In April, an explosion at a utility-scale lithium-ion battery facility owned by Arizona Public Service (in place to store power from a solar energy array) sent eight firefighters to the hospital. The firefighters were there to inspect hazardous chemical levels after someone reported seeing smoke at the facility.
This isn't the first time lithium-ion batteries have either exploded or caught fire. The hazardous batteries have been of all sizes, from the smallest ones used in cellphones to the largest used by utilities to store power from the grid. In fact, one of the main concerns about the growing popularity and use of lithium-ion batteries is their safety.
However, that concern may be set to rest. Last week, the U.S. Department of Energy's Argonne National Laboratory released a report that its scientists have developed a new cathode coating that can reduce these fire and explosion risks.
"The coating we've discovered really hits five or six birds with one stone," said Khalil Amine, Argonne distinguished fellow and battery scientist.
Unlike conventional battery coatings, which only protect the exterior surface of the cathode particles but leave the interior vulnerable to cracking, Argonne's new sulfur-containing polymer, called PEDOT, has the ability to penetrate to the cathode particle's interior, adding an additional layer of shielding.
Although PEDOT creates this additional barrier, it still allows for the necessary transport of lithium ions and electrons that are necessary for the battery to function.
"The coating is essentially friendly to all of the processes and chemistry that make the battery work and unfriendly to all of the potential reactions that would cause the battery to degrade or malfunction," said Guiliang Xu, Argonne chemist.
The PEDOT material also prevents oxygen release, which is a major factor in battery materials degradation at high voltages. Preventing oxygen release leads to better structural stability and improves safety, Amine said.
With the new coating, Argonne scientists believe the batteries will be able to run at higher voltages (thus increasing their energy output), have longer lifetimes or both.