Electrochemical cells like batteries are complex heterogeneous layered structures, and each layer is frequently porous. This brings out central questions like; how many and which interfaces play a role in energy conversion? And, how do we define and measure this role? In other words, how do we describe the interplay between the various fluxes of heat, mass and charge in each layer? Most often...
Numerous experimental and theoretical studies, conducted from the atomic to the field scales, have demonstrated that macroscopic properties of smectite clays, such as ion diffusivity and swelling potential, are governed by the underlying hierarchical organization of pores, and by the morphology and permanent charge deficit of the montmorillonite layers that form its finest fraction....
Two-phase transport plays a major role to improve peak power density at low Pt loading in polymer electrolyte membrane fuel cells (PEMFCs). In this regard, optimization of thin porous media of the membrane electrode assembly (MEA) plays an important role to alleviate cathode flooding for enhanced oxygen diffusivity, while maintaining good membrane hydration for high ionic conductivity [1]. In...
Simultaneous neutron and X-ray tomography (NeXT) harnesses the benefits of both X-rays and neutrons to enable truly correlative and high-contrast imaging of a wide range of multi-material systems. NeXT is especially well-suited to study fluid flow and morphological characteristics in porous media, such as porous layers found in electrochemical devices. In this study, we utilize operando NeXT...
We consider a classic problem of acoustic waves reflection at the interface between two visco-poroelastic saturated materials.
Decomposing the wavefield into downgoing and upgoing plane waves, we write down explicitely the polarisations for all waves (P-, Biot-, Sv- et Sh-waves). In analogy with the elastic case, the reflection-transmission-conversion (RTC) coefficients can then be obtained...
In this work, we present an efficient 2D/3D Finite Element implementation to simulate the propagation of elastic waves, in the time domain, in porous media. The input data for our solution are binary images, of which each voxel can be solid or pore. We consider regular structured meshes composed of cubic elements, compatible with the image-based approach. Our implementation takes advantage of...
Electrical properties play an important role in the study of rock media. Estimating effective electrical properties of materials by means of laboratory testing is usually time-consuming and does not provide a complete understanding of the material microstructure. On the other hand, it is well known that numerical homogenization in conjunction with micro-computed tomographic images allows an...
Sintering of ceramics consists in the formation of bulk materials from disperse partcicle systems (unconsolidated powder compacts). It always involves strengthening (i.e. due to the formation and growth of sinter necks between the particles or grains) and usually (but not always) also densification (i,e. the reduction of possibly complete elimination of pores) and coarsening (grain growth)....
