In Situ Monitoring of Gravimetric and Viscoelastic Changes in 2D Intercalation Electrodes

Abstract

Viscoelastic properties of battery electrodes in contact with electrolyte solutions may affect the electrodes' cycling performance. However, they are not easily assessed by in situ measurements. Herein, we show that an electrochemical quartz-crystal microbalance with dissipation (EQCM-D) enables extraordinary sensitive probing of intrinsic electrodes materials' properties such as intercalationinduced gravimetric and viscoelastic changes, using Ti 3 C 2 (OH) 2 (MXene) as a classical 2D intercalation model material. The insertion of each Li-ion into thin electrodes comprising this MXene is accompanied by insertion of one water molecule. Solvent-dependent viscoelastic changes and periodic stiffening/softening upon fully reversible Li-ion intercalation/deintercalation into an MXene electrode correlates well with its excellent long-term cycling performance. The experimental platform based on a commercial instrument, EQCM-D monitoring, and advanced viscoelastic modeling (extended Voight-type model) can be used for in situ real time characterization of intrinsic materials' properties of practical composite battery electrodes important for a deeper understanding of the factors controlling their cycling performance.

Nanoporous carbon for electrochemical capacitive energy storage

“…145,[147][148][149]151,169 By analyzing the mechanical properties of the deposited materials, studies have shown that the selection of a binder is crucial, whose viscoelastic behavior can vary based on the electrolyte environment, affecting in turn the accuracy of the EQCM results. [169][170][171] The analysis of EQCM-D signals and its subsequent modeling using complex equations and models allow for collecting textural, structural and mechanical data of the coating. 160 Despite the fact additional mechanical information can be extracted by monitoring the dissipation, EQCM used in gravimetric and dissipation modes has still some limitations.…”

In Situ Acoustic Diagnostics of Particle-Binder Interactions in Battery Electrodes

“…This inspired us to choose LFP and NFP composite electrodes (with commonly used poly(vinylidene fluoride) [PVdF] binder) cycled in both aqueous and non-aqueous electrolyte solutions for a quantitative study of the mechanical electrode/binder interactions using an electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D). [12][13][14][15][16][17][18][19][20] This acoustic technique 12,15,20 is ideally suited for a real-time mesoscopic mechanical characterization of composite batteries electrodes comprising expanding/contracting intercalation particles embedded into a continuous network of a polymeric binder.…”

Vacuum Filtration‐and‐Transfer Technique Helps Electrochemical Quartz Crystal Microbalance to Reveal Accurate Charge Storage in Supercapacitors

“…Importantly, the raw EQCM data for the sprayed sample showed a large resistance change (Figure b), by contrast, the raw EQCM data for the transferred film nearly did not show resistance change (Figure d), and the frequency variation showed more details on quality changes than the sprayed sample. Shpigel et al reported that thin MXene electrode has entirely gravimetric behavior in neutral aqueous Li 2 SO 4 electrolyte, but thick electrode shows obvious viscoelastic changes . In our test, the quality of MXene on two kinds of electrodes prepared by spray and VFT methods was almost the same (several micrometer grams), but they showed very different resistance variation properties.…”

“…Thinner quartz crystal enables higher fundamental resonance frequency and higher mass sensitivity. Moreover, the inhomogeneity of the film coated on quartz sensor will affect the actual viscosity effect in liquid . The mass sensitivity and the resonator vibration amplitude are both normal distribution with the center of quartz sensor as the origin .…”