Effect of Pt and Au current collector in LiMn₂O₄ thin film for micro-batteries

The crystal orientation and morphology of sputtered LiMn₂O₄ thin films is strongly affected by the current collector. By substituting Pt with Au, it is possible to observe in the x-ray diffraction pattern of LiMn₂O₄ a change in the preferential orientation of the grains from (111) to (400). In addition, LiMn₂O₄ thin films deposited on Au show a higher porosity than films deposited on Pt. These structural differences cause an improvement in the electrochemical performances of the thin films deposited on Au, with up to 50% more specific charge. Aqueous cells using thin film based on LiMn₂O₄ sputtered on Au or Pt as the cathode electrode present a similar retention of specific charge, delivering 85% and 100%, respectively, of the initial values after 100 cycles. The critical role of the nature of the substrate used in the morphology and electrochemical behaviour observed could permit the exploration of similar effects for other lithium intercalation electrodes.