Identifying lithium-air battery discharge products through super(6)Li solid-state MAS and super(1)H- super(13)C solution NMR spectroscopy

Discharged lithium-O sub(2) battery cathodes are investigated with different catalysts present including Pd, alpha MnO sub(2) and CuO, and containing two different electrolyte solvents, 1:1 ethylene carbonate/dimethyl carbonate (EC/DMC) and tetraethylene glycol dimethyl ether (TECDME). Solid-state super(6)Li magic angle spinning (MAS) NMR spectroscopy has been used identify lithium products that are formed in the cathodes and differences between products formed with the different catalysts and solvents. There are significant differences in the products formed in Li-O sub(2) cathodes with the two different solvents, EC/DMC and TEGDME. Due to the small chemical shift range of lithium it is difficult to determine exact speciation from super(6)Li MAS NMR data alone. Fitting of the super(6)Li NMR peaks with tested Li-oxide powder standards indicates that Li-O sub(2) cathodes discharged in EC/DMC produce primarily Li sub(2)CO sub(3) as a lithium product and those discharged in TEGDME produce mainly Li sub(2)O sub(2). Solution 2D correlation super(1)H- super(13)C NMR spectroscopy techniques allow for determination of side-products produced in Li-O sub(2) cathodes.