Singapore researchers develop way to simplify lithium-sulfur battery production

Pipped as a potential replacement for lithium-ion battery, lithium sulfur is touted to store up to 10 times more energy and Singapore's NanoBio Lab scientists say they have come up with a "simplified technique" to develop the component from inexpensive commercially available materials.

Researchers from Singapore's NanoBio Lab (NBL) say they have come up with a way to develop lithium-sulfur cathodes that is less complex and time-consuming than current methods. This can pave the way for the component to become a viable alternative for lithium-ion battery and for use in electronic vehicles and devices. 

The scientists added that the new "simplified technique" offered a practical way to scale up production of new materials to improve battery performance. This presented a "promising step" towards the commercialisation of lithium-sulfur batteries, which had been widely pipped as a potential replacement for their lithium-ion counterparts, the NBL researchers said in a statement. A lab incubator that focuses on the use of nanotechnology to create new materials, NBL is parked under government agency, the Agency for Science, Technology and Research (A*STAR).

In theory, lithium-sulfur batteries can store up to 10 times more energy than lithium-ion ones, which--while widely used today to power communication devices--had limited storage capacity and safety issues due to its inherent electrochemical instability. In addition, sulfur had high theoretical energy density and was low cost and in abundance. 

However, to date, lithium sulfur had been unable to sustain their higher storage capacity over repeated charging and discharging of the battery.

To address this, NBL said it developed a two-step approach to preparing the cathode, by first building the carbon host before adding the sulfur source. This enabled the research team to obtain a 3D interconnected porous nanomaterial, it said, adding that it also prevented the carbon scaffold from collapsing when the battery was charged, which was typical in cathodes developed using current methods. 

The collapses during the initial charge and discharge cycle resulted in a structural change, resulting in cathodes that were highly dense and compact with a lower surface area and smaller pores. This produced lower battery performance than NBL's carbon scaffold, the Singapore lab said. 

Using its technique, NBL said its cathode delivered 48% higher specific capacity and 26% less capacity fade than conventionally prepared sulfur cathodes. When more sulfur was added to the material, its cathode clocked a high practical areal capacity of 4mAh per cm2, it added.

NBL said its lithium-sulfur cathode demonstrated capacity of up to 1,220mAh/g, which means 1gram of this material could store a charge of 1,220mAh. In comparison, a typical lithium-ion cathode has an energy capacity of 140mAh/g. The lab's cathode also was able to retain its capacity over 200 charging cycles, with minimal loss in performance. 

The research team's lead Jackie Y. Ying said: "Our method is industrially scalable and we anticipate it would have a significant impact on the future design of practical lithium-sulfur batteries."

Apart from the cathode, the NBL scientists also were working on designing and optimising the anode, separator, and electrolyte through nanomaterials engineering, The aim here was to develop a complete cell system for lithium-sulfur battery that delivered higher energy storage capacity, compared to conventional lithium-ion batteries. 

NBL noted: "Such a new battery system can last much longer than current batteries, and would be of great interest for electronic devices, electric vehicles and grid energy storage."

The research team's other members are J.L Cheong and A.A AbdelHamid.

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