A joint research team led by Professor Jong Min Yuk from the Department of Materials Science and Engineering and Emeritus Professor Jeong Yong Lee, previously from the Institute for Basic Science (IBS) Center for Nanomaterials and Chemical Reactions, has developed a cathode material that can be utilized in sodium-ion batteries, which are cheaper and longer-lasting than their lithium-based counterparts. PhD student Jae Yeol Park and Dr. Sung Joo Kim from IBS were joint first authors for this research, which was published online in the March 2 issue of Nature Communications.

Lithium-ion batteries are commonly used in a variety of technologies, including mobile phones and electric cars. However, lithium only exists in 0.005 percent of the Earth’s surface. This limited supply and the surge in demand in recent years have led to the price of lithium increasing substantially; it has tripled since 2015. An alternative to lithium is sodium, which is approximated to be found in 2.6 percent of our planet’s surface — 500 times more than lithium. Furthermore, sodium can also be extracted from the ocean. The commercialization of sodium-ion cells is expected to reduce the price of mobile phones, electric cars, and laptops by about 30 percent.

However, the cathode material used in lithium-ion batteries, graphite, is not suitable for use in sodium-ion batteries. While the distance between the layers of graphite is ideal for the intercalation and storing of lithium ions, it is too small for sodium ions. To successfully commercialize sodium-ion batteries, a suitable cathode material had to be developed, which is what Professor Yuk and Professor Lee’s research team accomplished.

The researchers developed a nanoplate structure of copper sulfide, which has a high electrical conductivity and theoretical capacity. Through real-time analysis at the atomic level of the process of storing sodium in copper sulfide, the team confirmed that the crystal structure was flexible and could store sodium ions stably.

About the research, Professor Lee said, “The results of this research are expected to contribute greatly to the development of next-generation high-performance sodium-ion batteries.” Professor Jong Min Yuk stated, “We are interested in new renewable energy products because of environmental pollution such as yellow dust, and I think that through the results of our research, our country has taken a step forward to being able to take advantage of environmentally-friendly products.”