RVE generation and computational homogenization of structural battery electrolytes

The structural battery is multifunctional in the sense that it is able to carry mechanical loads, and at the same time store and deliver energy. This is made possible due to carbon fibers\u27 ability to act not only as structural reinforcement materials, but also as electrode components. While conventional batteries rely solely on liquid electrolyte to allow for ion transfer between the electrodes, structural batteries exploit the so-called structural battery electrolyte (SBE). The SBE consists of two continuous phases; a porous polymer skeleton and a liquid electrolyte. The role of the liquid electrolyte is to allow for ion transfer, while the porous polymer skeleton contributes to the mechanical properties. In short, the structural battery consists of carbon fibers (acting as electrodes) embedded in an SBE.In the first part of the thesis, we study the multifunctional performance of various SBE microstructures by performing virtual material testing on artificially generated Representative Volume Elements (RVEs). In particular, we obtain the effective ionic conductivity by solving a diffusion equation with Fick\u27s law, and the effective stiffness by assuming linear elasticity. The generated RVEs and the predicted performance are compared to experimental data.The second part covers the development of a multiscale modeling framework for electrochemically coupled ion transport in SBEs. After establishing the governing equations, we exploit Variationally Consistent Homogenization (VCH) to obtain a two-scale model. If the subscale RVE problem exhibits negligible transient effects for length scales relevant to the studied application, then an assumption of micro-stationarity can be introduced. This opens up for the possibility to devise a numerically efficient solution scheme for the macroscale problem that is based on a priori upscaling of the effective response. The procedure is demonstrated in a set of numerical examples, including validation toward a (single-scale) reference solution

Variationally consistent homogenization of electrochemical ion transport in a porous structural battery electrolyte

In this paper, we develop a multi-scale modeling framework for a multiphysics problem characterized by electro-chemically coupled ion transport in a Structural Battery Electrolyte (SBE). The governing equations of the problem are established by coupling Gauss law with mass conservation for each mobile species. By utilizing variationally consistent homogenization, we are able to establish a two-scale model where both the macro-scale and sub-scale equations are deduced from a single-scale problem. Investigations of the sub-scale RVE problem show that the transient effects are negligible for the length scales relevant to the studied application, which motivates the assumption of micro-stationarity. In the special case of linear constitutive response, we get a numerically efficient solution scheme for the macro-scale problem that is based on a priori upscaling. As a final step, we demonstrate the numerically efficient solution scheme by solving a 2D macro-scale problem using upscaled constitutive quantities based on a 3D RVE

Mucosal colonization of gastric endocrine tumors mimicking mixed neoplasms

Two cases of gastric tumors showing mixed composition of endocrine cell clusters and exocrine glands and originally diagnosed as mixed neoplasms are described. In both cases, the exocrine glandular component was restricted to the upper third of the neoplasms being consistently absent in areas of muscular wall invasion and, in case 2, in nodal metastases. These glands were in close anatomical contiguity with the glands of the overlying gastric mucosa or, in case 1, apparently derived from deep pouch-like invaginations of the mucosa. They showed either lack of dysplasia (case 1) or mild dysplasia (case 2) with a Ki67 proliferation index consistently lower than that of the intramucosal glands. The intratumoral glands presented intestinal metaplastic features confirmed by intense Cdx2 immunostaining that, conversely, was absent in the endocrine component of the tumors. The latter showed intense vesicular monoamine transporter 2 immunoreactivity consistent with its origin from the enterochromaffin-like cells of the gastric oxyntic mucosa. On the basis of these findings, it is proposed that the exocrine glands do not represent a true neoplastic component of the tumors. Although mucosal entrapment by the tumor cannot be ruled out, they more likely reflect a hitherto unrecognized mechanism of mucosal colonization of gastric endocrine tumors

Dataset for histopathological reporting of neuroendocrine neoplasms of the gastroenteropancreatic tract

The cancer datasets published by the Royal College of Pathologists (RCPath) are a combination of textual guidance, educational information and reporting proformas. The datasets enable pathologists to grade and stage cancers in an accurate, consistent manner in compliance with international standards and provide prognostic information, thereby allowing clinicians to provide a high standard of care for patients and appropriate management for specific clinical circumstances. This guideline has been developed to cover most common circumstances. However, we recognise that guidelines cannot anticipate every pathological specimen type and clinical scenario. Occasional variation from the practice recommended in this guideline may therefore be required to report a specimen in a way that maximises benefit to the patient

COMPARISION OF THREE DIGESTION METHODS FOR SOIL ARSENIC DETERMINATION. APPLICATION FOR HO CHI MINH CITY SOIL ARSENIC ANALYSIS

Joint Research on Environmental Science and Technology for the Eart

Finite Element Simulation of the Performance of a Structural Electrolyte

This contribution concerns the multi-scale and multi-physics finite element analysis of structural power composites, i.e. multifunctional composites with simultaneous load bearing and energy storing functionality. We are particularly interested in obtaining the effective macro-scale properties of the structural electrolyte by employing computational homogenization to capture the effects of micro-heterogeneities on the sub-scale. The sub-scale problem is defined by a statistical volume element that is numerically generated, and the effective properties are obtained by conducting virtual material testing on the synthetic microstructure

Computational modelling of structural batteries accounting for stress-assisted convection in the electrolyte

Structural batteries consist of carbon fibres embedded in a porous structural battery electrolyte (SBE), which is composed of two continuous phases: a solid polymer skeleton and a liquid electrolyte containing Li-salt. In this paper we elaborate on a computational modelling framework to study the electro-chemo-mechanical properties of such structural batteries while accounting for the combined action from migration as well as stress-assisted diffusion and convection in the electrolyte. Further, we consider effects of lithium insertion in the carbon fibres, leading to insertion strains. The focus is placed on how the convective contribution to the mass transport within the SBE affects the general electro-chemo-mechanical properties. The numerical results indicate that the convective contribution has only minor influence on the multifunctional performance when the mechanical loading is caused by constrained deformation of constituents during electro-chemical cycling. However, in the case of externally applied mechanical loading that causes severe deformation of the SBE, or when large current pulses are applied, the convective contribution has noticeable influence on the electro-chemical performance. In addition, it is shown that the porosity of the SBE, which affects the effective stiffness as well as the mobility and permeability, has significant influence on the combined mechanical and electro-chemical performance