Rechargeable aqueous lithium-air batteries with an auxiliary electrode for the oxygen evolution

A rechargeable aqueous lithium air cell with a third auxiliary electrode for the oxygen evolution reaction was developed. The cell consists of a lithium metal anode, a lithium conducting solid electrolyte of Li1+x+yAlx(Ti,Ge)(2-x)SiyP3-yO12, a carbon black oxygen reduction air electrode, a RuO2 oxygen evolution electrode, and a saturated aqueous solution of LiOH with 10 M LiCl. The cell was successfully operated for several cycles at 0.64 mA cm(-2) and 25 degrees C under air, where the capacity of air electrode was 2000 mAh g(cathod)(-1). The cell performance was degraded gradually by cycling under open air. The degradation was reduced under CO2-free air and pure oxygen. The specific energy density was calculated to be 810 Wh kg(-1) from the weight of water, lithium, oxygen, and carbon in the air electrode. (C) 2014 Elsevier B.V. All rights reserved.