Electrolyte Additives Boost Lithium-Sulfur Battery EfficiencyElectrolyte Additives Boost Lithium-Sulfur Battery Efficiency
Discover how Argonne National Laboratory's innovative electrolyte additives enhance lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries are a promising next-generation energy storage solution, offering two to three times the energy density of conventional lithium-ion (Li-ion) batteries while relying on Earth-abundant materials like sulfur instead of expensive and supply-constrained cobalt and nickel. Their lower cost and higher energy potential make them attractive for applications such as electric vehicles and grid storage. However, technical challenges, including short cycle life and stability issues, have slowed their commercial adoption. Researchers at Argonne National Laboratory are addressing these limitations with innovative electrolyte designs that could transform the future of Li-S batteries.
A breakthrough in electrolyte additives
One major issue with Li-S batteries is the “polysulfide shuttle” effect, where polysulfide compounds formed during battery operation dissolve into the electrolyte and degrade performance. Argonne chemist Guiliang Xu and his team have developed a groundbreaking additive for Li-S battery electrolytes that mitigates the "polysulfide shuttle" effect—a major obstacle in these batteries. “The additive, called a Lewis acid additive, is a salt that reacts with the polysulfide compounds, forming a film over the entire electrode,” explained Xu. “The key is to have a minor reaction to form the film, without a continuous reaction that consumes the material and reduces energy density.”
In Li-S batteries, energy storage relies on the conversion of sulfur in the cathode into polysulfide compounds. These compounds, however, can dissolve into the electrolyte, leading to material loss and reduced performance. The Lewis acid additive minimizes this dissolution by forming a protective film on the cathode and anode, suppressing the shuttle effect and enhancing stability. This innovation also promotes uniform lithium-ion transport, creating what Xu describes as an "ion transport highway" that improves battery performance.

A schematic depiction of the synchrotron X-ray experiment used in this research at the APS to study the Li-S battery cell. (Image by Argonne National Laboratory/Guiliang Xu.)
Advanced X-ray techniques validate results
Argonne researchers conducted experiments using advanced X-ray techniques at the Department of Energy’s Advanced Photon Source (APS) and Brookhaven National Laboratory’s National Synchrotron Light Source II. These techniques revealed significant reductions in polysulfide dissolution and confirmed the additive's ability to maintain reaction homogeneity. “Synchrotron techniques provide powerful tools for characterizing battery materials,” stated Tianyi Li, a beamline scientist at the APS. “The new interface design effectively mitigates well-known issues including polysulfide shuttle. More importantly, this interface enhances ion transfer, which helps to reduce reaction heterogeneities.”
Xu noted that the team is also working on improving the stability of the lithium metal anode, which can react easily and pose safety risks. Future research aims to develop safer electrolytes with reduced flammability, further advancing the commercial viability of Li-S batteries.
A sustainable energy future
The research results, published in Joule, represent a significant step forward in making Li-S batteries a viable and sustainable alternative to Li-ion technology. Argonne's innovations bring us closer to the widespread adoption of these high-performance, low-cost energy storage solutions by tackling key challenges like polysulfide shuttling and lithium anode stability. Through their work, the researchers are helping to pave the way for a cleaner, more sustainable energy landscape.
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