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 LiCoO2 synthesized by pulsed laser deposition method. The orientation of the epitaxial film depends on the substrate plane; the 2D layer of LiCoO2 is parallel to the SrTiO3 (111) substrate ( ( 0 0 3 ) LiCo O 2 / / ( 1 1 1 ) SrTi O 3 ) , while the 2D layer is perpendicular to the SrTiO3 (110) substrate ( ( 1 1 0 ) LiCo O 2 / / ( 1 1 0 ) SrTi O 3 ) . The anisotropic properties were confirmed by electrochemical measurements. Ex situ X-ray reflectivity measurements indicated that the impurity layer existed on the as-grown LiCoO2 was dissolved and a new SEI layer with lower density was formed after soaking into the electrolyte. In situ X-ray reflectivity measurements indicated that the surface roughness of the intercalation (110) plane increased with applying voltages, while no significant changes in surface morphology were observed for the intercalation non-active (003) plane during the pristine stage of the charge–discharge process.