TiO2 protective coating processed by Atomic Layer Deposition for the improvement of MCFC cathode

• Nano-structured TiO2-coated nickel cathode by ALD, crystalline as-deposited.
• Progressive transformation in a Li–Ni–Ti–O compound, stable in molten carbonates.
• Lower Ni solubility with TiO2 protective coating.
• Feasibility of the coating in MCFC cathode conditions.

One of the main issues for optimizing the molten carbonate fuel cell (MCFC) is the control of the corrosion and dissolution of the state-of-the-art porous nickel oxide cathode. A protective coating constituted by more stable oxides seems to be the best solution. In this paper, very thin layers of TiO2 (50 and 300 nm) are processed by a sequential CVD technique, Atomic Layer Deposition (ALD), which produces high quality, homogeneous and conformal layers. Structural, morphological and electrochemical behaviors of TiO2-coated samples are tested in a Li2CO3–K2CO3 (62:38 mol%) eutectic melt under a standard cathode atmosphere: CO2/air (70:30 bar%). Ni solubility is determined by ICP-AES. The protective role of TiO2 layers and the consequent decrease in Ni solubility have been clearly evidenced.