Korea University: Next-generation batteries with magnesium anodes developed

A research team (first author: Kwak Jin-hwan, PhD program) led by Yu Seung-ho, a professor in the Department of Chemical and Biological Engineering under the College of Engineering, elucidated the growth behavior of Mg metal using operando imaging analysis and significantly suppressed Mg dendritic growth by coating a substrate with small traces of Au. Dendritic growth is the growth of dendrites in a tree-like structure and should be suppressed to increase safety in batteries.

Commercial lithium-ion batteries are made from expensive materials, such as lithium and cobalt. Because lithium is highly reactive with water and oxygen, battery safety is a key issue. Several attempts have been made to improve the cost competitiveness and safety of secondary batteries, and Mg metal has emerged as a suitable alternative to lithium. Mg is affordable due to its abundance in the earth’s crust, is environmentally friendly and is less reactive with water and oxygen. Mg metal electrodes have a high volumetric capacity of 3,833 mAh/cm3, which is higher than that of Li metal electrodes (2,093 mAh/cm3). Today, Mg secondary batteries are seen as a promising substitute for commercialized lithium-ion batteries thanks to their affordability, safety, and high volumetric capacity.

In general, secondary batteries with metal electrodes can be used up to their maximum theoretical capacity, but may suffer from dendritic growth at specific points in the charge/discharge process. Mg metal is known to be free of dendritic growth, making it more suitable for next-generation secondary batteries. However, some recent studies have reported the possibility of Mg dendritic growth under certain conditions, highlighting the need to investigate such conditions and develop strategies for the effective suppression of Mg dendritic growth.

The team led by Professor Yu Seung-ho elucidated the mechanism of Mg dendritic growth through electrochemical analysis, first principles calculations and operando imaging analysis with visible light and X-rays. Small traces of Au were coated on collectors to regulate Mg dendritic growth, thereby expanding the applications of Mg metal anode. The Au-coated collectors were verified as suppressing dendritic growth, even at a high current density of 10 mA/cm2.

The study was conducted jointly with Jeon Yun-seo (co-first author, Seoul National University), a master’s/PhD integrated program student, Professor Sung Yung-eun (co-corresponding author, Seoul National University) and Dr. Lim Hee-dae (co-corresponding author, Korea Institute of Science and Technology). The results were published in ACS Energy Letters (IF: 23.101), a leading international journal, on December 8.

Professor Yu Seung-ho said, “The proposed Au coating strategy demonstrated the vast possibilities of Mg metal batteries with high energy density. The systematic analysis and dendritic growth suppression will have an impact on not only Mg metal, but also various types of next-generation metal batteries.”

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