Structural Changes in Alloy Anodes for Li-Ion Batteries

2018 ◽  
Author(s):  
Jacob N. Adams ◽  
Logan J. Ausderau ◽  
George J. Nelson
Keyword(s):  
Size Distribution ◽  
Structural Changes ◽  
Substantial Reduction ◽  
High Capacity ◽  
Continuous Phase ◽  
Microstructural Changes ◽  
Volumetric Expansion ◽  
Electrochemical Testing ◽  
Pristine Sample ◽  
Phase Size

Tin (Sn) alloy electrodes show great potential for advancing battery performance due to the high capacity of tin. To realize this potential, the volumetric expansion during the lithiation process must be mitigated. One means of mitigating volumetric expansion of tin is to alloy it with copper to create Cu6Sn5. Such alloy electrodes retain some of the high capacity of tin, while attempting to accommodate volumetric changes with the addition of the malleable copper. Lithiation and delithiation tests were conducted with the Cu6Sn5 pellet electrodes to produce microstructural changes at the electrode surface. To observe and quantify these microstructural changes, x-ray microtomography was performed on electrode samples after electrochemical testing. The microtomography data was reconstructed into a 3D image, segmented, and the continuous phase size distribution (PSD) of each electrode sample was analyzed. The electrodes lithiated to 0 V vs Li/Li+ and then delithiated to 0.2 V vs. Li/Li+ showed the most substantial reduction in overall PSD compared to the other samples. This suggests that full lithiation of the Sn present in the alloy electrodes followed by partial delithiation of the Li4.4Sn to Li2CuSn can cause substantial microstructural changes related to volume expansion on lithiation and structural collapse upon delithiation. The electrodes fully lithiated to 0 V vs Li/Li+ and not delithiated show a higher overall phase size distribution, including all solid phases, than the pristine sample and the electrode samples that were partially lithiated to 0.2 V vs. Li/Li+ and delithiated to 1.5 V vs. Li/Li+. The higher overall phase size distribution that is shown by the sample that was fully lithiated and not delithiated is evidence of the significant volumetric expansion of the Cu6Sn5 compound due to lithiation. During this process of volumetric expansion, the phase size distribution of the Cu6Sn5/Sn phase is shown to decrease. When the volumetric expansion of the lithiated electrode samples and the volumetric contraction of the delithiated electrode sample are considered together, it can be inferred that the microstructural changes that are observed, such as the decrease in phase size distribution of the Cu6Sn5/Sn phase, can be attributed to the volumetric expansion and contraction of the compound during the lithiation and delithiation process.

Cycling Induced Microstructural Changes in Alloy Anodes for Lithium-Ion Batteries

2021 ◽  
pp. 1-33
Author(s):  
George Nelson ◽  
Jacob N. Adams
Keyword(s):  
Lithium Ion Batteries ◽  
Volume Expansion ◽  
Active Material ◽  
Substantial Reduction ◽  
High Capacity ◽  
Lithium Ion ◽  
Ex Situ ◽  
Mechanical Degradation ◽  
Microstructural Changes ◽  
Volumetric Expansion

Abstract High-capacity electrochemical alloying materials, such as tin and tin-based alloys, present an opportunity for advancement of lithium-ion batteries. However, the destructive effects of volumetric expansion must be mitigated in order to sustain this high capacity during extended cycling. One way to mitigate these effects is by alloying Sn with more malleable metals to accommodate the strain related to severe volumetric expansion. Ex situ X-ray microtomography data of cycled Cu6Sn5 pellets was used to quantify the microstructural changes that occur during lithiation and delithiation. The microtomography data was segmented into three distinct phases to evaluate phase size distributions, specific surface area and tortuosity. Electrodes lithiated and then delithiated showed the most substantial reduction in overall phase sizes. This suggests that full lithiation of the Sn followed by partial delithiation of the Li4.4Sn to Li2CuSn can cause substantial microstructural changes related to volume expansion on lithiation and structural collapse upon delithiation. When considering other microstructural characteristics, this subset of the electrodes analyzed showed the highest tortuosity values. These results show that in addition to the mechanical degradation of the electrodes, excessive volume expansion can also influence transport networks in the active material and supporting phases of the electrode. While based on studies the active-inactive alloy Cu6Sn5 for lithium-ion battery applications, the insights obtained are expected to be applicable to other alloy electrodes and battery chemistries.

