bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Glassy Carbon Electrodes Modified with Micromagnets: Magnetoelectrocatalysis of HER
Authors: Knoche Gupta Krysti , Lee Heung Chan , Coduto Joshua Richard , Leddy Johna
Published: November 2022

Electrode kinetics for the hydrogen evolution reaction (HER) on glassy carbon electrodes are inherently slow. Voltammetric responses are marked by large overpotentials η and small exchange current densities j0.

HER rates are markedly increased on glassy carbon electrodes modified with composites of Nafion® and siloxane coated micromagnets. Comparison of linear sweep voltammograms of glassy carbon electrodes modified with either Nafion films or composites of magnetized iron oxide microparticles identifies enhanced HER rates where magnetic gradients are established.

For magnetized 1 𝜇m γ-Fe2O3 microparticles in Nafion, η is decreased by 0.191 ± 0.019 V at 0.4 mA cm-2 compared to Nafion films. This corresponds to an energetic advantage of -18.4 kJ/mol and a 40-fold increase in j0.

For magnetized 5 𝜇m Fe3O4 microparticles in Nafion, η is decreased by 0.28 V at 0.4 mA cm-2, which corresponds to an energetic advantage of -27 kJ/mol and 230-fold increase in exchange current.

HER rate on platinum electrodes is unchanged for Pt electrodes modified with Nafion films and with composites of magnetized micromagnets in Nafion.

Enhancements are not due to either magnetohydrodynamics or mediation as there is no bulk solvent volume in Nafion to convect and siloxane coating renders the iron oxide microparticles chemically and electrochemically inert. Voltammetry for glassy carbon electrodes modified with Nafion films and with composites of Nafion and demagnetized microparticles are comparable.

The chemistry of magnetized and demagnetized composites are the same; the rate enhancements arises from the physical impact of the magnetic gradients in the magnetized composites.

The enhanced rate for HER on glassy carbon arises through magnetoelectrocatalysis.

Work is undertaken at the University of Iowa. The National Science Foundation (NSF CHE-1309366 and NSF CHE-0809745) and the Army Research Office (W911NF-19-1-0208 (74912-CH-II)) supported these projects.
(Invited) ALE Based Manufacturing of Nanostructures below 20 Nm
Authors: Suyatin Dmitry B. , Jafari Jam Reza , Karimi Mohammad , Khan Sabbir A. , Sundqvist Jonas
Published: November 2022

Continued downscaling of electronic components, such as transistors and capacitors for advanced processors and memory chips, is ever harder and at the same time very important for our society. Atomic layer etching (ALE) is the most advanced etching process used in industry today. ALE enables material removal with atomic precision and is potentially damage-free for remaining material, which motivated its introduction to the industry. Together with atomic layer deposition (ALD) and atomic layer cleaning (ALC) ALE enables the new era of atomic-scale processing which is critical for the most advanced semiconductor technology nodes. In new technology nodes, the ALE is expected to be used together with advanced lithographical tools [1] and may enable new patterning schemes [2]. In this talk, we will present an overview of recent progress in ALE for manufacturing nanostructures with critical dimensions (CD) below 20 nm with the main focus on our work.

We discovered that by combining ALE and other already existing production technologies in a unique way, we cut the number of process steps increasing the throughput, saving on production costs, and lowering the CO2 footprint [3, 4]. And we push the resolution limits also. This is enabled by the recently discovered ALE selectivity to inclined surfaces which turns walls of tapered structures into etch masks. The inclined surfaces can be readily fabricated by e.g. dry etching or epitaxial growth. This process provides access to the fabrication of extremely small structures in a very delicate, precise, and efficient way. All this by relying on changes in already existing equipment and processes, saving investments for the industry. We compete with already established semiconductor technologies and complement them at the same time.

References:

S. Khan, D.B. Suyatin, J. Sundqvist, et al. ACS Applied Nano Materials, 1, 6, 2476, DOI: 10.1021/acsanm.8b00509 (2018).

N. Marchack, K. Hernandez, B. Walusiak, J.-I. Innocent
‐
Dolor, S. Engelmann, Plasma Process Polym., DOI: 10.1002/ppap.201900008 (2019).

D. B. Suyatin, S. A. Khan, J. Sundqvist, et al. presented at 16th Int. Conf. on ALD, Dublin, Ireland, July (2016).

Sabbir Khan, Dmitry B. Suyatin, Jonas Sundqvist, A Method for Selective Etching of Nanostructures. WO2017157902A1 (2017).
(Invited) Investigating Surface Reaction Thermodynamics: In Situ Calorimetry for Atomic Layer Deposition
Authors: Bielinski Ashley R. , Martinson Alex B. F.
Published: November 2022

Atomic layer deposition (ALD) is comprised of sequential self-limiting surface reactions that are inherently sensitive to the surface chemistry of the substrate and the reactivity of the chosen precursors. In order to better understand ALD processes and direct their future development we must investigate the fundamental mechanisms of ALD reactions. This is commonly done using a combination of computational modeling and experimental investigations using techniques like spectroscopic ellipsometry and IR spectroscopy. We present pyroelectric calorimetry for ALD as an in situ technique to measure the time resolved heat generation from ALD reactions. This provides a new dimension of thermodynamic and kinetic reaction data.

