Startup unveils polymer battery electrolytes that eliminate thermal runaway

Battery acid, a popular term for liquid electrolytes, isn’t known for its safety or ease of use. It’s corrosive, messy and chemically unstable. Anthro Energy is betting it can eliminate those concerns.

How? Polymerization. 

The battery-tech startup that spun out of Stanford University and is based in San Jose, California, announced this week its proprietary Anthro Proteus technology. This new type of phase-change electrolyte is injected into batteries as a liquid, and then solidified to improve stability and lifespan. 

Many types of batteries (such as lithium-ion) rely on liquid electrolytes, which conduct energy between solid cathodes and anodes. But those electrolytes are flammable, volatile and toxic. 

“As you push to higher and higher energy density batteries, the liquid electrolyte becomes more and more of a problem,” Anthro Energy CEO and co-founder David Mackanic told pv magazine USA. He explained that reactions between liquid electrolytes and energetic battery materials can cause fires, explosions and structural instabilities. 

“We developed a polymer electrolyte that’s mechanically a solid material — it’s kind of like rubber,” Mackanic added. “The ability to remove a battery’s liquid electrolyte or transform it into something more solid has been pursued in the battery industry for a long time.” 

Anthro Proteus’ polymer electrolyte and the phase-change process were first developed at Stanford University during Mackinac’s doctorate program. Anthro Energy now licenses them from the university. Mackinac stressed that though other examples of phase-change electrolytes have been shown in academic contexts, Anthro Energy is the first company to tackle commercialization. 

“I had this realization when I was at Stanford: we had the technology to improve lithium-ion batteries and make them safer, but a lot of what we were doing was really hard to scale beyond the lab,” he said. That’s a large part of his motivation to develop transferable solutions capable of slotting into the existing battery ecosystem.  

Anthro Proteus’ phase-change electrolytes are compatible with most contemporary battery manufacturing infrastructure and processes. While Anthro Proteus is injected into a battery-like liquid electrolytes, unlike liquid electrolytes, it transitions to a solid-polymer material inside the battery once triggered by a stimulant. 

The resulting batteries have an extra protective layer around the active materials, which provides insulation against extreme temperatures, extends cycle life and makes the cells more resilient to damage. And, the polymer is nonflammable, making it safer than traditional lithium-ion batteries. 

“When you have energy storage systems that contain a lot of energy, there’s always going to be some risk of a thermal runaway,” said Mackanic, referencing the Moss Landing Battery Fire. But, he noted, nonflammable battery technologies like Proteus could reduce that risk in consumer electronics and long-duration energy storage alike. 

“If you view the risk curve as exponential, that reduction could massively reduce the amount of incidents like that and reduce their severity if events like that do occur,” Mackinac added. 

Under the Bipartisan Infrastructure Law, Anthro Energy received a $25 million grant from the U.S. Department of Energy. The U.S.-owned and operated company plans to use the funding to build a new 25 GWh advanced electrolyte production facility in an energy community. 

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