AN INVESTIGATION OF THE INTERFACE BETWEEN GRAPHITE AND BETA-BETA'' ALUMINA

The anodic degradation of beta/beta double prime alumina of different compositions was investigated by voltammetric techniques in cells of the type Cu/Rodar alloy/carbon fibers/graphite layer/solid electrolyte/NaNO//3/Pt/Cu at 350 degree C. The possibility was evaluated if the voltammetric results are useful as a diagnostic tool for the prediction of the failure of beta/beta double prime alumina electrolytes in sodium sulfur cells. Single voltage sweeps were applied into the anodic and also the cathodic direction at relatively low sweep rates (0. 1-100 mVs** minus **1), starting at the open circuit voltage and extending to different voltages of reversal. The anodic current-voltage curves display a continuous rise of current with voltage up to 4. 5V, vs a Na reference electrode, followed by a gradual decrease afterwards.