Rechargeable lithium-ion batteries have become commonplace in consumer electronics, but do pose some significant safety concerns. Most prominently, if the plastic layer between the two electrodes fails and they touch, that spark can set the battery’s liquid electrolyte on fire. A possible solution was recently presented during the 256th National Meeting & Exposition of the American Chemical Society.
To make these batteries safer, a research team based at Oak Ridge National Labs and led by Gabriel Veith mixed an additive into the conventional electrolyte to create an impact-resistant version that solidifies when encountering an impact. This modification to the electrolyte prevents the electrodes from touching if the battery is damaged during a fall or crash. If the electrodes don’t touch, the battery can’t catch fire.
This characteristic depends on a colloid, which is a suspension of tiny, solid particles in a liquid. In this case, Veith’s team used silica suspended in common liquid electrolytes for lithium-ion batteries. On impact, the silica particles clump together and block the flow of fluids and ions. The researchers used perfectly spherical, 200-nanometer-diameter particles of silica, or essentially superfine sand.
In addition to the safety improvements, this development could also have a major impact on how the batteries are produced. Traditionally, an electrolyte is injected into the battery case near the end of the production process, and then the battery is sealed. To capitalize on the impact-resistant nature of this new electrolyte composition, the silica is put in place before adding the electrolyte.
The team is currently seeking a patent, with future work focused on enhancing the system so the damaged portion of the battery will stay solid but the remainder of the battery will continue working. Applications could include drones and eventually, the automotive aftermarket. In addition to Oak Ridge Labs, the project is also being supported by the U.S. Department of Energy’s Advanced Research Projects Agency.
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