Chemical Kinetics in Dispersed-Phase Reactors

2003 ◽  
Vol 1 (1) ◽  
Author(s):  
Ben J McCoy ◽  
Giridhar Madras
Keyword(s):  
Size Distribution ◽  
Chemical Reaction ◽  
Chemical Engineering ◽  
Numerical Solutions ◽  
Continuous Phase ◽  
Reaction Engineering ◽  
Dispersed Phase ◽  
Mass Balances ◽  
Distribution Dynamics ◽  
Phase Size

Many chemical engineering processes occur under conditions when a dispersed phase undergoes fragmentation (breakup) and/or aggregation (coalescence). It is of considerable interest to model a chemical process that occurs at the interface and therefore depends on the evolving size distribution of the dispersed phase. We apply distribution kinetics to represent the evolution of the dispersed-phase size distribution for simultaneous fragmentation and coalescence. The continuous phase with dissolved reactant enters and exits a continuous-flow stirred-tank reactor. When the dispersed phase contained within the vessel satisfies a similarity solution, several rate expressions, including one for interphase mass transfer, that depend on mass moments of the size distribution allow analytical or simple numerical solutions. The solutions demonstrate how chemical reaction mass balances can be combined with distribution dynamics to extend chemical reaction engineering analysis.

scholarly journals Structural Changes in Israeli Family Farms: Long-Run Trends in the Farm Size Distribution and the Role of Part-Time Farming

Agriculture ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 518
Author(s):  
Ayal Kimhi ◽  
Nitzan Tzur-Ilan
Keyword(s):  
Size Distribution ◽  
Structural Changes ◽  
Farm Size ◽  
Farm Income ◽  
Higher Moments ◽  
Full Time ◽  
Family Farms ◽  
Income Sources ◽  
Part Time ◽  
The Mean

Israeli agriculture has experienced rapid structural changes in recent decades, including the massive exit of farmers, a resulting increase in average farm size, a higher farm specialization and a higher reliance on non-farm income sources. The higher farm heterogeneity makes it necessary to examine changes in the entire farm size distribution rather than the common practice of analyzing changes in the average farm size alone. This article proposes a nonparametric analysis in which the change in the distribution of farm sizes between two periods is decomposed into several components, and the contributions of subgroups of farms to this change are analyzed. Using data on Israeli family farms, we analyze the changes in the farm size distribution in two separate time periods that are characterized by very different economic environments, focusing on the different contributions of full-time farms and part-time farms to the overall distributional changes. We found that between 1971 and 1981, a period characterized by stability and prosperity, the farm size distribution has shifted to the right with relatively minor changes in higher moments of the distribution. On the other hand, between 1981 and 1995, a largely unfavorable period to Israeli farmers, the change in the distribution was much more complex. While the overall change in the size distribution of farms was smaller in magnitude than in the earlier period, higher moments of the distribution were not less important than the increase in the mean and led to higher dispersion of farm sizes. Between 1971 and 1981, the contributions of full- and part-time farms to the change in the size distribution were quite similar. Between 1981 and 1995, however, full-time farms contributed mostly to the growth in the average farm size, while the average farm size among part-time farms actually decreased, and their contribution to the higher dispersion of farm sizes was quantitatively larger. This highlights the need to analyze the changes in the entire farm size distribution rather than focusing on the mean alone, and to allow for differences between types of farms.

Effect of Shear and Water Cut on Phase Inversion and Droplet Size Distribution in Oil–Water Flow

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Mo Zhang ◽  
Ramin Dabirian ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Size Distribution ◽  
Droplet Size ◽  
Phase Inversion ◽  
Droplet Size Distribution ◽  
Continuous Phase ◽  
Dispersed Phase ◽  
Water Emulsion ◽  
Inversion Region ◽  
Oil Water ◽  
Water Cut

Oil–water dispersed flow occurs commonly in the petroleum industry during the production and transportation of crudes. Phase inversion occurs when the dispersed phase grows into the continuous phase and the continuous phase becomes the dispersed phase caused by changes in the composition, interfacial properties, and other factors. Production equipment, such as pumps and chokes, generates shear in oil–water mixture flow, which has a strong effect on phase inversion phenomena. The objective of this paper is to investigate the effects of shear intensity and water cut (WC) on the phase inversion region and also the droplet size distribution. A state-of-the-art closed-loop two phase (oil–water) flow facility including a multipass gear pump and a differential dielectric sensor (DDS) is used to identify the phase inversion region. Also, the facility utilizes an in-line droplet size analyzer (a high speed camera), to record real-time videos of oil–water emulsion to determine the droplet size distribution. The experimental data for phase inversion confirm that as shear intensity increases, the phase inversion occurs at relatively higher dispersed phase fractions. Also the data show that oil-in-water emulsion requires larger dispersed phase volumetric fraction for phase inversion as compared with that of water-in-oil emulsion under the same shear intensity conditions. Experiments for droplet size distribution confirm that larger droplets are obtained for the water continuous phase, and increasing the dispersed phase volume fraction leads to the creation of larger droplets.

