Cathode having high rate performance for a secondary Li-ion cell surface-modified by aluminum oxide nanoparticles

In order to enhance the electrochemical properties, the spinel LiMn₂O₄ electrode surface was modified with amorphous Al₂O₃ nanoparticle as heterogeneous phase. LiMn₂O₄ was in preparation based on a conventional solid-state reaction. The LiMn₂O₄ procedure was soaked in aluminum tri 2-propoxide solution. The LiMn₂O₄ whose surface was modified by aluminum oxide was obtained through the heat treatment at 400 °C for 4 h. The Al₂O₃-modified LiMn₂O₄ electrode exhibits a capacity higher than that of the unmodified LiMn₂O₄ electrode. On the other hand, no variation was shown with open circuit potential and apparent chemical diffusion coefficient of Li ion for LiMn₂O₄ before and after the surface modification. The charge-transfer resistance of Al₂O₃-modified LiMn₂O₄ decreased significantly in comparison with the unmodified LiMn₂O₄. The improved charge-transfer kinetics was largely attributed to Al₂O₃ which plays an important role of increasing the chemical potential at the electrode/electrolyte interface.