(January 11, 2016) Stanford
researchers have developed the first lithium-ion battery that shuts down before
overheating, then restarts immediately when the temperature cools.
The new technology could prevent the kind of fires that have
prompted recalls and bans on a wide range of battery-powered devices, from
recliners and computers to navigation systems and hoverboards.
"People have tried different strategies to solve the
problem of accidental fires in lithium-ion batteries," said Zhenan Bao, a
professor of chemical engineering at Stanford. "We've designed the first
battery that can be shut down and revived over repeated heating and cooling
cycles without compromising performance."
Bao and her colleagues describe the new battery in a study
published in the Jan. 11 issue of the new journal Nature Energy.
A typical lithium-ion battery consists of two electrodes and
a liquid or gel electrolyte that carries charged particles between them.
Puncturing, shorting or overcharging the battery generates heat. If the temperature
reaches about 300 degrees Fahrenheit (150 degrees Celsius), the electrolyte
could catch fire and trigger an explosion.
Several techniques have been used to prevent battery fires,
such as adding flame retardants to the electrolyte. In 2014, Stanford engineer
Yi Cui created a "smart" battery that provides ample warning before
it gets too hot.
"Unfortunately, these techniques are irreversible, so
the battery is no longer functional after it overheats," said study
co-author Cui, an associate professor of materials science and engineering and
of photon science. "Clearly, in spite of the many efforts made thus far,
battery safety remains an important concern and requires a new approach."