Researchers at the Cockrell School of Engineering at the University of Texas at Austin in the US have found a way to stabilize a lithium sulfur battery cell so that it lasts four times longer.
“Sulfur is abundant and environmentally benign with no supply chain issues in the US,” said Arumugam Manthiram, a professor of mechanical engineering and director of the Texas Materials Institute. “But there are engineering challenges. We’ve reduced a problem to extend the cycle life of these batteries.”
Every cycle of a lithium sulfur battery can cause mossy, needle-like dendrite deposits to form on the lithium-metal anode. This starts a reaction that can lead to the battery’s overall degradation. The deposits break down the electrolyte that shuttles lithium ions back and forth. This can trap some of the lithium, keeping the electrode from delivering the full power across a useable lifetime. The reaction can also cause the battery to short-circuit and potentially catch fire.
Using tellurium to create an artificial layer on the lithium electrode protects the electrolyte from being degraded and reduces the mossy structures that trap lithium from forming during charges.
“The layer formed on lithium surface allows it to operate without breaking down the electrolyte, and that makes the battery last much longer,” said Amruth Bhargav, who, along with fellow graduate student Sanjay Nanda, co-authored the paper in Joule.
This method can be applied to other lithium- and sodium-based batteries, and the researchers have filed a provisional patent application for the technology.
“The stabilizing layer is formed by a simple in-situ process and requires no expensive or complicated pre-treatment or coating procedures on the lithium-metal anode,” said Nanda.
Solving the instability is key to extending its cycle life and bringing about wider adoption. Manthiram said that lithium sulfur battery technology are currently best suited for devices that need lightweight batteries and can run for a long time on a single charge and don’t require a large number of charge cycles, such as drones. But they have the potential to play an important role in extending the range of electric vehicles and increased renewable energy adoption.
Both the positive and negative electrodes in lithium-sulfur batteries hold 10 times as much charge capacity as the materials used in today’s lithium-ion batteries, Manthiram said, which means they can deliver much more use out of a single charge. Sulfur is widely available as a byproduct from the oil and gas industry, making the batteries inexpensive to produce.