bluuebunny/crossref_metadata_2025 huggingface dataset:
(Digital Presentation) On the Effect of Sizing on Electrochemical Response and Localized Corrosion Behavior of Alumix 123 P/M Alloy
Authors: Valizade Nima , Judge William , Jarjoura George , Kipouros Georges
Published: November 2022

Powder metallurgy (PM) as an additive technique for fabricating parts has been used by many industries such as automotive, aerospace, and medical. However, it has been centered mostly around automotive industry which has benefited from large volume production, low cost, and near-net-shape manufacturing that comes with PM. High demand for producing fuel-efficient and light vehicles in automotive industry provides a driving force for extensive research activity on PM of aluminum alloys. Among different aluminum alloys, PM of 2xxx series are among the best choices due to their good sinterability and mechanical response. But industrial PM parts need post processing treatments such as sizing to meet the real-world applications. While sizing is widely used in industry to provide tighter tolerance, it can also help improving density, fatigue behavior, yield strength, and hardness. But there were very few studies on the effect of sizing on electrochemical response. In this study we produced Alumix 123 PM alloy using a press-and-sinter process and then sizing was applied on some of the samples to compare their long-term electrochemical behavior. The changes in the surface profile and roughness of the samples were investigated using confocal laser scanning microscopy. Electrochemical impedance spectroscopy (EIS) as a powerful technique for investigating long-term electrochemical behavior has been used to find the effect of sizing on corrosion response of Alumix 123 PM. In addition, effect of sizing on localized corrosion and pitting tendency was thoroughly discussed using electrochemical polarization results, scanning electron microscope images, and EIS outcomes.
Corrosion of Ru-Free Ni-Fe-Cr-Mo-W-X Multi-Principal Element Alloys
Authors: Panindre Anup , Khalifa Yehia , Colijn Hendrik , Taylor Christopher , Frankel Gerald S.
Published: November 2022

In this study, the passivity and localized corrosion of single- and multi-phase Ru-free Ni-Fe-Cr-Mo-W-X (X= Mn, Al, and Cu) multi-principal element alloys (MPEAs) were studied using AC and DC electrochemical methods. While each alloy was found to resist localized pitting corrosion at ambient temperature, X-ray photoelectron spectroscopy of passivated alloy specimen surfaces revealed constituent elements to dissolve in a non-congruent manner. Heat treatment of the single-phase alloys at 800 °C to promote precipitation of hard, strength-enhancing secondary phases resulted in the formation of Cr,Mo-rich σ-type phases in varying volume fractions. Copious in-grain precipitation and several metastable phases were observed in the Al-containing MPEA. This phase transformation increased the hardness of the alloy from 180 HV to 340 HV. After the aging heat treatment, the MPEAs containing Al, Mn and Cu became susceptible to breakdown at the matrix/precipitate interface at ambient temperatures.
(Invited) Slug-Flow Manufacturing of Nickel-Cobalt-Manganese-Oxide Cathode Particles for Lithium-Ion Batteries
Authors: Gupta Ram B. , Jiang Mo , Mou Mingyao , Patel Arjun , Mugumya Jethrine H. , Mallick Sourav , Lopez Herman , Paranthaman Mariappan
Published: November 2022

With expanding demands of lithium-ion batteries in portable electronic devices (e.g., smartphones, tablet PCs) and environmental-friendly vehicles (e.g., electric and/or hybrid vehicles), it is important to further improve safety, extend battery life, increase charge capacity, and reduce cost. A key missing component is effective and efficient manufacturing of complex active cathode materials at needed scales, such as nickel-cobalt-manganese (NCM) oxide microparticles with layered structures. Specifically, the material microparticle quality and uniformity have been difficult to control within the current reactors, thus extra correction procedures are needed, which risk product quality and reduce process efficiency. This study examines the innovative slug-flow continuous manufacturing process to directly produce well-controlled microparticles with advanced battery performance and accelerated scale-up, while enhancing fundamental understandings. The process utilizes a slug-flow reactor in which a multiphase mixture of liquid and gas in a tube spontaneously separates into slugs of liquid or slurry separated by slugs of gas. We have devised the milli-fluidic reactor and flow conditions so that hydrodynamically stable slugs form spontaneously immediately upon contact of the liquid and gas. Typical liquid/slurry slugs are 2-mm in length and 2-mm in diameter. In addition, we are able to selectively inject additional reactants in individual slugs to carry out the follow-on reactions. The sequential addition of the desired NCM precursors have allowed us to control the NCM radial profile in each particle. Microscopically, in a slug-flow reactor, each particle experiences the same environment with spatially uniform reaction conditions (kinetics, hydrodynamics) throughout the nucleation-growth process, leading to uniform particles with controlled composition and properties. Macroscopically, the manufacturing setup and conditions can remain the same while allowing convenient tuning of the production rate (scaling up or down). The electrochemical performance of the produced cathode particles is further enhanced by innovating coating treatment. Nonetheless, the technology/process equipment is being so developed that new battery chemistry can be easily incorporated with new future developments. Battery performance using NCM811 are tested and the results will be reported.

Figure 1
Redox Testing and Control for Corrosion Control in Molten Flinak
Authors: Sankar Krishna Moorthi , Singh Preet M
Published: November 2022

Fluoride Cooled High-Temperature Reactors (FHRs) are Generation IV Nuclear Reactor designs which will use molten fluoride salts as coolants. FHRs operate at a much higher temperature than the water-cooled reactors and have lower operating pressure. This greatly improves their thermal efficiency and decreases the likelihood of severe accidents. Fluoride salts such as FLiNaK (46.5-11.5-42 mol% LiF-NaF-KF) are considered for use as coolants in FHRs.

