Characterization of the 3-dimensional microstructure of a graphite negative electrode from a Li-ion battery

Shearing, Paul R.; Howard, Lauren E.; Jørgensen, Peter Stanley; Brandon, Nigel P.; Harris, Stephen J.

doi:10.1016/j.elecom.2009.12.038

Cited by 271 publications

(188 citation statements)

References 25 publications

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“…Hence, the tortuosity itself does not give a full picture of the microstructure and the performance of the analysed sample, but has to be evaluated with respect to other microstructural characteristics. 111,151 Also, care must be taken when applying purely continuum based models which do not account for Knudsen diffusion effects, such as the heat flux simulation. Such simplifications might cause visible differences between experimental and simulation based results.…”

Section: Discussionmentioning

confidence: 99%

“…It can be used to explain regions of increased charge transfer, areas of low fuel conversion, uneven charging or catalyst utilisation and degradation. Shearing et al 111 extended the approach of spatial distribution of geometric tortuosity to include additional characteristics such as volume specific surface area (VSSA) and porosity. A reconstructed graphite Li-ion battery electrode was segmented into a mosaic of equally sized volumes.…”

Section: Figure 6: Geometric Tortuosity Histogram Achieved By Fmm Formentioning

confidence: 99%

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Tortuosity in electrochemical devices: a review of calculation approaches

Tjaden

Brett

Shearing

2016

International Materials Reviews

200

188

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The tortuosity of a structure plays a vital role in the transport of mass and charge in electrochemical devices. Concentration polarisation losses at high current densities are caused by mass transport limitations and are thus a function of microstructural characteristics. As tortuosity is notoriously difficult to ascertain, a wide and diverse range of methods has been developed to extract the tortuosity of a structure. These methods differ significantly in terms of calculation approach and data preparation techniques. Here, we review tortuosity calculation procedures applied in the field of electrochemical devices to better understand the resulting values presented in the literature. Visible differences between calculation methods are observed, especially when using porosity-tortuosity relationships and when comparing geometric and flux based tortuosity calculation approaches.

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Section: Discussionmentioning

confidence: 99%

Section: Figure 6: Geometric Tortuosity Histogram Achieved By Fmm Formentioning

confidence: 99%

Tortuosity in electrochemical devices: a review of calculation approaches

Tjaden

Brett

Shearing

2016

International Materials Reviews

200

188

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“…This type of transport is of importance for modern energy conversion technologies, which attempt to harvest green energy sources (e.g. transport of charged species in electrodes of fuel cells, solar cells or batteries) [8][9][10][11][12]. Thereby, it is necessary to understand which microstructural features influence the charge-transport, to improve the electrode performance by a controlled optimization of the microstructure.…”

Section: Introductionmentioning

confidence: 99%

The influence of constrictivity on the effective transport properties of porous layers in electrolysis and fuel cells

et al. 2012

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The aim of the present investigation is to define microstructure parameters, which control the effective transport properties in porous materials for energy technology. Recent improvements in 3D-imaging (FIB-nanotomography, synchrotron X-ray tomography) and image analysis (skeletonization and graph analysis, transport simulations) open new possibilities for the study of microstructure effects. In this study, we describe novel procedures for a quantitative analysis of constrictivity, which characterizes the so-called bottleneck effect. In a first experimental part, methodological tests are performed using a porous (La,Sr)CoO 3 material (SOFC cathode). The tests indicate that the proposed procedure for quantitative analysis of constrictivity gives reproducible results even for samples with inhomogeneous microstructures (cracks, gradient of porosity). In the second part, 3D analyses are combined with measurements of ionic conductivity by impedance spectroscopy. The investigations are preformed on membranes of electrolysis cells with porosities between 0.27 and 0.8. Surprisingly, the tortuosities remain nearly constant (1.6) for the entire range of porosity. In contrast, the constrictivities vary strongly and correlate well with the measured transport resistances. Hence, constrictivity represents the dominant microstructure parameter, which controls the effective transport properties in the analysed membrane materials. An empirical relationship is then derived for the calculation of effective transport properties based on phase volume fraction, tortuosity, and constrictivity.

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“…A variety of tomographic methods have been applied to battery electrodes to better understand these complex heterogeneous microstructures by facilitating evaluation of porosity, tortuosity, and surface area, and to inform more realistic models of electrode function and failure. X-ray tomography has been used to non-destructively reconstruct composite electrodes [39,40] [42,43]. Clague et al converted this 3-D structure into a mesh for finite element (FE) simulation of stresses developing within the material as temperature increased.…”

Section: Chemical Structural and Morphologicalmentioning

confidence: 99%

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

et al. 2014

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Functional materials for energy conversion and storage exhibit strong coupling between electrochemistry and mechanics. For example, ceramics developed as electrodes for both solid oxide fuel cells and batteries exhibit cyclic volumetric expansion upon reversible ion transport. Such chemomechanical coupling is typically far from thermodynamic equilibrium, and thus is challenging to quantify experimentally and computationally. In situ measurements and atomistic simulations are under rapid development to explore how this coupling can be used to potentially improve both device performance and durability. Here, we review the commonalities of coupling between electrochemical and mechanical states in fuel cell and battery materials, illustrating with specific cases the progress in materials processing, in situ characterization, and computational modeling and simulation. We also highlight outstanding questions and opportunities in these applications -both to better understand the limiting mechanisms within the materials and to significantly advance the durability and predictability of device performance required for renewable energy conversion and storage.

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Characterization of the 3-dimensional microstructure of a graphite negative electrode from a Li-ion battery

Cited by 271 publications

References 25 publications

Tortuosity in electrochemical devices: a review of calculation approaches

Tortuosity in electrochemical devices: a review of calculation approaches

The influence of constrictivity on the effective transport properties of porous layers in electrolysis and fuel cells

Chemomechanics of ionically conductive ceramics for electrical energy conversion and storage

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