A team of researchers from the Erik Jonsson School of Engineering and Computer Science at the University of Texas, Dallas (UTD) and the University of North Texas has developed an environmentally safe, higher-power battery substitute that could lengthen battery life up to five times longer.

Most smartphones and electronics use lithium-ion batteries, a type of rechargeable battery that doesn’t last particularly long. In smartphones, lithium-ion batteries may last roughly a day, often leaving users with the inconvenience of a dead battery.

To address this limitation, the researchers have developed a method to use lithium-sulfur batteries, a type of battery that stores almost twice the energy as lithium-ion batteries.

The research is published in the journal Nature Nanotechnology.

Why Lithium-Sulfur?

Lithium-sulfur batteries have long been considered a desirable step in the evolution of battery life.

According to the researchers, lithium-sulfur batteries are less expensive to make, weigh less, and are better for the environment than lithium-ion batteries.

“Usually, Cobalt and Nickel metals are used for conventional lithium-ion batteries,” said Jeongwoon Hwang, postdoctoral researcher in the Department of Materials Science and Engineering at UTD. “Those materials naturally exist in metal oxide forms, and they should be reduced to metal elements by using strong acid for use. When the disposal of byproducts of the reduction process is not processed properly, it is harmful for environment. In contrast, sulfur naturally exists in elemental form.”

Additionally, lithium-sulfur batteries have a capacity of about three to five times higher than lithium-ion batteries, Kyeongjae “KJ” Cho, professor of materials science and engineering and director of the Multiscale Simulation Lab at UTD, said in a statement.

In theory, this would mean that if your smartphone battery currently lasts only three hours, it could last for nine to 15 hours with a lithium-sulfur battery.

Unfortunately, lithium-sulfur batteries present their own challenges.

Lithium-Sulfur Battery Problems

One problem with lithium-sulfur batteries is that sulfur is a poor conductor and can become unstable very quickly.

Additionally, electrodes in lithium-sulfur batteries frequently break down, which explains why these batteries are not commonly used.

Scientists have tried to resolve these problems by putting lithium metal on one electrode and sulfur on the other to avoid breaking down electrodes and keep the batteries conductive. These attempts have failed because lithium metal is often too unstable and sulfur is too insulating.

The Solution

But the researchers at UTD have figured out how to circumvent these problems. Their new technology can produce a sulfur-carbon nanotube substance that creates more conductivity on one electrode as well as a nanomaterial coating to create stability for the other electrode.

The researchers found that molybdenum, a metallic element commonly used for its high-strength power, can create a material that adjusts the thickness of the coating, which is thinner than the silk of a spider web, when combined with two atoms of sulfur.

They found this to improve stability and help with the conductivity issue in sulfur, ultimately providing greater power density.

The researchers believe this technology is exactly what is needed to make lithium-sulfur batteries commercially viable.

“This was what everyone was looking for, for a long time,” Cho said in a statement. “That’s the breakthrough. We are trying to suppress side reactions. It’s a protection technology.”

Potential Applications

This technology could change battery life as we know it.

“We are taking this to the next step and will fully stabilize the material, and bring it to actual, practical commercial technology,” Cho said in a statement.

The researchers believe lithium-sulfur batteries will have many electrical applications.

“Sulfur is lightweight but has a large volume,” said Hwang. “Thus, a lithium-sulfur battery can be applied where the weight is more important than volume. One possible application is unmanned aerial vehicle (or drone), which does not need to be as small as a smartphone but should be light. Also, because lithium-sulfur batteries are cheaper than traditional lithium-ion batteries, it can be applied to large-scale storage of electrical energy, such as grid energy storage.”