Lithium silicate, a lithium-ion conducting ceramic, is coated on a layer-structured lithium nickel manganese oxide (LiNi_0.7Mn_0.3O₂). Residual lithium compounds (Li₂CO₃ and LiOH) on the surface of the cathode material and SiO₂ derived from tetraethylorthosilicate are used as lithium and silicon sources, respectively. Powder X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy analyses show that lithium silicate is coated uniformly on the cathode particles. Charge and discharge tests of the samples show that the coating can enhance the rate capability and cycle life performance. The improvements are attributed to the reduced interfacial resistance originating from suppression of solid-electrolyte interface (SEI) formation and dissolution of Ni and Mn due to the coating. An X-ray photoelectron spectroscopy study of the cycled electrodes shows that nickel oxide and manganese oxide particles are formed on the surface of the electrode and that greater decomposition of the electrolyte occurs for the bare sample, which confirms the assumption that SEI formation and Ni and Mn dissolution can be reduced using the coating process.

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• Artificial cathode-electrolyte interphases on nickel-rich cathode materials modified by silyl functional group
  Hye Ji Song, Seol Heui Jang, Juhyeon Ahn, Si Hyoung Oh, Taeeun Yim
  Journal of Power Sources.2019; 416: 1.     CrossRef