Electron microscopy analysis of Ti-substituted Li2MnO3 positive electrode before and after carbothermal reduction.

Abstract: 40%-titanium substituted Li2MnO3 (Li1+x (Ti0.4Mn0.6)1−x O2, 0 < x < 1/3) before and after carbothermal reduction was characterized by annular dark field scanning transmission electron microscopy (ADF-STEM) and electron energy-loss spectroscopy (EELS) to investigate the effects of the pre-reduction treatment. EELS spectra with high energy resolution using monochromator clearly reveal the appearance of reduced Mn ions after the reduction process. The spatial distribution of the reduced phase was visualized by multi-linear least-squares (MLLS) fitting method using Mn L-edge energy-loss near-edge structure (ELNES). The morphology change of a primary particle was observed around the Mn reduction phase. [Copyright &y& Elsevier]