Alikin Denis, Slautin Boris, Abramov Alexander, Rosato Daniele, Shur Vladimir, Tselev Alexander, Kholkin Andrei
School of Natural Sciences and Mathematics, Ural Federal University, 620000 Ekaterinburg, Russia.
Robert Bosch GmbH, 70839 Gerlingen-Schillerhoehe, Germany.
Materials (Basel). 2019 Apr 30;12(9):1416. doi: 10.3390/ma12091416.
In this contribution, a correlative confocal Raman and scanning probe microscopy approach was implemented to find a relation between the composition, lithiation state, and functional electrochemical response in individual micro-scale particles of a LiMnO spinel in a commercial Li battery cathode. Electrochemical strain microscopy (ESM) was implemented both at a low-frequency (3.5 kHz) and in a high-frequency range of excitation (above 400 kHz). It was shown that the high-frequency ESM has a significant cross-talk with topography due to a tip-sample electrostatic interaction, while the low-frequency ESM yields a response correlated with distributions of Li ions and electrochemically inactive phases revealed by the confocal Raman microscopy. Parasitic contributions into the electromechanical response from the local Joule heating and flexoelectric effect were considered as well and found to be negligible. It was concluded that the low-frequency ESM response directly corresponds to the confocal Raman microscopy data. The analysis implemented in this work is an important step towards the quantitative measurement of diffusion coefficients and ion concentration via strain-based scanning probe microscopy methods in a wide range of ionically active materials.
在本研究中，采用了相关共聚焦拉曼和扫描探针显微镜方法，以探寻商用锂电池阴极中LiMnO尖晶石的单个微观粒子的组成、锂化状态与功能电化学响应之间的关系。在低频（3.5 kHz）和高频激发范围（高于400 kHz）下均实施了电化学应变显微镜（ESM）。结果表明，由于针尖-样品静电相互作用，高频ESM与形貌存在显著串扰，而低频ESM产生的响应与共聚焦拉曼显微镜揭示的锂离子和电化学惰性相的分布相关。还考虑了局部焦耳热和挠曲电效应对机电响应的寄生贡献，发现其可忽略不计。得出的结论是，低频ESM响应与共聚焦拉曼显微镜数据直接对应。本工作中进行的分析是朝着通过基于应变的扫描探针显微镜方法在广泛的离子活性材料中定量测量扩散系数和离子浓度迈出的重要一步。
