Direct carbon fuel cells (DCFCs) converts the chemical energy of elemental carbon, derived from coal and eventually from non-fossilized carbon resources such as biomass, electrochemically into electricity without combustion and, hence, the cells have almost twice the efficiency (i.e., to 65-70%) of fossil fuel power plants and half the greenhouse emissions. Corrosions by the electrolytes, such as molten carbonates or hydroxides at high temperatures is one of the challenges that determine the long-term stability of DCFCs. Depending on the cell designs (cathode-, electrolyte-, or anode-supported), corrosions may occur on anode and seals if perovskite-carbonate electrolyte is used. During corrosion, a thick layer of corrosion products is formed on the electrodes. This layer has very high electrical resistivity and low catalytic activity for carbon electrochemical oxidation, leading to decreased cell performance. The compatibility of stainless steel 304 with molten eutectic carbonate salts Li2CO3 + K2CO3 at 503 °C, 526 °C, 551 °C, 577 °C, and 600 °C in air was examined using electrochemical methods including linear polarization resistance (LPR), Tafel, and electrochemical impedance spectroscopy (EIS). It was observed that an oxidation layer was formed on the alloy surface. With increasing temperature, the oxide layer will not form or dissolved. The EIS showed that the attack on the alloy was uniform and not localized.

Electrochemical study on the corrosion of structural materials for DCFC

2019 Fall National Meeting

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