Erickson Evan M, Li Wangda, Dolocan Andrei, Manthiram Arumugam
Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
ACS Appl Mater Interfaces. 2020 Apr 8;12(14):16451-16461. doi: 10.1021/acsami.0c00900. Epub 2020 Mar 27.
We present a comprehensive study of cycled high-Ni (LiNiMO, M = metals), Li-rich (LiMnMO), and high-voltage spinel (LiMnNiO) electrodes with time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy in conjunction with electrochemical techniques to better understand their evolving cathode-electrolyte interphase structure during cycling. TOF-SIMS provides fragment-specific information regarding the surface film content for each of the electrodes. High-Ni cathodes show thick surface films initially containing LiCO, later developing oxidized organic carbonates throughout cycling. Li-rich electrode surface films develop strong characteristics during their first activation cycles, where released O oxidizes organic carbonates to form polymeric carbons and decomposes LiPF. High-voltage spinel electrodes operate outside the standard electrolyte stability window, generating reactive oxidized electrolyte species that further decompose LiPF. The distribution and concentration of these different chemical fragments measured by TOF-SIMS are finally summarized by color-coded high-resolution images of cycled high-Ni, Li-rich, and high-voltage spinel electrodes.
我们采用飞行时间二次离子质谱（TOF-SIMS）和X射线光电子能谱，并结合电化学技术，对循环使用的高镍（LiNiMO，M = 金属）、富锂（LiMnMO）和高压尖晶石（LiMnNiO）电极进行了全面研究，以更好地了解它们在循环过程中不断演变的阴极-电解质界面结构。TOF-SIMS提供了有关每个电极表面膜成分的特定碎片信息。高镍阴极最初显示出含有LiCO的厚表面膜，在整个循环过程中，随后会生成氧化有机碳酸盐。富锂电极表面膜在其首次活化循环期间呈现出强烈的特征，其中释放出的O会氧化有机碳酸盐形成聚合物碳，并分解LiPF。高压尖晶石电极在标准电解质稳定性窗口之外运行，会产生活性氧化电解质物种，进一步分解LiPF。通过TOF-SIMS测量的这些不同化学碎片的分布和浓度，最终通过循环使用的高镍、富锂和高压尖晶石电极的彩色编码高分辨率图像进行总结。