As an experimental technique, pyroelectric calorimetry measures ALD reactions on realistic surfaces as opposed to idealized models. We have designed and constructed custom calorimeters that are compatible with typical ALD process parameters. These calorimeters have been calibrated with a thermal resolution down to 0.1 μJ/cm2 and a temporal resolution of 50ns. To put this in perspective for an ALD reaction, this corresponds to about 0.1% of the heat evolved in the trimethylaluminum (TMA) and water ALD process and about 104 faster than our measurement of the TMA half reaction. The temporal resolution of our calorimeters is orders of magnitude faster than most complementary in situ analysis techniques including ellipsometry, IR spectroscopy, quartz crystal microgravimetry, and mass spectrometry. This time resolution provides information on precursor flow dynamics and reaction kinetics.

Pyroelectric calorimetry was used to investigate the TMA and water half reactions for ALD Al2O3 along with in situ spectroscopic ellipsometry thickness measurements and Rutherford backscattering spectrometry (RBS) composition analysis. This enabled comparisons of the change in thickness with the amount of heat generated as each half reaction saturates. Atomic growth rates calculated form RBS were used to calculate the heat generated on a per-atom basis. These results were then compared with proposed reaction mechanisms and energy changes from density functional theory (DFT) computational modeling.

Measurements of reaction and adsorption heats can also be used to compare and evaluate different precursors and inhibitor molecules for ALD growth inhibition in area-selective ALD. We investigated how the thermodynamics of adsorption can guide our choice of precursor-inhibitor pairs when using small molecule inhibitors that rely on competitive adsorption and chemical passivation to prevent ALD growth. Pyroelectric calorimetry offers new insight into what drives and limits ALD reactions and provides many opportunities for future investigations.
In-Situ Resistance Optimization for ALD Nanocomposite Resistive Materials
Authors: Mane Anil U. , Elam Jeffrey W.
Published: November 2022

Atomic layer deposition (ALD) made resistive nanocomposite materials can be used in many emerging applications such as charge draining layers for electron optic and MEMS devices, functional resistive layers in electron/ion amplifying microchannel plates (MCPs) which are used in photodetectors and mass spectrometry, HF resistance with tunable electrical conductivity coatings for stabilizing Li-ion battery cathode materials, selective solar absorbing coatings for concentrated solar power (CSP), and barrier and encapsulation coatings. Over the last decade, we have worked broadly on the research and development of resistive nanocomposite coatings. In this context, we have developed many nanocomposite materials with tunable resistance based on mixing conducting ALD metal and insulating ALD metal oxide or metal fluoride processes. These ALD nanocomposite materials show robust material performance in many of the applications listed above. Here we are particularly targeting a functional resistive coating that now commercially used for manufacturing large area ALD-MCPs. For this, there are two key topics that we are addressing a) Minimum thickness requirement for resistive coating which provides a stable targeted resistance behavior for MCPs, and b) Can we tune the temperature coefficient of resistance (TCR) of the ALD nanocomposite materials so that the ALD MCPs can operate over a wide temperature range without affecting their performance. To address these two topics, we have utilized in-situ resistance monitoring during the ALD nanocomposite process. With this method we have optimized resistive nanocomposite material ALD processes e.g. (M:Al2O3 where M= W and Mo) for MCPs and also targeted the desired TCR of the materials and achieved ultra-low TCR values. We believe these optimized coatings will reduce the ALD-MCP processing time substantially and enable ALD-MCPs and photodetectors to operate over a broader temperature range compared to existing ALD-MCPs.
Kinetics of TiCl4 Vapor Phase Infiltration (VPI) into PMMA and the Resulting Thermophysical and Optical Properties of the TiOx -PMMA Hybrids
Authors: Balogun Shuaib Adesina , Steiner Adam , Losego Mark D
Published: November 2022

Vapor phase infiltration (VPI) is a post-polymerization modification technique that imbues inorganic materials into polymers to create organic-inorganic hybrid materials with new properties distinct from the parent polymer. While several VPI precursor-polymer chemistries have been explored, a lack of chemical intuition remains for fully understanding the thermodynamics and kinetics that govern the VPI process. This study seeks to continue to build this knowledge by examining the VPI process kinetics for TiO2 infiltration into PMMA via the use of TiCl4 and H2O precursors. In this research, polymethylmethacrylate / TiO2 hybrid materials are prepared using VPI. The depth of infiltration of the TiO2species into ~200 nm PMMA thin films is studied using x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy and spectroscopic ellipsometry. The kinetics for TiCl4 infiltration increases with both VPI process temperature and TiCl4 exposure time. However, the rates of infiltration are considerably slower than those observed in the more commonly studied trimethylaluminum (TMA) / PMMA system. Even at 150 °C, process times of at least 12 hours are required to fully infiltrate a 200 nm PMMA film whereas using TMA similar films are fully infiltrated within 1 hour at the same process temperature. Films that we believe to be fully infiltrated at 150 °C and 24 hours of TiCl4 exposure have a 6 at% Ti in the innermost bulk, as determined by XPS. Interestingly, unlike AlOx-PMMA hybrids, these TiOx – PMMA hybrids exhibit significant changes in their optical properties. Increased titanium loading leads to a 4% increase in refractive index and increased UV absorbance in the UV range of 270-350nm. Furthermore, films infiltrated at 150 °C and 24 hours of TiCl4 exposure had a 50 % and 70 % reduction in coefficients of thermal expansion (CTE) below and above Tg respectively. Reduced CTE trends with increased titanium loading. We will discuss possible opportunities to use these new properties for various applications.

