Resistivity change of cathode graphite during and after electrolysis in alumina molten salt was determined at different temperatures between 870°C and 980°C. Resistivity of cathode graphite decreased remarkably in the initial stage of electrolysis and then became almost constant for further electrolysis. On the other hand, resistivity increased with time by interrupting electrolysis. Just after the interruption, resistivity increased rapidly with time, followed by a characteristic plateau, and again increased towards a final steady value. Repeating of this cycle resulted in remarkable enlargement of resistivity. It should be noted that a large increasing ratio of resistivity of cathode graphite before and after electrolysis was observed at relatively low temperature such as 870°C. This observation suggested intercalated sodium is stabilized at lower temperature and the amount of sodium uptake increased during electrolysis. Correspondingly, the electrolysis at lower temperature provides an effective way for evaluation on degradation of cathode graphite.
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