Cycling-induced degradation of LiCoO2 thin-film cathodes at elevated temperature

The cycle life of LiCoO2-based all solid-state thin-film cells has been studied at room temperature, and at elevated temperatures of 50, 100, and 150 °C. X-ray diffraction, as well as Raman analysis, has been used to complement the electrochemical data in examining structural and chemical changes. XRD and Raman spectroscopy data indicate that elevated temperature soaks of the thin-film batteries in the quiescent state causes no discernable changes in the LiCoO2 cathode layer. However, when the thin-film batteries are cycled at elevated temperatures, decreases in average grain size of the LiCoO2 film occur with dramatic concomitant charge and discharge capacity loss.