Surface modification of thin-film based LiCoPO45Vcathode with metal oxide

The electrochemical performance of LiCoPO4 as a 5 V cathode material for lithium batteries was investigated in LiBF4 electrolyte. It was demonstrated that using this electrolyte salt significantly improves the electrochemical behavior of LiCoPO4, as it is accompanied by a faster diffusion process. In addition, another approach, viz., surface/chemical modification of the cathode with a metal oxide, was employed to reduce capacity fades appearing at elevated temperatures. To this aim, a thin layer of Al2O3 was deposited on the cathode surface by a sputtering method. The results obtained from experimental investigations are indicative of the fact that both approaches significantly improve cyclability of the cathode. Such improvements provide a satisfactory cyclability for LiCoPO4 to be used as a 5 V cathode material. (C) 2004 The Electrochemical Society.