Ionic Materials Expands Lab Where It Makes Safer, More Efficient Lithium Batteries From Plastic

Boston tech startup launches new facility promising powerful, flame-resistant, solid-state batteries

Workers developing the Ionic Materials solid polymer electrolyte material.
Photo: Ionic Materials
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With representatives from major tech companies and venture capital firms in the audience alongside financial backing from investors like the Renault-Nissan-Mitsubishi alliance, the solid-state battery company Ionic Materials cut the ribbon on an expansion of their Woburn, Mass., battery materials fab last week.

Ionic Materials emerged from stealth mode last year, and has built out an enviable list of supporters. They say the company has pioneered a polymer electrolyte that could bring about a revolution in solid-state battery performance and safety. Prototype batteries with Ionic Materials’ solid plastic electrolyte (as opposed to the flammable liquid electrolyte found in most lithium-ion batteries today) promise higher energy densities at low cost, and use less of the rare and troublingly sourced metals such as cobalt that are found in today’s batteries.

Crucially, Ionic Materials’ batteries are also more malleable and durable, and far less prone to battery fires. A video shown on endless loop in the company’s lunchroom and touted more than once at the day’s event was a segment from an episode of PBS’s NOVA that featured Ionic Materials among other entities developing next-generation battery technology. The show’s host, David Pogue, used a pair of kitchen scissors to cut an Ionic Materials prototype battery into, as he joked, a “doily.” He later pierced another similar battery through multiple times with a screwdriver. In both cases, the battery not only did not even warm up (let alone burst into dangerous pyrotechnics as lithium ion batteries infamously do), the cut and pierced rechargeable batteries even continued to power the LED light and the iPad they were each attached to.

Pogue also delivered some remarks before the day’s ribbon cutting celebrating the opening of the company’s expanded R&D, processing, assembly, testing and prototyping facilities. He noted that Ionic Materials’ solid, plastic electrolyte prevents both battery short-circuits and dendrite formation that can lead to battery shorts. And that, he said, means that the company’s plastic electrolytes would allow for a battery made with higher energy density pure lithium anodes.

“If you can use lithium metal rather than lithium ions, you get five to ten times the energy density,” Pogue said. “That means ten days on a charge instead of one day on a charge, a thousand miles on a charge of your car instead of 200 miles.”

Ionic Materials CEO Mike Zimmerman invented the super-plastic that is both flame-retardant and electrically insulating but also conductive to ions. He said his inspiration came in the early 2000s when he saw what small and incremental improvements rechargeables made with changes to the cathodes and anodes. “I realized the electrolyte was the roadblock,” he said in his remarks at the ribbon cutting ceremony.

Afterwards, in an interview, Zimmerman said Bell Labs—where he worked for 15 years after he got out of graduate school—taught him to invent his way around that roadblock. “We invented everything, and we also had the approach of being here to solve problems, not just to identify them,” Zimmerman said.

When he first began investigating the battery electrolyte problem, Zimmerman said two possible solid electrolyte materials being discussed at the time were glasses and ceramics. (Spectrum recently profiled one such glass electrolyte discovery.) But at the time, these materials were brittle and fragile, hard to scale up, and and tended to emit toxic gases when in use. Plastics were already being used as separators between cathodes and anodes, Zimmerman said. So he figured, why not ditch the separator and the liquid electrolyte altogether. Or, in a sense, just make the plastic separator into the solid electrolyte.

Sun Microsystems founder Bill Joy, one of two named investors (along with Renault-Nissan-Mitsubishi) in Ionic Materials’ latest Series C funding, said the English language doesn’t even have a word for the kind of polymer that Zimmerman made and that Ionic Materials is now manufacturing. As a battery electrolyte, the substance provides a medium through which ions travel back and forth between cathode and anode. But most electrolytes are liquids. What, Joy asked, does one call a solid that performs this task inside a battery?

“Solids that conduct electricity we call metals,” Joy said. “But we don’t have a single word for something that conducts ions at room temperature. They call it ‘room-temperature solid electrolytes.’ But they should be called ‘ionyls’ or something like that. This is one of the few buildings in the world in which there are lots of such materials.”

(Spectrum will soon publish an in-depth conversation with Bill Joy on Ionic Materials’ technology and the promise of a solid-state rechargeable battery.)

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