News Column

Scientists might triple battery life

August 3, 2014

By Wendy Koch, USA TODAY

Annoyed by how often your cellphone needs recharging? Stanford researchers say they've made a major step toward the "holy grail" of energy storage -- a pure lithium battery.

A team that includes former Energy secretary Steven Chu says it's building a lithium-anode battery that might give electric vehicles a 300-mile driving range and triple a cellphone's juice. Stanford professor Yi Cui says it will likely take three to five years to bring the product to market.

Their work is part of an intensifying push to build a better battery -- not only for portable electronics but also for storing solar and wind power for times when the sun doesn't shine and the wind doesn't blow. Universities, start-ups and big companies are trying new materials, such as vanadium, or tweaking the lithium-ion battery that Sony introduced in 1991.

The Stanford team says its breakthrough involves using nanotechnology to make a pure lithium battery -- an advance sought for decades because of its light weight and superior efficiency.

Today's lithium batteries only have lithium in the electrolyte, which is one of three basic parts of a battery. The electrolyte provides electrons, while the anode discharges them and the cathode receives them.

The Stanford team is also putting lithium in the anode. This is tricky because lithium expands during charging, and it can eat up the electrolyte.

The solution? Cui's lab has built a honeycomb-like microscopic layer -- called "nanospheres" -- that creates a flexible non-reactive film to protect the unstable lithium. It describes the work in a study published this week in the journal Nature Nanotechnology.

The layer improves battery efficiency. To become commercially viable, batteries generally need to put back 99.9% of the lithium lost in use during recharging. Previous anodes of unprotected lithium got about 96% efficiency, but Cui says his version is approaching 99.6%, and he expects it can reach 99.9% in two years.

Some experts are skeptical. John Goodenough, who helped invent the original lithium-ion battery of the late 1970s and is still working to improve the technology, says Cui's protective layer is not an "ideal" solution.

"It's not clear he has achieved that goal with a sufficiently cheap process," says Goodenough, now a 92-year-old professor of materials science and engineering at the University of Texas-Austin.

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Source: USA Today

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