Fibrous metal-carbon composite structures as gas diffusion electrodes for use in alkaline electrolyte

The fabrication of novel fibre composite electrode structures and the performance assessments for oxygen reduction in alkaline electrolyte is reported. An array of 2 mu m diameter activated carbon fibres interlocked within a network of 2 mu m sinter-bonded metal fibres to form the composite structure was used. The resulting electrode structure is stable, highly conductive and can maintain void fraction exceeding 95%. Electrode physical properties including thickness, macroporosity, volume and mass fractions of constituent carbon and metal fibres have been controlled, characterized, and related to the electrode polarization in a KOH half cell. Comparisons have been made with a commercial Teflon-bonded gas diffusion electrode (GDE). It has been demonstrated that this novel method allows reproducible and low-cost fabrication of GDEs with the optimal balance between macropores for gas access, micropores for liquid access, and conductive paths for electron access.