Liquid metal battery from MIT spinoff to be operational by 2024

More than a decade ago, Donald Sadoway, a professor emeritus at MIT, had begun work on reducing these costs. The result is a liquid metal battery closer to commercialization and deployment.

What makes lithium-ion batteries expensive?

Traditional batteries are constructed by utilizing solid electrodes and a liquid electrolyte. These components subsequently require segregation into individual units through the implementation of membranes and separators.

Larger battery packs are being constructed to increase energy density. But, the expenses associated with the additional components contribute to a heightened overall production cost.

Throughout the process of charging and discharging, ions migrate into and out of electrodes, resulting in the expansion and contraction of these components. Over multiple cycles, this activity leads to the deterioration of the materials employed and a subsequent decline in battery capacity. This is why lithium-ion batteries have limited lifespans.

However, Sadoway's liquid metal concept necessitates fewer components, thereby offering the potential for substantial cost reduction.

How does liquid metal battery work?

The liquid-metal design consists of three separate layers of liquid that stack upon each other due to differences in their densities. The densest is molten antimony which serves as a cathode, while the lightest is calcium, functioning as the anode. Bridging the gap between them is a calcium chloride salt solution, which acts as the electrolyte.

In the discharge phase, the anode releases calcium ions that migrate towards the cathode, resulting in the creation of a calcium-antimony alloy. Throughout this discharge process, the negative terminal is fully utilized and subsequently regenerated during the subsequent charging cycle.

The advantageous aspect of this chemistry lies in the absence of a memory effect within the battery, as asserted by its creators. According to them, this battery can operate effectively for two decades without experiencing a decline in performance.

As they didn't rely on lithium, Sadoway's group couldn't leverage the progress in lithium-ion battery technology. Instead, they faced the challenge of meticulously resolving all the complexities to bring their batteries into widespread use.

Ambri was set up in 2010 and more than a decade later, its energy storage solution has obtained the UL 1973 certification allowing it to be used for stationary as well as motive auxiliary power applications.

Ambri's projected energy storage cost hovers around $200 per kWh, which is almost fifty percent lower than lithium-ion storage. However, this figure is far from their ultimate goal of making a more substantial environmental impact.

The technology will be deployed at a 300 kWh storage system built for the utility company Xcel Energy in Aurora, Colorado, and is expected to be operational by next year. In the future, you could potentially see Ambri's liquid metal batteries support Microsoft's data centers after the Redmond-Washington-based company trialed them last year.

This report contains information that appeared inIEEE Spectrum.