Three-dimensional reconstruction of a composite cathode for lithium-ion cells

Ender, Moses; Joos, Jochen; Carraro, Thomas; Ivers-Tiffée, Ellen

doi:10.1016/j.elecom.2010.12.004

Cited by 145 publications

(133 citation statements)

References 15 publications

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“…140 Joos et al 141 used this tool to investigate the representative volume element of tortuosity of an SOFC cathode for both phases, namely the pore and the mixed ionic-electronic conducting LSCF phase. In total, the RVE of porosity, volume specific surface area and tortuosity were calculated for three separate volumes, of which the latter one is presented in Figure 10.…”

Section: Mesh Based Calculation Methodsmentioning

confidence: 99%

Tortuosity in electrochemical devices: a review of calculation approaches

Tjaden

Brett

Shearing

2016

International Materials Reviews

211

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: Mesh Based Calculation Methodsmentioning

confidence: 99%

Tortuosity in electrochemical devices: a review of calculation approaches

Tjaden

Brett

Shearing

2016

International Materials Reviews

211

188

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“…LIB cathode reconstructions have been used to investigate intrinsic features of the microstructure, such as porosity and tortuosity, 10-15 focusing on the solid particles only. Later, researchers differentiated between particle, binder, and electrolyte, 16,17 getting a better grasp of the effective material properties.More recent studies have used these reconstructed geometries to perform detailed species transport and electrochemical simulations, typically in a finite volume framework. [18][19][20] clearly demonstrated how the complex shape of reconstructed particles changed the electrochemical behavior over more simplistic spherical representations.…”

mentioning

confidence: 99%

A Framework for Three-Dimensional Mesoscale Modeling of Anisotropic Swelling and Mechanical Deformation in Lithium-Ion Electrodes

Roberts

Brunini

Long

et al. 2014

J. Electrochem. Soc.

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Lithium-ion battery electrodes rely on a percolated network of solid particles and binder that must maintain a high electronic conductivity in order to function. Coupled mechanical and electrochemical simulations may be able to elucidate the mechanisms for capacity fade. We present a framework for coupled simulations of electrode mechanics that includes swelling, deformation, and stress generation driven by lithium intercalation. These simulations are performed at the mesoscale, which requires 3D reconstruction of the electrode microstructure from experimental imaging or particle size distributions. We present a novel approach for utilizing these complex reconstructions within a finite element code. A mechanical model that involves anisotropic swelling in response to lithium intercalation drives the deformation. Stresses arise from small-scale particle features and lithium concentration gradients. However, we demonstrate, for the first time, that the largest stresses arise from particle-to-particle contacts, making it important to accurately represent the electrode microstructure on the multi-particle scale. Including anisotropy in the swelling mechanics adds considerably more complexity to the stresses and can significantly enhance peak particle stresses. Shear forces arise at contacts due to the misorientation of the lattice structure. These simulations will be used to study mechanical degradation of the electrode structure through charge/discharge cycles. Capacity fade in lithium-ion batteries (LIB) is potentially influenced by a large number of mechanisms, 1 one of which is mechanical degradation of the electrode microstructure. Both electrodes experience mechanical deformation, and in this paper, we focus on the cathode of the lithium-cobalt-oxide (LiCoO 2 , or LCO) system.2 Cathodes are made up of a three-dimensional (3D), percolating, bicontinuous network consisting of solid, electroactive particles, a polymer binder, and electrolyte. The bicontinuous nature of this network is critical, as Li + ions must be able to transport from the anode, through the separator, to any particle in the cathode via the electrolyte. At the same time, electrons must be able to transport through the solid particle network to the current collector. Any particle that becomes physically isolated from, or poorly connected to, its network or from the electrolyte does not contribute to the electrochemical reactions, resulting in capacity loss.One way in which particles may become disconnected from their network is by the swelling, shrinking, and fracture mechanisms that may occur through many charge-discharge cycles.3-6 As lithium intercalates into the electrode particles, the crystal lattice spacing may change either isotropically or anisotropically. For LiCoO 2 cathodes in particular, the crystal lattice shrinks anisotropically upon lithium intercalation 7,8 As was measured by Reimers and Dahn, 7 and later in more detail by Amatucci et al., 8 the lattice shrinkage upon lithiation can be quite significant and is anisotropic in n...

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“…This procedure was completed within ~ 4 min after terminating the charge, significantly faster than typical voltage relaxation times. 91,92 Because LFP particles are not in direct contact with one another in typical electrode microstructures (as shown recently by tomographic reconstruction 93 ), further equilibration between LFP particles is unlikely after removing the electrolyte. We recognize, however, that lithium can re-distribute within each particle without external mass transport (e.g., a solid-solution particle undergoes phase separation 71,73 ).…”

Section: Experimental Methodsmentioning

confidence: 90%

Probing surface & transport phenomena in energy materials under operating conditions.

Chueh¹,

Marquez²,

McCarty³

et al. 2012

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Efficient conversion of energy between sunlight, chemical bonds, and electricity is crucial towards a closed-loop energy cycle. We have applied synchrotron-based Xray spectroscopy and microscopy techniques to investigate the conversion of electricity to and from chemical bonds in fuel cells, electrolyzers, and intercalation batteries. Using these techniques, we have tracked the motions from electrons, oxygen ions, and lithium ions at interfaces and in the bulk of electrochemically-active materials. New insights in gas-solid surface electrochemistry, and solid-solid phase transformation are guiding the development of better materials for a wide range of energy conversion and storage devices. 4 ACKNOWLEDGMENTS

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Three-dimensional reconstruction of a composite cathode for lithium-ion cells

Cited by 145 publications

References 15 publications

Tortuosity in electrochemical devices: a review of calculation approaches

Tortuosity in electrochemical devices: a review of calculation approaches

A Framework for Three-Dimensional Mesoscale Modeling of Anisotropic Swelling and Mechanical Deformation in Lithium-Ion Electrodes

Probing surface & transport phenomena in energy materials under operating conditions.

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