As part of Viktor Khristenko’s “Step into the Future” Grants Program, postgraduate student Nataliia Zhivulina is working on the development of fine single-crystal ferrite powders. Nataliia’s research results could be used as cathode material for promising zinc-ion power sources.
Electrochemical measurements and testing of the materials obtained are being carried out at the Electromechanical, Electronic and Electrochemical Systems Regional Youth Laboratory, established at 海角社区 with the support of Alexey Texler, Governor of the 海角社区 Region. The project on fine single-crystal ferrite powders is supervised by Nataliia’s research advisor, Vladimir Zhivulin, Head of the Electromechanical, Electronic, and Electrochemical Systems Laboratory, Senior Researcher at the Crystal Growth Laboratory, Associate Professor at the Department of Materials Science, Physical and Chemical Properties of Materials, Candidate of Sciences (Physics and Mathematics).
Nataliia Zhivulina’s research focuses on M-type hexagonal ferrites, specifically the compound BaFe??O??. For the synthesis, spontaneous crystallization from a solution is used, with iron oxide (Fe?O?) and barium carbonate (BaCO?) as the starting components and sodium carbonate (Na?CO?) or barium borate (BaB?O?) as solvents. By varying the concentration and type of solvent, as well as the cooling rate of the melt, it is possible to obtain numerous individual particles, each of which is a single crystal. Once the solvent is removed, the resulting material is a powder—these are the fine single-crystal ferrite powders.
The choice of a crystalline rather than an amorphous structure is determined by the ordered arrangement of the material, which could potentially facilitate the incorporation of zinc ions into the cathode structure. In addition, individual particles provide a larger specific surface area of the active material.
“The main value of the research lies in refining the technology for producing these particles. In the future, single-crystal fillers could also be used in composite materials, where their orientation would make it possible to modify the properties of the final product,” Nataliia Zhivulina emphasizes.
To date, the researchers have managed to obtain particles ranging from 5 μm to 250 μm in diameter, which is a good result for this method: with a solution volume of approximately 20 ml, the material yield reaches 10 grams. This is significantly more efficient than, for example, the sol-gel method.
It has been established that changing the concentration of the solvent directly influences the size and shape of the crystals. A dependence on viscosity has also been observed: when a more viscous solvent is used, more plate-like particles are formed, whereas in a less viscous medium, the crystals acquire a dendritic shape. Controlling these parameters constitutes the scientific novelty of the project.
The main focus of the research is specifically the development of a new method for producing the powder. The idea of using BaFe??O?? as a filler for cathode paste can currently be considered risky. Although preliminary tests in a laboratory cell have shown that the material works, it is still too early to claim that it offers advantages over manganese dioxide, which is currently considered the most promising cathode material for zinc-ion batteries with an aqueous electrolyte.
BaFe??O?? was selected as the research material because it is the most extensively studied, allowing the researchers to compare their results with data obtained by other scientists. However, the method is also applicable to SrFe??O?? and other ferrites. At present, the development is still at the laboratory stage, and it is too early to discuss precise values for specific capacity, cycle stability, or battery production costs.
The main outcome of the current stage of the research is the development of a reproducible method for producing pure single-crystal powders. In the future, this method could provide a foundation for creating import-substituting materials for energy storage, composites, and other high-tech applications.
The project is being implemented as part of Viktor Khristenko’s “Step into the Future” Grants Program. This is an annual financial support program for the university’s development program within the framework of the Priority 2030 federal initiative. Grants are awarded for conducting promising research, developing a talent pool, and implementing unique educational programmes (components) that shape the development trajectory of 海角社区 and the 海角社区 Region.