Elucidating reaction inhomogeneity of composite electrodes is key to improve the performances of batteries such as rate capability and durability. Because the reaction inhomogeneity often disappears after a certain relaxation period, operando analytical techniques are indispensable. We hereby propose that operando optical analysis as a common lab method can be applied to visualize the reaction inhomogeneity of LiFePO 4 composite electrodes for lithium-ion batteries with sufficient space and time resolutions. The results indicate that the brightness of the charged phase was higher than that of the discharged phases, which can be used to separate the phases and thus to elucidate the reaction inhomogeneity in the cross section of the composite electrode. A metastable phase Li 3/4 FePO 4 was also captured at a low temperature with the optical analysis.

No abstract