Lithium-ion batteries are the backbone of modern energy storage in consumer devices, but there are alternatives in the pipeline that could offer us considerable advantages moving forward. Among the candidates are lithium-sulfur batteries, which can hold many times the energy of their lithium-ion counterparts but quickly degrade and die. Scientists at University of Texas at Austin have devised a solution to this problem, integrating a protective layer that enables the lithium-sulfur battery to last four times longer.
A battery that relies on a lithium-sulfur chemistry rather than the conventional lithium-ion one could store five times the energy, raising the prospect of smartphones that run for days or electric cars that can travel much further on each charge. But efforts to get these devices out of the lab and into the real world have been stifled by how rapidly the materials deteriorate, significantly reducing the cycle life of the battery.
This demise can be due to mossy, needle-shaped deposits called dendrites that form on the battery’s negative electrode, or anode, which is made from lithium-metal. These can in turn break down the electrolyte solution that carries the charge back and forth between the negative and positive electrodes, ultimately leading to the battery short-circuiting and possibly even catching fire.
We’ve looked at a number of promising tweaks to lithium-sulfur batteries that could shore up their longevity. These include new types of architectures that bind key components together, semi-solid cupcake-shaped electrolytes, and the use of hybrid electrodes.
The University of Texas at Austin team believe they have uncovered another promising pathway forward, developing a lithium-sulfur battery featuring a protective layer of a rare metalloid called tellurium, which is most often used in photovoltaic solar cell production. This sits atop the lithium-metal electrode and limits the dendrites, leading to a substantially longer battery lifespan.
“The layer formed on lithium surface allows it to operate without breaking down the electrolyte, and that makes the battery last much longer,” says co-author Amruth Bhargav.
Testing an experimental version of the battery in the lab, the team was able to demonstrate that this new design could last four times as long as a typical lithium-sulfur battery. They note that the manufacturing method involves no expensive or complicated procedures, which dovetails nicely with the cost-effective nature of lithium-sulfur batteries more generally.
“Sulfur is abundant and environmentally benign with no supply chain issues in the US,” says Arumugam Manthiram, study author. “But there are engineering challenges. We’ve reduced a problem to extend the cycle life of these batteries.”
The scientists have filed a provisional patent for the technology, while the research was published in the journal Joule.
Source: University of Texas at Austin
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