One of the major concerns for FHR designs is the significant corrosion of structural alloys in the FLiNaK. The corrosion in the form of selective dissolution of active alloying elements in these molten salts depends on the redox potential of the salt. This redox potential can be controlled by various chemical and electrochemical techniques and thereby corrosion of structural alloys in the salt can be controlled. However, the lack of reliable and reproducible reference electrodes for application in molten fluoride salts limits the ability to study redox control in these salts. Most tested reference electrodes in molten FLiNaK salt do not give stable potential due to a combination of the high electronegativity of fluorine and the high temperature of the medium. As such, the development of a reliable and stable reference electrode for these salts is paramount.

In this study, various kinds of reference electrodes that could be used for molten FLiNaK salt such as Dynamic Reference Electrodes (DRE), Quasi Reference Electrodes (QRE) etc. have been studied. In addition, in this study, corrosion behaviour of selected Ni and Fe based alloys were studied in molten FLiNaK at 700 oC. The effect of various chemical and electrochemical redox control techniques such as addition of reducing agents to the salt, purification of the salt, and the use of applied potential against a QRE were studied to understand their ability to mitigate corrosion of selected alloys in FLiNaK. This presentation will discuss our results on different reference electrode designs as well as the efficacy of each tested redox control method in controlling the corrosion of candidate alloys in molten FLiNaK.
Electrochemical Corrosion Study on Nickel and Chromium with Different Surface Orientations in Molten MgCl2-KCl
Authors: Peng Yuxiang , Halstenberg Philip , Bawane Kaustubh , He Lingfeng , Gill Simerjeet , Dai Sheng , Wishart James F. , Sasaki Kotaro
Published: November 2022

In the present work, the electrochemical corrosion tests were performed on single-crystal nickel and chromium with different surface orientations having (100), (110), and (111) facets, in a MgCl2-KCl eutectic molten salt at 500oC under an argon atmosphere. The corrosion rate of Ni is lower than that of Cr, indicating that Ni is electrochemically more stable than Cr in the molten salt. The anodic corrosion rates of different single crystals increase in the order of (111) < (100) < (110). This observation shows that the degree of electrochemical stability is related to the coordination of surface atoms and lower density surfaces yield higher corrosion rates. In addition, the corrosion rate of a polycrystalline sample is similar to that of the single-crystal (110) sample, which suggests that the corrosion rate of the polycrystalline surface is dominated by the orientation with the lowest surface density.

This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science.

Keywords: Tafel, Nickel, Chromium, MgCl2-KCl, Single crystal.
Bipolar Electrochemistry for the Synthesis of Anodic TiO2 Nanotube Layers
Authors: Sopha Hanna , Macak Jan M.
Published: November 2022

Self-organized TiO2 nanotube (TNT) layers have attracted considerable scientific and technological interest over the past 17 years motivated for their wide range of applications including (photo-) catalysis, hydrogen generation and biomedical uses [1,2]. The synthesis of these TNT layers is carried out by electrochemical anodization of valve Ti metal substrates in various F--containing electrolytes using a conventional 2-electrode set-up with the Ti substrate as anode and a Pt-foil as cathode.

Instead of using a conventional set-up, also bipolar electrochemistry can be employed for the anodization of valve metals [3-7]. In this set-up, the Ti substrate is placed in an electrolyte between two so-called feeder electrodes, which are connected to the potentiostat. Due to the electric field between the feeder electrodes, the Ti substrate is polarized. If the applied potential between the feeder electrodes is high enough, redox reactions can be driven on the Ti substrate. This method opens new doors for the preparation of TNT layers with gradients in dimensions (i.e. diameter and length of the nanotubes) [3-5] as well as for the preparation of TNT layers on Ti substrates, which cannot be directly connected to the potentiostat, e.g. Ti spheres [8].

In this presentation, the preparation of TNT layers on small Ti spheres [8] as well as on 3D printed Ti substrates [9] using bipolar electrochemistry will be shown and discussed. Furthermore, we will also show the possibility of using closed bipolar electrochemical cells, consisting of two closed half-cells with the Ti substrate as obstacle between the cells [10].

References:

[1] J.M. Macak et al., Curr. Opin. Solid State Mater.
2007, 11, 3.

[2] Lee, K. et al., Chem. Rev.
2014, 114, 9385.

[3] G. Loget et al, J. Mater. Chem A
2014, 2, 17740.

[4] G. Loget et al., Langmuir
2014, 30, 15356.

[5] W. Wei et al., Electrochim. Acta
2015, 176, 1393.

[6] H. Asoh et al., RSC Adv.
2016, 6, 90318.

[7] H. Asoh et al., J. Electrochem. Soc.
2018, 165, C295.

[8] H. Sopha et al., Electrochem. Commun.
2020, 111, 106669.

[9] H. Sopha et al., Nano Lett.
2021, 21, 8701.

