THE ELECTROCHEMICAL AND DISSOLUTION PROPERTIES OF NICKEL OXIDE.
WESTERN RESERVE UNIV CLEVELAND OHIO DEPT OF CHEMISTRY
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The dissolution of lithiated single crystal nickel oxide was studied in HCl and H2SO4 as functions of potential, temperature, time, and lithium content with in situ photomicrographic examination of the dissolving surface. This research indicates that the dissolution rate is extremely low even at elevated temperatures in concentrated acids and increases very rapidly by at least several fold over a narrow range of potentials as the potential is adjusted to more anodic values. The potential region of rapid transition corresponds to a prominent peak in the linear sweep voltammetry curves as well as in the a.c. capacity versus potential curves and correlates with the potential assigned by Pourbaix to the NiIINiIII couple for the nickel oxide-water system. In HCl the dissolution increases much more slowly with increasing adodic potential. Some evidence exists that the logarithm of the dissolution rate is linearly dependent on potential and has the same slope both below and above the rapid transition region. The steady state surface topography at potentials anodic to the rapid transition region is characterized by well formed etch pits, while at more cathodic potentials, no etch pits are evident even after prolonged dissolution. The dissolution kinetics are interpretated in terms of a quantitative model according to which the rate-determining step is the transfer of nickel ions over a potential energy barrier from the oxide to the Helmholtz plane in the solution phase. Author
- Physical Chemistry
- Energy Storage