Rf. Plivelich et al., DEGRADATION MECHANISMS OF NICKEL-OXIDE ELECTRODES IN ZINC NICKEL-OXIDE CELLS WITH LOW-ZINC-SOLUBILITY ELECTROLYTES, Journal of Applied Electrochemistry, 25(5), 1995, pp. 433-440
Nickel oxide electrodes that suffered capacity degradation during exte
nded cycling in zinc/nickel oxide cells were examined by a variety of
chemical and physical techniques. Nickel hydroxyzincates, which have b
een speculated to cause such capacity degradation, were also examined.
Powder X-ray diffraction experiments indicated that the intersheet di
stance between layers of turbostratic nickel hydroxide increased when
zinc was incorporated. Photoelectron spectra (XPS) showed that this ma
terial is probably a mixture of Ni(OH)(2) and ZnO or Zn(OH)(2). Raman
spectroscopy data also supported this conclusion. XPS indicated that t
he form of zinc in degraded-nickel oxide electrodes is probably ZnO or
Zn(OH)(2). Significant increases in resistivity were found in cycled
nickel oxide electrodes, and optical microscopy provided visible evide
nce of mechanical damage during cycling. These results suggest that th
e observed capacity degradation was largely mechanical in nature, and
not due to the formation of nickel-zinc double hydroxides, as had been
reported by others. Cell-cycling experiments indicated that the mecha
nical degradation is largely irreversible.