Team led by Yu Seung-ho develops next-generation cathode materials for sodium-ion batteries
Enhanced performance achieved through lithium-ion doping
Study on high-performance sodium-ion cathode materials published in Energy Storage Materials
The research team led by Professor Yu Seung-ho (first author: Park Sung-joon, a first year student in the integrated master-doctoral degree program) of the Department of Chemical and Biological Engineering in the College of Engineering developed cathode materials featuring improved capacity, stability, and speed using lithium-ion doping, and identified the structural factors contributing to the enhanced performance.
Due to the scarcity and increasing cost of lithium, sodium-ion batteries have been recognized as a potential alternative. This is because sodium is more widely available and more affordable. However, sodium-ion batteries have a smaller capacity and lower energy density than lithium-ion batteries. Researchers have attempted to solve this drawback by inducing oxygen-based redox reactions.
The cathode of a sodium-ion battery has a layered structure comprised of sodium, a transition metal, and oxygen. Here, the transition metal serves as a catalyst of the redox reactions during charging and discharging, known as cation redox. The energy density of a battery increases with the number of redox reactions. Oxygen may also be involved in the redox reactions, and such reactions are called anion redox. The total number of redox reactions can be increased by utilizing anion redox, resulting in a significantly larger cathode capacity and higher energy density. However, the low reversibility of anion redox reactions causes a deterioration in battery life, and is associated with other issues, such as slow kinetics.
The team doped small amounts of lithium into the lattice sites of the transition metal layer of sodium-ion batteries to enhance structural stability and accelerate the diffusion of sodium ions, and thereby ultimately succeeded in developing cathode materials featuring improved capacity, life span, and speed. Electrochemical analysis was conducted to aid understanding of the enhanced performance in terms of structural factors. The study was jointly conducted with the team led by Professor Kim Duho of Kyung Hee University, and the results were published in the international journal Energy Storage Materials (IF=17.8) on July 18.
Professor Yu said, “Our lithium-ion doping strategy demonstrates the potential of sodium-ion batteries, which have been considered less preferable due to their low energy density. We have also identified the structural factors contributing to the enhanced performance and increased redox reactions, and these insights are expected to boost the development of cathode materials for sodium-ion batteries.”