INSITU X-RAY ABSORPTION SPECTROSCOPIC STUDIES OF NICKEL-OXIDE ELECTRODES

In situ transmission x-ray absorption spectroscopy was used to investigate changes in the structure of Ni(OH)2 as it was cycled as a nonsintered nickel oxide electrode in concentrated alkali. Results were obtained for dry as-prepared electrodes and electrodes that were charged or discharged. Changes were observed in the (0001) plane of the Ni(OH)2 as a function of cycling. In the charged material there was a contraction in the Ni-O and Ni-Ni distances. The EXAFS results and the XANES spectra strongly indicate that the Ni-O coordination is symmetrical in Ni(OH)2, whereas the coordination is asymmetric in the charged material. © 1990, The Electrochemical Society, Inc. All rights reserved.