Li Menghao, Yang Xuming, Wei Xianbin, Zhu Yuanmin, Sun Xueliang, Gu M Danny
Eastern Institute for Advanced Study, Eastern Institute of Technology, Ningbo, Zhejiang 315200, P. R. China.
Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Nano Lett. 2025 Feb 19;25(7):2769-2776. doi: 10.1021/acs.nanolett.4c05838. Epub 2025 Feb 11.
The cathode-electrolyte interphase (CEI) is recognized as a crucial component in battery systems; however, knowledge regarding its structure and function remains limited and often controversial. This study demonstrates the feasibility of revealing atomic-resolution CEI structures via cryogenic transmission electron microscopy (cryo-TEM). Using Ni-rich oxide (LiNiCoMnO, NCM811) microparticles as the model cathode, ultrafine images of CEI were obtained, revealing its dynamic evolution over cycling and its impact on battery performance. In ethylene carbonate (EC)-based electrolytes, the CEI forms an amorphous organic-rich layer, while, in fluoroethylene carbonate (FEC)-based electrolytes, the CEI contains abundant LiF grains. Both CEIs thicken with cycling but exhibit different structural evolutions: the former adopts a mosaic structure, while the latter forms a dual-layer structure with a compact LiF inner layer. These unprecedented high-resolution images and comprehensive analysis advance the understanding of CEI dynamics, addressing existing controversies and providing insights for improving battery performance.
阴极-电解质界面（CEI）被认为是电池系统中的关键组成部分；然而，关于其结构和功能的认识仍然有限，且常常存在争议。本研究证明了通过低温透射电子显微镜（cryo-TEM）揭示原子分辨率CEI结构的可行性。以富镍氧化物（LiNiCoMnO，NCM811）微粒作为模型阴极，获得了CEI的超精细图像，揭示了其在循环过程中的动态演变及其对电池性能的影响。在基于碳酸亚乙酯（EC）的电解质中，CEI形成富含无定形有机物的层，而在基于氟代碳酸亚乙酯（FEC）的电解质中，CEI含有大量LiF颗粒。两种CEI都会随着循环而增厚，但表现出不同的结构演变：前者采用镶嵌结构，而后者形成具有致密LiF内层的双层结构。这些前所未有的高分辨率图像和全面分析推进了对CEI动力学的理解，解决了现有争议，并为改善电池性能提供了见解。