[10] H. Sopha et al., ChemElectroChem
2021, 8, 3827.
Effect of pH on the Corrosion Mechanism of Zinc Magnesium Aluminium Alloy Coatings for Steels
Authors: Cooze Nathan , Sullivan James , Lewis Thomas , Gallagher Callum , Prosek Tomas , Thierry Dominique
Published: November 2022

The microstructural corrosion mechanism of a zinc-magnesium-aluminium (ZMA) alloy coated steel (Zn- 2wt%- Al- 2wt% Mg) immersed in 0.17 M NaCl was observed using in-situ time-lapse optical microscopy. The effect of pH on the corrosion mechanisms was assessed by using 0.17 M NaCl adjusted to pH 3, 7, 10 and 13 respectively. The pH of the electrolyte had an influence on the corrosion mechanism of the ZMA alloy. At pH 7 and 10, preferential corrosion of the MgZn2 lamellae within the eutectic phases was observed followed by subsequent dissolution of Zn-rich phases. A reduction in corrosion was observed using time-lapse microscopy at pH 10, most likely due to the magnesium hydroxide corrosion products being more stable in alkaline conditions, thereby retarding the kinetics of cathodic oxygen reduction and overall rate of corrosion. At pH 3 and 13, the corrosion mechanism appeared to change from localised corrosion, seen at pH 7 and 10, to more generalised corrosion. At pH 3, the MgO corrosion products that seemingly impart benefit to the substrate are dissolved in such acidic conditions. Gravimetric analysis and polarisation experiments were also conducted at the varying pH levels, to compliment the results from time-lapse microscopy.
Visualization of Hydrogen Penetration Generated in an Atmospheric Corrosion and a Crevice Corrosion
Authors: Azumi Kazuhisa , Katsuie Yosuke
Published: November 2022

Hydrogen could form in the corrosion reaction and sometimes causes hydrogen-related deterioration of steel. Spatial distribution of hydrogen penetration in steels has been observed using a photocurrent mapping method. In this method, hydrogen penetrated from the backside of the steel sheet formed by the cathodic polarization or corrosion reaction causes an enhancement of photocurrent intensity under the photo-irradiation to the passive film in the anodic biased condition. This photocurrent enhancement may be provided by the photo-generated holes that oxidize hydrogen atoms efficiently on the passive film surface. This work conducted hydrogen penetration mapping using a photo-charge mapping method newly developed for rapid mapping measurement. In this method, a polarization current during single UV-light pulse irradiation was integrated to obtain the charge Q
a, and then a charge Q
b during the irradiation was subtracted to obtain a photo-charge Q
PC = Q
a-Q
b for a single pulse. This process was performed by the electronics circuit controlled by the computer. Combination of pulse system and X-Y galvano-mirror-scanning device for a light beam emitted from pulse UV (405 nm, 0.2 W) pulse laser, rapid photocharge mapping was achieved, e.g., 24 s for 40 x 40 = 1600 pixel map.

In the experiments, a Devanathan-type cell composed of a top cell of a humidity control room and a bottom electrochemical cell was constructed. A UV laser beam was induced to the bottom cell via a quartz window to scan the bottom iron surface. Fig. 1 shows an example of the time-transition of photocharge maps measured for an iron sheet. In the experiment, a droplet of NaCl solution was put on the surface, and the humidity of the top cell was changed to wet/dry/wet conditions. In the figure, a droplet grew with absorbing moisture at 48 ks, rust expanded and precipitated in the droplet at 131 ks, dried to form rust at 668 ks, and soaked again at 534 ks. In this process, penetration of hydrogen was observed at the bottom face. Initially, hydrogen appeared only at the center of the droplet and then expanded to the lateral direction by increasing the photocharge.

Fig. 1. Time-transition of top images of an iron sheet (0.1 mmt) with a single NaCl solution droplet and photocharge maps measured for the bottom side of the iron sheet polarized at 0.7 V vs. Ag/AgCl in pH8.4 borate solution.

Figure 1
Stress-Affected ORR on Stainless Steel
Authors: Hangarter Carlos M , Anderson Rachel M. , Policastro Steven A
Published: November 2022

Oxygen reduction reaction (ORR) is an important cathodic reaction that often drives galvanic corrosion. In atmospheric environments, this reaction is responsible for accelerated corrosion from enhanced transport associated with discontinuous electrolytes. In load bearing structures, galvanic couples are subject to mechanical stresses that often necessitates these dissimilar metal unions. Greater understanding of mechanical stress effects on fundamental reactions of galvanic corrosion, such as ORR, is important from a forecasting perspective for improved prediction of component lifetimes and service requirements. Furthermore, extension of this behavior to confined, concentrated electrolytes is important to understand stress effects in atmospheric environments.

This work reports the impact of tensile stress upon oxygen reduction reaction (ORR) for stainless steel fastener materials. Chronoamperometry was used to observe and quantify the influence of tensile stress profiles on ORR under NaCl droplet electrolytes. NaCl was utilized as a seawater proxy at concentrations of 0.6 M NaCl and 4.6 M NaCl, the latter corresponding to 80% relative humidity, which is near the deliquescence point for NaCl. The ORR current was shown to increase with tensile stress and displayed reversible behavior with simple stress profiles. Deoxygenated experiments were performed to isolate ORR contributions from oxide dynamics. Details of current transients during strain ramping are used to demonstrate these features are distinct from the ORR current shift observed during static tensile stress. Polarization experiments were performed during static tensile holds in the elastic and plastic regime for greater insight of stress effects on reduction kinetics. EIS and Mott-Schottky experiments were conducted to gain insight into the oxide behavior.
(Invited, Digital Presentation) Maximizing the Layered Structure and Interlayer Anion Exchange Characteristics of Nico-Based Layered Double Hydroxides for Battery-Type Supercapacitors
Authors: Wang Yang , Pan Qianfeng , Zheng Fenghua
Published: November 2022

