Adding A Membrane Improves Lithium-Air Batteries

Lithium-air batteries look amazing on paper, but so far they don’t live up to their potential. These batteries, which draw oxygen from the air, pack roughly 10 times as much energy per weight as lithium-ion batteries. But they operate sluggishly and have short lifetimes because of formation of lithium oxides such as Li₂O₂ during discharge. The oxides accumulate on electrode surfaces and bury catalytic sites that drive the battery’s chemical reactions. Won-Hee Ryu and André D. Taylor of Yale University and colleagues have taken a step toward mitigating that problem through a battery design modification—including a mesh membrane made from polyacrylonitrile nanofibers dotted with catalytic palladium nanoparticles (Nano Lett. 2014, DOI: 10.1021/nl503760n). The research team found that covering the oxygen-converting electrode with the insulating membrane limits formation of lithium oxides on the fiber-bound nanoparticles. Pristine nanoparticles thereby remain accessible during charging to catalyze the reverse reaction. The team reports that in contrast to membrane-free batteries, which begin to fail after about 40 charging cycles, the new batteries remain stable for 60 cycles and operate more efficiently.