600

Figure 2 shows analyzed result of each cell performance of the stack. Nernst loss is not shown. Voltage drops by R,r of Li/Na cells (No. 1 - 6) are almost half of these of Li/K cells (No. 7 - 26) since the ionic conductivity of Li/Na is approximately two times larger than of Li/K. Cathode polarizations located top and bottom of the stack are large since temperatures of these cells are lower than of middle cells. Cathode polarization of Li/Na cell (No. 6) is approximately equal to of Li/K cells (No. 7 - 21). Good performance of Li/Na cell at 7 ata is brought by low cathode polarization and low voltage drop by Rir. Anode polarization analyzed by this method agrees with the result of single cell test. The method can analyze each cell performance of the stack with good accuracy.

Figure 3 shows relationship between cell voltages and parameter A. Circles indicate measured cell voltages and squares indicate cell voltages compensated using R,r. There is a obvious relationship between compensated cell voltage and parameter A. Based on the result, it can be

Pressure 7ata Mxa. temp. 675°C

Hj/C02/H20=54.4/13.6/32 Uf=60!i. Air/C02=70/30 Uox=8.2!i

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