AVS 60th International Symposium and Exhibition
    Applied Surface Science Thursday Sessions
       Session AS-ThP

Paper AS-ThP3
Evaluating the Stability of Li-O2 Battery Components on Cathode/Electrolyte Interface by XPS

Thursday, October 31, 2013, 6:00 pm, Room Hall B

Session: Applied Surface Science Poster Session
Presenter: M. Engelhard, Pacific Northwest National Laboratory
Authors: E. Nasybuiln, Pacific Northwest National Laboratory
M. Engelhard, Pacific Northwest National Laboratory
W. Xu, Pacific Northwest National Laboratory
J. Zhang, Pacific Northwest National Laboratory
Correspondent: Click to Email
The development of rechargeable Li-O2 batteries is a fast growing research field. Scientific interest is driven not only by high theoretical energy density of Li-O2 batteries (3,500 Wh kg-1 including masses of lithium and oxygen) but also by many aspects of material science and engineering involved in the development. At the current stage, Li-O2 batteries suffer from poor rechargeability because of the wide variety of side reactions between battery components (electrolyte solvent, electrolyte salt, and electrode materials – Li anode, cathode substrate, binder, catalyst) and reduced oxygen species (O2-•, O22-) generated during the discharge. These side reactions predominantly happen at the cathode/electrolyte interface simultaneously with the reversible formation/oxidation of Li2O2 during the discharge/charge processes. Unlike Li2O2, the side products are difficult to decompose and accumulate with cycling forming an insulating layer at the interface and eventually leading to the battery failure. Therefore, analysis of side products is important to evaluate the stability of battery components and may suggest new robust materials for the application in Li-O2 batteries. Considering the side products form only a thin layer on the interface, characterization of these products by bulk methods is problematic. X-ray photoelectron spectroscopy (XPS) is a powerful surface sensitive technique which is probably the most suitable for the analysis of such interfaces. In the present study, XPS is applied to evaluate the stability of various components of Li-O2 batteries, including electrolyte solvents, electrolyte salts, polymer binders and organic catalyst on the surface of carbon-based cathodes during the discharge process of the Li-O2 batteries. With the support from other techniques, the most stable components are identified and suggested for the rechargeable Li-O2 batteries. Decomposition pathways are proposed for a number of components based on their decomposition products. Contributions from the degradation of various battery components to the overall failure of Li-O2 batteries are estimated. It is demonstrated that the chemical and electrochemical stability of the components has a drastic effect on the discharge capacity and cycling stability of Li-O2 batteries. Details of this study will be reported in the presentation.