The three primary constituents of the battery are: left, aluminum; center, sulfur; and right, rock salt crystals. All are domestically available Earth-abundant materials not requiring a global supply chain. Credit: Rebecca Miller
Key Points:
- Scientists have created a battery made of cost-effective and common materials that can replace the lithium-ion batteries currently used for power storage.
- The new batteries are made with aluminum and sulfur electrodes, with a molten salt electrolyte to regulate the transfer of energy.
- The molten salt electrolyte prevents the formation of dendrites, which often lead to short circuits in batteries with electrolytes made of unstable chemicals.
Renewable sources of energy, such as wind and solar, require batteries to store electricity and provide power during times when electricity is not actively being generated. The storage options currently available are either too expensive or impractical, which is critical, because the production of electricity from renewable sources of energy is rapidly increasing. In the United States alone, the renewable energy sector grew by more than 40% between 2010 and 2020.
To help solve the problem, an international team of scientists has created a novel battery fabricated from commonly found, low-priced components. The endeavor, spearheaded by Donald Sadoway at MIT, was published in Nature.
“I wanted to invent something that was better, much better, than lithium-ion batteries for small-scale stationary storage and ultimately for automotive [uses],” said Sadoway.
Rather than the expensive components used in lithium-ion batteries, the team’s new battery includes electrodes made of aluminum and sulfur, and an electrolyte made of salt.
Sadoway scoured the periodic table in search for a metal that he could use to create an electrode. His search led him to aluminum, the most common metal in the earth’s crust, which possesses ideal electrochemical characteristics. He later discovered that sulfur, an inexpensive nonmetallic chemical, served as an ideal counterpart to aluminum, and therefore decided to use it for the second electrode.
Batteries require the presence of an electrolyte, a solution that allows the two electrodes to transfer charged ions between them. Sadoway experimented with a variety of materials, and found that molten salt was a stable, nonflammable alternative to the chemicals currently used in batteries.
In their experiments, Sadoway and team showed that the battery cells could endure hundreds of cycles at exceptionally high charging rates, with a projected cost per cell of about one-sixth that of comparable lithium-ion cells. They showed that the charging rate was highly dependent on the working temperature, with 110 C showing 25 times faster rates than 25 C.
What’s more, the battery requires no external heat source to maintain its operating temperature. The heat is naturally produced electrochemically by the charging and discharging of the battery.
The new battery formulation, Sadoway says, would be ideal for installations of about the size needed to power a single home or small to medium business, producing on the order of a few tens of kilowatt-hours of storage capacity.
The new technology is already the basis for a new spinoff company called Avanti, which has licensed the patents to the system.
“The first order of business for the company is to demonstrate that it works at scale,” said Sadoway.