Numerous sophisticated diagnostic techniques have been designed to monitor Electrode-Electrolyte Interfaces that mainly govern the lifetime and reliability of batteries. Among them, is the electrochemical quartz crystal microbalance that offers valuable insights of the interfaces once the required conditions of the deposited film in terms of viscoelastic and hydrodynamic properties are fulfilled. Herein, we propose a friendly protocol that enlists the elaboration of a homogeneous deposit by spray coating followed by QCM measurements at multiharmonic frequencies to ensure the film flatness and rigidity for collecting meaningful data. Moreover, for easiness of the measurements, we report the design of a versatile and airtight EQCM cell setup that can be used either with aqueous or non-aqueous electrolytes. We also present, using a model battery material, LiFePO 4 , how dual frequency and motional resistance monitoring during electrochemical cycling can been used as a wellsuitable indicator for achieving reliable and reproducible electrogravimetric measurements. We demonstrate through this study the essential role of the solvent assisting the lithium ion insertion at the LiFePO 4 interface with a major outcome being the solvent dependent interfacial behavior. Namely in aqueous media, we prove a near surface desolvation of lithium ions from its water solvation shell as compared with organic molecules. This spatial dissimilarity leads to a smoother Li-ion transport across the LFP-H 2 O interface, hence accounting for the difference in rate capability of LFP in the respective electrolytes. Overall, we hope our analytical insights on interface mechanisms will help in a wider acceptance of EQCM-based methods by the battery community.