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KIST develops new batteries 40% cheaper, stronger than lithium-ion batteries

Process of coating molybdenum disulfide anodes with silicon oil (ACS Nano)
Process of coating molybdenum disulfide anodes with silicon oil (ACS Nano)

The Korea Institute of Science and Technology on Monday said it has developed sodium-ion batteries that are 40 percent cheaper and can store 1.5 times more charge per gram than conventional lithium-ion batteries.

The batteries use sodium instead of lithium. As sodium is far more common than lithium -- it’s in regular salt -- this brings down the price significantly. However, sodium ions are bigger and heavier than lithium ions, so existing anode materials -- made of graphite and a small amount of silicon -- cannot properly accommodate them.

A team of researchers led by Kim Sang-ok have developed new anode materials customized to handle sodium ions.

Anodes are one of the four key components of lithium-ion batteries along with cathodes, separators and electrolytes. Anodes account for batteries’ stability and lifespan. Lithium-ion batteries are charged and discharged when lithium ions move between cathodes and anodes.

Sodium-ion batteries have the same structure as lithium-ion batteries, but the anodes are made of different materials.

For the new anode materials, Kim used a metallic compound called molybdenum disulfide. This compound can store a lot of electricity, but has a high resistance and is structurally unstable. Kim’s team said that they solved these issues by coating molybdenum disulfide particles with silicon oil, encapsulating those particles inside nano ceramic shells.

Pound-for-pound, these batteries also store more electricity.

“The new molybdenum disulfide anodes applied with silicon oil coating technology exhibit a capacity of 600 milliampere-hours per gram and can maintain the same performance after being charged and discharged rapidly in five minutes 200 times,” a KIST official said. The maximum theoretical capacity of lithium-ion batteries’ graphite anodes is 372 milliampere-hours per gram.

The research has been published in the latest issue of ACS Nano, a global nanoscience journal issued every month.

By Kim Byung-wook (kbw@heraldcorp.com)
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