The transition metal-based layered double hydroxides (LDHs) have been extensively studied as promising electrode materials for battery-type supercapacitors owing to their excellent electrochemical activity and tunable chemical composition. In our work, we firstly built a novel three-dimensional composite with a core-shell structure by self-assembling NiCo-LDHs nanosheets on dual surface-modified halloysite nanotubes (D-HNTs) via in-situ electrodeposition and hydrothermal method (NiCo-LDH/D-HNTs). HNTs were pretreated by a dual surface modification for the first time including a carbonization process and cobalt doping to enhance electrical conductivity and chemical stability. This multicomponent hierarchical nanocomposite, NiCo-LDH/D-HNTs, has a specific capacity of 1401.4 C g-1 at 1 A g-1, a rate capability of 52.9% increasing the current density to 30 A g-1, and cycling stability of 80.8% after 2000 cycles. Moreover, using acetate anions (Ac-) as intercalating element, the NiCo-LDH nanosheets arraying on Ni Foam were prepared with the optimized amount of Ac- anions expanding the interlayer space of LDH nanosheets from 0.8 to 0.94 nm. An ultrahigh specific capacity of 1200 C g-1 at 1 A g-1 (690 C g-1 without Ac- anions), outstanding rate capability of 72.5% at 30 A g-1 and cycle stability of 79.90% after 4500 cycles were achieved. The enlarged interlayer spacing was beneficial for stabilizing the α-phase of LDH and accelerating the electron transport and electrolyte penetration in the electrochemical reaction. In addition, ionic surfactants like sodium dodecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB) were introduced to regulate the morphology of LDHs and alter the electrochemical performance. The original NiCo-LDHs shows microspheres formed by nanorods, and NiCo-LDHs-CTAB is similar, yet more tangled, while NiCo-LDHs-SDS is like microflowers consisting of interwoven nanosheets. NiCo-LDHs-SDS achieved better electrochemical performance (1003.6 C g-1 at 1 A g-1 and 73.84% after 3500 cycles) than NiCo-LDHs-CTAB (430.54 C g-1, 57.3%), and both higher than original NiCo-LDHs (278.5 C g-1, 54.3%), clearly showing the importance of morphology regulation in the synthesis of nanomaterials. Our work offers a promising strategy to synthesize functional nanomaterials with excellent electrochemical performance via integrating its unique layered structure and interlayer anion exchange characteristics.
(Digital Presentation) Electrochemical Corrosion Evaluation of Metallic Materials in Hahm Pyrolysis Bio-Oil
Authors: Jun Jiheon , Sulejmanovic Dino , Keiser James , Kass Michael
Published: November 2022

Biomass-derived pyrolysis oils contain organic acids, water and oxygenates that can degrade metallic materials with low corrosion resistance. To construct storage tanks for such bio-oils, the selection of metallic materials with sufficient corrosion compatibility is of high importance. This work evaluated corrosion compatibility of Cr-alloyed steels and stainless steels in a pyrolysis bio-oil using electrochemical impedance spectroscopy (EIS). High-Ash High-Moisture (HAHM) bio-oil, produced from a forest residue feedstock by National Renewable Energy Laboratory in Golden, CO, was used as the test liquid for EIS measurements. The corrosion reaction resistance, determined from the impedance data, indicated that stainless steels with the critical value of Cr or Cr + Mo content exhibit corrosion resistance in the bio-oil. In post-exposure optical inspection, no change was found for the specimens with high corrosion reaction resistance while visually changed surfaces were observed from the specimens with low corrosion reaction resistance.
Coupling Electro-Chemo- Thermodynamics with Water in Salt (WIS) Electrolyte for Enhanced Pseudocapacitive Charge Storage
Authors: Benhaddouch Tinsley Elizabeth , Dong Dongmei , Thundat Thomas , Bhansali Shekhar
Published: November 2022

Distinguishing and fundamental understanding of different charge storage mechanisms is critical for advancing sustainable energy developments. Pseudocapacitive materials combine the Faradaic charge transfer and partial surface-controlled process with the advantages of large energy density and fast response compared to electrical double-layer capacitors and batteries. Electrochromic oxides thin films, as an emerging class of energy storage materials, allow the synchronous visible color change to indicate the energy level. This work involves comprehensive research on the effect of the electrolyte concentration, solvent, and temperature on the charge storage behavior at the interface and the electrochromic properties of amorphous WO3-x films. The Li+ and e- dual insertion/extraction process depends not only on the electrochemical kinetics but also related to the viscosity of the ionic liquid LiCl water-in-salt (WIS) electrolyte varying from room temperature to 70°C. The de-solvation-free cations insertion feature differs the WIS from the low concentration. The electro-chemo coupling thermo-dynamics significantly improve the peak current (by a factor of 10 from 0.15 to 1.5 mA/cm2), charge capacity, and meanwhile shift the redox peak to lower potential (1.0 to 0.5V). This finding opens new avenues to developing safe, inexpensive, and high-capacity aqueous energy storage devices.

