A new battery design for a grid energy storage battery built with sodium and aluminium could provide a pathway to a safer and more scalable stationary energy storage system, according to a study published in Energy Storage Materials.
A research team, led by the US Department of Energy’s Pacific Northwest National Laboratory, demonstrated that the new design has the potential to charge and discharge much faster than other conventional high-temperature sodium batteries, operate at a lower temperature, and maintain an “excellent energy storage capacity.”
Guosheng Li, a materials scientist at PNNL and the principal investigator of the research, said: “We are getting similar performance with this new sodium-based chemistry at over 100°C [212°F] lower temperatures than commercially available high-temperature sodium battery technologies, while using a more Earth-abundant material.”
The new sodium-based molten salt battery uses two distinct reactions. The team previously reported a neutral molten salt reaction. The new discovery shows this neutral molten salt can undergo a further reaction into an acidic molten salt.
It said this second acidic reaction mechanism increases the battery’s capacity. After 345 charge/discharge cycles at high current, this acidic reaction mechanism retained 82.8% of peak charge capacity.
The battery is in early-stage testing, but the researchers think it could result in a practical energy density of up to 100Wh/kg.
The sodium-aluminium design would be inexpensive and easy to produce in the US from relatively much more abundant materials, they said.
The design is flat and scalable, and can be stacked and expanded as the technology develops from coin-sized batteries to a larger grid-scale demonstration size.
“We have eliminated the need for nickel, a relatively scarce and expensive element, without sacrificing battery performance,” said Li. “Another advantage of using aluminium over nickel is that the aluminium cathode charges more quickly, which is crucial to enable the longer discharge duration demonstrated in this work.”
