One example of this is the modula-on of the (dis)charge behaviour of Fe2(MoO4)3 (FMO) on solid electrolytes. FMO is an an--NASICON-type polyanion compound that can reversibly intercalate lithium and sodium ions, making it a promising electrode material for lithium-ion and sodium-ion ba5eries . In liquid electrolytes, the lithia-on/delithia-on reac-on of FMO proceeds via a typical two-phase reac-on between FMO and Li2FMO, as confirmed by electrochemical measurements and synchrotron X-ray diffrac-on (XRD) measurements . Consequently, its (dis)charge curve exhibits a dis-nct poten-al plateau in liquid electrolytes . On the other hand, a recent study has reported that when FMO is deposited as a thin film on a solid electrolyte, its (dis)charge behaviour differs from that previously reported in liquid electrolytes. Specifically, the poten-al plateau during the (dis)charge becomes less pronounced, exhibi-ng a gradual poten-al varia-on instead . This implies that the lithia-on/delithia-on mechanism of FMO can be modulated on a solid electrolyte. If the use of solid electrolytes causes the modula-ons of the lithia-on/delithia-on behaviour of the electrode materials, inves-ga-ng the underlying mechanisms is important for the proper design of ASSLIBs. Therefore, in this work, we examined the lithia-on/delithia-on behaviour of FMO thin films deposited on solid electrolytes using operando synchrotron XRD, aiming to gain insights into the influence of the solidifica-on of LIBs on the (dis)charge mechanisms of electrode materials.