The effect of removing the native passivation film on the electrochemical performance of lithium metal electrodes

• Published in: Journal of power sources 2022-02, Vol.520, p.230817, Article 230817
• Main Authors: Wang, Hao, Yi, Zong-Lin, Su, Fang-Yuan, Song, Ge, Xie, Li-Jing, Wang, Zhen-Bing, Chen, Cheng-Meng
• Format: Article
• Language: English
• Subjects: Electrode materials evaluation; Lithium ion batteries; Lithium reference electrodes; Native passivation film; Potential stability
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2021.230817

Lithium metal is accepted as the promising anode for next-generation Li batteries such as solid-state, Li–S, and Li-air batteries, etc. Besides, it is commonly employed as the reference electrodes for evaluating the electrode materials of Li-ion batteries (LIBs) in a half-cell. However, native passivation film (NPF), which is inevitable on the surface, can change the topography and surface composition distribution, and thus deteriorate the performance stability of lithium metal electrodes. Unfortunately, these effects are always neglected during the evaluation of anode or cathode materials of LIBs. Here, we conduct a comprehensive study on the effects of NPF on the electrochemical performance of lithium metal electrodes. After the removal of NPF by polishing, both the interfacial impedance and electrode overpotential are significantly decreased, with a more homogeneous lithium deposition during the charge/discharge process. When it is employed as the reference electrode for characterizing the commercial LiFePO4 or graphite materials in a coin cell, the consistency of the results is remarkably improved. This work not only provides an insight for the interfacial electrochemistry of lithium metal electrodes, but also helps characterize electrode materials in a reliable way. [Display omitted] •Native passivation film is inevitably existed on the reactive lithium metal.•Lithium electrode is instable due to large overpotential caused by the native film.•Polished lithium promotes evaluation of electrodes to show reliable performance.