Figure 1
Asymmetric Ultracapacitor Produced By Sulphur Reduced Graphene Oxide/Metal Oxide Composite with High Energy Density and Outstanding Cycling
Authors: Tarimo Delvina Japhet , Oyedotun Kabir O. , Mirghin Abdulmajid , Sylla Ndeye Fatou , Manyala Ncholu
Published: November 2022

The morphology comprises of nano-rods/fibers, nano-sheet and nano-flower like structure were successfully produced from sulphur reduced graphene oxide/manganese dioxide composite for ultracapacitor application. The electrochemical evaluations of the optimal sample presented a specific capacitance of 180.40 F g-1 at 1 A g-1 in 2.5 M KNO3 electrolyte in a three-electrode set-up. An asymmetric device made up of sulphur reduced graphene oxide/manganese dioxide composite and activated carbon as a positive and negative electrode, respectively, delivered a high specific energy and power of 71.74 Wh kg-1 and 850 W kg-1 at 1 A g-1. It was further noticed that the device was able to retain a specific energy of 55.30 Wh kg-1 even at high specific current of 5 A g-1. An outstanding cycling stability with a capacitance retention of 94.5 % and energy efficiency of 99.9 % for up to 10,000 cycles was noted at 5 A g-1. The device revealed an excellent stability after being subjected to a voltage holding of up to 90 h and an exceptional self-discharge of about 1.45 V was recorded within the first 10 h and 1.00 V after 72 h from its maximum voltage of 1.7 V. The results obtained confirms that the produced material offers a great potential for the application of high energy density supercapacitor.

Keywords: Graphene oxide; Energy density; Supercapacitor; Shuttle effects; Composite materials; Sulphur.
Improving the Performance of Bimetallic Thermally Regenerative Ammonia Batteries
Authors: Cross Nicholas R. , Sweeney Alana , Hall Derek M.
Published: November 2022

Greenhouse gas emissions produced during electricity generation can be reduced by increasing the energy efficiency of power generation systems. One approach to increase generation efficiency is by extracting additional electrical energy from low-grade waste heat (< 100 °C) using thermally regenerative redox flow batteries (TRABs). TRAB chemistries with the largest equilibrium potentials use two different active metals and are referred to as bimetallic TRABs (B-TRAB). In most designs, copper is the positive electrode and zinc is the negative electrode. Using thermal energy, ammonia is moved between battery electrolytes to favorably modify the cell potential of the two electrochemical steps within the cycle. A typical B-TRAB system has four steps to complete a full cycle: 1) high-voltage electrochemical discharge, 2) thermal ammonia separation, 3) low-voltage electrochemical charge, and 4) thermal ammonia separation. During step 1, copper is reduced at the positive electrode and zinc is oxidized at the negative electrode creating aqueous zinc-ammonia complexes. Next, ammonia is separated from the zinc complexes and introduced to the copper electrode electrolyte, thereby increasing the equilibrium potential of the negative electrode, and decreasing the potential of the positive electrode. This creates a smaller cell potential required for electrochemical charging during step 3. After charging, ammonia is thermally separated from the electrolyte and re-introduced to the zinc-containing electrolyte returning the system to step 1. Currently, B-TRAB designs use solid zinc and copper electrodes which lead to low coulombic efficiencies at the copper electrode. Here, we demonstrate how the B-TRAB system can be improved by the addition of ammonium bromide to the positive electrolyte stabilizing Cu(I) species and replacing copper deposition/dissolution reaction with the Cu(I, II) reaction on a carbon felt. As a result, the open circuit potential during charging can be as small as 0.8 V, and as large as 2 V for the discharge step. Polarization curves showed that peak power for the discharge cycle was 98 mW cm-2, a significant improvement over previous B-TRABs.
(Invited) Reaction-Diffusion Modeling for Reliability Assessment of Heterogeneously Integrated Packages
Authors: Prasad Sudarshan , Liao Huanyu , Jois Chetan , Subbarayan Ganesh
Published: November 2022

Heterogeneous Integration provides a powerful and cost-effective means for building complex Systems-in-Package (SiPs). Recently, sophisticated examples of heterogeneously integrated packages containing nearly 50 dies, many fabricated by different vendors on different technological nodes, have been demonstrated. In general, interconnect pitch scaling and integration of large number of dies on a package leads to an exponential increase in material interfaces. Furthermore, the shrinking of the size of vertical interconnects in proportion to the pitch makes them heterogeneous in material phase composition or susceptible to oxide growth at the bond interfaces. Thus, reaction-diffusion problems play a critical role in the reliability of Heterogeneously Integrated packages. In general, numerical modeling can serve as a critical aid to understanding the formation of the phases and their evolution with current or temperature. Two significant challenges to modeling reaction-diffusion problems are the derivation of governing balance laws at the moving interface and developing an efficient computational technique for tracking the motion of the interface. Diffuse interface methods that use implicit geometric description of the interface such as the phase field method is widely used for solving problems with moving interfaces. The disadvantages of implicit interface methods are the complexity of the governing equations in diffuse form, the need for adaptive mesh refinement near the interface and the computational expense due to the implicitization of the geometry. In this study, we describe the derivation of general thermodynamic conditions governing the motion of the interface and develop diffuse as well as sharp interface computational methods to simulate reaction-diffusion problems in general. We then model the growth of Cu-Sn intermetallic compound in microbumps as well as voiding in the solder joint under elevated temperature and current. The models are compared against observations of phase evolution in fabricated test devices.
(Invited) Empirical Modeling of Broadband Insertion Losses in TSV-Interconnects
Authors: Coakley Kevin J , Kabos Pavel , Moreau Stephane , Obeng Yaw
Published: November 2022

