In situ Raman scattering measurements of a LiMn2O4 single crystal microelectrode

Qingfang Shi, Yasuhiko Takahashi, Junji Akimoto, Ionel C. Stefan, Daniel Alberto Scherson

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Abstract

Raman spectra of a LiMn2O4 single crystal microelectrode have been recorded in situ as a function of potential in 1 M LiPF6 ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1) solutions at room temperature. Measurements were acquired during a linear voltammetric scan at 0.1 mV/s over the potential (E) range in which the material undergoes redox transitions, i.e., 3.6 < E < 4.4 V vs Li/Li +. Spectral data were analyzed using both classical least squares (CLS) and multivariate curve resolution (MCR) techniques. A plot of the state of charge of the LiMn2O4 single crystal microelectrode derived from the optical data vs the applied potential obtained from data collected during the reduction of the fully oxidized material displayed two well-defined steps. A similar behavior was found for corresponding plots extracted from a coulometric analysis of the voltammetric scan, except that the curves in this latter case were shifted along the potential axis by ca. 40 mV toward more negative values. This effect was attributed to the slow rates of Li+ diffusion within the lattice, allowing the surface region probed by the laser beam to reach equilibrium with the applied potential much faster than the particle as a whole.

Original languageEnglish
JournalElectrochemical and Solid-State Letters
Volume8
Issue number10
DOIs
Publication statusPublished - 2005 Oct 7
Externally publishedYes

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ASJC Scopus subject areas

  • Electrochemistry
  • Materials Science(all)

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