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Another Step Taken Toward Commercialization of High-Safety All-Solid-State Lithium-Ion Batteries
- Date : 22-03-25
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- Solid electrolytes with high ionic conductivity comparable to that of liquid electrolytes have been developed
- Exhibits a 70% reduction in toxic hydrogen sulfide gas generation compared to other sulfide-based electrolytes when exposed to air
Owing to the rapid growth of the electric vehicle and energy storage system (ESS) markets, the demand for lithium-ion batteries has been swiftly increasing. Conventional lithium-ion batteries use flammable liquid electrolytes and there have been continuous reports recently about such electrolytes causing accidents such as fires and explosions, raising concerns about their safety. Consequently, all-solid-state lithium-ion batteries using non-flammable solid electrolytes have been receiving significant attention as a next-generation secondary battery which can resolve these safety concerns. However, solid electrolytes have generally exhibited a low ionic conductivity in comparison to liquid electrolytes.
The research team, led by Dr. Seungho Yu from the Energy Storage Research Center at the Korea Institute of Science and Technology (KIST, President: Seok Jin Yoon), recently developed a solid electrolyte with a high ionic conductivity, comparable to that of liquid electrolytes, by optimizing the material properties and synthesis process for sulfide solid electrolytes.
Various candidate materials for solid electrolytes with a high ionic conductivity have been reported successively, and sulfide solid electrolytes exhibit a relatively high ionic conductivity, leading researchers to attempt to improve the material properties and synthesis process for sulfide electrolytes. However, sulfide solid electrolytes react with moisture when exposed to air, generating toxic hydrogen sulfide gas, which is a major concern. Therefore, further studies to resolve this issue were necessary.
Dr. Yu’s team successfully developed a solid electrolyte with a high ionic conductivity of 16.1 mS/cm, by introducing antimony and germanium and inserting additional lithium into the argyrodite sulfide solid electrolytes. The ionic conductivity of these solid electrolytes is comparable to that of commercial liquid electrolytes (~10 mS/cm) and exceeds the maximum-level ionic conductivity of the previously developed argyrodite sulfide solid electrolytes (14.8 mS/cm). The research team then assembled a solid-state battery using the argyrodite sulfide solid electrolytes and obtained a similar initial discharge capacity to that of a liquid electrolyte Li-ion battery. These results are promising for the subsequent development of all-solid-state lithium batteries with a high energy capacity and long lifecycle through optimization of the fabrication process.
While existing sulfide solid electrolytes react with moisture when exposed to air, leading to the evolution of toxic hydrogen sulfide gas, this study resulted in the successful reduction of hydrogen sulfide gas evolution by more than 70% through the introduction of antimony to minimize the reaction with moisture.
Dr. Yu at KIST stated that “the solid electrolytes developed in this study exhibit a high ionic conductivity comparable to that of liquid electrolytes, and significantly improved air-stability, which is expected to accelerate the commercialization of all-solid-state lithium batteries.”
This study was supported by the KIST Institutional Program and the Technology Development Program to Solve Climate Change of the National Research Foundation of Korea funded by the Ministry of Science and ICT of Korea (Minister: Hye-Sook Lim); by the Lithium-based Next-Generation Secondary Battery Performance Advancement and Manufacturing Technology Development Program, and the Automobile Industry Core Technology Development Program funded by the Ministry of Trade, Industry and Energy of Korea (Minister: Sung Wook Moon). The research findings were published in the latest issue of the international journal ACS Energy Letters (IF: 23.101, top 3.302% in the JCR field).
[1] Solid electrolytes with high ionic conductivity
Schematic illustration of the synthesis process, Li-ion migration path, and Li-ion conductivity of Li6.5Sb0.5Ge0.5S5I.
[2] Solid electrolytes with high air-stability
Images of P and Sb/Ge based sulfides after exposure to air and their amount of H2S generation.
[3]Corresponding Author(Dr. Yu, Seungho)