Abstract
<jats:p>Graphite is widely used as a promising anode material for various battery systems because of its low cost, high capacity, and low operation potential. During Li intercalation and deintercalation, graphite undergoes a series of stage transitions, the behavior of which depends on the electrolyte system. However, the Li intercalation/deintercalation behavior of graphite in all-solid-state batteries (ASSBs) is not fully understood because previous Raman spectroscopy studies on ASSBs have reported inconsistent stage transition behaviors. Herein, we investigate the Li intercalation/deintercalation behavior of graphite in ASSBs using operando Raman spectroscopy while simultaneously tracking the spatial reaction distribution within the electrode by optical imaging. During the intercalation process, graphite exhibits the same stage transition behavior as in conventional lithium-ion batteries, whereas Li deintercalation follows an apparently irreversible stage transition pathway. This apparent irreversibility originates from an inhomogeneous reaction distribution across the thickness of the graphite electrode rather than the intrinsic staging behavior of graphite. These findings resolve the inconsistencies reported in previous Raman spectroscopy studies and demonstrate that spatial information on the reaction distribution within electrodes is essential for accurately interpreting the stage transition mechanism of graphite in ASSBs.</jats:p>