Statistical Analysis of Li-Oxygen Batteries

Abstract

In this article we develop a mathematical model and analyze the variability of discharge characteristics and impedance spectra in Li-air batteries with organic electrolyte. These batteries are well known to display a large variability of their characteristics from battery to battery (particularly of their specific capacity, energy and power densities), however, the exact reasons of this variability are still under investigation. Our model shows that the intrinsic variability of the pore microstructure which include the variability of the porosity and specific area from one macroscopic location to another macroscopic location inside the same battery and from one battery to another battery can be, at least in part, responsible for the large discrepancy of the results reported in the literature for the discharge characteristics and impedance spectra. It is shown that, while the variance of the specific capacity decreases slightly when the discharge current of the cell is increasing, the relative variance-to-mean ratio increases dramatically.