Review of gas diffusion cathodes for alkaline fuel cells

This paper gives a technical background to alkaline fuel cells (AFCs), introducing the advantages and drawbacks of the technology. AFCs offer the potential for low cost, mass producible fuel cells, without the dependency on platinum based catalysts and (currently) expensive membrane electrolytes. The AFC uses relatively low cost electrolytes based on aqueous bases such as potassium hydroxide. The inherent CO2 sensitivity of the electrolyte can be addressed by filtering out the CO2 from the air intake using a simple scrubber and periodically replacing the liquid electrolyte.A review of the state-of-the-art in gas diffusion cathode development is given. The overall cell performance and stability is dominated by the behaviour of the cathode, leading to a focus of research effort on cathode development. The performance and durability of the gas diffusion electrode is very much dependent on the way in which the layer structures are fabricated from carbon and polytetrafluoroethylene (PTFE). The choice and treatment of the carbon support is of prime importance for the final catalytic activity. Noble metal and non-noble metal catalysts have been investigated and show good performance, however, more work is still needed on cathode durability to ensure the long term success of the alkaline fuel cell.