Researchers have created a new method for producing large quantities of sodium-containing sulfides. The ability to mass produce electrolytes with high conductivity and formability is crucial for making all-solid-state sodium batteries more practical. These batteries are seen as a safer and more cost-effective alternative to lithium-ion batteries, as sodium is more abundant than lithium. The researchers’ process can result in solid sulfide electrolytes with the highest reported sodium ion conductivity in the world, as well as glass electrolytes with high formability. This is a significant advancement in the quest for more environmentally friendly energy sources.The use of rechargeable batteries is essential for storing energy, with lithium-ion batteries being the most commonly used. However, there is growing interest in all-solid-state sodium batteries due to the abundance of sodium compared to lithium. This could potentially make sodium batteries more cost-effective, and solid-state batteries are considered to be safer. Despite these advantages, the challenges in processing have made mass production difficult.
Atsushi Sakuda, an Associate Professor at Osaka Metropolitan University, and Akitoshi Hayashi, a Professor at the Graduate School of Engineering, have led a research team in developing a process that could facilitate mass synthesis for sodium-containing sulfides. This development could pave the way for advancements in sodium battery technology.The team used polysulfides, which are sulfides with two or more sulfur atoms, both as the material and the flux. This helped to promote fusion and create a solid sulfide electrolyte with the highest reported sodium ion conductivity in the world. The conductivity is about 10 times higher than what is needed for practical use. They also created a glass electrolyte with high reduction resistance.
The mass production of electrolytes with high conductivity and formability is crucial for the practical use of solid-state sodium batteries. The newly developed process can be used for the production of almost all sodium-containing sulfide materials, including solid electrolytes and electrode active materials.Professor Sakuda noted that the process of using reactive polysulfides flux Na2S for the synthesis of Na3SbS4 can lead to better performance in materials for all-solid-state sodium batteries. The results were documented in the journals Energy Storage Materials and Inorganic Chemistry. The research team believes that this process will be the way forward for the future development of materials for such batteries.The creation of sulfide solid electrolytes for all-solid-state sodium batteries has been researched in the article “Energy Storage Materials”. It was published in 2024 and can be accessed using the DOI 10.1016/j.ensm.2024.103307.