Making Advanced Electrogravimetry as an Affordable Analytical Tool for Battery Interface Characterization

Abstract

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.

Alkali Ions Pre‐Intercalated Layered MnO2 Nanosheet for Zinc‐Ions Storage

“…The net mass increase of 38 g.mol −1 obtained from EQCM measurements in this potential region (Figure 6d) is consistent with nearsurface desolvation of H + ions from their water solvation, as previously observed by EQCM for Li intercalation in LiFePO 4 from aqueous electrolyte. [51] The resulting local pH increase at the electrode surface further leads to the precipitation of ZHS according to Equation (3) [44] -which leads to both a mass and ∆R increase, consistent with the formation of a precipitate, as shown in Figure 6b,c. The intercalation of H + cation in KMO well agrees with the local pH increase at the electrode surface for further ZHS precipitation, absence of important change in the interlayer distance of the KMO structure observed from in situ XRD measurements (Figure 5), and with faster diffusion of H + versus Zn 2+ .…”

Preventing Graphene from Restacking via Bioinspired Chemical Inserts: Toward a Superior 2D Micro-supercapacitor Electrode

“…65 The applicability of the gravimetric conditions were verified by analyzing the motional resistance change, ΔR, (with)out loading in air and in the electrolyte, using electroacoustic admittance measurements (Figure S12 and S13). 66 The loadings of the electrodes were also calculated by measuring Δf (the difference between blank quartz and loaded quartz frequency in air) and converting it to Δm using Equation S1.…”

Understanding Battery Interfaces by Combined Characterization and Simulation Approaches: Challenges and Perspectives

“…What is more, the possibilities offered by electrochemical analysis are multiple, and researchers have already departed from conventional approaches and techniques to develop specific electrochemical tools such as scanning electrochemical microscope (SECM) [58,59] and electrochemical quartz crystal microbalance (EQCM) [60,61] to access further information about electron and ion transfers at the local scale. [62] In gravimetric mode, EQCM tracks the electrode weight change during electrochemical polarization due to the variation of the resonance frequency of a quartz crystal.…”