Researchers develop low-cost flexible high-energy density lithium-sulfur battery

By Lim Chang-won Posted : April 11, 2022, 16:09 Updated : April 11, 2022, 17:56

[Courtesy of the Korea Electrotechnology Research Institute ]

SEOUL -- South Korea's government-funded research body has developed a low-cost flexible high-energy-density lithium-sulfur battery that lowered manufacturing costs by using resource-rich sulfur as a cathode material instead of expensive rare-earth.

The energy density of lithium-sulfur batteries developed by a research team at the Korea Electrotechnology Research Institute (KERI) is the world's highest level. The institute said lithium-sulfur batteries would be widely used in future aviation mobility batteries such as flying cars and drones.

Lithium-sulfur batteries are a necessary technology for countries like South Korea, which lack rare earth resources, because they use cheap and rich sulfur and carbon materials," Park Joon-woo, a KERI researcher, said in a statement on April 11. 

lithium-sulfur batteries have higher energy density than lithium-ion batteries, but it was not easy to commercialize them as their life and safety degrade. When lithium and sulfur meet during charging and discharging, it becomes lithium sulfide, also known as lithium polysulfide. Due to the high solubility in the electrolyte, the material can be lost during repeated charging and discharging.

Park's team has physically captured lithium polysulfide using activated carbon as a coating material for a separator and succeeded in preventing performance degradation caused by lithium polysulfide by doping phosphorus with high adsorption power to carbon materials and inducing chemical capture.

The research team strengthened the flexible function of lithium-sulfur batteries. By using a carbon nanotube material with high electrical conductivity, strong strength, and flexibility for the sulfur cathode, researchers removed a heavy current collector, improved energy density, and endured durability.

Park said his team would try to secure the source technology of next-generation lithium-sulfur solid-state batteries by using its technology for the mass synthesis of solid electrolytes. All-solid-state batteries are seen as a next-generation power source for electric vehicles as solid electrolytes are nonflammable and more stable. They can have a higher energy density than lithium-ion batteries.

In October 2021, KERI transferred technology to Daejoo Electronic Materials for the mass production of sulfide-based solid electrolytes for all-solid-state batteries at low prices. The company would develop various silicon materials that can replace lithium metal anodes for solid-state batteries.

Solid-state batteries enable faster charging, higher voltage and longer cycle life. However, challenges to widespread adoption include energy and power density, durability, material costs, sensitivity and stability. Sulfide-based solid-state batteries use lithium metal as anode material to enable high energy density and safety.
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