The reliability of through silicon via (TSV)-interconnects depends

on various factors including construction materials, fabrication

location on wafers, thermal history, operating conditions and

integration schemes. The magnitude of the frequency-dependent

$S_{21}$ microwave scattering parameter quantifies insertion losses

in TSV-interconnects. We attribute these losses (which affect device

reliability) to reorientation of electrically active defects, cracks,

voids, dielectric constant variation, and water molecules affected

by heat. We model these insertion losses with an equivalent circuit

model. We estimate model parameters with a stochastic optimization

implementation of the Levenberg-Marquadt method. For TSV-interconnects

from two different providers, we quantify how estimated model

parameters vary spatially (on a wafer), and how estimated parameters

vary with thermal cycles for TSV-interconnects fabricated at particular wafer

locations.
Quantitative Phase Field Modeling of Li Dendrite Growth
Authors: Zhang Jin , Chadwick Alexander F. , Voorhees Peter W.
Published: November 2022

Modeling and understanding dendrite growth on lithium metal anodes during charging is vital for improving battery safety. The phase field method has become an increasingly popular tool to achieve this due to its flexibility in handling complex morphologies and coupled physical processes. However, quantitative phase field models under realistic electrochemical conditions are rare. In this work, we derive a thermodynamically consistent phase field model in the grand potential framework. The design of this model emphasizes quantitative modeling of electrodeposition with experimental loading conditions and realistic length and time scales. First, electrostatic potentials in both the electrode and the electrolyte are considered to account for the interfacial potential difference. Second, the electrochemical driving force can be large even with an applied voltage of a few hundred millivolts; therefore, the grid size usually must be as small as a few nanometers to maintain a stable phase field profile. This hinders the modeling of system sizes of practical interest. To solve this problem, a mapping approach is introduced to maintain stability with moderate grid sizes and realistic applied voltages. Third, we thoroughly compare the phase field model with results from a sharp interface model for various cases that permit analytical solutions. Numerical studies demonstrate that the proposed model can quantitatively reproduce the sharp interface results. Moreover, lithium has highly anisotropic interfacial energy, which leads to corners on the equilibrium electrode-electrolyte interface shape. A convexification method is used to remove the ill-posedness due to this strong anisotropy. Finally, a parallel solver is developed to handle large systems. The overall framework is demonstrated by studying lithium dendrite morphologies under various conditions. In future work, the model can be used as a computational tool for the high-throughput screening process in battery design.
Mechanically Reinforced Ionogel Membranes via Layer-By-Layer Assembly Strategy for High Performing Lithium Metal Batteries (LMBs)
Authors: Prasad Thapaliya Bishnu , Wang Zongyu , Adigun Babafemi , Dai Sheng
Published: November 2022

Ionogel electrolytes offer excellent ionic conductivity at the expense of mechanical strength because of entrapped electrolytes. Poor mechanical strength coupled with a very low lithium-ion transference number accelerates the lithium dendrite proliferation because of the large polarization gradient. Herein, we propose layer-by-layer (LbL) assembly strategy for simultaneously enhancing mechanical strength, lithium-ion transference number, and electrochemical potential window without affecting ionic conductivity. The essence of our strategy is centered to create the intrinsic ionic structure to reengineer the ionogel membrane’s interfaces. The resulting ultrathin LbL reinforced membrane enhanced the mechanical strength, lithium-ion transference number, and electrochemical potential window, maintaining high ionic conductivity (~ 10-4 Scm-1 at 10 °C)1. The Li|LbL|LFP and Li|LbL|NMC811 full cells exhibit promising electrochemical performances. Comprehensive characterization reveals that LbL membranes enhance the electrochemical performances that will lead to the design of robust electrolyte membranes for high energy density LMBs.
(Digital Presentation) Ultra-Thick Electrodes Utilizing Short Diffusion Path Via Novel Micro-Casting Process for Lithium-Ion Batteries
Authors: Plateau Tazdik Patwary , Pham Hiep , Zhu Yaqi , Park Jonghyun
Published: November 2022

For achieving high energy density, one effective way is to increase the active materials which makes thick electrodes for Lithium-ion Batteries (LIBs). However, thickening electrode limits the charge transport and generates significant mechanical stress that results in poor performance and eventually failure. In this work, a novel micro-casting (µ-casting) process has been introduced to fabricate ultra-thick and 3D structured electrodes which can address the issues with low charge transport by establishing short diffusion path (SDP). SDP reduces the intercalation-induced stress, improves energy density and long-term stability. The µ-casting allows ultra-thick (~280 µm) cathode (NMC 811, LiNi0.8Mn0.1Co0.1O2) and anode (MCMB, MesoCarbon MicroBeads) to achieve 40% higher specific capacity and 30% higher areal capacity after 200 cycles, high C-rate performance and longer cycle life with a intensive high mass loading of 35.7 mg/cm2.
Quantification of the Mesoscale Spatiotemporal Heterogeneities in Nickel-Rich Layered Oxide Cathodes By Raman Spectroscopy
Authors: Agrawal Shubham , Gupta Rohit , Sittisomwong Poom , Singamaneni Srikanth , Bai Peng
Published: November 2022

Lithium-ion batteries consisting of the particulate porous electrodes, are the dominant energy storage devices, however, they suffer from random failures and safety-related accidents. Such arbitrary incidents arise from the spatiotemporal heterogeneities occurring due to the material thermodynamics[1] which results to local hot and cold spots and early battery failures. The past investigations of the heterogeneities in the battery materials rely on the sophisticated synchrotron X-ray methods[2]–[4], which are not easily accessible. Instead, in this study, we employ Raman spectroscopy on an in situ benchtop setup which provides several advantages while investigating the true electrochemical kinetics in graphite electrodes, such as: (i) the setup houses practical porous NMC532 cathodes under realistic electrochemical surroundings; (ii) the high resolution of 1-2 µm provides sufficient information on the larger cathode particles; (iii) the method can analyze hundreds of particles, statistically representing the entire composite electrode; and (iv) the spectra can be quantified to reveal the actual reaction area, thus revealing high-fidelity real-time electrochemical performance. We use this simple but precision method to track and analyze the active reaction regions at the mesoscale in the NMC532 electrode to obtain the true local current density, which was found to be an order of magnitude higher than the globally-averaged current density adopted by the existing studies.