Microstructural Changes Induced during Hydrogen Charging Process in Stainless Steels with and without Nitrided Layers

2012 ◽  
Vol 186 ◽  
pp. 305-310 ◽  
Author(s):  
Bartosz Gołębiowski ◽  
Wiesław Świątnicki
Keyword(s):  
Hydrogen Embrittlement ◽  
Glow Discharge ◽  
Stainless Steels ◽  
Structural Changes ◽  
High Stress ◽  
High Concentration ◽  
Two Phase ◽  
Microstructural Changes ◽  
Hydrogen Charging ◽  
Expanded Austenite

The purpose of this study is to analyze the effect of glow discharge nitriding on hydrogen degradation of two types of steels: two-phase austenitic-ferritic and single-phase austenitic. The nitriding process resulted in formation of surface layers composed of expanded austenite (S phase), and in the case of two-phase steel of expanded austenite and expanded ferrite. Microstructural changes occurring under the influence of hydrogen on steels without and with nitrided layers were investigated with the use of scanning (SEM) and transmission (TEM) electron microscopy techniques. It was shown that the density of cracks formed during cathodic hydrogen charging is higher on the surface of the non-nitrided steels compared to the nitrided steels after identical hydrogen charging process. Moreover in non nitrided steel hydrogenation leads to considerable increase of dislocation density, which results from the high concentration of hydrogen absorbed to the steel during its cathodic charging. This leads in turn to high stress concentration and local embrittlement giving rise to cracks formation. Conversely nitriding reduces the absorption of hydrogen and prevents structural changes resulting in hydrogen embrittlement. The conducted studies show that glow discharge nitriding can be used to increase resistance to hydrogen embrittlement of austenitic and austenitic ferritic stainless steels.

Dissolution and precipitation reactions during acidic fluid percolation through different limestone samples

2020 ◽  
Author(s):  
Linda Luquot
Keyword(s):  
Diffusion Coefficient ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Transport Properties ◽  
Size Distribution ◽  
High Capacity ◽  
Co2 Injection ◽  
Geometrical Parameters ◽  
Calcite Dissolution ◽  
Geological Formation

<p>CO2 sequestration in deep geological formation is considered an option to reduce CO2 emissions in the atmosphere. After injection, the CO2 will slowly dissolve into the pore water producing low pH fluids with a high capacity for dissolving carbonates. Limestone rock dissolution induces geometrical parameters changes such as porosity, pore size distribution, or tortuosity which may consequently modify transport properties (permeability, diffusion coefficient). Characterizing these changes is essential for modelling flow and CO2 transport during and after the CO2 injection. Indeed, these changes can affect the storage capacity and injectivity of the formation.</p><p>Very few published studies evaluate the transport properties changes (porosity, permeability, pore size distribution, diffusion coefficient) due to fluid-rock interactions (dissolution and/or precipitation).</p><p>Here we report experimental results from the injection of acidic fluids (some of them equilibrated with gypsum) into limestone core samples of 25.4 mm diameter and around 25 mm length. We studied two different limestone samples: one composed of 73% of calcite and 27% of quartz, and the second one of 100% of dolomite. Experiments were realized at room temperature. Before and after each acidic rock attack, we measure the sample porosity, the diffusion coefficient and the pore size distribution.</p><p>We also imaged the 3D pore network by X-ray microtomography to evaluate the same parameters. During percolation experiments, the permeability changes are recorded and chemical samples taken to evaluate calcite dissolution and gypsum precipitation. Several dissolution/precipitation-characterization cycles are performed on each sample in order to study the evolution and relation of the different parameters.</p><p>These experiments show different dissolution regimes depending of the fluid acidity and of the</p><p>limestone samples in particular the initial local heterogeneity, and pore size distribution.</p>

The Influence of Microstructures on the Thermal Conductivity of Polycrystalline UO2

2016 ◽  
Author(s):  
Enze Jin ◽  
Chen Liu ◽  
Heming He
Keyword(s):  
Thermal Conductivity ◽  
Finite Element Method ◽  
Grain Size ◽  
Finite Element ◽  
Pore Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Structural Changes ◽  
Property Changes ◽  
Design Guidance

The thermal conductivity is one of the most important properties for UO2. The influences of microstructure are especially important for UO2 due to the severe structural changes under irradiation conditions. In this study, we have investigated the thermal conductivity of UO2 with different microstructures using Finite Element Method. The thermal conductivity increases with increasing grain size. The grain size distribution has obvious influence on the thermal conductivity especially when there are pores in the polycrystal. The influences of porosity and pore size are very sensitive to the position of the pores. The results obtained in this study are useful for prediction of property changes of UO2 fuel in pile and important to gain some design guidance to tune the properties through the control of the microstructure.

scholarly journals Plasma p tau 181 levels is associated with white matter microstructural changes in across the Alzheimer’s disease stages

