In this article we compare the impedance spectra of Li-air batteries using two models: one based on the analytical solution of the oxygen diffusion equation in the cathode and the other one based on finite element simulations. The first model was recently introduced by us to compute the impedance of lithium-air batteries with organic electrolyte and, here, is presented in slightly different form. The second model is based on the solution of the transport equations in concentrated solutions; the complex impedance is computed by the linearizing the partial differential equations that describe the mass and charge transport in Li-air batteries and includes the effects of the oxygen and lithium diffusion, finite electrolyte conductivities of the electrolyte and electrons, and Butler-Volmer kinetics at the anode and cathode.
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