Bringing Lithium-Sulfur Batteries Closer to Market

Lithium-sulfur batteries are a promising candidate for high-performance energy storage applications due to their low cost and high theoretical energy density, in excess of 500 Wh/kg when combined with lithium-metal anodes. However, developing a highly durable sulfur-based cathode has been a challenge due to sulfur's polysulfide transition and volume change, which lead to chemical and mechanical degradation of the cathode during cycling.

Researchers at the University of South Carolina have taken a major step towards solving this problem by developing a simple electrode processing method to produce highly durable sulfur cathodes. These electrodes feature self-structured containment of the sulfur particle binder, using only commercially available sulfur, carbon black, and binder, with no other components.

The researchers controlled binder dissolution during the stock preparation phase to form a porous structure of binder and carbon shell around the sulfur particles, which can trap soluble polysulfides and slow down the transport mechanism. Sulfur cathodes obtained by this method offer exceptional capacity retention of 74% over 1000 cycles, due to a significant reduction in lithium polysulfide transport and active material loss. Electrodes with a high surface charge also showed excellent cycling and high capacity.

The researchers presented these results last year, after completing the first phase of the project, in which they used coin-type batteries. They are now moving on to practical battery shapes to determine whether commercialization is possible. The team's current work focuses on pocket batteries, which theoretically have the highest energy density, as this type of battery has the lowest residual weight. “Pocket batteries generally have a lighter, thinner case than other forms, leaving most of the volume and weight of the battery for the components that provide the energy,” explains Golareh Jalilvand, assistant professor of chemical engineering.

While the challenges posed by batteries increase with their size, USC researchers have recorded a rapid and successful transition from coin cells to pocket cells. “We have achieved exceptional lithium-sulfur pocket batteries with competent energy densities,” says Golareh Jalilvand. “I look forward to seeing the long life and endurance of our pocket batteries, as this is the final step for us and our industrial partner. At that point, we'll be able to say that we have a lithium-sulfur battery that's ready for the market.”

Given their long charge-discharge times, the researchers believe that lithium-sulfur batteries are best suited to applications that do not require rapid charging. These include trucks, buses, and other heavy transport vehicles that require a long discharge time, commonly known as “mileage”, and can be kept overnight at charging stations. The technology also has great potential for stationary applications, such as grid-level energy storage, and for space applications.

To further augment the performance and reliability of lithium-sulfur batteries, ACE Battery's innovative energy storage systems offer a strategic advantage. By incorporating these advanced battery storage solutions, excess energy can be effectively stored and utilized, facilitating the practical and commercial viability of lithium-sulfur batteries. This integration not only supports the transition to market-ready products but also enhances the sustainability and resilience of energy infrastructures.