Ambri is a Boston-area startup making molten salt batteries from calcium and antimony. Recent company announced a demonstration project energy storage deployment for Microsoft data centers and last year it increased more than 140 million USD to build its production capacity.
The company says its technology can be 30-50% cheaper over the life of a comparable lithium-ion system. Molten salt batteries can also reach efficiencies in excess of 80%, meaning that a relatively low amount of energy used to charge the battery is lost to heat.
Ambri was founded in 2010 based on research from Donald Sadoway’s lab at MIT. The goal was to develop a low-cost product for the stationery storage market, said David Bradwell, the company’s founder and CTO.
Inspiration came from an unlikely place: aluminum production. Using chemical reactions similar to those used to smelt aluminum, the team built a low-cost, laboratory-scale energy storage system. But turning this concept into a real product is not so simple.
The magnesium and antimony based chemicals that the company started proved difficult to produce. In 2015, after continuing to have problems with the battery’s sealing ring, Ambri laid off a quarter of its employees and return to the drawing board.
In 2017, the company switched to a new approach to its batteries, using calcium and antimony. Bradwell said the new chemistry is based on cheaper materials and will prove simpler to manufacture. Since the pivot, the company has fixed technical problems and made progress in commercialization, undergoing third-party safety testing and signing its first commercial agreements, including including the Microsoft agreement.
There are still big challenges ahead for startups. Batteries operate at high temperatures, above 500°C (about 900°F), which limits the materials that can be used to make them. And the move from single battery cells, about the size of a lunchbox, to giant container-sized systems can pose challenges in system control and logistics.
Not to mention deploying a product into the real world means “dealing with what happens in the real world,” as Bradwell put it. Everything from lightning strikes to rodents can damage a new battery system.