Raman spectroscopy can distinguish the vibrational modes of NMC532 with varying Li ion concentration. Since NMC532 is a solid-solution material, the Raman spectrum at each selected location can be deconvoluted into three distinct phases: empty, completely lithiated and partially lithiated. The partially lithiated regions participate in the surface reaction and can be identified to reveal the active reaction area. Thus, we quantified the active area fraction under slow galvanostatic conditions and generated a map of active regions with varying global Li ion fractions. Our results show that only 18% – 50% of the total particle area is active at any instant leading to higher local current densities than the globally-averaged electrode responses. The methods developed in this study are critical to estimate the kinetic parameters using true electrochemical responses and further aid in the design of the particulate porous electrodes.

References

[1] S. Agrawal, P. Bai, Cell Reports Phys. Sci.
2022, 3, 1.

[2] S.J. Harris, A. Timmons, D.R. Baker, C. Monroe, Chem. Phys. Lett.
2010, 485, 265.

[3] C. Tian, Y. Xu, D. Nordlund, F. Lin, J. Liu, Z. Sun, Y. Liu, M. Doeff, Joule
2018, 2, 464.

[4] S. Fang, M. Yan, R.J. Hamers, J. Power Sources
2017, 352, 18.
(Invited) Advances in Synthesis of Nanomaterials By Atmospheric Arc Discharge with Pulsed Power
Authors: Corbella Roca Carles , Portal Sabine , Kundrapu Madhusudhan , Keidar Michael
Published: November 2022

Plasmas are common tools used for synthesis and modification of nanoparticles. All techniques aim at providing high quality, nanostructured materials with well-defined crystalline state and functional properties. The most consolidated cold plasma nanosynthesis methods are pulsed-DC physical/chemical vapour deposition (PVD/CVD), high power impulse magnetron sputtering (HiPIMS), and pulsed cathodic arc. However, atmospheric arc discharge processes excel in production of stand-alone nanomaterials thanks to their high throughput and excellent quality and wide variety of obtained materials. Carbon nanostructures, like graphene and carbon nanotubes, core-shell nanoparticles, and transition metal dichalcogenide monolayers constitute some remarkable examples. Pulsed atmospheric arc nanosynthesis shows unique capabilities due to its flexibility and wide range of plasma parameters achievable by adjusting repetition frequency, pulse length, and peak values of pulse waveform. Here, we review the highlights of pulsed arc discharges applied on synthesis of low-dimensional materials, and the main contributions of this technique and other concurrent plasma methods are compared. The advantages of operating atmospheric pressure arc discharges in pulsed mode have enabled addressing instability issues via a more efficient arc control. Such milestones are discussed according to the intended research goal or application, namely: high-temperature tailoring of material nanostructure, control of deposition with a spatial resolution, nanosynthesis using liquids in plasma, and enhanced stabilization and power management of anodic arcs.
(Invited) Atmospheric Plasmas Synthesized Nanocrystals with Quantum Confinement and Quantum Hybrids in Photovoltaics
Authors: Svrcek Vladimir
Published: November 2022

Nanocrystals share lot of advantages of organics namely scalable and controlled synthesis, an ability to be processed in solution while additionally retaining the broadband absorption and superior transport properties of traditional photovoltaic semiconductors. Nanocrystal solar cells have the potential to considerably increase the maximum attainable thermodynamic conversion efficiency (> 50%). Nanocrystal solution-processed can be used in solar cell structure not only as an absorber but also as electron and hole transport layer where the HOMO and LUMO levels can be efficiently controlled by size and/or plasma induced surface engineering directly in colloidal solution. Solution-processed and surface engineered nanocrystals with quantum confinement can be then further used to fabricate new class of quantum hybrids when blended for instance with polymers or perovskites and serves as absorbing and/or e-h transporting material. In this presentation, we overview the atmospheric plasma-based approaches to synthesis and surface engineering of nanocrystals with quantum confinement. We will compare surface engineering by fs laser processing in liquid solutions and synthesis of nanocrystals with strong quantum confinement by atmospheric plasmas. Moreover, to understand the thermal stability of nanocrystals observed experimentally, we calculate the cohesive and the formation energies of nanocrystals by means of first-principle calculations. Finally, we overview our recent progress in integration of surface engineered nanocrystal as a quantum hybrids incorporated within perovskites solar cells.
(Invited) Functionalization of Vertically Aligned Graphene Nanowalls for Applications in the Field of Renewable Energies: From Coatings to Decoration
Authors: Kovacevic Eva , Jagodar Andrea , Strunskus Thomas , Radicic Rafaela , Marath Santhosh Neelakandan Marath , Zavašnik Janez , Cvelbar Uros , Krstulovic Niksa , Berndt Johannes
Published: November 2022

