zaiping GuoAs
an important class of multielectron reaction materials, the
applications of transition-metal oxides (TMOs) are impeded by volume
expansion and poor electrochemical activity. To address these intrinsic
limitations, the renewal of TMOs inspires research on incorporating
an advanced interface layer with multiple anionic characteristics,
which may add functionality to support properties inaccessible to
a single-anion TMO electrode. Herein, a transition-metal oxycarbide
(TMOC, M = Mo) with more than one anionic species was prepared as
an interface layer on a corresponding oxide. A multiple anionic TMOC
possesses advantages of structural stability, abundant active sites,
and elevated metal cation valence states. Such merits mitigate volume
changes and enhance multielectron reactions significantly. The TMOC
nanocomposite has a well-maintained capacity after 1000 cycles at
2 A·g–1 and fully resumed rate performance. In situ synchrotron X-ray powder diffraction (SXRPD) analysis
unveils negligible volume expansions occurring upon oxycarbide layer
coupling, with lattice spacing variation less than 1% during cycling.
The lithium storage mechanism is further inspected by combined analysis
of kinetics, SXRPD, and first-principles calculations. Superior to
TMO, multielectron reactions of the TMOC electrode have been boosted
due to easier rupture of the metal–oxygen bond. Such improvements
underscore the importance of incorporating an oxycarbide configuration
as a strategy to expand applications of TMOs.
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Multiple Anionic Transition-Metal OxycarbideSXRPDlattice spacing variationTMOCmultielectron reactionsmetal cation valence stateslithium storage mechanismmultielectron reaction materialssingle-anion TMO electrodeFacilitated Multielectron Reactionstransition-metalinterface layerSuchsynchrotron X-ray powder diffractionvolumeoxideoxycarbideapplicationBetter Lithium Storageanalysis
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