Heterogeneity in MacMullin Number of Li-Ion Battery Electrodes Studied by Means of an Aperture Probe

Liu, Baichuan; Prugue, Kayci; Nikpour, Mojdeh; Ward, Kristopher R.; Mazzeo, Brian A.; Wheeler, Dean R.

doi:10.1149/1945-7111/ac4542

Cited by 3 publications

(14 citation statements)

References 41 publications

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“…In the limit that σ ? k, which is consistent with experimental data of graphite anodes including the EnPower anode, 25,33 the electronic potential in the electrode becomes effectively constant (φ 1 = 0) for both upper and lower layers. Given that the ionic potential is independent of the azimuth, the model only needs to be solved in 2 dimensions, r and z.…”

Section: Model Developmentsupporting

confidence: 89%

“…To distinguish the two types of 2D transmission-line models, we name the 2D transmission-line model developed in previous publication 33 the single-layer 2D transmission-line model (singlelayer 2D TLM), and we name the 2D transmission-line model with step-function configuration the dual-layer 2D transmission-line model (dual-layer 2D TLM). The same notation is also applied to 1D transmission-line models.…”

Section: Model Developmentmentioning

confidence: 99%

“…Dual-layer transmission-line model development.-The impedance model is similar to the one developed in the previous publication, 33 using the cylindrical coordinate system (see Fig. 4).…”

Section: Model Developmentmentioning

confidence: 99%

“…Based on the same principle as the blocking-electrolyte method, we developed a technique called the aperture probe method to conduct the localized MacMullin number measurement at millimeter length scale. 33 During the localized measurement, the current is confined by the aperture to a small area on the separator side of the electrode. Then, a 2-dimensional transmission-line model is used to invert the impedance data and obtain the MacMullin number in the vicinity of the probe.…”

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confidence: 99%

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Direct Measurements of Ionic Transport Behavior of Dual-Layer Porous Electrodes

Liu

James

Hamedi

et al. 2023

J. Electrochem. Soc.

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To improve power and cycling performance of lithium-ion batteries, dual-layer or porosity-gradient electrodes have been proposed. By using a higher porosity close to the separator, the intention is to improve ion transport where it is most needed. Here, MacMullin numbers of two dual-layer anode samples are tested using an impedance measurement technique developed previously. To characterize the microstructure of each layer independently, we developed an improved transmission-line model that accounts for each layer's properties. Virtual experiments in which impedance measurements were simulated using COMSOL Multiphysics were used to examine and improve the accuracy of experimental inversion process. The results for the two dual-layer anodes studied show that MacMullin numbers follow expected trends, though the anodes are quite different from each other.

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Section: Model Developmentsupporting

confidence: 89%

Section: Model Developmentmentioning

confidence: 99%

“…Dual-layer transmission-line model development.-The impedance model is similar to the one developed in the previous publication, 33 using the cylindrical coordinate system (see Fig. 4).…”

Section: Model Developmentmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Direct Measurements of Ionic Transport Behavior of Dual-Layer Porous Electrodes

Liu

James

Hamedi

et al. 2023

J. Electrochem. Soc.

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“…The pseudo‐3D (P3D) model is developed in COMSOL multiphysics, with parameters and equations reported in the Supporting Information. To induce in‐plane heterogenous utilization, the electrolyte tortuosity is assumed to vary in accordance with work from Liu et al [ 28 ] and details are shown in the Supporting Information. This heterogeneous tortuosity is implemented in both the cathode and anode domains.…”

Section: Methodsmentioning

confidence: 99%

Dynamic In‐Plane Heterogeneous and Inverted Response of Graphite to Fast Charging and Discharging Conditions in Lithium‐Ion Pouch Cells

et al. 2023

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Solutions for improving fast charging of lithium‐ion batteries have largely focused on alleviating through‐plane lithiation gradients while little is understood about in‐plane heterogeneities and how to resolve them. Herein, high‐speed synchrotron X‐ray diffraction (XRD) resolves graphite lithiation spatially and temporally during 6 C charging and 2 C discharging. At every point during operation, considerable differences in the state of lithiation across the pouch cell are present. Some regions are more responsive to operation than others, reaching full lithiation early during charge and full delithiation during discharge. Other regions within the cell never fully delithiate during discharge, despite a prolonged voltage hold at 2.8 V. Using time‐resolved XRD data, the calculated local current density (mA cm−2) at the graphite surface shows an unexpected occurrence of local inverted current densities where regions of graphite are observed to delithiate during charging and lithiate during discharging. A pseudo‐3D model is developed for the graphite electrode with spatially varying microstructural tortuosity to show how microstructural heterogeneity could influence spatial charge dynamics. The model could not predict the complex in‐plane charge behavior observed within the cell. Consequently physics‐based charging protocols based on homogeneous electrode assumptions may underestimate the local variations in charge dynamics and occurrence of lithium plating.

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Li-ion Electrode Microstructure Evolution during Drying and Calendering

et al. 2022

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The drying process of electrodes might seem to be a simple operation, but it has profound effects on the microstructure. Some unexpected changes can happen depending on the drying conditions. In prior work, we developed the multiphase-smoothed-particle (MPSP) model, which predicted a relative increase in the carbon additive and binder adjacent to the current collector during drying. This motivated us to undertake the present experimental investigation of the relationship between the drying rate and microstructure and transport properties for a typical anode and cathode. Specifically, the drying rate was controlled by means of temperature for both an NMC532 cathode and graphite anode. The material distribution was analyzed using a combination of cross-section SEM images and the energy-dispersive X-ray spectroscopy elemental maps. The binder concentration gradients were developed in both the in- and through-plane directions. The through-plane gradient is evident at a temperature higher than 150 °C, whereas the in-plane variations resulted at all drying temperatures. The measurements identified an optimum temperature (80 °C) that results in high electronic conductivity and low ionic resistivity due to a more uniform binder distribution. Trends in transport properties are not significantly altered by calendering, which highlights the importance of the drying rate itself on the assembled cell properties.

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Heterogeneity in MacMullin Number of Li-Ion Battery Electrodes Studied by Means of an Aperture Probe

Cited by 3 publications

References 41 publications

Direct Measurements of Ionic Transport Behavior of Dual-Layer Porous Electrodes

Direct Measurements of Ionic Transport Behavior of Dual-Layer Porous Electrodes

Dynamic In‐Plane Heterogeneous and Inverted Response of Graphite to Fast Charging and Discharging Conditions in Lithium‐Ion Pouch Cells

Li-ion Electrode Microstructure Evolution during Drying and Calendering

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