Reactions of the LiMnO cathode in an all-solid-state thin-film battery during cycling

Hikima, Kazuhiro*; Hinuma, Yoyo*; Shimizu, Keisuke*; Suzuki, Kota*; Taminato, So*; Hirayama, Masaaki*; Masuda, Takuya*; Tamura, Kazuhisa; Kanno, Ryoji*

ACS Applied Materials & Interfaces, 13(6), p.7650 - 7663, 2021/02

https://doi.org/10.1021/acsami.0c18030

We evaluated the structural change of the cathode material LiMnO that was deposited as an epitaxial film with an (001) orientation in an all-solid-state battery. In case of the electrode with LiPO coating. Experiments revealed a structural change to a high-capacity (activated) phase that proceeded gradually and continuously with cycling. The activated phase barely showed any capacity fading. We propose a mechanism of structural change with cycling: charging to a high voltage at a sufficiently low Li concentration typically induces irreversible transition to a phase detrimental to cycling that could, but not necessarily, be accompanied by the dissolution of Mn and/or the release of O into the electrolyte, while a gradual irreversible transition to an activated phase happens at a similar Li concentration under a lower voltage.