Limitations in Rechargeability of Li-O 2 Batteries and Possible Origins

TitleLimitations in Rechargeability of Li-O 2 Batteries and Possible Origins
Publication TypeJournal Article
Year of Publication2012
AuthorsMcCloskey, Bryan D., Donald S. Bethune, Robert M. Shelby, Takashi Mori, Rouven Scheffler, Angela Speidel, M. Sherwood, and Alan C. Luntz
JournalThe Journal of Physical Chemistry Letters
Pagination3043 - 3047
Date Published10/2012
Keywordselectrolyte stability, Li air battery, oxygen evolution, oxygen reduction, parasitic electrochemistry, salt stability

Quantitative differential electrochemical mass spectrometry (DEMS) is used to measure the Coulombic efficiency of discharge and charge [(e/O2)dis and (e/O2)chg] and chemical rechargeability (characterized by the O2 recovery efficiency, OER/ORR) for Li-O2 electrochemistry in a variety of nonaqueous electrolytes. We find that none of the electrolytes studied are truly rechargeable, with OER/ORR <90% for all. Our findings emphasize that neither the overpotential for recharge nor capacity fade during cycling are adequate to assess rechargeability. Coulometry has to be coupled to quantitative measurements of the chemistry to measure the rechargeability truly. We show that rechargeability in the various electrolytes is limited both by chemical reaction of Li2O2 with the solvent and by electrochemical oxidation reactions during charging at potentials below the onset of electrolyte oxidation on an inert electrode. Possible mechanisms are suggested for electrolyte decomposition, which taken together, impose stringent conditions on the liquid electrolyte in Li-O2 batteries.

Short TitleJ. Phys. Chem. Lett.