Development of cobalt doped lithiated NiO composites and hot corrosion testing of nano-LiAlO2 matrices for molten carbonate fuel cell (MCFC) applications /

Abstract

The increase in global energy demand and depletion in available energy resources have attracted engineers, researches and scientists to work on alternative energy technologies and devices. In modern world, fuel cells have undoubtedly reached at a level where their efficiencies are very much comparable to the conventional energy producing technologies. Molten carbonate fuel cells (MCFCs) are one of the types of fuel cells which can achieve efficiency of up to 90% in combined heat and power (CHP) systems. The deterioration of conventional NiO cathode for molten carbonate fuel cells is a major technical obstacle in its commercialization. Cathode dissolution problems and poor chemical strength of NiO based materials must be addressed to attain an acceptable life-time. Recent studies have shown that if doping parameters can be carefully controlled, an increase in exchange current density of cobalt doped cathode materials can be achieved. In this work, sol-gel method has been employed to synthesize lithiated NiO and cobalt doping has been done to improve the chemical stability and electrical conductivity of cathode material. Lower-cost precursors have been used with reduced calcination temperature of 650 °C for material synthesis. Structural characterization tools such as XRD, SEM, etc. have been used to investigate into high efficiency cobalt doped lithiated NiO prepared with various process parameters. Moreover, electrical properties show an improvement in the electrical conductivity with a value of 12.16 Scm-1. Meanwhile, highly pure matrix material, tetragonal nano-LiAlO2, stable at high operating temperatures, has been in-house developed by simple and reliable sol-gel method. Structural purity and surface morphology is enunciated using XRD and SEM techniques. The tolerance of LiAlO2 pellets is further reported in corrosive molten salt environment at 650 °C using Li/Na/K, Li/Na and Li/K carbonates mixtures at a loading rate of 15 mg/cm2. Studies revealed that sodium carbonate had a pronounced impact on the chemical and structural stability of LiAlO2 causing formation of NaAlO2 impure phase due to surface reactions. However, potassium containing mixture had a minimal influence on matrix material and treated pellet remained chemically unaffected.