有望な正極材料の性能低下の謎を解く(Unlocking the mystery behind the performance decline in a promising cathode material)

ad

2024-06-17 アルゴンヌ国立研究所(ANL)

有望な正極材料の性能低下の謎を解く(Unlocking the mystery behind the performance decline in a promising cathode material)
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.)

科学者たちは、リチウムイオン電池のニッケルリッチな正極が性能劣化する原因を発見しました。新しい分析方法がこの発見の鍵となりました。ニッケル、マンガン、コバルト酸化物(NMC)を用いた正極材料は、従来の多結晶から単結晶に変えても劣化が続く問題がありました。アルゴンヌ国立研究所の研究チームは、マルチスケールX線回折と高分解能電子顕微鏡を組み合わせた方法で、充放電により結晶格子が膨張・回転することで性能が低下することを明らかにしました。この研究は、より安価で長寿命な電気自動車の実現に貢献する可能性があります。

<関連情報>

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.

0402電気応用
ad
ad
Follow
ad
タイトルとURLをコピーしました