Team Develops New Fire Retardant Lithium-Ion Batteries That Are 80% Lighter

Researchers at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have joined forces to produce current collectors in batteries that weigh 80% less and quench any fires that flare-up.  

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“The current collector has always been considered dead weight, and until now it hasn’t been successfully exploited to increase battery performance,” said in a statement Yi Cui, a professor at SLAC and Stanford and investigator with the Stanford Institute for Materials and Energy Sciences (SIMES) who led the research.

“But in our study, making the collector 80% lighter increased the energy density of lithium-ion batteries – how much energy they can store in a given weight – by 16-26%. That’s a big jump compared to the average 3% increase achieved in recent years.”

The scientists hope this new technology will increase the driving range of electric vehicles and reduce the chances that laptops, cell phones, and other electronics will catch fire. The development could also have a big impact on recycling.

Since the batteries will be much lighter, the transportation of recycled materials will be less expensive. This is not the first time people have tried to make batteries lighter and more fire-resistant.

Researchers have tried a variety of techniques and all have failed. “People have also tried adding fire retardant to the battery electrolyte, which is the flammable part, but you can only add so much before it becomes viscous and no longer conducts ions well," said Yusheng Ye, a postdoctoral researcher in Cui’s lab.

Cui, Ye, and graduate student Yayuan Liu tackled the issue by making and testing collectors based on a lightweight polymer called polyimide, which is fire resistant and quite adept at standing up to the high temperatures generated by fast battery charging. They then added a fire retardant ­(triphenyl phosphate) and an ultrathin layer of copper to protect the polymer.

The researchers tested the new batteries by exposing them to an open flame. They found that the fire never really got going and went out within a few seconds, refusing to light up again. Now that's impressive!