A new design for molten metal batteries could make the technology cheaper for use in storing renewable energy for the grid, US researchers say.
Scientists at Massachusetts Institute of Technology (MIT) have developed a battery that uses one layer of molten lithium and another of molten lead and antimony to store energy at a temperature over 200°C lower than previous liquid metal designs.
The battery has an operating efficiency of around 70 per cent – which the researchers say puts it in competition with other types of storage such as pumped hydro – and should retain 85 per cent of its efficiency after 10 years’ daily use.
The researchers had previously used magnesium and antimony layers to form the battery’s electrodes, but switching to the new design lowered the operating temperature from 700°C to between 450°C and 500 C – and cut the battery’s production cost.
They found the antimony provided a high operating voltage while the lead gave a low melting point, so combining the two gave offered allowed the battery to operate at a lower temperature without reducing the battery performance.
’We hoped [the characteristics of the two metals] would be nonlinear,’ research leader Prof Donald Sadoway said in a statement. ‘They proved to be [nonlinear], but beyond our imagination. There was no decline in the voltage. That was a stunner for us.’
The team now plans to search for other combinations of metals that might provide even lower-temperature, lower-cost, and higher-performance systems. ‘Now we understand that liquid metals bond in ways that we didn’t understand before,’ said Sadoway.
The research was supported by the US Department of Energy’s Advanced Research Projects Agency-Energy and by French energy company Total.