Influence of Ti and Zr dopants on the electrochemical performance of LiCoO2 film cathodes prepared by rf-magnetron sputtering
Résumé
In an attempt to enhance the microstructural and electrochemical properties, LiCoO2 thin films were doped with titanium or zirconium. RF magnetron sputtering technique has been employed for the deposition of films on Au/Ti/SiO2/Si substrates from lithium-rich LiCoO2 target with mosaic configuration. The as-deposited and Ti- and Zr-doped LiCoO2 thin films at lower doping concentration exhibited the α-NaFeO2 structure with R m symmetry as confirmed from X-ray diffraction and Raman studies. The cyclic voltammogram of micro-electrodes in aqueous electrolyte exhibited perfect redox peaks with good reversibility. The chronopotentiometry studies revealed that the discharge capacity of pure LiCoO2 was 64 µAh cm-2 µm-1, while 2% Ti- and Zr-doped films showed enhanced capacities 69 and 68 µAh cm-2 µm-1 (248 mC cm-2 µm-1, 245 mC cm-2 µm-1) respectively. The Zr-doped films exhibited good structural stability even after 25 cycles with the capacity retention of 95%.