Wednesday, August 22, 2018

Fireproof Lithium-Ion Batteries that Harden When Hit

Liquid electrolyte that solidifies on impact could keep batteries from shorting and catching fire.

Adding powdered silica (in blue container) to the plastic layer (white sheet) that separates electrodes inside a test battery (gold bag) will prevent lithium-ion battery fires. (Credit: Gabriel Veith) Click to Enlarge.
To make lithium-ion batteries safer, researchers have come up with a novel solution: a liquid electrolyte that becomes solid on impact.  The electrolyte could keep batteries from heating up and bursting into flames when they are in a car crash or take a hard fall.  And it could be cost-effectively and easily employed in today’s battery production lines, its developers say.

Lithium-ion battery cells contain two electrodes separated by a thin plastic sheet and submerged in a liquid electrolyte.  If the plastic separator breaks, the electrodes can “touch” each other, shorting the battery and heating it up, which could cause the volatile liquid electrolyte to ignite.

For years, researchers have been trying to make batteries safer with non-flammable solid electrolytes.  But these solids, typically plastics or ceramics, don’t conduct ions as well as their liquid counterparts.  Some groups are also making batteries with paste-like semi-solid electrolytes and glassy electrolytes.

Gabriel Veith and his colleagues at Oak Ridge National Laboratory instead made an electrolyte that is normally a liquid but becomes solid when subjected to strain.  So if a battery is crushed or penetrated, the electrolyte would harden, keeping the electrodes from coming in contact.  The researchers are presenting their work at the American Chemical Society’s meeting in Boston.

Read more at Fireproof Lithium-Ion Batteries that Harden When Hit

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