Will metal-free catalyst lower rechargeable zinc-air battery costs?

April 07, 2015 // By Paul Buckley
Researchers from Case Western Reserve University and the University of North Texas are claiming to have developed the first metal-free bifunctional electrocatalyst that performs as well or better than most metal and metal oxide electrodes in zinc-air batteries.

Zinc-air batteries are regarded as being safer, lighter, cheaper, more powerful and durable than lithium-ion batteries.

The carbon-based catalyst works efficiently in both the oxygen reduction reaction and oxygen evolution reaction, making the battery rechargeable. The catalyst is also inexpensive, easy to make and more ecological than most of the alternative materials.

The research is reported in the online edition of Nature Nanotechnology.

“With batteries, cost is always an issue and metal-free catalysts can reduce cost while improving performance,” said Liming Dai, professor of macromolecular science and engineering at Case Western Reserve University and senior author of the study. “These batteries could be used in computers, data stations, for lighting - anyplace batteries are used now.”

Dai worked with Case Western Reserve postdoctor Jintao Zhang, who performed experimental work; and North Texas University’s Zhenhai Xia, professor of materials science and engineering, and Zhenghang Zhao, a PhD student, who performed theoretical simulations.

Zinc-air batteries mix oxygen from the air with zinc in a liquid alkaline electrolyte to create a charge. The batteries can have three times the energy density of lithium-ion batteries, but have been sluggish. To counter that problem, researchers are seeking different catalyst materials.

The catalyst developed by the researchers is a stable carbon aerogel, or foam, with pores ranging from 2 to 50 nanometers in diameter, providing enormous surface area and room for the battery electrolyte to diffuse.