UNIST Reveals Precise Structure of Double Solid Electrolyte Interface Layer

A joint research team from UNIST, Korea University, and Rice University in the United States conducted a collaborative study utilizing cryogenic electron microscopy analysis (Cryogenic electron microscopy) and density functional theory (DFT) calculations.

The research team included Professor Hyunwook Lee from the Department of Energy Chemical Engineering at UNIST, Professor Sangkyu Kwak from the Department of Chemical and Biomolecular Engineering at Korea University, and Professor Haotian Wang from Rice University.

In this study, the team elucidated the nanostructure and performance enhancement principles of the solid electrolyte interphase (SEI) layer formed on the surface of lithium metal anode materials.

Lithium metal anode materials are actively researched as next-generation battery anode materials due to their capacity approximately 10 times higher than that of commercially used graphite anode materials.

However, commercialization is challenging due to the instability of the material, and various issues have been identified, especially the lack of understanding of the structure and operating principles of the solid electrolyte interphase layer formed on the material surface during battery operation.

The research team utilized cryogenic electron microscopy analysis to analyze the lithium metal and solid electrolyte interphase layer. This technique, which was the subject of the 2017 Nobel Prize in Chemistry, involves cooling the material to an ultra-low temperature of approximately -175°C to perform high-resolution analysis at the nanoscale.

Using this analysis method, they succeeded in accurately identifying the structure of lithium metal and its interphase layer, which had been difficult to analyze due to their sensitive nature.

High-magnification cryogenic transmission electron microscopy image of the SEI layer formed on the surface of lithium metal anode material by a commercial carbonate-based electrolyte containing lithium hexafluorophosphate salt.

Dr. Taiwo Wei, the first author of the paper and a postdoctoral researcher at Rice University, stated, “Most analyses of the solid electrolyte interphase layer on lithium metal materials have been limited to inferring compositional changes, but through this study, we identified the precise nanostructure, presenting a new direction for interphase layer research.”

He added, “By revealing the previously unknown structure of the dual solid electrolyte interphase layer and the principles of performance enhancement, this research can contribute to the commercialization of lithium metal batteries.”

Professor Hyunwook Lee from the Department of Energy Chemical Engineering said, “Many researchers agree on the importance of interphase analysis, which can affect the overall battery performance. However, there is a lack of advanced analysis centers suitable for secondary batteries in South Korea.”

Professor Lee explained the expected impact of the research, saying, “UNIST is establishing an all-in-one analysis center capable of advanced analysis of secondary and next-generation batteries, and building such infrastructure is necessary to maximize South Korea’s capabilities in secondary batteries.”

The dual solid electrolyte interphase layer identified in this study is evenly distributed on the inorganic lithium metal anode surface, enabling rapid lithium-ion conduction. In other words, it prevents local lithium concentration and suppresses the formation of dendrites, which are detrimental to battery operation.

This research was supported by the Ulsan National Institute of Science and Technology (UNIST) Future Leading Specialized Project, the Ministry of Science and ICT and the National Research Foundation of Korea’s Mid-career Linked New Follow-up Project, and the Korea Energy Technology Evaluation and Planning (KETEP) Energy New Industry Global Talent Development Project.

Additionally, the study was published on April 13 in the internationally renowned energy journal ‘ACS Energy Letters’ and was selected as one of the top 20 most downloaded papers from the journal in the past 30 days.

This content was produced with the assistance of AI translation services.