Characterization of electrode/electrolyte interface using in situ X-ray reflectometry and LiNi_0.8Co_0.2O₂ epitaxial film electrode synthesized by pulsed laser deposition method

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• 作者：Masaaki Hirayama ; Kazuyuki Sakamoto ; Tetsuya Hiraide ; Daisuke Mori ; Atsuo Yamada ; Ryoji Kanno ; Noriyuki Sonoyama ; Kazuhisa Tamura ; Jun’ ; ichiro Mizuki
• 关键词：Epitaxial thin film ; Lithium battery ; Cathode materials ; SEI layer ; Reflectivity
• 刊名：Electrochimica Acta
• 出版年：2007
• 出版时间：1 December 2007
• 年：2007
• 卷：53
• 期：2
• 页码：871-881
• 全文大小：1954 K

文摘

An in situ experimental technique was developed for detecting structure changes at the electrode/electrolyte interface of lithium cell using synchrotron X-ray reflectometry and two-dimensional model electrodes with a restricted lattice plane. The electrode was constructed with an epitaxial film of LiNi_0.8Co_0.2O₂ synthesized by the pulsed laser deposition method. The orientation of the epitaxial film depends on the substrate plane; the 2D layer of LiNi_0.8Co_0.2O₂ is parallel to the SrTiO₃ (1 1 1) substrate ((0 0 3)_{LiCo0.2Ni0.8O2}//(1 1 1)SrTiO₃), while the 2D layer is perpendicular to the SrTiO₃ (1 1 0) substrate ((1 1 0)_{LiCo0.2Ni0.8O2}//(1 1 0)SrTiO₃). These films provided an ideal reaction field suitable for detecting structure changes at the electrode/electrolyte interface during the electrochemical reaction. The X-ray reflectometry indicated a formation of a thin-film layer at the LiNi_0.8Co_0.2O₂ (1 1 0)/electrolyte interface during the first charge–discharge cycle, while the LiNi_0.8Co_0.2O₂ (0 0 3) surface showed an increase in the surface roughness without forming the surface thin-film layer. The reaction mechanism at the electrode/electrolyte interface is discussed based on our new experimental technique for lithium batteries.