A new insight into the oxygen diffusion in porous cathodes of lithium-air batteries

Slow air transport in the cathodes limits the performance of the metal-air battery. In this work, the diffusion mechanisms in the lithium-air battery have been investigated. It has been found that Knudsen diffusivity can be influenced dramatically by the different pore sizes while bulk diffusivity is almost a constant at a fixed temperature. Limiting current density and concentration polarization, both limited by impeded gas diffusion in the porous cathode, have been evaluated systematically. The analysis of the correlation between those electrochemical parameters and diffusivities improves the quantitative evaluation of gas-based batteries at various materials and operation conditions.