Structure and electrochemical properties of LiNi_0.5Mn _1.5O₄ epitaxial thin film electrodes

The structure and electrochemical properties of epitaxial thin film LiNi_0.5Mn_1.5O₄ electrodes are investigated for lithium ion secondary batteries applications. The orientation and thickness of the LiNi_0.5Mn_1.5O₄ films are controlled by changing the substrate orientation and the pulse laser deposition time, respectively. The lattice parameters of the films increase with film thickness and the manganese valence decreases without any change in the nickel valence. Regardless of their orientation, all the films exhibit reversible capacities of 80-130 mAh g^-1. The dependence of the discharge capacity on film thickness indicates a nanosize effect. The electrochemical properties of the high voltage spinel system are significantly dependent on their electronic properties, lattice orientations, and film thicknesses of the electrodes.