Bi-functional oxygen catalysts for metal-air flow-batteries

The rise in wind, solar and tidal renewable power generation presents a new challenge for the future stability of electrical networks on the national and international scale. The modal nature of renewable power and its incompatibility with consumer demand necessitates a means for largescale energy storage with high efficiency and relatively low cost. Zinc-air flow batteries represent one possible solution to this problem. The energy is stored in the metallic zinc, and reversed with the oxidation to form zincate releasing the energy on demand. The majority of energy losses in the zinc-air battery are for the O2 evolution and reduction reactions on the air electrode. A stable, durable and low-cost bi-functional air electrode would allow the introduction of zinc-air flow batteries to support the power grids of the future.The work in this thesis will investigate the activity of NiCo2O4 electrocatalysts prepared by various methods, for their use as bi-functional electrocatalysts in the air-electrode. The electrocatalyst prepared on to a gas diffusion electrode, to determine activity in lab-scale half-cells. Improvements to catalyst activity are then considered through the addition of metal nanoparticles to the surface of NiCo2O4, with in-situ X-ray absorbance measurements to determine the oxidation states of ruthenium during the O2 evolution reaction. The activity of NiCo2O4 was compared to alternative perovskite mixed metal oxide electrocatalysts