This project is supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Tailoring the Interfacial Interactions of Porous Polymer Membranes to Accelerate Atomic Layer Deposition: The Latent Path to Antifouling Membranes
Authors: Shevate Rahul , Rozyyev Vepa , Pathak Rajesh , Mane Anil U. , Darling Seth B. , Elam Jeffrey W.
Published: November 2022

Atomic layer deposition (ALD) is a powerful strategy to engineer hybrid organic-inorganic membranes with emergent functionalities. The combination of atomic-level thickness control, wide materials palette, and unprecedented conformality allow the physiochemical properties (e.g., hydrophilicity) of mesoporous polymer membranes to be precisely tuned. The nucleation of ALD materials growth on polymer surfaces relies on chemical interactions between the ALD metalorganic precursor and functional groups in the polymer structure and these interactions dictate the number of ALD cycles required to achieve a continuous coating. Strategies to enhance these interactions could enable desirable properties such as anti-fouling behavior to be imparted on inert polymer surfaces that lack the necessary functional groups for ALD nucleation. In this study, we demonstrate that the reactivity of polyacrylonitrile (PAN) membranes towards ALD metal oxide (MO) precursors with Lewis acid characteristics is enhanced by introducing Lewis base functional groups (amidoxime: Am) on the PAN backbone. The resulting Lewis acid-base interactions accelerates the MO nucleation in Am-PAN and reduce the number of deposition cycles required to achieve hydrophilicity compared to the untreated PAN membrane. Unveiling the reaction mechanism, the in-situ FTIR intensity changes established enhanced interaction dynamics between the ALD MO precursors and the Am-PAN membrane, unlike the PAN membrane. For similar MO cycles, through both spectroscopic and thermogravimetric analysis, we observe enhanced MO loading in the Am-PAN membrane compared to the PAN membrane. Here we have verified that strong Lewis acid-base interactions led to enhanced loading for a range of ALD MO materials including Al2O3, TiO2, SnO2, and ZnO. Most importantly, the Al2O3-Am-PAN hybrid membrane showed 23.3% higher antifouling capability compared to the pristine PAN membrane. Our approach expands the scope of design options for fouling-resistant porous hybrid inorganic-organic membranes and may reduce manufacturing costs of water treatment membranes.
(Digital Presentation) Cost-Effective Processing of Nickel-Rich Layered Cathodes for Li Batteries
Authors: Fung Kuan-Zong , Tsai Shu-Yi
Published: November 2022

The layered structured cathode material can provide a higher capacity and stable cycle retention, which is a desired property for lithium-ion batteries. Among them, NMC composed of Ni, Mn and Co as transition metals is considered a promising positive electrode. However, because Co is slightly toxic and an expensive strategic resource, reducing the Co content and maintaining the capacitance and cycle stability are the objectives of this study.

In this study, LiNi0.8Mn0.1Co0.1O2 were investigated. Adjust the amount of Li2CO3 and the temperature of calcination to control the size of the crystal grains to achieve better retention. The value of the I(003) and I(104) ratio in XRD pattern represent cation mixing in layered structure. And this parameter is closely related to its electrochemical properties. Discussion will be carried out based on the results of XRD analysis and the charge–discharge profiles and cycling performance.

The layered structured cathode material may provide a high capacity and stable cycle retention, which is a desired property for lithium-ion batteries. Among them, NMC composed of Ni, Mn and Co as transition metals is considered a promising positive electrode. However, because Co is slightly toxic and an expensive strategic resource, reducing the Co content and maintaining high capacity and cycle stability are the objectives of this study. In addition, the fabrication of NMC adopting single-crystal (grain size: 1~6 mm) process tends to give better long-term performance than ones with particles in nanometer range.

In this study, LiNi0.8Mn0.1Co0.1O2 (NMC811) with substitution of Ni/Mn for Co were selected as the Ni-rich layered cathode investigated. Due to the low melting point of Li2CO3, the heating temperature/time of powder mixture become crucial to control the adequate grain size of to achieve better retention. The value of the I(003) and I(104) ratio in XRD pattern represent cation mixing in layered structure. And this parameter is closely related to its electrochemical properties. Discussion will be carried out based on the results of XRD analysis and the charge–discharge profiles and cycling performance.
The Role of Ion-Correlation in Reducing the Lithium Transference Number in Lithium-Ion Polyelectrolyte Solutions
Authors: Bergstrom Helen K. , Fong Kara D. , McCloskey Bryan D.
Published: November 2022

