Boston tech startups bet big on batteries

Behind these companies are key technological advances in chemistry and materials, many of which were pioneered at the Massachusetts Institute of Technology. These breakthroughs have put battery startups at the forefront of the region’s climate tech sector. But companies still have a long way to go.

“Boston is a great place for that because there’s all this intellectual power,” said Michael Aziz, a professor of materials and energy technologies at Harvard University. “It’s a good ecosystem to think about things like that.”

Indeed, the Boston area has a long history of battery innovation and a vast pool of talent. For decades battery manufacturer Duracell based its research labs in Needham, until parent company Procter & Gamble closed the facility in 2009. SES, Form Energy and Ambri are all based on MIT research . Another MIT spin-off, A123 Systems, at one time employed up to 300 people in Waltham to develop electric car batteries, before filing for bankruptcy in 2012.

A decade later, local battery companies are once again money magnets, with venture capitalists and automakers pouring in hundreds of millions of dollars. Ten-year-old SES went public in February in a merger with Ivanhoe Capital Acquisition Corp., a blank check company listed on the New York Stock Exchange. The deal included $450 million in new investments led by automotive giants like General Motors, Honda, Kia, Hyundai and Chinese automaker Geely.

While today’s lithium-ion batteries contain a lithium electrode mixed with another material such as cobalt or nickel, SES builds lithium-metal batteries, with a pure lithium electrode. This provides approximately twice the energy density of today’s batteries, which means twice as much stored energy per kilogram of weight. So an electric car that travels 250 miles with a lithium-ion battery could, travel in theory 800 km with a lithium-metal battery of the same size. Or the automaker could use a lighter battery, add more cargo space and further increase range because the car would weigh less.

But there is a catch. Since the 1970s, scientists have tried to develop lithium-metal batteries that would not break down after just a few recharge cycles. SES chief executive Qichao Hu said his 150-person company finally got the hang of it. And just in time for the world’s major automakers, who have pledged to replace their internal combustion engines with battery-powered electric motors.

“They really need a very safe, high-energy-density battery,” Hu said, “and that’s what we can deliver.”

Meanwhile, Factorial Energy, which came out of stealth mode in 2021, raised $200 million in January, in a funding round led by Mercedes-Benz and Stellantis, the Netherlands-based automotive conglomerate that includes Chrysler and Jeep brands.

Factorial’s 100 employees focus on upgrading the lithium battery’s electrolyte – the substance that allows electrons to flow between electrodes to generate electricity. Today’s lithium-ion batteries use a liquid electrolyte, but factorial batteries use a polymeric material similar to plastic. The company claims its solid-state battery has up to 50 percent higher energy density than standard lithium batteries.

A solid electrolyte could also solve the dangerous problems of lithium batteries habit of igniting. While the liquid electrolyte in a standard lithium battery has a flash point of around 140 degrees Fahrenheit, the solid electrolyte in the Factorial battery can be heated to nearly 400 degrees without a fire hazard, said the society.

And while factor batteries could make sense for all sorts of mobile devices, chief executive Siyu Huang says the real sweet spot is the automotive market. “That’s where our passion lies,” Huang said. “We really wanted to create a product that would change the landscape of clean technology transportation.”

Beyond electric vehicle batteries, local companies are developing large-scale systems that could one day power thousands of homes.

Form Energy has raised $370 million from investors, including a $240 million seed round last August led by steel giant ArcelorMittal. The company is also backed by The Engine, MIT’s venture capital fund, and Microsoft co-founder Bill Gates’ Breakthrough Energy fund. Gates is also the largest individual investor in Ambri, which has raised more than $200 million, including a $144 million seed round also announced last August.

Both companies try to ensure that excess electricity from renewable sources is not wasted. A solar power plant, for example, can produce too much electricity during the day, but not at night. This is a classic problem that has held back the adoption of solar energy. “You cannot guarantee that you can supply electricity at a certain level at a certain time of day,” said Adam Briggs, chief commercial officer of Ambri.

Ambri’s solution is a large battery bank that captures excess electricity, then releases it as needed. Based on technology developed in the lab of MIT materials scientist Donald Sadoway, Ambri uses batteries based on calcium and metallic antimony. They are safe and stable chemicals that do not ignite and cost less than lithium and other minerals found in lithium-ion batteries. And while lithium batteries lose their ability to hold a charge after a few years, Ambri’s battery is designed with a lifespan of 20 years, even if fully discharged and recharged every day.

Ambri will soon begin testing its system in a major data center and said so will deploy its first battery system for electric utilities in 2023.

While Ambri’s batteries are designed to provide no more than 24 hours of continuous power, Form Energy builds batteries that could keep a city’s lights on for days. And the company plans to do so with two of the most common materials on earth: air and iron.

Since the 1960s, scientists have been trying to invent a practical iron-based battery, which generates an electric current when it rusts. Such a battery would have a high energy density and could be recharged by reversing the current flow and “derusting” the iron. It would be inexpensive to manufacture, use non-flammable materials, and last for decades. In contrast, iron-air batteries are much heavier than lithium batteries, and they release their energy over a long period of time, so they won’t provide the quick acceleration you need in an electric car.

Research on iron-based batteries languished for years. “There was no market for a very cheap battery that charges and discharges for over a hundred hours,” Form Energy president Ted Wiley said.

But that has changed, as iron-air batteries could provide excellent backup power for a power grid that increasingly relies on solar and wind power. An array of these batteries occupying the same space as a typical coal-fired power plant could store enough energy to power 300,000 homes for about 100 hours, Wiley said. With so much energy in reserve, there would be no need to fall back on fossil fuel power plants at night or when there is no wind.

“A 100% renewable grid becomes not only possible but economical,” Wiley said.

To this end, Form Energy is building a pilot plant in cooperation with Great River Energy of Minnesota. The 40,000 square foot battery array, designed to power up to 400 homes for 100 hours, is expected to be activated late next year.

In total, Boston battery startups have raised more than $1 billion from venture capital funds and giants, just in time to support the global quest for cleaner energy.

“I’ve been in batteries since 1984,” said Ambri executive Briggs, a 17-year Duracell veteran. “This is the greatest time ever for batteries.”


Hiawatha Bray can be contacted at [email protected] Follow him on Twitter @GlobeTechLab.

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