The surface chemistry of the cathode material lithium cobalt oxide (LiCoO₂) in contact with the Li-ion battery solvent ethylene carbonate (EC) was studied by means of synchrotron based soft X-ray photoelectron spectroscopy (SXPS). By stepwise in-situ adsorption of EC onto a rf-magnetron sputtered LiCoO₂ thin film and consecutive recording of SXPS spectra, the chemical and electronic properties of the interface were determined allowing to deduce the behavior of lithium ions. Physisorption as well as decomposition can be detected for the EC molecules forming a complex reaction layer, as common for a solid electrolyte interface (SEI) in lithium ion secondary batteries. Upon interface formation, lithium ions deintercalate from the electrode and are dissolved in the adsorbate phase.

中文翻译：

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碳酸亚乙酯在钴酸锂薄膜上的吸附：基于同步加速器的表面化学光谱研究

通过基于同步加速器的软X射线光电子能谱（SXPS）研究了与锂离子电池溶剂碳酸亚乙酯（EC）接触的正极材料钴酸锂（LiCoO ₂）的表面化学。通过逐步地将EC逐步吸附到射频磁控溅射LiCoO ₂薄膜上并连续记录SXPS光谱，确定了界面的化学和电子性质，从而可以推断出锂离子的行为。可以检测形成复杂反应层的EC分子的物理吸附和分解，这对于锂离子二次电池中的固体电解质界面（SEI）来说很常见。在形成界面时，锂离子从电极上脱嵌并溶解在吸附相中。