Professor Yong-mook Kang and his research team have successfully developed a stabilization technology for anode materials in sodium secondary batteries with excellent price competitiveness using widely available resources compared to current lithium secondary batteries. 

The energy storage system (ESS) and electric vehicle (EV) industries will be essential to power storage and distribution in the era of renewable energy but require the emergence of secondary batteries capable of simultaneously realizing high output, high energy density, and low unit costs. In particular, interest in sodium ion secondary batteries with low unit cost and resource utilization has grown due to limited resources and the high price of the lithium precursor used in lithium ion secondary batteries. 

For many years professor Yong-mook Kang and his team have studied manganese oxides for sodium ion secondary battery anodes and hard carbon for cathode, to developed comparable performance to lithium ion secondary battery cathodes and anodes but with lower costs. First, the group succeeded in eliminating critical structural factors such as Jahn-Teller distortion and phase separation that destabilize Mn oxides with layered structures by substituting Zn at the sodium ion position of the layered Mn oxide (P2). They confirmed the effects predicted by Ab Initio calculations through cutting-edge analyses via electron microscopy and synchrotron radiation X-ray, achieving remarkably improved electrochemical and lifetime characteristics of the materials. 

Professor Kang said, “In many countries including the United States where the sharing economies of Uber and Grab are spreading, the transition to EVs with fewer malfunctions and lower charging costs has rapidly progressed. At the end of the day, concerns regarding the unit price of EVs and charging systems have been industrially important. Considering these aspects, this research team has focused on Mn-based anode materials and hard carbon-based cathode materials with the low unit costs for studies on sodium ion secondary batteries. In particular, for anode materials, research has focused on only the crystalline phase which is the path through which alkaline ions such as sodium and lithium can move. However, I believe that the transition to quasi-crystalline and non-crystalline materials will be necessary in the future to overcome material limitations while maintaining a low unit cost.”. 

Dr. Kai Zhang of Dongguk University who is supported by a “Korea Research Fellowship (KRF) of National Research Foundation of Korea (NRF)” participated in the research and has published as a first author. This research was jointly conducted by the research groups of Professor Doo-ho Kim of Kyung Hee University, Professor Si-young Choi of POSTECH, and Maeng-hyo Cho of Seoul National University with support from the “Korea Research Fellowship (KRF) and Mid-career Research of National Research Foundation of Korea (NRF)”. The results of their research were published online in Nature Communications on January 7th.