As a recognition of its excellent work, the research outcome of Korea Electrotechnology Research Institute (KERI) related to affordable and flexible high-energy-density lithium-sulfur batteries was reported on the front cover of one of the world’s renowned scientific journals.
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Unlike present lithium-ion batteries (LIBs) that make use of cobalt, nickel and other highly-priced rare-earth elements like cathode materials, the lithium–sulfur battery applied sulfur, one of the amplest elements, contributing to decreasing its manufacturing costs.
The lithium–sulfur battery is known to be a hopeful candidate for the next-generation battery as it can display a particular energy density that is around five times greater compared to that of LIBs in a theoretical way.
But there are various difficulties to overcome for the commercialization of lithium–sulfur batteries. When lithium comes into contact with sulfur during the time of charge or discharge process, the alleged “lithium polysulfides” are produced as an intermediate product.
Lithium exhibits high solubility and as a result, this leads to the shuttle phenomena of dissolved lithium polysulfides, thereby leading to the loss of cathode materials following repeated charge or discharge. In particular, it implies the loss of sulfur as it continues to dissolve in the electrolyte.
The polysulfide shuttle was regarded as the greatest hurdle standing in the way of the commercialization of lithium–sulfur batteries as this issue has been linked directly to the longevity and safety degradation of batteries.
In this respect, KERI employed activated carbon and phosphorus (P). Activated carbon fibers along with micropores are largely utilized in several types of filters and bleaches as a result of their high absorption property.
Activated carbon was applied as a coating material by the research team to the separator to capture lithium polysulfides that have been physically generated at the time of the charge or discharge cycle.
Furthermore, the researchers employed highly absorbent P to the carbon material for chemical capturing. This multimodal capturing method helped avoid the performance degradation of lithium–sulfur batteries as a result of the shuttle effect of lithium polysulfides.
Moreover, the research team was successful in increasing the usability of the Li–S battery by reinforcing its flexibility. Hence, the team employed carbon nanotube materials exhibiting high intensity, conductivity, and flexibility to the sulfur cathode to remove the heavy current collector (to increase energy density). This was done while securing the durability along with bending property.
The lithium–sulfur battery that was developed by KERI via the process listed above is known to have the world’s greatest energy density of 400 Wh/kg. Chances of commercialization of this lithium-sulfur battery are high thanks to its combination of high energy density, performance safety (longevity), flexibility (duration) with the existing benefits including lightweight and low cost.
Specifically, it is anticipated that lithium-sulfur batteries will be widely used in the area of future aviation mobility that necessitates lightweight and long duration, such as aerospace, flying cars, drones, etc.
The lithium–sulfur battery is an essential technology for rare-earth elements and resource scarce countries like Korea as it uses abundant and inexpensive sulfur and carbon materials. We are planning to combining this research outcome with the ‘large scale synthesis of solid electrolyte’ technology developed and owned by KERI to secure the original technology for the next-generation solid-state lithium-sulfur battery.
Dr. Jun-Woo Park, Study Lead, Korea Electrotechnology Research Institute
Dr. Jun-Woo Park headed the research team.
This study result was chosen as the cover article of Small, one of the world’s leading journals for materials science by German publisher Wiley in recognition of its excellent work.
Journal Reference:
Jo, S.-C., et al. (2022) Multimodal Capturing of Polysulfides by Phosphorus-Doped Carbon Composites for Flexible High-Energy-Density Lithium–Sulfur Batteries. Small. doi.org/10.1002/smll.202200326.