A catalytic kick for better batteries

The potential advantages of lithium-sulfur rechargeable batteries over the more common lithium-ion technology might be realised with help from a catalyst.

Researchers worldwide are interested in improving lithium-sulfur batteries as they could offer very high energy storage capacities while also being lightweight and relatively inexpensive. They are already used in some specialist applications, but are limited by the unwanted generation and accumulation of soluble performance-degrading compounds called lithium polysulfides in the battery’s multi-step reaction sequence.

Researchers in the US, UK and Saudi Arabia discovered a specific reaction in the electrochemical cycle requires a lot of energy to initially stimulate the soluble polysulfides into forming desired insoluble compounds of lithium and sulfur, leading to polysulfide accumulation. When the scientists added a catalyst made of graphene doped with nitrogen and sulfur, the energy required to initiate the reaction was reduced and polysulfide conversion to the insoluble lithium-sulfur compounds was accelerated.

“Our findings suggest that the catalyst offers a promising pathway to tackle the fundamental challenges to enable high-rate and robust lithium-sulfur batteries,” concludes Xiangfeng Duan of the research team based at the University of California at Los Angeles. Collaborators at King Saud University in Saudi Arabia contributed to the analysis of the results.

The team is also exploring other catalysts, hoping to find the best way to build better batteries for the future.

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