Non-aqueous polyelectrolyte solutions (PESs) have been suggested as a promising route to high conductivity, high transference number (t+) electrolytes.1–3 State-of-the-art liquid electrolytes suffer from low t+, meaning the majority of ionic conductivity results from motion of the anion rather than the electrochemically active Li+ ion. Increasing t+ requires decreasing the mobility of the anion, which is dictated by both the diffusion of the anion as well as its net charge. PESs are intuitively appealing because anchoring the anion to a polymer backbone slows down the motion of the electrochemically inactive anion while maintaining higher ion conductivity through improved ion dissociation and solvent-mediated Li+ transport. However, in polyelectrolyte systems, increasing molecular weight both decreases polymer diffusion and increases charge, which will act as competing effects for t+.Recent molecular dynamic simulations of PESs have highlighted the critical importance of correlated ion motion in these systems and have called into question oligomeric PESs as a feasible strategy to achieving high t+ and conductivity electrolytes4,5

In this work we discuss complete studies of transport properties in lithium-ion and lithium metal battery-relevant PESs- specifically lithium triflimide appended polystyrene (PS-LiTFSI) and polymethacrylate (PM-LiTFSI) dissolved in carbonate blends. All prior PES experimental work in the literature has relied on ideal solution assumptions for measuring transport properties. This work represents the first rigorous characterization of transport properties for a battery-relevant polyelectrolyte solution. Using electrophoretic NMR and electrochemical experiments, we characterized the transport properties, including the electrophoretic ion mobilities, conductivity, diffusion coefficients, and t+ of these model PESs. While previous studies that rely on ideal assumptions predict that PESs will have higher t+ than monomeric solutions, we demonstrate that below the entanglement limit, t+ decreases with increasing degree of polymerization. For higher degrees of polymerization, we directly observe Li+ move in the “wrong direction” in an electric field, evidence of a negative transference number due to correlated motion through ion clustering. Using calculated Onsager transport coefficients and insights from molecular dynamics modeling, we demonstrate that despite selectively slowing anion motion using polyanions, anion-anion correlation through the polymer backbone and cation-anion correlation through ion aggregates reduce the t+ in non-entangled PESs.

References

Diederichsen, K. M. et al. ACS Energy Lett. (2017).

Diederichsen, K. M. et al. Macromolecules (2018).

Dewing, B. L., et al. Chem. Mater. (2020).

Fong, K. D. et al.
ACS Cent. Sci. (2019).

Fong, K. D., et al. Macromolecules (2020).
(Battery Division Research Award) A New Perspective on Layered Transition Metal Oxides As Cathode Active Materials
Authors: Liaw Boryann (Bor Yann) , Li Meng
Published: November 2022

High energy rechargeable lithium batteries (RLBs) continue to be the most favorite choice for vehicle electrification [1]. Among all cathode active materials, layered transition metal oxides containing nickel (Ni), manganese (Mn), or cobalt (Co), remain the most desired to improve energy density and performance [2]. As the current electrolyte system restricts high voltage operation, new cathode active materials with higher capacity are being sought today. How to seek a better cathode active material needs some better guidance as well. Here, a new perspective on the layered transition metal oxide cathode active materials is proposed based on our recent analysis of the performance characteristics of these current cathode active materials that were evaluated or reported in the literature. This new perspective is supposed to provide a more coherent framework to explain their commonality of the performance in realizing higher capacity within the same stability range. With this perspective, the principle of seeking a better cathode active material could be improved with this understanding.

References:

Bao, Y. Cui, E. Dufek, J. Goodenough, P. Khalifah, Q. Li, B.Y. Liaw, A. Manthiram, Y.S. Meng, et al. “Pathways for practical high-energy long-cycling lithium metal batteries.” Nat. Energy 4 (2019) 180–186. https://doi.org/10.1038/s41560-019-0338-x.

A. Manthiram. Reflection on lithium-ion battery cathode chemistry. Nat. Commun. 11 (2020) 1550. https://doi.org/10.1038/s41467-020-15355-0.
(Si)GeSn Isothermal Multilayer Growth for Specific Applications Using GeH4 and Ge2H6
Authors: Concepción Díaz Omar , Søgaard Nicolaj Brink , Krause Oliver , Bae Jin Hee , Brazda Thorsten , Tiedemann Andreas T. , Zhao Qing-Tai , Grützmacher Detlev , Buca Dan
Published: November 2022

The experimental demonstration of Ge1-xSnx alloys lasers opened group-IV materials towards high-performance electronic and photonic devices that can be easily integrated with the current Si semiconductor technology. In recent years, GeSn-based optoelectronic devices including light-emitting and detectors, modulators, and CMOS have been proven.

The major challenges for the Ge1-xSnx epitaxy arise from the low solid solubility of Sn in Ge, the large lattice mismatch, and the reduced thermal stability between Ge and Sn. All these are becoming extremely critical at higher Sn contents. Non-equilibrium conditions offered by molecular beam epitaxy (MBE), chemical vapor deposition (CVD), flash lamp, or laser annealing have been lately investigated. Between them, CVD is to date the preferred growth technique for its current development compatible with the industry offering micron-thick layers with the highest crystal quality.

