Tohoku University · Materials Science
Professor Yuichi Ikuhara's research lab specializes in advanced electron microscopy and materials characterization, focusing on the atomic-scale understanding of complex oxide materials, particularly in energy storage systems. The lab investigates the structural evolution, phase transitions, and defect dynamics in cathode materials for lithium-ion batteries, with a strong emphasis on lithium-rich layered oxides and spinel-type oxides. Using state-of-the-art in situ transmission electron microscopy techniques, including aberration-corrected STEM, the lab uncovers the behavior of dislocations, grain boundaries, and light elements such as lithium and oxygen at the atomic level. Their work bridges fundamental materials science with practical applications in next-generation batteries for electric vehicles and sustainable energy technologies.
Figures are computed from collected data and may differ slightly.
About phase: The coexistence of rhombohedral LiTMO2 (TM=Ni, Co, or Mn) and monoclinic Li2MnO3-like structures inside Li1.2Mn0.567Ni0.166Co0.067O2 is revealed directly at atomic resolution. The hetero-interface along the [001]rh/[103]mon zone axis direction is demonstrated, indicating the two-phase nature of these lithium-rich cathode materials (green Li, blue Mn, red O, cyan TM).
In deformation processes, the presence of grain boundaries has a crucial influence on dislocation behavior; these boundaries drastically change the mechanical properties of polycrystalline materials. It has been considered that grain boundaries act as effective barriers for dislocation glide, but the origin of this barrier-like behavior has been a matter of conjecture for many years. We directly observe how the motion of individual dislocations is impeded at well-defined high-angle and low-angle
Cathodes of lithium-rich layered oxides for high-energy Li-ion batteries in electrically powered vehicles are attracting considerable attention by the research community. However, current research is insufficient to account for their complex reaction mechanism and application. Here, the structural evolution of lithium-manganese-rich layered oxides at different temperatures during electrochemical cycling has been investigated thoroughly, and their structural stability has been designed. The resul
Direct observation of light elements (Li and O) in oxygen-deficient lithium manganese spinel by spherical aberration-corrected scanning transmission electron microscopy is reported. A previously unknown ordered structure was revealed by annular dark-field (ADF) imaging of oxygen columns, while Li ions are visualized successfully by annular bright-field (ABF) imaging (see picture).
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