To visualize the electrochemical reactivity and obtain the diffusion coefficient of the anode of lithium-ion batteries, we used scanning electrochemical cell microscopy (SECCM) in a glovebox. SECCM provided the facet-dependent diffusion coefficient on a Li₄Ti₅O₁₂ (LTO) thin-film electrode and detected the metastable crystal phase of Li_xFePO₄.