Mohammed B. EffatAssiut University · Department of Mechanical Engineering
Mohammed B. Effat
Ph.D. in Mechanical Engineering, HKUST, 2019
About
25
Publications
7,100
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
647
Citations
Citations since 2017
Introduction
I am an Assistant Professor in the Mechanical Engineering (ME) Department, Assiut University (AU), Egypt. Before joining AU, I got my Ph.D. from and worked as a postdoctoral fellow in ME department, Hong Kong University of Science & Technology (HKUST), Hong Kong. My research interests are in the areas of energy storage & water desalination. My research expertise includes thermal-fluids & electrochemical engineering, material science, continuum modeling, atomistic simulations, & data analysis.
Additional affiliations
September 2015 - August 2019
January 2009 - May 2015
Publications
Publications (25)
Lithium ion batteries (LIBs) are no doubt a primary power source for numerous applications around us. Therefore, it is intrinsic to be long lasting and safe during operation— two issues that are tackled by thermal management. The purpose of this article is to enable the reader to get an informative overview about thermal management and safety of LI...
With the advance of miniaturization technology, more and more electronic components are placed onto small electronic chips. This leads to the generation of high amounts of thermal energy that should be removed for the safe operation of these electronic components. Microchannel heat sinks, where electronic chips are liquid cooled instead of the conv...
Solar greenhouses can be considered as efficient places for biological CO2 capture and utilization if CO2 enrichment becomes a common practice there. As CO2 enrichment is applied only when greenhouses are closed, ventilated greenhouses––which represent a large percentage of greenhouses all over the world––cannot be considered for this practice. Con...
The suitability of a battery for a given application depends on its metrics for energy (W h kg⁻¹ and/or W h L⁻¹), power (W kg⁻¹ and/or W L⁻¹), cost ($ per kWh), lifetime (cycles and/or years), and safety. This paper provides a data-driven perspective explaining how material properties, cell design decisions, and manufacturing costs influence and co...
Electrochemical impedance spectroscopy (EIS) is used widely in electrochemistry. Obtaining EIS data is simple with modern electrochemical workstations. Yet, analyzing EIS spectra is still a considerable quandary. The distribution of relaxation times (DRT) has emerged as a solution to this challenge. However, DRT deconvolution underlies an ill-posed...
Li 2 OHCl is a promising solid-state electrolyte (SSE) for all-solid-state Li˗ion batteries thanks to its simple synthesis and low precursor costs. However, its low ionic conductivity is a challenge for its...
Electrochemical impedance spectroscopy (EIS) is a characterization technique used widely in electrochemistry. Obtaining EIS data is simple when modern electrochemical workstations are used; however, analyzing EIS spectra is still a considerable quandary. The distribution of relaxation times (DRT) has emerged as a solution to this challenge. Neverth...
BaFeO3−δ-derived perovskites are promising cathodes for intermediate temperature solid oxide fuel cells. The activity of these perovskites depends on the number of oxygen vacancies in their lattice, which can be tuned by cationic substitution. Our first-principle calculations show that Ag is a promising substitute for the Fe site, resulting in a re...
Rechargeable batteries with Li‐metal anodes and Ni‐rich LiNixMnyCozO2 (x + y + z = 1, NMC) cathodes promise high‐energy‐density storage solutions. However, commercial carbonate‐based electrolytes (CBEs) induce deteriorative interfacial reactions to both Li‐metal and NMC, leading to Li dendrite formation and NMC degradation. Moreover, CBEs are therm...
Lithium-rich antiperovskites (APs) have attracted significant research attention due to their ionic conductivity above 1 mS cm-1 at room temperature. However, recent experimental reports suggest that proton-free lithium-rich APs, such as Li3OCl, may not be synthesized using conventional methods. While Li2OHCl has a lower conductivity of about 0.1 m...
The oxygen evolution reaction (OER) is the bottleneck of many sustainable energy conversion systems, including water splitting technologies. The kinetics of the OER is generally sluggish unless precious metal-based catalysts are used. Perovskite oxides have shown promise as alternatives to these expensive materials. However, for several perovskites...
Li-ion batteries (LIBs) are the energy storage systems of choice for portable electronics and electric vehicles. Due to the growing deployment of energy storage solutions, LIBs are increasingly required to function safely and steadily over a broad range of operational conditions. However, the conventional electrolytes used in LIBs will malfunction...
In this article, we show that succinonitrile-based lithium metal batteries (SN-LMB) can cycle over 1000 times at 1 C and at room temperature with a coulombic efficiency (CE) of ~99.8% when low amounts of fluoroethylene carbonate (FEC) are added into SN. FEC loadings as low as 5 and 10 wt% (of SN and Li salt) are sufficient to overcome the polymeriz...
Electrochemical impedance spectroscopy (EIS) is a technique widely used to characterize electrochemical systems. While EIS is powerful and simple to use, interpreting EIS experiments is not a straightforward task. Equivalent circuits are by far the most commonly used EIS models. However, these circuits models are not unique. To overcome this issue,...
Li-metal batteries (LMBs) with composite polymer electrolytes (CPEs) have attracted considerable attention compared with conventional Li-ion batteries. However, the uncontrolled Li deposition and the flammability of CPEs are still pressing issues. In this article, a non-flammable CPE is fabricated. The CPE consists of a poly(vinylidene) matrix, Li6...
The dissolution of Mn ions from Mn-containing cathodes and the growth of Na dendrites are two critical issues that deteriorate the life time of Na batteries. In this work, we develop a novel solid-state composite-polymer-electrolyte based on a polyvinylidene fluoride matrix and Na3Zr2Si2PO12 fillers to simultaneously tackle these two problems. Elem...
