M. RAJČIĆ-VUJASINOVIĆ ET AL.
66
lutions. In the next polarisation phases, the product formed
at the electrode surface causes a slow diffusion in solid
state that leads to the increase of serial resistance and
controls further reaction. The existance of a compact
solid reaction product remaining on the electrode surface
was proved by electron microscopy.
In alkaline solution covellite exhibits a capacitance of
the same order of magnitude, although for about three
times lower; at the same time leakage, i.e. self-discharge
is bigger. The investigations on covellite in acidic and
alkaline solutions had a goal to enable optimization of
the electrochemical systems in the sense to obtain per-
formances as high as possible (usually the lowest serial
and biggest parallel resistance at the same time).
6. Acknowledgment
The authors gratefully acknowledge financial support
from the Ministry of Education and Science, Government
of the Republic of Serbia through the Project No. 172
060: “New approach to designing materials for energy
conversion and storage”.
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