Safer, Longer-Lasting Batteries for Cars

A startup company has a printing method for solid-state batteries.

An Orlando startup has developed new manufacturing techniques that could improve the stability and lifetime of batteries used in electric vehicles. Planar Energy, a spin-off of the National Renewable Energy Laboratories (NREL), is working on scaling up solid-state lithium-ion batteries.

Solid power: Planar Energy CEO Scott Faris holds a solid-state battery cathode printed using new manufacturing techniques. Credit: Planar Energy

Conventional batteries, which typically use a liquid electrolyte, can suffer from undesirable chemical reactions that damage the battery's cathode. Replacing the liquid electrolyte with a solid ion conductor can improve battery stability and lifetime, and also allow a battery to be smaller because additional components aren't needed to maintain stability. Solid electrolytes are also compatible with a wider range of battery chemistries that could potentially offer higher power or storage density.

But solid-state batteries are expensive to make and have been difficult to scale up to the size needed for laptops or vehicles. Like other solid-state devices, solid-state batteries are normally made using complex, costly, vacuum-based deposition methods. The vacuum deposition limits the thickness of solid-state batteries, which, in turn, limits their energy storage capacity. So these thin-film batteries have been limited to use in small devices.

Efforts to use printing processes to make thicker solid-state batteries have been stymied by the lack of a printable solid electrolyte material (printed electrodes must usually be combined with a liquid electrolyte to carry the ions back and forth during charging and recharging).

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Planar Energy has developed a roll-to-roll process for making larger solid lithium-ion batteries. The company, which received $4 million in funding from the Advanced Research Projects Agency Energy program this spring, says it can print solid batteries that offer three times more storage than liquid lithium-ion batteries of the same size. This boost in energy storage is possible primarily because the company's all-solid batteries don't require many of the support structures and materials that take up space in conventional batteries, making more space for energy storage.

Planar Energy expects to reduce capital costs by half compared with solid-state battery manufacturing using high-vacuum machinery. And the company says its processes can be used to make cells big enough to power electric vehicles.