Internal Resistance of ZEBRA Cells

The power of the Z E B RA cell depends on the resistance of the cell during discharge. The resistance of the ZEBRA cell rises with increasing depth of discharge (DOD). There is a contribution to the resistance from the fixed values of the solid metal 

The reason for this increase can be found in the way the positive electrode operates. During charge as well as during discharge the reaction always starts from a point which represents the lowest internal cell resistance. This is at the inner surface of the -alumina, and a reaction front moves through the positive electrode 

The ZEBRA cell shows similar behavior during the charging reaction, in which the nickel is converted to nickel chloride within the reaction front. During the charging reaction the reaction front also moves from the /9 -alumina into the positive electrode. 

Reduction of the internal resistance of the cell can obviously be achieved by two measures  

The power of the ZEBRA cell depends on the resistance of the cell during discharge. The resistance of the ZEBRA cell rises with increasing depth of discharge (DOD). There is a contribution to the resistance from the fixed values of the solid metal components and of the/ -alumina solid electrolyte. The variable parts of the resistance arc the sodium electrode and the positive electrode. The increase in internal resistance during discharge is almost entirely due to the positive electrode, as can be seen from Fig. 4. 

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Figure 4. Qminbuuun.v to the internal resistance of a ZEBRA cell.

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