Graphite Aluminum‐ and Silicon Carbide‐Coated Current Collectors for Sodium‐Sulfur Cells

Abstract

The electrical performance and corrosion of current collectors made from graphite foil bonded to aluminum and from stainless steel protected by silicon carbide coating are compared to current collectors protected by chromium coatings. The testing is done in corrosion cells operated under dynamic conditions in melts at 350°C. The cells are operated under both cathodic and anodic potentials of 100–300 mV measured with respect to carbon reference electrodes. The current collectors made from graphite foil, 127 μm thick, bonded to aluminum have lowest total impedances (ohmic plus polarization) of 2.0 and 5.4 Ω‐cm2 under cathodic and anodic potential of 300 mV. The corresponding values for silicon carbide coatings, 1.8–2.0 μsm thick, are 2.9 and 19.0 Ω‐cm2, and, for chromium coatings ∼50 μm thick, 3.2 and 10.7 Ω‐cm2. No, or very little, corrosion is observed on the graphite/aluminum samples or on the silicon carbide‐coated samples over a period of 2–3 months.