Impedance analysis of PLD LiNi0.8Co0.2O2 film electrode

The kinetics of intercalation are discussed using a pulsed laser deposition (PLD) film electrode and electrochemical impedance analysis. Films of LiNi_0.8Co_0.2O₂, deposited on single crystal substrates, were used for the study. The films have intercalative or blocking orientations on different crystal surfaces of the substrates. Impedance spectra show that there are at least three elemental processes in intercalation. Two processes at higher frequencies suggest that they occur at the electrode surface and are influenced by the orientation of the film. The third process appearing at low frequencies below 1 Hz indicates lithium motion in the bulk structure and shows the largest resistance among the three processes. This lithium conduction in a thin PLD film shows a semicircular response and is considered to be influenced more by the structure due to the nanometer-scale thickness.