A low-cost production technology for silicon disulfide (SiS2) for solid-state electrolytes (argyrodite-type) has been developed by a team led by Dr. Ha Yoon-Cheol, a Principal Researcher at the Korea Electrotechnology Research Institute (KERI), and Dr. Cheol-Min Park, a Professor of School of Materials Science and Engineering at Kumoh National Institute of Technology (KIT). This technology has the potential to accelerate the commercialization of
A solid that is less likely to catch fire or explode is used in ASSBs to replace the liquid-state electrolytes that carry ions between the anode and cathode. However, commercialization still faces numerous obstacles, including difficulties with processing and mass production, high material costs, and so on. Many research groups around the world are putting in a lot of effort to address these issues, and KERI has also demonstrated a number of successes.
The team led by Dr. Ha chose silicon disulfide for this study. The fact that adding silicon disulfide to solid-state electrolytes for ASSBs improves their ionic conductivity and moisture stability is well known in academia. However, the synthesis of silicon disulfide from sulfur and silicon necessitates a high reaction temperature, which causes spikes in sulfur’s vapor pressure, making the production of silicon disulfide particularly challenging. Because of this, silicon disulfide is a very expensive material; each 20 grams currently costs approximately KRW 1.7 million.
“Many researchers at home and abroad have struggled to solve the elevated vapor pressure of sulfur, which necessitated the use of expensive raw materials or the introduction of novel techniques. What we’ve accomplished will help make making silicon disulfide for solid-state electrolytes cheaper and easier.”
Dr. Ha Yoon-Cheol, a Principal Researcher of Next Generation Battery Research Center at the Korea Electrotechnology Research Institute (KERI) .
KERI has fostered a handling innovation for the ideal creation of silicon disulfide and made it ready for its application in strong state electrolytes for ASSBs. By optimizing the arrangement of sulfur and silicon powders and creating a perfectly sealed environment that could withstand the sulfur vapor pressure at 800 degrees of reaction temperature, the team was able to establish the conditions for synthesis. The finished product was of a quality that was comparable to that of products that are available in stores. Using their silicon disulfide, the group created solid-state electrolytes and discovered that it had more than twice the ionic conductivity and moisture stability of other materials. Additionally, the optimized procedure will facilitate production simplification and lower production costs.
Dr. Ha stated, “Many researchers domestically and internationally have struggled to address the elevated vapor pressure of sulfur, necessitating the use of expensive raw materials or the introduction of special processes.” Because of what we’ve accomplished, producing silicon disulfide for solid-state electrolytes will be simpler and less expensive.”
In addition, the team used the new silicon disulfide as an anode active material for liquid electrolyte-based lithium-ion batteries and discovered for the first time that layered structures were destroyed and recovered during charging and discharging. The group’s discoveries from their silicon disulfide study were distributed as the cover article in the new version of the Diary of Materials Science A.
More information: Ki-Hun Nam et al, Silicon disulfide for high-performance Li-ion batteries and solid-state electrolytes, Journal of Materials Chemistry A (2023). DOI: 10.1039/D2TA08877K
