A Reversible and Higher-Rate Li-O 2 Battery

Improving Lithium Batteries Lithium-oxygen batteries have similar volumetric energy densities to lithium-ion batteries, but, because the oxygen part of the battery can be extracted from the air, they have a significant advantage in their gravimetric energy densities. One of the fundamental problems plaguing the nonaqueous Li-O 2 system is that the Li 2 O 2 that forms on discharge must be completely reversed on charging, but for most systems, a range of side products form instead of Li 2 O 2 . Peng et al. (p. 563 , published online 19 July) show that by using dimethyl sulfoxide as the electrolyte, and a porous gold cathode, they can get reversible production and removal of Li 2 O 2 during discharge and charge cycles. Furthermore, the electrolyte-electrode system operates with much faster kinetics than carbon electrodes.