Study on the Deterioration of LiCoO2 Layers in NH3 Atmospheric Conditions; 암모니아 가스 분위기에서 리튬 코발트 산화물 (LiCoO2)의 열화 연구

초록

Lithium phosphorus oxynitride (LiPON) and lithium cobalt oxide (LCO) are representative solid-electrolyte and anode material in solid-state batteries. LiPON films were deposited on LCO-formed substrates through metal-organic vapor deposition. The deterioration of LCO films during LiPON deposition in ammonia (NH<inf>3</inf>) atmosphere was studied, and effects of the ultrathin aluminum oxide (Al<inf>2</inf>O<inf>3</inf>) layer on preventing damage to LCO were investigated. During the deposition, LCO underwent reduction reactions with active NH3-species. The LCO phase changed into a metallic cobalt phase while losing oxygen components. The increase in the cobalt layer thickness was almost linearly proportional to the rise in the temperature. The activation energy was ∼25 kJ/mol, and the reduction of LCO occurred at a low temperature of 350 ◦C. These findings implied that the cobalt components in LCO acted as an effective catalyst for the activation of NH<inf>3</inf> and accelerated the chemical reaction; furthermore, Al<inf>2</inf>O<inf>3</inf> films effectively prevented the deterioration of LCO films. Therefore, this reduction-prevention layer is universally applicable in processes using NH3 precursors. © 2023 The Korean Physical Society. All rights reserved.

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