While Tin-tetrachloride (SnCl4) becomes the standard Sn precursor, for Ge different gasses, like germane (GeH4) and digermane (Ge2H6) are used attempting to archive high Sn incorporation and high material quality. While Ge1-xSnx films with the same high Sn content can be obtained regardless of the used precursor, the advantages and disadvantages of each precursor are discussed in this work. The use of Ge2H6 is accompanied by high growth rates, being favorable in applications where relatively thick films are needed, such as laser structures. On the other hand, with a relatively low growth rate, GeH4 provides a greater thickness control, achieving clear and sharp interfaces in heterostructures. For this reason, GeH4 is the appropriate precursor for quantum transport or spintronic.

The biggest challenge in heterostructure designs is going up and down in Sn content. The growth of a Ge1-ySny on a Ge1-xSnx, y<x, or SiGeSn layer cannot be performed by increasing the growth temperature. Post-annealing processes lead to strong crystallinity degradation of the already grown layer by strong Sn diffusion or Sn segregation due to the limited thermal stability of Ge1-xSnx alloys.

In this work, we address simple methodologies to enhance the gradient or step Sn content without changing the process temperature. Controlling only the carrier gas flow while keeping the standard growth parameters constant, high-quality Ge1-xSnx alloys with uniform Sn content up to 15 at.% are obtained. The proposed method acts as guidance to produce Ge1-xSnx heterostructures that can be extended to any CVD reactor, independently of the used precursor, GeH4 or Ge2H6. Different devices structures are presented proving the applicability of the isothermal multilayer growth.

Figure 1
Gesn Bonding Technology for Integrated Laser-on-Chip Photonics
Authors: Tan James Zi Jing , Burt Daniel , Kim Youngmin , Joo Hyo-Jun , Chen Melvina , Shi Xuncheng , Zhang Lin , Tan Chuan Seng , Lim Khee Yong , Quek Elgin , Huang Yi-Chiau , Assali Simone , Moutanabbir Oussama , Nam Donguk
Published: November 2022

With the numerous recent demonstrations of germanium-tin (GeSn) semiconductor lasers, this material has become the strongest candidate for the realization of photonic-integrated circuits (PICs). However, the high defect density of this material often results in high lasing thresholds, making them undesirable for real-world applications. Furthermore, the low-thermal budget of high Sn content (>9 at.%) GeSn makes it exceptionally hard to grow onto other materials without introducing point defects. Herein, we present a novel method of directly combining GeSn with other materials through low-temperature wafer bonding. Through this technique, we can reduce the harmful high defect density and improve the lasing performance. To cater to the low thermal budget, we optimized the bonding processes which is critical in preventing Sn segregation to the surface. Through this method, we provide compelling evidence for the enhancement in photoluminescence in GeSn. Additionally, this technique can be extended to fabricate new material stacks, presenting unforeseen opportunities in other fields such as non-linear photonics.
A Renewed Focus on Surface Chemistry for Advanced Logic-Node Epitaxial Growth Processes
Authors: Margetis Joe , Tolle John
Published: November 2022

Increased CMOS logic and memory scaling has forced chip architectures into 3D design spaces such as finFET, GAA, nanosheet, etc. These applications require epitaxial structures to be grown in complicated and restrictive geometries which are composed of an increasingly different range of materials. Epi growth selectivity to conventional dielectric materials such as SiO2 and SiNx as well as less conventional materials like SiOxN1-x, Al2O3, and SiOCN must be maintained as usual. However changing demands on epi doping levels and thermal budgets places a large burden on conventional selectivity approaches, which most-often rely on higher HCl partial pressures or HCl etch-back steps. Cl2 etch-back processes have also been used in limited cases as an alternative to HCl, but apart from that, new selective epi growth technology has become somewhat stagnant.

The 3D nature of advanced logic architectures means that epi must also be grown on multiple crystal surface orientations like the (100), (110), and (111). For epitaxial growth processes, which by-definition are highly sensitive to the starting surface structure, this represents unique challenges to epitaxial engineers. New approaches to achieve orientation selective growth is now also paramount. Each surface orientation can have different growth rates, etch rates, and dopant incorporation efficiencies which can result in undesirable morphology, defects, and inhomogeneous chemical compositions. Depending on the application the growth rate may need to be maximized on one surface and minimized on another, for example to facilitate “bottom-up” growth from the (100) surface. In other instances, the growth rates may need to be matched as closely as possible, for example to achieve symmetric “diamond-shaped” epi-growth on a Si fin.

These issues are at a fundamental level related to surface chemical interactions and finding new solutions will require a molecular-level understanding. In this work we present a fundamental chemical view of these challenges using both theoretical (density functional theory) calculations and in-situ surface analytical results. We analyze the reactive sites on dielectric surfaces and how various deposition precursors interact with these sites. Based on these results we will discuss alternative and/or novel routes to achieving selective epitaxial growth. We apply similar methods to analyzing the structure and reactivity of the Si (100), (110), and (111) surfaces and how deposition precursor molecules react on each surface. Our results reveal why changing Si surface orientations can result in such varied reactivity and ultimately in differing growth and etching rates. We similarly use these results to suggest methods for controlling facet/plane selective epitaxy and/or etching. Central to both dielectric and facet selectivity is precursor engineering, which entails designing new molecules to customize their reactivity (or lack of reactivity) toward specific dielectric surfaces or surface orientations.

