Characterization of electrode/electrolyte interface for lithium batteries using synchrotron X-ray reflectometry; A New experimental technique for LiCoO model electrode

Hirayama, Masaaki*; Sonoyama, Noriyuki*; Abe, Takashi*; Minoura, Machiko*; Ito, Masumi*; Mori, Daisuke*; Yamada, Atsuo*; Kanno, Ryoji*; Terashima, Takahito*; Takano, Mikio*; Tamura, Kazuhisa   ; Mizuki, Junichiro

A new experimental technique was developed for detecting structure changes at electrode/electrolyte interface of lithium cell using X-ray reflectometry and two-dimensional model electrodes with a restricted lattice-plane. The electrodes were constructed with an epitaxial film of LiCoO synthesized by pulsed laser deposition method. The anisotropic properties were confirmed by electrochemical measurements. X-ray reflectivity measurements indicated that the impurity layer existed on the as-grown LiCoO was dissolved and a new SEI layer with lower density was formed after soaking into the electrolyte. X-ray reflectivity measurements indicated that the surface roughness of the intercalation (1 1 0) plane increased with applying voltages, while no significant changes in surface morphology were observed for the intercalation non-active (0 0 3) plane during the pristine stage of the charge-discharge process.