Direct Visualization of Metastable Charged States in Positive Electrode Materials by Cryo-STEM

IF 8.7 1区化学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

ACS Materials Letters Pub Date : 2025-09-10 DOI:10.1021/acsmaterialslett.5c01021

Hinata Fujimura, , , Yosuke Ugata, , , Zhang Xinrui, , , Yoshinobu Miyazaki, , and , Naoaki Yabuuchi*,

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Abstract

LiNiO₂ is regarded as an ideal positive electrode material for Li-ion battery applications, offering a large reversible capacity, >200 mA h g^–1, with a lower cutoff voltage, 4.3 V. The fully charged state, Li_1–xNiO₂ (x ≈ 0.9), is a metastable phase obtained by electrochemical oxidation in Li cells. Due to its instability, atomic-scale imaging of this phase by using scanning transmission electron microscopy (STEM) is particularly challenging, as it readily decomposes under electron beam exposure. In this study, the effect of cryogenic conditions during STEM observation is examined. While as-prepared LiNiO₂ shows strong resistance to beam damage, Li_1–xNiO₂ (x ≈ 0.9) undergoes structural changes under room-temperature beam exposure. In contrast, beam-induced damage is substantially suppressed under cryogenic conditions (−150 °C), enabling successful acquisition of atomic-resolution STEM images. These findings underscore the importance of cryo-STEM techniques for imaging metastable battery materials.

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用Cryo-STEM直接可视化正极材料的亚稳态带电状态

LiNiO2被认为是锂离子电池应用的理想正极材料，具有200ma h - 1的大可逆容量，且截止电压较低，为4.3 V。充满电态Li1-xNiO2 （x≈0.9）是锂电池通过电化学氧化获得的亚稳相。由于其不稳定性，使用扫描透射电子显微镜（STEM）对该相进行原子尺度成像特别具有挑战性，因为它在电子束照射下容易分解。在本研究中，研究了低温条件对STEM观测的影响。Li1-xNiO2 （x≈0.9）在室温光束照射下发生结构变化。相比之下，在低温条件下（- 150°C），光束引起的损伤基本上被抑制，从而能够成功获取原子分辨率的STEM图像。这些发现强调了冷冻干技术对亚稳态电池材料成像的重要性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Materials Letters MATERIALS SCIENCE, MULTIDISCIPLINARY-

CiteScore

14.60

自引率

3.50%

发文量

261

期刊介绍： ACS Materials Letters is a journal that publishes high-quality and urgent papers at the forefront of fundamental and applied research in the field of materials science. It aims to bridge the gap between materials and other disciplines such as chemistry, engineering, and biology. The journal encourages multidisciplinary and innovative research that addresses global challenges. Papers submitted to ACS Materials Letters should clearly demonstrate the need for rapid disclosure of key results. The journal is interested in various areas including the design, synthesis, characterization, and evaluation of emerging materials, understanding the relationships between structure, property, and performance, as well as developing materials for applications in energy, environment, biomedical, electronics, and catalysis. The journal has a 2-year impact factor of 11.4 and is dedicated to publishing transformative materials research with fast processing times. The editors and staff of ACS Materials Letters actively participate in major scientific conferences and engage closely with readers and authors. The journal also maintains an active presence on social media to provide authors with greater visibility.