Reflectivity measurements of superionic conductors for Li ion secondary battery materials Original Research Article

The reflection measurements of superionic conductors LiCoO2 and Li1-xCoO2, which are already in use for the positive electrode material of 4 V rechargeable lithium batteries, have been performed in the millimeter wave region from 6 to 60 cm−1 using the electron storage ring facilities of Institute of Molecular Science in Okazaki. The increase of the reflectivity has been observed in the low wavenumber region below 10 cm-1 above 300 K in Li1-xCoO2 for the first time, while the reflectivity of LiCoO2 has almost the constant value in all observed temperature region between 77 to 380 K. The results will be discussed in connection with our previous results of LiNiO2.