Smart Lithium-Ion Battery Warns of Potential Fire Hazards

October 21, 2014

The ultrathin copper sensor is deposited atop a conventional battery separator (white square) as part of an early warning system to alert users that a lithium-ion battery is overheating.

Stanford University scientists have developed a "smart" lithium-ion battery that gives ample warning before it overheats and bursts into flames. The new technology is designed for conventional lithium-ion batteries now used in billions of cellphones, laptops, and other electronic devices, as well as a growing number of cars and airplanes.

A series of well-publicized incidents in recent years has raised concern over the safety of lithium-ion batteries. In 2013, Boeing temporarily grounded its 787 Dreamliner fleet after battery packs in two airplanes caught fire. The cause of the fires has yet to be determined.

A typical lithium-ion battery consists of two tightly packed electrodes – a carbon anode and a lithium metal-oxide cathode – with an ultrathin polymer separator in between. The separator keeps the electrodes apart. If it's damaged, the battery could short-circuit and ignite the flammable electrolyte solution that shuttles lithium ions back and forth. To address the problem, nanolayer of copper was applied onto one side of the polymer separator, creating a third electrode halfway between the anode and the cathode. This allows measurement of the voltage difference between the anode and the separator.

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