<sup>6</sup>Li MAS NMR investigation of electrochemical lithiation of RuO<sub>2</sub>: evidence for an interfacial storage mechanism
Langue
en
Article de revue
Ce document a été publié dans
Chemistry of Materials. 2009, vol. 21, n° 5, p. 856-861
American Chemical Society
Résumé en anglais
Nanocrystalline RuO<sub>2</sub> was electrochemically lithiated using a <sup>6</sup>Li-enriched negative electrode, and selected samples at various states of lithiation-delithiation were characterized ex situ by <sup>6</sup>Li ...Lire la suite >
Nanocrystalline RuO<sub>2</sub> was electrochemically lithiated using a <sup>6</sup>Li-enriched negative electrode, and selected samples at various states of lithiation-delithiation were characterized ex situ by <sup>6</sup>Li magic-angle spinning nuclear magnetic resonance (<sup>6</sup>Li MAS NMR). In the first plateau (up to one Li per RuO<sub>2</sub>), a signal with considerable shift and loss of intensity is observed, showing a strongly paramagnetic character for the LiRuO<sub>2</sub> phase. A signal due to solid electrolyte interphase (SEI) appears at 0 ppm on this first plateau, but significantly grows only on the subsequent conversion plateau (from 1 to 4 Li/RuO<sub>2</sub>). Li<sub>2</sub>O is detected only at the very end of the latter plateau. On further lithiation (4 to 5.5 Li/RuO<sub>2</sub>), the magnitude of the Li<sub>2</sub>O signal remains constant, and a new signal at 4 ppm appears, that we can assign to interfacial Li hypothesized earlier in this system. Upon subsequent delithiation, NMR shows that the interfacial Li first disappears, then Li<sub>2</sub>O also disappears, and the reconstructed Li-RuO<sub>2</sub> phase is clearly different from the one formed during the initial lithiation of RuO<sub>2</sub>. Besides, the SEI signal slightly changes but does not decrease in magnitude upon delithiation. NMR results are in satisfactory agreement with the characteristic features of the proposed “job-sharing” mechanism.< Réduire
Mots clés en anglais
Electrochemistry
NMR
Storage
Mechanism
Inorganic compound
Ruthenium
Origine
Importé de halUnités de recherche