Surface Layer Formation and Stripping Process on LiMn[sub 2]O[sub 4] and LiNi[sub 1∕2]Mn[sub 3∕2]O[sub 4] Thin Film Electrodes

Surface layer formation and stripping processes on and thin film electrodes were analyzed by using in situ Fourier transform infrared (FTIR) spectroscopy. For , the peak intensity of in situ FTIR gradually increased up to vs during anodic polarization and decreased more anodic electrode potential. In situ FTIR spectra of showed a strong peak intensity at a two electrode potential, vs and vs . These observations indicated that a surface layer formation process is accelerated by a redox couple of transition metals ( or ) in active materials. In addition, in situ FTIR spectra for a plateau area of were also investigated to confirm the surface layer formation and stripping by redox couple of transition metals at low electrode potential. The surface layer stripping was observed at vs , and the lower electrode potential and formation process was also observed from vs . It can be explained that the surface layer was formed by immersing the cathode materials into the electrolyte solution.