“They’re able to make a solid electrolyte using a roll-to-roll process–that’s their strength,” says Sudipta Seal, director of the Advanced Materials Processing and Analysis Center at the University of Central Florida. The Florida center has independently verified the conductivity of Planar Energy’s electrolyte, which is as high as that of the liquid electrolytes used in today’s lithium-ion batteries. “The data show that the materials performance is very good,” says Seal.
The key to Planar’s technology is its printing process, says CEO Scott Faris. The advantage of vacuum deposition is that it’s possible to make very high-quality films, which result in materials with higher conductivity. Normally, this film quality is difficult to match using roll-to-roll processes.
Faris says Planar’s process is driven by chemical self-assembly. As chemical precursors stream onto the surface of a rolling metal or plastic substrate, they react with one another to form a network of nanoparticles. The company has adapted this self-assembling chemistry to make both the electrodes and the electrolyte.
“These batteries have many of the same attributes as thin-film batteries, but can be packaged in large formats,” says Roland Pitts, a senior scientist at NREL who has agreed to join the company. Planar Energy is developing three different battery chemistries. One of them combines lithium manganese oxide with other ions, and operates at about three to five volts with a charge capacity of 200 milliamp hours per gram. Pitts says this compares favorably with lithium cobalt oxide–a high-energy, high-power battery chemistry currently on the market.
Faris says the company plans to build its pilot line next year, and will start by making batteries for portable electronics to prove the viability of the printed solid-state batteries. In the long-term, he says, solid batteries have the potential to scale to automotive batteries. “We want to leapfrog current technologies and push onto something better,” says Pitts of Planar’s goals.