A new low temperature plasma based method for the growth of the vertically aligned graphene nanowalls is developed. The method allows growth of the vertically (or horizontally) aligned graphene at the temperatures of the surfaces as low as 450°C. This low surface temperature growth enables growth suitable for the coating of various surfaces that could not stand the temperatures above that limit and make the method appropriate for the production of different new types of eletrodes for different batteries /supercapacitors. In addition, such low temperature plasma grown vertically aligned graphene can be in a one-step, or in a two-step procedure easily treated by means of grafting, various coatings or decorated by metal oxide and other nanoparticles. All the methods aim for production in a green environment, by the procedures that are fast, dry and non-toxic. We will present briefly different procedures of production and functionalization, as well as material analysis obtained by means of NEXAFS, XPS, TEM, SEM and other methods.
Single-Step Atmospheric Pressure Plasma-Enabled Designing of Graphene Hybrids: A Green Approach for Energy Storage Materials
Authors: Marath Santhosh Neelakandan Marath , Dias Ana , Zavašnik Janez , Tatarova Elena Stefanova , Cvelbar Uros
Published: November 2022

Considering the increasing demand for advanced energy materials for future energy-related applications, designing promising materials at a low cost is critical. Given the importance of structural design and morphological features of the designed material in energy applications, fabricating materials at the nanoscale with controlled morphology and orientation is important. Recently 2-dimensional graphene-based materials have emerged as a potential candidate for next-generation energy applications. However, conventional chemical and physical routes for producing high-quality graphene have certain limitations either due to the cost or the processing time. Therefore, an advanced technique for designing and processing graphene structures at the atomic scale is needed to produce high-quality materials. In this regard, safe and clean environmentally-friendly plasma-enabled techniques have been explored as a potential method to tailor different structures at the nanoscale. As a synthesis approach, plasma assembles the nanostructures from gaseous into a solid form. Therefore, this paper suggests the advantages of atmospheric pressure plasma-enabled approaches to design and engineer graphene-based materials at the nanoscale with high structural quality and controllability with hybrid morphologies. Here, a novel, single-step microwave plasma-enabled approach at atmospheric conditions used to design hybrid high-quality graphene-based nanostructures is presented. The plasma techniques allow the synthesis of high-quality N-graphene (nitrogen-doped graphene) metal-based nanostructures at one of the fastest production rates of ∼ 19 mg/min. The graphene production is carried out in the high energy density zone of microwave plasma, and the growth of N-graphene sheets occurred in the afterglow region. Spraying metal particle-containing gases into this zone allows the formation of hybrid N-graphene structures anchored with metal oxide/sulphide nanoparticles. Structural and morphological analysis of these hybrids using different microscopic and spectroscopic techniques confirmed the high structural quality and distribution of metal-based nanostructures on N-graphene sheets. This fast and facile approach is expected to provide a significant impact on designing high-quality graphene hybrids, which can be used for sustainable energy storage applications.
Investigation of Carbon Nanostructure Synthesis Pathway with Plasma Treatment of Ethanol
Authors: Jurov Andrea , Zavašnik Janez , Cvelbar Uros
Published: November 2022

Plasma conversion of ethanol into carbon nanostructures is easily achieved by in-liquid plasmas but also possible with atmospheric pressure plasmas, where plasma forms in the gas phase over the liquid’s surface. Two plasma configurations were used – atmospheric pressure plasma jet (APPJ) and dielectric barrier discharge (DBD). These plasmas configurations should help reveal synthesis paths of different carbon allotropes. Moreover, this focus is on the determination of the importance of the in-liquid electrode material on nanostructure production and the possibilities of controlling nano-carbon allotropes by controlling plasma parameters. Plasma-liquid interaction was additionally influenced by an electrode placed under the treatment chamber or the addition of a graphite foil in the liquid ethanol. The experiments were conducted in ethanol with argon plasma, indicating an interesting pathway for converting ethanol into nanocarbons. Ethanol solution was analysed with UV-Vis spectroscopy, while carbon nanostructures were more thoroughly investigated with SEM and TEM. In the beginning, obtained carbon allotropes were mostly amorphous, whose size reduced with longer treatment times and structured carbon was synthesised.
Mid-Infrared Photoconductive Detectors Fabricated from Solution-Processed PbSe Nanocrystals
Authors: Ko Dong-Kyun , Park Junsung , Al Mahfuz Mohammad M. , Huebner Rock
Published: November 2022

Lead selenide (PbSe) was the first semiconductor used for photosensors operating in the mid-wavelength infrared spectral region (3-5 um) and is still the primary choice for low-cost, uncooled photoconductive detector applications. Even through PbSe has been studied for over 70 years, more understandings on its physical mechanism for high photoresponsivity is still emerging. Common methods of fabricating PbSe detectors involve physical/chemical vapor deposition or chemical bath deposition (CBD) techniques, followed by post-deposition sensitization processes including oxygen annealing and iodization. Here, we present a new approach to fabricating photoconductive devices based on PbSe colloidal nanocrystals. This infrared colloidal ink can serve as a critical component to enabling digital additive manufacturing of mid-infrared sensor arrays and simultaneously lower the fabrication cost by removing multiple masking steps required in conventional approaches. We report on the synthesis and fabrication of PbSe nanostructured film and the effects of thermal annealing as well as oxygen and iodide incorporation on the photoconductive properties.