SMU Researchers Create Cheaper, Longer Lasting Batteries

Lithium-sulfur batteries are cheaper, lighter, more powerful, and more sustainable than the lithium-ion batteries used to power cellphones, tablets, and electric vehicles. So why aren’t we using lithium-sulfur batteries instead?

The answer is that they don’t work well for very long. The same sulfur that makes these batteries inexpensive and lightweight is also the source of their crucial flaw — over multiple charges and discharges, it causes the batteries to degrade.

But SMU mechanical engineer Donghai Wang and his research team have found a way to make the batteries last longer, while still delivering 1.5 to two times as much energy as lithium-ion batteries. 

The team has seen its lithium-sulfur batteries discharge and recharge without degrading as many as 1,000 times depending on the conditions, said Wang, who is the Brown Foundation Chair of Mechanical Engineering and Professor of Mechanical Engineering at SMU. 

The group’s research was recently published in the journal Nature Sustainability. And the SMU researchers are working to make their high-performance batteries even more efficient. One day, lithium-sulfur batteries could be used in drones or heavy-duty vehicles. And passengers could even fly in large, battery-powered commercial airliners.

“That is our dream,” Wang said. “That we can have this technology to make it happen.”

Wang has spent more than a decade tackling the problem of how to make lithium-sulfur batteries last longer. 

All batteries, including lithium-ion and lithium-sulfur batteries, have a positive and a negative terminal. Lithium-sulfur batteries pair a sulfur-containing positive terminal with a negative terminal containing lithium. But when the lithium binds with the sulfur, molecules drift into the substance between the terminals, and the sulfur begins to destroy the battery.

It’s taken Wang and his team more than two years to develop a “hybrid polymer network cathode,” a project he began at Penn State and continued to further develop at SMU when he joined the faculty in 2024.

The “hybrid polymer network cathode” has multiple tethers that capture the sulfur before it’s able to bind with the lithium. Because the sulfur stays in the cathode’s framework, it can’t damage the battery.

“This breakthrough could lead to more durable, long-lasting batteries,” Wang said.