Technion-Israel Institute of Technology scientists have developed an environmentally friendly silicon-air battery that can supply non-stop power for thousands of hours without needing to be replaced.

Created from oxygen and silicon—the second most plentiful element in the earth's crust—such batteries would be lightweight, have an unlimited shelf life, and have a high tolerance for both humid and extremely dry conditions. Potential uses include medical applications such as for powering diabetic pumps or hearing aids; sensors; and microelectronics structured from silicon.

"Silicon-air batteries will be used like the ones already in use today," says lead researcher Yair Ein-Eli of the department of materials engineering. "But by using silicon—a safe, non-toxic, stable and more common material—we can create very lightweight batteries with infinite shelf life and high energy capacity."

Silicon-air batteries would provide significant savings in cost and weight because they lack the built-in cathode of conventional batteries. The cathode in silicon-air (and metal-air) batteries is the oxygen that comes from the atmosphere through the membrane.

Ein-Eli estimates that in three to four years, silicon-air batteries can be made more powerful, as well as rechargeable. In 10 years, he says, it may be possible to build "electric car batteries made from silicon that will turn into sand that would be recycled into silicon and then into power again."

Yair Ein-Eli: We can create very lightweight batteries with infinite shelf life and high energy capacity

According to Ein-Eli, lightweight, long-lasting metal-air batteries are already used in hearing aids. There have also been attempts, he says, to upgrade such batteries for use in electric cars and portable electronic devices, and that interest in the matter was sparked recently when Toyota and Panasonic began joint efforts to adapt the zinc-air battery for future electronic cars.

The silicon-air battery research by Ein-Eli was financed by the Bi-National Research Foundation. Also involved in the research were David Starosvetsky and graduate student Gil Cohen from the Technion, Digby Macdonald from Penn State University, and Rika Hagiwara of Kyoto University.