Ambri (formerly Liquid Metal Battery Corporation) is developing an electricity storage solution that was invented in the lab of Dr. Donald Sadoway, a professor at the Massachusetts Institute of Technology, along with Dr. David Bradwell (Ambri’s Chief Technology Officer and co-founder). (Earlier post.) The research on campus has been supported by the US Department of Energy’s ARPA-E program, Total, the Deshpande Center, and the Chesonis Family Foundation.

Sadoway’s basic principle is to place three layers of liquid inside a container: two different metal alloys (e.g., antimony and magnesium), and one layer of a salt. With different densities, the materials separate naturally into three distinct layers, with the salt in the middle separating the two metal layers.

The energy is stored in the liquid metals that want to react with one another but can do so only by transferring ions across the electrolyte, which results in the flow of electric current out of the battery. When the battery is being charged, some ions migrate through the insulating salt layer to collect at one of the terminals. Then, when the power is being drained from the battery, those ions migrate back through the salt and collect at the opposite terminal.

The whole device is kept at a high temperature, around 700 °C, so that the layers remain molten.

In a 2014 progress report, Ambri noted it has operated more than 1,000 cells in the lab and demonstrated that the cells can run for more than 1,000 cycles at full depth of discharge with negligible fade rate (less than 0.0002% per cycle). The cells are still in operation.

In July 2013, Ambri’s systems team operated its first 36-cell (2 kWh) battery system in the Cambridge lab, along with the first-generation battery management system (BMS). Ambri has begun work on Ambri’s Alpha Core, its first 20 kWh system that will be deployed in Ambri’s lab headquarters in Cambridge later in 2014.

This latest funding round will enable Ambri to deliver commercial systems to customers, build its initial commercial-scale manufacturing plant, and continue technology development.

Ambri has recently been awarded projects to deploy prototype systems in Massachusetts, Hawaii, New York and Alaska, alongside project partners that include First Wind, Joint Base Cape Cod, Con Edison, Energy Excelerator (Hawaii), Alaska Center for Energy and Power, and Raytheon. Ambri announced the opening of its prototype cell manufacturing facility in Marlborough, MA in the fall of 2013.

Ambri has raised more than $50 million in equity financing since its founding in 2010 and is the exclusive licensee of the Liquid Metal Battery intellectual property developed at MIT. Ambri has also received grants from the Office of Naval Research and the Massachusetts Clean Energy Center.