Lithium-sulfur batteries have struggled to reach their potential as the next major renewable energy solution for electric vehicles and other gadgets. However, researchers from SMU have discovered a method that can prolong the life of these batteries while also increasing their energy capacity compared to current renewable options.
Lithium-sulfur batteries have struggled to achieve their expected role as a leading renewable battery type for electric vehicles and various devices. However, ?SMU mechanical engineer Donghai Wang and his team have developed a technique that enhances the lifespan and energy levels of these Li-S batteries beyond what is seen in other renewable batteries.
The research group has successfully addressed a problematic issue known as polysulfide dissolution, which occurs over time and leads to a reduced lifespan for Li-S batteries.
“This significant advancement could result in batteries that last longer and are more resilient,” commented Wang, who is the Brown Foundation Chair of Mechanical Engineering and a Professor at SMU Lyle. His work emphasizes creating and synthesizing nanostructured materials and energy storage technologies, including both Li-ion and emerging battery technologies.
A recent study published in Nature Sustainability indicates that the team’s innovative hybrid polymer network cathode allows Li-S batteries to achieve a capacity of over 900 mAh/g (milliampere-hours per gram), in contrast to the typical range of 150-250 mAh/g seen in lithium-ion batteries. This represents a significant increase in the amount of electrical energy that can be stored.
“Additionally, it demonstrates excellent cycling stability, exceeding that of standard lithium-sulfur batteries,” Wang stated.
Cycling capacity refers to how many times a battery can be charged and discharged before its capacity declines significantly. A higher cycling capacity equates to a battery with a longer lifespan.
Wang collaborated with fellow researchers from Pennsylvania State University, Pacific Northwest National Laboratory, Brookhaven National Laboratory, the University of Illinois at Chicago, and Argonne National Laboratory to optimize the cathode design.
An affordable solution with greater energy output
The appeal of Li-S batteries lies in their cost-effectiveness and enhanced energy capacity compared to traditional lithium-ion rechargeable batteries.
Despite this promise, a major challenge has persisted.
“For years, the battery industry has grappled with addressing the adverse effects of polysulfide dissolution,” said Wang.
All batteries consist of a positive and a negative terminal. Inside the battery, chemical reactions that occur between these terminals generate power or electricity.
In a Li-S battery, there’s a sulfur-rich positive terminal called the cathode paired with a lithium metal negative terminal known as the anode. The electrolyte, situated between these components, facilitates ion movement between both ends of the battery.
However, sulfur isn’t an ideal electrode material.
When lithium ions bond with sulfur atoms at the cathode, they produce soluble polysulfides that migrate into the electrolyte, leading to the deterioration of the cathode and diminishing the battery’s ability to withstand multiple charging cycles. This process is what is known as polysulfide dissolution.
Wang and his team have developed a solution to this problem through their hybrid polymer network cathode.
“Our cathode employs multiple sulfur bonding tethers, atomic adsorption, and rapid Li-ion/electron transport on a molecular scale,” explained Wang. “This synergy enables real-time re-bonding and adsorption of unbound sulfur species, effectively eliminating soluble polysulfides and enhancing the battery’s cycle longevity.”
