Modification of Ni-based cathode material for molten carbonate fuel cells using Co3O4

The degradation of cathode materials due to the so-called ‘NiO dissolution’ problem, is one of the most critical issues restricting the long-term operation of molten carbonate fuel cells (MCFCs). To overcome this problem, a modified NiO powder is prepared by the annealing of a pre-mixed powder consisting of Ni powder and Co3O4 nano-particles (n-Co3O4) at 650 °C. Annealing above 300 °C plays an important role in converting the physically bound mixed oxide system to a chemically bound system and, therefore, the separation of n-Co3O4 from Ni is prevented. This modification leads to the formation of a Ni0.9Co0.1O solid solution, and the lithiated Ni0.9Co0.1O has a core–shell structure that consists of different Li contents. Whereas the core phase has a low concentration of lithium, the outer layer is a highly lithiated phase. Since the highly lithiated outer phase, acting as a barrier, minimizes the dissolution of NiO, the modified cathode demonstrates good electrochemical properties and chemical stability under actual operating conditions. This study can provide an effective way to mass produce MCFC cathode materials.