Multilayered TiO2/Ni/Ag cathode with reduced solubility for efficient molten carbonate fuel cells

This study presents a multilayer TiO 2 /Ni/Ag cathode designed to improve its stability and increase the efficiency of molten carbonate fuel cells (MCFCs). The architecture consists of a tape-cast porous nickel catalytic layer supported by nickel foam, providing mechanical stability. A TiO 2 coating was selectively electrophoretic deposited on the electrolyte-facing side to suppress nickel dissolution in the molten carbonate electrolyte, which is one of the main degradation mechanisms in MCFCs. Additionally, a 300 nm silver layer was sputtered onto the current collector side to reduce charge transport resistance, thereby improving fuel cell performance. Microstructural uniformity and chemical compatibility were confirmed by SEM/EDX analysis, while phase stability was verified by XRD. Nickel solubility in the molten electrolyte was quantified under realistic cathode operating conditions using a dedicated experimental protocol. Single-cell tests performed at 650°C under various gas flow rates, supported by electrochemical impedance spectroscopy, demonstrated a clear positive effect of the dual modification. The TiO 2 layer reduced nickel dissolution twice. Additional silver coating resulted in a 67% increase in power density compared to an unmodified cathode. At the same time, material consumption is reduced by limiting the use of functional layers to only where they are most needed.