Figure 1
Quantum-Ready Germanium and Silicon
Authors: Scappucci Giordano
Published: November 2022

The semiconductor industry knows how to make and integrate billions of excellent transistors. What materials do we need to integrate excellent qubits at large scale for the quantum information age of tomorrow? What are the properties that we search in these materials to make them quantum-ready? I will focus on isotopically-engineered, strained silicon-germanium heterostructures enabling high-performance hole spin-qubits in germanium and electron spin qubits in silicon. In particular, I will make a case for the germanium quantum information route [1]. Germanium is emerging as a versatile material to realize devices capable of encoding, processing and transmitting quantum information. I will examine the materials science progress underpinning germanium-based planar heterostructures, review our most significant experimental results demonstrating key building blocks for quantum technology, and identify the most promising avenues toward scalable quantum information processing in germanium-based systems.

[1] G. Scappucci et al, The germanium quantum information route, Nat Rev Mater (2020). https://doi.org/10.1038/s41578-020-00262-z

Figure 1
(Invited) Optoelectronic Quantum Information Processing: An All-Group IV Integrated Platform
Authors: Moutanabbir Oussama , Del Vecchio Patrick , Attiaoui Anis , Fettu Gabriel , Rotaru Nicolas , Assali Simone
Published: November 2022

Achieving coherent optical photon-to-spin conversion is a long-sought-after strategy for surmounting current fundamental limits in optical schemes that hinder the long-distance distribution of entanglement. Moreover, photon-to-spin interfaces are also essential for a direct mapping of the quantum information encoded in photon flying qubits to stationary spin processors. However, the lack of scalable materials offering an efficient interaction with optical photons along with optimal spin properties remains a formidable obstacle hindering the development of these quantum technological components. With this perspective, this presentation will discuss strategies to address these challenges by leveraging the degrees of freedom offered by group IV (Si)GeSn semiconductors, namely strain and composition, to tailor the electronic structure and eventually fulfill these prerequisites. These innovative systems do not only have the potential to enable coherent photon-to-spin interfaces, but because of their compatibility with the semiconductor industry they will also offer scalability, manufacturability, and cost-effectiveness.

We will show that this family of semiconductors provide an additional flexibility to control the charge carrier states and achieve a selective confinement of holes. The latter benefit from a quiet quantum environment that has been at the core of increasingly reliable quantum processors and memories. However, most if not all available experimental studies of two-dimensional gas systems have been thus far focused on heavy-hole (HH) states. This is attributed to the nature of the heterostructures currently available (e.g, Ge/SiGe, InGaAs/GaAs), where compressive strain lifts the valence band degeneracy and leaves HH states energetically well above the light-hole (LH) states. We will demonstrate that tensile strained Ge/GeSn quantum wells alleviate these limitations and allow to selectively confine LH provided the strain is higher than 1%. This requires strain relaxed, high Sn content GeSn buffer layers to be used to grow Ge quantum wells with LH ground state, high g-factor anisotropy, and a tunable splitting of the hole subbands. The optical and electronic properties of these low-dimensional systems will be described and discussed. Spin injection and coherent control will also be addressed. Additionally, qubit designs exploiting the ability to engineer LH states and the Ge large spin-orbit coupling allowing fast all-electrical spin-manipulation schemes will also be presented and discussed.
Negating Crosstalk in High Voltage Spinel (LiNi0.5Mn1.5O4)/ Graphite Full Cellsby Electrode Modifications
Authors: Badami Pavan , Trask Stephen E. , Mane Anil U. , Elam Jeffrey W. , Abraham Daniel P.
Published: November 2022

Since its discovery, the high-voltage spinel oxide LiNi0.5Mn1.5O4 (LNMO, sg: Fd-3m) has been widely pursued as a promising cathode for next generation Li-ion batteries due to advantages that include the following: high operating voltage, excellent rate capability and low manufacturing cost (1, 2). However, the LNMO cathode when paired with graphite shows poor capacity retention and increased cell impedance due to oxidation of the organic liquid electrolyte and Mn2+ migration onto the anode (2, 3). Herein, we aim to understand the causes of poor capacity retention in LNMO/graphite full cells and systematically address those issues with various electrode modification strategies. Cycling performance of cells with carbon-nanotube (CNTs) in the LNMO electrode (LNMO-CNT), and with a thin layer of Al2O3 on the graphite electrode (Gr-Al2O3), is examined in half, full and three-electrode cell configurations. The cells with LNMO-CNT electrode show significantly lower cell impedance than cells with LNMO electrodes (without the CNT). Additionally, cells with the Al2O3-coated graphite electrode show improved capacity retention compared to cells with the uncoated graphite. Furthermore, cells containing Li4Ti5O12 anodes display the best capacity retention. We investigate and compare the physiochemical changes in electrodes and electrolyte using various diagnostic techniques; data from these experiments will be reported during the presentation.

References
:

M. M. Thackeray, W. I. F. David, P. G. Bruce and J. B. Goodenough, Materials Research Bulletin, 18, 461 (1983).

S. Patoux, L. Daniel, C. Bourbon, H. Lignier, C. Pagano, F. Le Cras, S. Jouanneau and S. Martinet, J Power Sources, 189, 344 (2009).

