Understanding of Electrolyte Stability and Its Impact to Lifespan of Li-O₂ Battery

The impact to the Li-O₂ battery performance from the insoluble lithium salts formed from the electrolyte decomposition during discharge-charge cycle was investigated by a microfocused synchrotron X-ray diffraction (m-XRD) technique, together with the conventional imaging and spectroscopic methods. Lithium alkyl carbonate deposit was found throughout the battery. Surprisingly, the concentration of Li₂CO₃ in the separator is significantly higher than that in both electrodes. Imaging method such as Scanning electron microscopy revealed that the precipitates grew on the separator fiber surface, ultimately obstructing the pores serving as the ion-transport channel. A model based on finite-element analysis was developed to qualitatively illustrate the possible chemical/physical processes leading to high accumulation of insoluble precipitates in the separator region.