The search for next-generation solid-state superionic conductors has attracted significant attention. Among Na superionic conductors, Na11Sn2PS12 has been reported to have a room temperature ionic conductivity of 1.4 mS/cm. In this study, we employ density functional theory to study the stability of Na11Sn2PS12 and further explore the substitution...
Solid-state batteries (SSBs) with Li7La3Zr2O12 (LLZO) ceramic oxide electrolytes are attracting significant interest because of LLZO's non-flammability, excellent ionic conductivity, electrochemical stability against Li metal anodes, and processability in air. However, the poor solid-solid contact between the electrolyte and the electrodes leads to...
Solid‐state batteries hold great promise because of their safety and high projected energy density. However, the sizeable interfacial resistance between the electrodes and the electrolyte of such batteries is a significant bottleneck in the development of this technology. In this work, we develop a Li6.4La3Zr1.4Ta0.6O12 (LLZTO) and polyvinylidene f...
Mixed ionic electronic conductors (MIECs) are materials able to conduct both ions and electrons and are used in many applications including solid oxide fuel cells, electrolyzers, and oxygen sensors. The performance of these materials can be assessed using electrical conductivity relaxation (ECR) technique. This technique is used to obtain two physi...
Electrochemical impedance spectroscopy (EIS) is a powerful electrochemical characterization technique used in scientific research and industry. Interpreting the EIS data correctly is the essential step to unravel the nature of the underlying physical processes happening inside the electrochemical system ( e.g. Li-ion battery) and to obtain the quan...
The distribution of relaxation times (DRT) is a fast-growing methodology that is used to interpret data obtained from electrochemical impedance spectroscopy (EIS) experiments. However, the DRT deconvolution is often difficult to interpret. We tackle this issue by framing the DRT problem within a Bayesian statistical framework. This is critically im...
Electrical Conductivity Relaxation (ECR) is an experimental procedure used to assess the chemical diffusion and reaction coefficients (i.e. Dchem and kchem) of mixed ionic electronic conductors (MIECs). The analytical model usually employed to fit the ECR data is based on linear physics. In fact, it is obtained from a linear partial differential eq...
This paper introduces the photosynthesis-stomatal conductance coupled model, well known and frequently used in the studies of vegetation-atmosphere interaction, to be incorporated into the studies of modeling greenhouses' microclimate. The use of this model, unlike many of other models in the literature, allows accurate modeling of stomatal conduct...
This paper investigates carbon dioxide enrichment in commercial greenhouses to improve CO 2 capture and utilization. The paper develops and numerically solves a mathematical model that simulates the CO 2 capturing process through the coupled-non steady-energy and mass species (CO 2 , H 2 O) balance equations in the greenhouse components. The model...
Questions
Questions (3)
Dear all,
Can you list to me few names of good and quick to use software for building complex materials for MD simulations using LAMMPS? The system I gonna model is a mixture/slurry composed of two ceramics and organic solvent. My experience in materials visualization is with VESTA, but looking to geometries LAMMPS can simulate, I feel there are many more powerful packages that can do such complex geometries in a quick manner.
Please let me know your suggestions.
Best regards
Dear all,
My question is about the correct arrangement of layers for making a slab model in VESTA for adsorption studies.
In the attachments 2 and 3, I tried to build two slab models from the perovskite material SrTiO3 (attachment 1) with two different terminations. I always get the arrangement of atomic layers that the bottom layer is identical to the uppermost layer (due to periodic boundary), and the first layer facing the vacuum (the one necessary for adsorption) is different than the bottom and uppermost layers.
My question is whether this ordering of layer is appropriate or; the bottom layer, the first layer facing the vacuum and the uppermost layer should be the same? If the later is the case, can you provide insight on how to do it in VESTA?
Best regards
Dear phonon expert,
I am new to phonon studies. I did my first study using the settings as below:
The material is Li anti-perovskite ionic conductor. Size of supercell: 3x3x3 (~11.5 A each direction) and is discretized using: M-P algorithm on a 2x2x2 grid. Functional used: GGA-PBE.
INCAR for Relaxation:
ALGO = Fast
EDIFF = 0.00675
ENCUT = 520
IBRION = 2
ICHARG = 1
ISIF = 3
ISMEAR = -5
ISPIN = 2
LORBIT = 11
LREAL = Auto
LWAVE = False
MAGMOM = 135*0.6
NELM = 100
NSW = 99
PREC = Accurate
SIGMA = 0.05
NPAR = 8
INCAR for Phonon:
PREC = Accurate
ENCUT = 500
IBRION = 8
EDIFF = 1.0e-08
IALGO = 38
ISMEAR = 0; SIGMA = 0.1
LREAL = .FALSE.
ADDGRID = .TRUE.
LWAVE = .FALSE.
LCHARG = .FALSE.
However, I got the results in the attached figure.
The k-path is
Γ—X|Y—Γ—Z|R—Γ—T|U—Γ—V|Γ—X'|Y'—Γ—Z'|R'—Γ—T'|U'—Γ—V'
and it is generated from:
In addition to the negative frequencies I got, I am surprised by that flat pattern of dispersion.
My questions are:
1) Does such flat pattern has any physical meaning? What is it? and if not, what could be the problem in my settings that lead to such strange pattern?
2) I know that the structure may not be dynamically stable and negative frequencies are OK in that case, but as the pattern I got is weired, I don't trust the negative frequencies as well. Is there any way I can check if negative frequencies are physically relevant or numerical issues?
Thanks in advance for your help!
