Rechargeable Lithium/TEGDME-LiPF6/O2 Battery

A rechargeable Li-air cell utilizing an electrolyte composed of a solution of LiPF6 in tetraethylene glycol dimethyl ether, CH3O(CH2CH2O)(4)CH3 (TEGDME), and an uncatalyzed porous carbon electrode, investigated to elucidate the baseline Li-air battery chemistry, is reported. From the x-ray diffraction patterns of the discharged carbon electrodes, the discharge product of the cell was identified to be Li2O2 during normal discharge to 1.5 V. Discharging the cell to 1.0 V or below produces Li2O as well. The cell can be recharged without a catalyst in the carbon cathode, albeit at low depths of discharge. The high resistance of the discharged carbon cathode is a major impediment to recharging cells displaying a high specific capacity. The cell capacity decreases with continued cycling, which was found to be due to the poor cycling efficiency of the Li anode and the high resistance of the discharge products, which slowly accumulate in the porous electrode. (C) 2011 The Electrochemical Society. [DOI:10.1149/1.3531981] All rights reserved.