2024-06-17 アルゴンヌ国立研究所(ANL)
Method used for studying failure mechanisms in battery materials at sizes from 1 to 1000 particles. HEXRD = high energy X-ray diffraction; MCRC = multi-crystal rocking curve; SDXM = scanning diffraction X-ray microscopy. Lower right: lattice shape change with charge and discharge. (Image by Argonne National Laboratory.)
＜関連情報＞
- https://www.anl.gov/article/unlocking-the-mystery-behind-the-performance-decline-in-a-promising-cathode-material
- https://www.science.org/doi/10.1126/science.ado1675
回復不可能な格子回転が単結晶カソードの構造劣化を支配する Unrecoverable lattice rotation governs structural degradation of single-crystalline cathodes
WEIYUAN HUANG, TONGCHAO LIU, LEI YU, JING WANG, […], AND KHALIL AMINE
Science Published:23 May 2024
DOI:https://doi.org/10.1126/science.ado1675
Editor’s summary
In theory, larger metal crystals in high-nickel-content nickel-manganese-cobalt (NMC) cathodes should have a higher practical capacity than polycrystalline ones because of the absence of grain boundaries and heterogeneous volume changes. However, in practice, single-crystalline NMC particles with more than 70% nickel exhibit worse performance with more rapid capacity fade. Huang et al. developed a technique to capture both statistical and individual lattice distortions in an ensemble of particles, thus bridging between the information provided by x-ray diffraction and electron microscopy methods. The authors observed that lattice rotation, a frequently occurring but often underdetected lattice distortion, is a primary factor initiating structural and electrochemical degradation in single-crystal cathode particles. —Marc S. Lavine
Abstract
Transitioning from polycrystalline to single-crystalline nickel-rich cathodes has garnered considerable attention in both academia and industry, driven by advantages of high tap density and enhanced mechanical properties. However, cathodes with high nickel content (>70%) suffer from substantial capacity degradation, which poses a challenge to their commercial viability. Leveraging multiscale spatial resolution diffraction and imaging techniques, we observe that lattice rotations occur universally in single-crystalline cathodes and play a pivotal role in the structure degradation. These lattice rotations prove unrecoverable and govern the accumulation of adverse lattice distortions over repeated cycles, contributing to structural and mechanical degradation and fast capacity fade. These findings bridge the previous knowledge gap that exists in the mechanistic link between fast performance failure and atomic-scale structure degradation.
