Electrochemical investigation of LiNi 0.5Mn 1.5O 4 thin film intercalation electrodes

Abstract

This work provides kinetic and transport parameters of Li-ion during its extraction/insertion into thin film LiNi 0.5Mn 1.5O 4 free of binder and conductive additive. Thin films of LiNi 0.5Mn 1.5O 4 (0.2 μm thick) were prepared on electronically conductive gold substrate utilizing the electrostatic spray deposition technique. High purity LiNi 0.5Mn 1.5O 4 thin film electrodes were observed with cyclic voltammetry, to exhibit very sharp peaks, high reversibility, and absence of the 4 V signal related to the Mn 3+/Mn 4+ redox couple. The electrode subjected to 100 CV cycles of charge/discharge delivered a capacity of 155 mAh g −1 on the first cycle and sustained a good cycling behavior while retaining 91% of the initial capacity after 50 cycles. Kinetics and mass-transport of Li-ion extraction at LiNi 0.5Mn 1.5O 4 thin film electrode were investigated by means of electrochemical impedance spectroscopy. The apparent chemical diffusion coefficient ( D app) value determined from EIS measurements changed depending on the electrode potential in the range of 10 −10–10 −12 cm 2 s −1. The D app profile shows two minimums at the potential values close to the peak potentials of the corresponding cyclic voltammogram.