2020 ◽  
Author(s):  
Fardin Nabizadeh ◽  
Seyed Behnamedin Jameie ◽  
Saghar Khani ◽  
Aida Rezaei ◽  
Fatemeh Ranjbaran ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
White Matter ◽  
Behavioral Problems ◽  
Structural Changes ◽  
Cognitive Impairments ◽  
Mean Diffusivity ◽  
Region Of Interest ◽  
Diagnostic Procedures ◽  
Microstructural Changes

Abstract Alzheimer’s Disease (AD) is characterized by cognitive impairments and memory difficulties, which hinder daily activities and lead to personal and behavioral problems. In recent years, blood-based biomarkers like plasma phosphorylated tau protein at threonine 181 (p tau 181) emerged as new tools and showed sufficient power in detecting AD patients from healthy people. Here we investigate the correlation between p tau 181 and white matter microstructural changes in AD. We add 41 patients diagnosed with Alzheimer’s, 119 patients with mild cognitive impairments and 43 healthy controls with baseline plasma p tau 181 level and DTI values for each region of interest from the ADNI database. The analysis revealed that the plasma level of p tau 181 could predict changes of MD (Mean Diffusivity), RD (Radial Diffusivity), DA (Axial Diffusivity) and FA (Fractional Anisotropy) parameters in widespread regions and there is a significant association between white matter pathway alteration in different regions and p tau 181 plasma measurements within each group. In conclusion, our findings showed that plasma p tau 181 levels are associated with cellular and molecular changes in AD, which enhance the biomarkers for diagnostic procedures and support the application of plasma p tau 181 as a biomarker for white matter changes and neurodegeneration. Longitudinal studies are also necessary for proving the efficacy of these biomarkers and predicting the role in structural changes.

scholarly journals Plasma p tau 181 are associated with white matter microstructural changes in Alzheimer’s disease

2020 ◽  
Author(s):  
Fardin Nabizadeh ◽  
Seyed Behnamedin Jameie ◽  
Saghar Khani ◽  
Aida Rezaei ◽  
Niloofar Deravi
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
White Matter ◽  
Structural Changes ◽  
Cognitive Impairments ◽  
Mean Diffusivity ◽  
Region Of Interest ◽  
Diagnostic Procedures ◽  
Microstructural Changes ◽  
Sufficient Power

Abstract Alzheimer’s Disease (AD) is characterized by cognitive impairments and memory difficulties, which cause daily activities, personal and behavioural problems. In recent years blood-based biomarkers like plasma phosphorylated tau protein at threonine 181 (p tau 181) emerged as new tools and showed a sufficient power in detecting AD patients from healthy people. Here we investigate the correlation between p tau 181 and white matter microstructural changes in AD. We add 41 Alzheimer diagnosed patients, 155 participants with mild cognitive impairments and 43 healthy controls with baseline plasma p tau 181 level and DTI values for each region of interest from the ADNI database. The analysis revealed that the plasma level of p tau 181 could predict changes of MD( Mean Diffusivity), RD(Radial Diffusivity), DA(Axial Diffusivity) and FA(Fractional Anisotropy) parameters in widespread regions and there is a significant association between white matter pathways alteration in different regions and p tau 181 plasma measurement within each group. In conclusion, our findings showed that plasma p tau 181 levels are associated with cellular and molecular changes in AD, which enhance this biomarker's for diagnostic procedures and support the application of plasma p tau 181 as a biomarker for white matter changes and neurodegeneration. Longitudinal studies are also necessary to prove the efficacy of these biomarkers and predicting role in structural changes.

scholarly journals Alternative Procedures for Estimating the Size Distribution of Farms

1980 ◽  
Vol 9 (2) ◽  
pp. 36-40
Author(s):  
R. N. Stavins ◽  
B. F. Stanton
Keyword(s):  
New York ◽  
World War Ii ◽  
Size Distribution ◽  
Milk Production ◽  
Structural Changes ◽  
New York State ◽  
World War ◽  
Milk Supply ◽  
Functional Forms ◽  
Alternative Procedures

Changes in the number and size distribution of dairy farms in the Northeast have come rapidly in the years since World War II. The objective of this study was to examine some of the newer methods of forecasting changes in this size distribution and ascertain the gains, if any, associated with these methods. Different formulations using Markov processes were compared with simple trend analyses and various functional forms in making projections. During the twenty-year period between 1958 and 1977 the number of farms delivering milk to plants in New York State decreased from slightly more than 45,800 to 16,500, a net decrease of approximately 64 percent. Over the same twenty-year period, annual milk production fluctuated between 9.8 and 11.0 billion pounds with a peak in 1965 and a low point in 1973. During the last five years, 1975–79, the number of farms delivering milk has continued to decline but milk production the the State has increased yearly and is expected to reach an all-time high in 1980. Such structural changes in the dairy industry have stimulated continued interest in problems of milk supply response and future variations in the size distribution of farms.

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