Researchers at Massachusetts Institute of Technology (MIT) and elsewhere have developed a new kind of low-cost battery, made entirely from abundant and inexpensive materials. The aluminium-chalcogen battery charges in less than a minute and is resistant to dendritic shorting.
It uses aluminium and sulfur as its two electrode materials, with a molten salt electrolyte in between. It is described in the journal Nature, in a paper by MIT Professor Donald Sadoway, along with 15 others.
“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, who is the John F Elliott Professor Emeritus of Materials Chemistry.
Sadoway settled on aluminium and sulfur, as they are abundant and cheap. As for the electrolyte, they decided against volatile, flammable organic liquids to reduce fire risk. They tried some polymers but ended up looking at a variety of molten salts that have relatively low melting points, close to the boiling point of water.
MIT said in experiments, the 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 demonstrated that the charging rate was highly dependent on the working temperature, with 110 degrees Celsius (230 degrees Fahrenheit) showing 25 times faster rates than 25 C (77 F).
The team said one of the biggest problems in battery reliability is the formation of dendrites, narrow spikes of metal that build up on one electrode and eventually grow across to contact the other electrode, causing a short-circuit.
The chloro-aluminate salt they chose “essentially retired these runaway dendrites, while also allowing for very rapid charging,” said Sadoway. “We did experiments at very high charging rates, charging in less than a minute, and we never lost cells due to dendrite shorting.”
This new battery formulation, he says, would be ideal for installations needed to power a single home or small to medium businesses.
Photo: The three primary constituents of the new battery are aluminium (left), sulfur (centre), and rock salt crystals.
Credit: Rebecca Miller