Materials Selection and Construction Development for Ensuring the Availability and Durability of the Molten Hydroxide Electrolyte Direct Carbon Fuel Cell (MH-MCFC)

Abstract

The molten hydroxide electrolyte Direct Carbon Fuel Cell (MH-DCFC) is a promising type of DCFC due to its advantages, such as high ionic conductivity, higher electrochemical activity of carbon (higher anodic oxidation rate and lower overpotentials) and high efficiency of carbon oxidation due to lower operating temperature (the dominant product of carbon oxidation is CO2 vs. CO). Accordingly, the MH-DCFC can be operated at lower temperatures (roughly 673–873 K), and thus cheaper materials can be used to manufacture the cell. Nonetheless, MH-DCFCs are still under development due to several fundamental and technological challenges such as corrosion problems. Selection of materials and development of a structure that ensures adequate availability and durability of the cell is crucial for the optimization of the MH-DCFC performance and the further development of that technology. This article presents the operating characteristics of the MH-DCFC made of different construction materials, such as carbon steel, stainless steel, and nickel and its alloys. Nickel and its alloys have proven to be the best materials for the construction of individual elements of the fuel cell. Inconel alloy 600 was a good catalytic material for cathodes with good corrosion resistance.