F. Zou, H. C. Nallan, A. Dolocan, Q. Xie, J. Y. Li, B. M. Coffey, J. G. Ekerdt and A. Manthiram, Energy Storage Materials, 43, 499 (2021).

Acknowledgements: This document has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
Update on Systematic Cycle and Calendar Aging of NMC and NCA 18650 Li-Ion Batteries
Authors: Wittman Reed M , Fresquez Armando , Chalamala Babu , Preger Yuliya
Published: November 2022

The true useful life of secondary Li-ion batteries is currently not well characterized. 80% of initial capacity, a decades old metric for vehicle applications, is a common endpoint in literature cycling studies and commercial cell specification sheets. As such, much is not known about cell performance beyond this metric. The 80% cutoff may not be applicable for non-vehicle applications, like grid energy storage, where there are different requirements for performance. Degradation data beyond the 80% capacity threshold is needed to make these evaluations.

To address this, we have been conducting a multi-year study of both cycling and calendar aging of 18650 cells. During this study, LiNixCoyAl1-x-yO2/NCA, and LiNixMnyCo1-x-yO2/NMC cells have been cycled at systematically varied temperature, state of charge (SOC) ranges, and cycling rates. Cells were cycled at different state of charge (SOC) ranges (0-100%, 20-80%, and 40-60%), temperatures (15, 25, and 35 °C) and discharge rates (0.5C, 1C, 2C, and 3C). Additionally, we present data from a concurrent calendar aging study at different temperatures (15, 25, and 35 °C) and SOCs (25, 50, and 90%). Our group has previously reported on trends for cycle aging down to 80% capacity [1]. Here, we present an update on performance of cells cycled beyond 80% capacity to an end of life (EOL) of 40% capacity and cells undergoing calendar aging.

Results so far suggest that SOC range continues to be the largest factor in capacity fade rate for both chemistries. Combining stress factors (NMC at high SOC and low temperature) causes rapid capacity fade beyond what would be expected by simple addition of degradation rates from the individual stress factors. Depending on the conditions of cycling, so called knee points do not always appear when a cell is cycled beyond 80%. When a knee point occurs varies by cycling conditions. We also consider additional metrics by which battery performance can be measured such as round-trip efficiency (RTE), total discharged energy, and internal resistance (IR). And find that IR increases generally matches well with capacity fade and appear to increase dramatically at observed knee points. For the calendar aging study, we find that holding cells at higher SOCs and temperatures generally increases the rate of fade. This study represents the broadest public report of post 80% capacity cycling across multiple chemistries. It will inform cell lifetime prediction and allow for better utilization of battery systems.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND2022-5089 A

References:

1Preger et al. “Degradation of Commercial Lithium-Ion Cells as a Function of Chemistry and Cycling Conditions” J. Electrochem. Soc.,
2020
, 167, 120532.
A Multi-Phase Niobium Oxide Electrode for High-Power Lithium-Ion Batteries
Authors: Ahn Yoojin , Nam Gyutae , Khan Kishwar , Liu Meilin
Published: November 2022

Niobium oxide-based materials are promising anodes for high-power lithium-ion batteries. The electrochemical performance of these oxides depends sensitively on the crystal and the defect structures. For example, a recent study revealed that the planar defects introduced to the H-phase of Nb2O5 shear structure greatly enhanced the rate capability and structural durability. Our recent study indicates that the M-phase with a tetragonal crystal structure displayed the highest electrochemical performance among all crystalline phases of Nb2O5 studied, due likely to its fast transport of lithium ions and electrons through the ‘block structures’. In this presentation, we will report our findings in the development of a composite electrode composed of a tetragonal and a monoclinic phase of niobium pentoxide with desired defect structures (denoted as d-H,M-Nb2O5), synthesized using a solvothermal process followed by annealing under controlled conditions. Microscopic analysis reveals that the d-H,M-Nb2O5 has NbO6 and NbO4 block structures of both the M-Nb2O5 and the H-Nb2O5. The electrode based on the d-H,M-Nb2O5 exhibits the highest rate capability (142 mAh g-1 at 20 A g-1) and excellent cycling stability (86% capacity retention after 2000 cycles at 6 A g-1) among recently reported niobium pentoxides. Further, detailed crystallographic and defect structures, the physicochemical characteristics, and the long-term cycling behavior will be discussed.
Modeling Cathode/Separator/Lithium Metal Sandwich Including Porous Electrode Effects and Plating/Stripping - Proper Formulation, Transformation, and Efficient Numerical Simulation
Authors: Uppaluri Maitri , Mishra Lubhani , Subramaniam Akshay , Jang Taejin , Subramanian Venkat R.
Published: November 2022

The high theoretical capacity (3860 mAh g-1) and electrochemical potential of lithium (-3.040V v/s standard hydrogen electrode) makes it a promising candidate as a negative electrode for next-generation batteries.1 However, lithium electrodeposition on the metal anode surface creates dendrites that can lead to short-circuiting of the cell and loss of cyclability.

