Electrochemical and in situ Raman spectroscopic characterization of nickel hydroxide electrodes. 1: Pure nickel hydroxide
- Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.
In situ laser Raman spectra of electrochemically precipitated thin-film Ni(OH){sub 2} electrodes in alkaline NaOH electrolytes were recorded, and the effect of repeated charge-discharge cycling on the structure and phase composition of the discharged and charged films was investigated. Careful deconvolution analyses of the Raman and surface-enhanced Raman spectra showed that freshly precipitated films of Ni(OH){sub 2} contain not only an {alpha}-like phase but also small amounts of a {beta}-phase. By combining cyclic voltammetry with in situ Raman spectroscopy, spectral changes that accompanied charge-discharge cycling could be associated with a partial transformation of the predominant {alpha}-phase into a disordered {beta}-Ni(OH){sub 2} phase. A new phase characterized by a vibration at 522 cm{sup {minus}1} was also discovered in the film at the end of the cycling procedure. Analysis of the Raman spectra of the oxidized electrode (NiOOH Active material) revealed for the first time a slight variation of the 477/559 cm{sup {minus}1} peak pair ratio, which corresponds to phase transitions in the Ni(III) hydrous oxide film, as the electrode was cycled. Significant differences between the low-frequency-region Raman spectra of chemically synthesized {alpha},{beta}-Ni(OH){sub 2} and those of highly disordered hydrous Ni(OH){sub 2} films, as well as the absence of characteristic vibrations in the OH stretching region of the in situ Raman spectra of the Ni(OH){sub 2} electrode, suggest that chemically prepared {alpha},{beta}-nickel hydroxides should not be regarded as structural models for electrochemically precipitated thin-film materials.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 465093
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 2 Vol. 144; ISSN JESOAN; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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