Ambri is developing a lithium-antimony-lead liquid-metal battery for grid-scale energy storage applications.
The materials used in Ambri’s original design were magnesium and antimony separated by a molten salt, but this is typified by relatively low voltage and high temperatures.
A recent article in Nature revealed the Li-Sb-Pb battery comprises a liquid lithium negative electrode, a molten salt electrolyte, and a liquid antimony-lead alloy positive electrode, which self-segregate by density into three distinct layers owing to the immiscibility of the contiguous salt and metal phases. No membranes or separators are used.
At charge-discharge current densities of 275mA per square centimere, the cells cycled at 450 degrees Celsius with 98% Coulombic efficiency and 73% round-trip energy efficiency.
In an email to Green Tech Media, Ambri’s CTO David Bradwell stated: “The performance of our cells now far exceeds even the strong cell performance described in the Nature paper. Our cells have reached a much lower fade rate of ~0.0002%/cycle.”
Ambri is a spin-off from the research of Donald Sadoway, MIT’s professor of materials chemistry. Bill Gates and French energy giant Total are among its investors.
The firm is working on prototype storage systems in Massachusetts, Hawaii, New York and Alaska, with project partners such as First Wind, Hawaiian Electric, and Con Edison. Ambri hopes to have 35kWh commercial units available in 2015.