Massachusetts Institute of Technology (MIT) researchers have created a new liquid battery system, which can enable wind and solar facilities to compete with traditional power plants.
John F Elliott material chemistry professor Donald Sadoway and his colleagues have developed a new formula that enables the battery to work at a temperature of more than 200°C, lower than the earlier formulation developed by them.
In addition to this, the team has simplified the battery's design and extended its working life and is less costly to manufacture.
This battery system has two layers of molten metal that are separated by a layer of molten salt, which serves as the battery's electrolyte.
Given that each of the three materials come with varied density, they act like separate layers.
As the previous battery system used magnesium for one of the battery's electrodes and antimony for the other, it required an operating temperature of 700°C.
However, the latest battery version can operate at temperatures of 450°C to 500°C due to the new formulation, which has one electrode made of lithium while the other is a combination of lead and antimony.
Following several rounds of testing, the researchers found that even after ten years of charging and discharging on a daily basis, the system can retain around 85% of its initial efficiency, thereby making this technology an attractive option for electric utilities.
In this process, the water is pumped uphill to a storage reservoir when additional power is available, and then flows back down through a turbine to produce power.
However, due to friction in pumps and turbines, such systems achieve only 70% efficiency.
The new liquid battery system easily achieves this efficiency and with more refinements, the efficiency levels could increase.
Unlike the pumped hydro system, the liquid batteries could be built anywhere and be of any size.
Pumped hydro systems, on the other hand, are viable only in sites where there is a hillside and sufficient water.
The research has received support from the US Department of Energy's Advanced Research Projects Agency-Energy and French energy firm Total.
Image: A physical model of the liquid metal battery at room temperature, in a glass container. Photo: courtesy of Felice Frankel / Massachusetts Institute of Technology.