Planar Energy, a 3-year-old start-up company in Orlando, FL, is using a high-throughput surface-deposition process to build solid-state electrolytes for thin-film lithium-ion batteries that in independent lab tests performed as well as the standard liquid electrolytes. The low-cost film-making method—a printing-type process that resembles airbrushing—can also produce cathode and anode materials layer by layer, said Planar founder and Chief Executive Officer Scott Faris.
The firm’s engineering team is now working to scale up its proprietary production process to larger volumes while maintaining the high purity of the inorganic film compounds. If Planar can successfully manufacture solid-state electrodes and electrolytes from multiple stacks of these films, the resulting batteries will be big enough to power laptops and consumer electronics—and not long thereafter, electric vehicles, Faris claimed. To that end, the U.S. Department of Energy's ARPA-E (Advanced Research Projects Agency - Energy) stimulus grant program has recently awarded the company $4 million in matching commercialization R&D funds.
Existing thin-film Li-ion batteries offer high-performance capabilities but have so far remained costly and too small for vehicle applications because of the slow speed at which conventional chemical vapor deposition (CVD) and slurry-based production methods can make them.
The big plus that solid-state battery technology brings is operational stability.
“If you think about it, today’s large-format batteries are almost like living organisms,” said Faris, a self-described serial entrepreneur. Because they contain electrolyte salts dissolved in organic solvents that can cause corrosion and safety problems, success, he continued, depends on maintaining a balance among the many factors that determine operations in all potential circumstances.
“Existing EV batteries also need long formation cycles to initially power up,” he said.
Solid-state batteries, in contrast, “are phase-locked from day one,” said Faris. If done right, the solid-state electrolyte—the central bus that carries ions back and forth during charging and recharging—can provide improved battery stability and life, while shedding superfluous support systems. Solid electrolytes can, in addition, present designers with a broader range of cell chemistries to exploit, some of which may offer better battery performance.
Planar, which focuses on developing “leapfrog technology in the solid-state energy storage area,” was established several years ago when Faris worked with Battelle Ventures, which provided seed funding for the company, to secure the rights to license a portfolio of processes, materials, and device technologies that had been developed in the Battelle National Lab network. They targeted the development of a rapid way to produce inorganic thin-film batteries in thicker, higher-capacity configurations.
The start-up’s foundation technology, which was developed by a former Bell Labs semiconductor materials researcher named Isaiah O. Oladeji, is called “streaming process for electroless electrochemical deposition,” or SPEED.
“In simple terms, we have a spray-based printing-type methodology to produce semiconductor type materials a thousand times faster than traditional semiconductor manufacturing,” said Faris, adding that the process can produce high-quality films on large surface areas for solar panels, electrochromical devices, and other applications.
The vaporized chemical nanoparticles react on the surface and self-assemble into crystalline form at ambient pressure and near room temperature. The resulting films grow with a fine microstructure at high rates on flexible substrates or directly on top of other films. The SPEED process readily produces 40-micron-thick ceramic films that have achieved 95 to 98% of theoretical energy density, Faris explained.
The flexible, water-based fabrication process is “chemistry agnostic,” he noted. “Anything you can CVD you can do with SPEED, and you can do more complex compounds that CVD can’t produce.”
Faris added that “it’s a simple process, so when we need to test a new formulation, we just mix up a new batch and test it.” Therefore, he said, Planar has the ability to choose cathode materials that provide an operating voltage and discharge profile that is most desirable with substantially higher performance characteristics and dramatic improvements in safety.
Earlier this year, University of Central Florida researchers independently confirmed that the company’s new generation of solid-state electrolytes has ionic conductivity metrics comparable to those of liquid electrolytes used in traditional chemical batteries.
Right now, the firm’s researchers are studying existing battery chemistries, especially ones that may operate better in the solid state or ones that cannot be made otherwise. In particular, work is going on to develop a new, high-performance separator “that’s a perfect electrical insulator [glass] and is chemically stable and mechanically solid but enables a high rate of ion conduction, all in low-cost thin film,” said Faris. The company is also building a test cell for internal demonstrations.
Once the battery formulation, design, and manufacturing process are in place, “we think that we can produce batteries at roughly one-third the cost of conventional Li-ion units while delivering a 300% energy-density improvement," Faris said. "That's in the first-generation product. There are no liquids, binders, or polymers, which gives you substantial savings in weight and volume.”
The targeted energy densities are 400 W·h/kg and 1,080 W·h/L, with system costs of $200/kW·h and a cycle life of 5,000.
Planar Energy “is getting meaningful interest from automotive and consumer electronics companies” about its technology, Faris said, while “some collaborators are comparing the performance of their own cell chemistries made with SPEED.”
Two other makers of thin-film batteries (both of which use fundamental technology that was developed at Oak Ridge National Laboratory), Infinite Power Solutions of Littleton, CO, and Cymbet Corp. of Elk River, MN, are said to be working on scaling up their battery products for EV applications as well.