Key Highlights:
- A sodium-sulfur battery developed by engineers at The University of Texas at Austin overcomes one of the barriers that has prevented it from becoming an alternative to lithium-ion batteries.
- The researchers’ findings were recently published in the Journal of the American Chemical Society.
- The researchers intend to expand on their discovery by testing it with larger batteries to see whether it can be used to technologies such as electric vehicles
Battery ‘Dream Technology’
A sodium-sulfur battery developed by engineers at The University of Texas at Austin overcomes one of the major barriers that has prevented the technology from becoming a commercially viable alternative to the ubiquitous lithium-ion batteries that power everything from smartphones to electric vehicles.
Sodium and sulfur stand out as interesting materials for future battery manufacture because they are less expensive and more generally available than lithium and cobalt, both of which have environmental and human rights problems. As a result, researchers have been working over the past two decades to develop room-temperature, sodium-based batteries.
“I call it a dream technology because sodium and sulfur are abundant, ecologically friendly, and the cheapest you can imagine,” said Arumugam Manthiram, head of the Texas Materials Institute and professor in the Walker Department of Mechanical Engineering at UT. “In the future, with more electrification and growing demand for renewable energy storage, cost and affordability will be the single most important aspect.”
Addressing sodium battery issues
In one of two recent sodium battery improvements from UT Austin, the researchers changed the composition of the electrolyte, the liquid that allows ions to travel back and forth between the cathode and anode to drive battery charging and discharging. They addressed a frequent issue with sodium batteries: the formation of needle-like structures on the anode, known as dendrites, which may cause the battery to rapidly deteriorate, short circuit, and even catch fire or explode.
The researchers’ findings were recently published in the Journal of the American Chemical Society.
Previously, the intermediate compounds generated from sulfur would dissolve in the liquid electrolyte and travel between the two electrodes of the battery in sodium-sulfur batteries. This dynamic, known as shuttling, can result in material loss, component deterioration, and dendrite growth.
The researchers developed an electrolyte that inhibits sulfur from dissolving, so resolving the shuttling and dendritic issues. This allows the battery to have a longer life cycle, with constant performance through 300 charge-discharge cycles.
Expanding discovery
In a similar vein, the new battery electrolyte was created by diluting a concentrated salt solution with an inert, nonparticipating solvent, which retains the “half-dissolved” condition. The researchers discovered that such an electrolyte inhibits undesired reactions at the electrodes, hence extending the battery’s life.
The price of lithium has risen dramatically in the last year, emphasizing the need for alternatives. Lithium mining has been chastised for its negative environmental effects, which include excessive groundwater consumption, soil and water contamination, and carbon emissions. In comparison, sodium is found in the ocean, is less expensive, and is better for the environment.
Lithium-ion batteries generally contain cobalt, which is costly and is mostly mined in Africa’s Democratic Republic of the Congo, where it has serious consequences for human health and the environment. Manthiram exhibited a cobalt-free lithium-ion battery last year.
The researchers intend to expand on their discovery by testing it with larger batteries to see whether it can be used to technologies such as electric vehicles and renewable energy storage such as wind and solar.
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