Scientists have developed a new method that combines an automated reactor system with a mathematical framework to enable unlimited customization of full concentration gradients (FCG) and independent parameter control, allowing the production of lithium-ion batteries (LIBs) with higher safety and stability.
Hyun Deog Yoo, Associate Professor in the Department of Chemistry and the Institute for Future Earth at Pusan National University, stated: "Unlike traditional methods, where adjusting one parameter affects others, our method allows independent and precise control of multiple descriptors, including average composition, slope, and curvature."
With the continuous growth in demand for electric vehicles, researchers are focusing on improving the performance of lithium-ion batteries. The performance and stability of LIBs largely depend on the cathode material, which accounts for approximately 40% to 45% of the total battery cost. In cutting-edge technologies, high-nickel cathode materials stand out due to their high energy density and cost-effectiveness. However, researchers note that increasing nickel content exacerbates side reactions, severely damaging interface stability and mechanical integrity, thus limiting large-scale application.
Scientists revealed that adopting full concentration gradient (FCG) or core-shell designs is a promising solution. Traditionally, FCG cathodes are synthesized via co-precipitation, involving two metal precursor solution tanks. The first tank is nickel-rich (Ni) and fed directly into the reactor; the second tank contains cobalt (Co) and manganese (Mn), which is mixed with the first tank to gradually reduce nickel concentration over time. According to the press release, in traditional systems, the flow rate of the second tank is fixed, meaning that for a given average composition, only one specific gradient can be achieved.
In this study, the researchers overcame this limitation by representing the flow rate of the second tank as a time-dependent mathematical function. This innovation allows independent adjustment of average composition, slope, and curvature, enabling the generation of nearly infinite ranges of concentration gradients using only two tanks.
By combining this method with an automated reactor system, the research team successfully synthesized five FCG Ni0.8Co0.1Mn0.1(OH)₂ precursors with finely tuned gradients and experimentally verified them through two-dimensional and three-dimensional elemental mapping.
Dr. Yoo said: "For this, we assembled an excellent international research team and collaborated with the University of Illinois Chicago, Argonne National Laboratory, and multiple research laboratories in Korea and the United States."