There have been several approaches to modeling lithium electrodeposition in literature. Our past work entailed modeling the deposition as a moving interface, where the equations undergo coordinate transformation to track the changes in concentration and potential as deposition occurs.2 We have also shown that inducing convection in the boundary conditions at the moving interface that properly conserves the mass of lithium in the domain.3

The electrodeposition of lithium on the metal anode produces signatures in the voltage response of the cell. In the past, we have shown that these signatures can be simulated with models that capture the transport phenomena during electrodeposition.

This work extends our previous approaches to model the electrodeposition on the surface of the metal anode for a full-cell configuration, which includes a porous cathode. The influences of lithium electrodeposition on the voltage response for different cathode materials are analyzed.

References

D. Lin, Y. Liu, and Y. Cui, Nat. Nanotechnol., 12, 194 (2017).

M. Uppaluri, A. Subramaniam, L. Mishra, V. Viswanathan, and V. R. Subramanian, J. Electrochem. Soc., 167, 160547 (2020).

L. Mishra et al., J. Electrochem. Soc., 168, 092502 (2021).
Heuristic Solution for High Energy Density and Long Cycle Stability for Ni-Rich Layered Cathodes
Authors: Kim Un-Hyuck , Sun Yang-Kook
Published: November 2022

The demand for energy sources with high energy densities continues to push the limits of Ni-rich layered oxides that are currently the most promising cathode materials in automobile batteries. Although most current research is focused on extending battery life using Ni-rich layered cathodes, long-term cycling stability using a full cell is yet to be demonstrated. Here, we introduce Li[Ni0.90Co0.09Ta0.01]O2 which exhibits 90% capacity retention after 2,000 cycles at full depth of discharge (DOD) with an energy density > 850 Wh kg−1. In contrast, the currently most sought-after Li[Ni0.90Co0.09Al0.01]O2 cathode loses ~40% of its initial capacity within 500 cycles at full DOD. Cycling stability is achieved by radially aligned primary particles with [003] crystallographic texture that effectively dissipate the internal strain occurring in the deeply charged state, while the substitution of Ni3+ withhigher valence ions induces ordered occupation of Ni ions in the Li slab and stabilizes the delithiated structure.

Nam et al. ACS Energy Lett.
2019, 4, 2995-3001.

Kim et al. Energy Environ. Sci.
2018, 11, 1271-1279.

Yoon et al. Mater
2018, 30, 1808-1814.

Kim et al. ACS Energy Lett.
2019, 4, 576-582.
Combinatorial Study of Systematic Aluminum Substitution into NMC Cathode Materials
Authors: Hebert Alex , McCalla Eric
Published: November 2022

Li-ion batteries power our modern mobile world. They are the cornerstone of the electric vehicle, a market whose growth is accelerating rapidly; and the mobile phone, which encompasses billions of devices used by most people on the planet. The cathode material of Li-ion batteries is the limiting factor of battery capacity, as well as one of the culprits of battery failure and thus improving this material is critical to realize better performing batteries. The layered metal oxide LiNixMnyCozO2 is the current market-leader in the cathode space. Many compositions are in use with the industry pushing capacity higher with high-Ni compositions. However, high-Ni compositions come at the cost of material stability, i.e., battery lifetime. To stabilize the cathode, many metals have been substituted into the material to resist structural transformations and to prevent surface reactions with the electrolyte. Of the substituted metals, aluminum has been explored extensively. However, most studies are limited to a few key compositions of NMC and a systematic study of the structural and electrochemical impact of Al substitution has not been completed on the full range of NMC compositions. In this work, the effects of different levels of aluminum substitution are investigated and, in total, 320 different compositions are explored using high-throughput techniques. X-ray diffraction is used to understand the structures at all compositions and combinatorial electrochemistry is performed to extract important battery metrics related to energy density, cycling performance, and irreversible capacity. This work provides insight into how accommodating different NMC compositions are to aluminum substitution and the effects of the substitutions on their electrochemistry.
A Comparative Analysis of the Capacity Fading Mechanisms in Ni-Rich Single-Crystal and Polycrystalline Cathodes
Authors: Ryu HoonHee , Lim Hyung-Woo , Sun Yang-Kook
Published: November 2022

Layered [Ni1–x–yCox(Mn or Al)y]O2 (NCM or NCA) oxides are the main cathode materials for powering current electric vehicles. Increasing the Ni fraction is the primary approach to increase the energy density of NCM and NCA cathodes, and thus enhancing the driving range of associated electric vehicles. However, high–Ni NCM and NCA cathodes with Ni contents near 90% suffer from inherent structural instability, especially in the deeply charged state, resulting in rapid capacity fading and high thermal instability. One method to address this inherent structural instability involves removing the interparticle boundaries by growing a single-crystal cathode. Single-crystal cathodes, free from interparticle microcracking, are regarded to improve cycling and thermal stability by minimizing parasitic surface degradation. Despite mechanical stability, the single-crystal cathode has some problems. In this presentation, we report a comprehensive evaluation of the fundamental properties of single-crystal and polycrystalline cathodes with a wide range of Ni-rich compositions. The electrochemical performances of single-crystal and polycrystalline cathodes are correlated with their structural changes to elucidate the dominant capacity fading mechanism of single-crystal cathodes.