Capillary Forces Enhance Lithium Sulfur Batteries

A team of researchers in South Korea has found that capillary forces in carbon nanofibers help prevent electrode degradation in lithium sulfur batteries.

AsianScientist (May 25, 2018) – A team of scientists at the Korea Advanced Institute of Science and Technology (KAIST) in South Korea has succeeded in developing high-capacity lithium sulfur (Li-S) batteries. Their findings are published in Nano Letters.

Electrical vehicles and large-scale energy storage systems necessitate the development of batteries with high energy density. Li-S batteries are known to be one of the promising alternatives to the predominantly used lithium ion batteries.

However, several issues make it challenging to commercialize Li-S batteries. The low electrical conductivity of sulfur, volumetric expansion and contraction of the battery during charge and discharge, and permanent damage of the electrode caused by the dissolution of the lithium polysulfide into the electrolyte—known as the ‘shuttle effect’—are three of the biggest obstacles to commercial-grade Li-S batteries.

In the present study, Professor Kim Do Kyung and his team from KAIST used one-dimensional (1D) carbon materials—carbon nanofibers (CNFs)—which have a large surface area and a long-range conduction path for electrons and lithium ions, to improve the performance of Li-S batteries and reduce the extent of the ‘shuttle effect’ in their Li-S battery.

The researchers showed that sulfur was successfully contained in between the CNFs due to capillary forces. The sulfur contained per unit area of CNFs was five times greater than that of previously known methods, which enabled the Li-S battery to achieve an areal capacity of 7 mAh/cm2, almost seven times more than that of conventional lithium ion batteries.

“This study brought us closer to [manufacturing] commercial-grade high-capacity Li-S batteries, which are applicable in a wide variety of products, including electric vehicles, unmanned aerial vehicles and drones,” said Kim.

The article can be found at: Yun et al. (2018) Suppressing Polysulfide Dissolution via Cohesive Forces by Interwoven Carbon Nanofibers for High-Areal-Capacity Lithium–Sulfur Batteries.


Source: Korea Advanced Institute of Science and Technology; Photo: Shutterstock.
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