bluuebunny/crossref_metadata_2025 huggingface dataset:
Recovery of Iron from Nickel Production Waste By Electrolysis in Alkaline Aqueous Solution
Authors: Haarberg Geir , Khalaghi Babak
Published: December 2020

The global iron and steel industry is responsible for a noticeable part of energy consumption and anthropogenic CO2 emissions in the world. Different low-emission pathways have been taken by steel making companies around the world to replace the current iron and steel production. Among these evolving processes, low-temperature electrolysis of iron oxide, called SIDERWIN process, has shown promising results. Solid particles of iron oxide (Fe2O3) are reduced at the cathode in a strong NaOH solution at ~100 oC. This process has the flexibility to use different iron-containing raw materials as well as pure iron oxide. In the current study a waste product from nickel production (Glencore Nikkelverk, Kristiansand, Norway) was used as raw material. This waste material is in the form of sludge and contains up to 50 wt% FeOOH (akageneite). Cyclic voltammetry was performed to study the electrochemical properties of this material. Then, galvanostatic electrolysis was carried out and the product was analysed by SEM-EDS and X-ray diffraction. Pure iron was successfully deposited on the cathode. The faradaic efficiency was not very high in these initial trials. However, earlier studies using other raw materials (pure iron oxide and bauxite residue) have proved that optimisation of the electrolysis parameters can lead to significant increase in the efficiency.
Spent Fuel Cell Electrocatalyst Recycling through Potentiodynamic Dissolution of Platinum
Authors: Sharma Raghunandan , Andersen Shuang Ma
Published: December 2020

Large-scale commercialization and sustainable growth of proton exchange membrane fuel cells (PEMFCs) technology is throttled largely by high cost and scarce nature of Pt, the most preferred electrocatalyst for both the anode and cathode reactions. Recycling of the electrocatalyst from spent PEMFC electrodes through a commercially scalable and environmentally benign process is of significant interest. Here, we present technical details of a closed loop recycling of spent electrocatalyst from a PEMFC electrode. The process includes electrochemical dissolution of the Pt nanoparticles in dilute acidic bath, precipitation of the dissolved Pt in form of a chloride-free Pt precursor and synthesis of carbon supported Pt (Pt/C) electrocatalyst through reduction of the Pt precursor. The presentation will highlight some of the studies from our group aiming to enhance the Pt dissolution efficiency and to optimize the process steps for synthesis of the Pt/C electrocatalyst from the dissolved P. With a demonstrated recovery efficiency >90%, the process may be utilized for large-scale recycling of the spent electrocatalysts, especially suitable for PEMFC electrodes.

References

R Sharma, S Gyergyek, P Morgan and S M Andersen, Electrochem. Soc., 2020,
167
(2): p. 024521.

R Sharma, K R Nielsen, P B Lund, S B Simonsen, L G Madsen, and S M Andersen, ChemElectroChem, 2019. 6(17): p. 4471-4482.

R Sharma, S J Andreasen, J Chamier, and S M Andersen, Electrochem. Soc., 2019. 166(13): p. F963-F970.

R Sharma, S B Simonsen, P Morgen, and S M Andersen, Acta, 2019. 321: p. 134662.

R Sharma, S Gyergyek and S M Andersen, ChemSusChem 2018, 11(21), 3742-3750

R Sharma, Y Wang, F Li, J Chamier, and S M Andersen, ACS Appl. Energy Mater., 2019. 2(9): p. 6875-6882.

R Sharma, P. Morgan and S M Andersen, PCCP, 2020 (Accepted manuscript), https://doi.org/10.1039/C9CP06066A

Figure 1
Impedance Spectroscopic Study of PbOx/Au-Pd Solar Cells: Analysis of Capacitive and Resistive Loads
Authors: Patel Dipal B , Mukhopadhyay Indrajit , Chauhan Khushbu
Published: December 2020

In this study, we have used impedance spectroscopy to understand the current mechanisms in photovoltaic cells of non-stoichiometric PbOx/Au-Pd. Potential pulse anodization technique was used to synthesis PbOx films which also enabled nanowall assemblies all over the substrate. The first ever solar cells of PbOx showed an overall efficiency of 0.38% with a high open circuit voltage of 0.7 V and short circuit current density of 2.04 mA/cm2 for 10 nm thick Au/Pd Schottky contact. However, the device suffered with a low fill factor of 26% and DC analysis only gave an approximate idea about the physical phenomena behind it. Impedance spectroscopy is an important tool to analyze critical and complex interfaces either of solid-liquid or solid-solid interfaces. In this technique, a small A.C. signal is applied over the scanned potential range to perturb the junctions. After fitting an appropriate distributed circuit model to the recorded data and variation of each element of the circuit was plotted against applied bias. With the use of this tool, we were able to understand the charge transport at each and individual interface of the device and hence to know about the shunting sites which hindered the performance of the cell. The variations of various interfacial resistances and capacitive loads have been discussed in detail to understand the functioning of the device. This study will be helpful in determining the loads in the actual devices and work upon it to improve the overall efficiency of the solar cells.

Figure 1
The Effects of Non-Ideal, Lithiation-Based Active Material Volume Change on Mechano-Electrochemical Pouch Cell Simulation
Authors: Pereira Drew Joseph , Fernandez Miguel , Streng Kathryn Corine , Hou Xu Xian , Gao Jay , Garrick Taylor R. , Weidner John W.
Published: December 2020

Automotive battery manufacturers are working to improve individual cell and overall pack design by increasing their performance, durability, and range, while reducing cost; and active material volume change is one of the more complex aspects that needs to be considered during this process. In the study presented here, thermodynamically non-ideal (non-linear), lithiation-based volume change behavior for the anode and cathode active materials were incorporated into a previously developed mechano-electrochemical model.(1-4) Before, an ideal (linear) relationship between active material volume change and state-of-lithiation was assumed.

Using the non-ideal active material volume change behavior, the changing thickness of an automotive relevant, large-format pouch cell was predicted while simulating cell discharge. Measurements were taken using an experimental setup capable of simultaneous mechanical and electrochemical operation and observation. Figure 1 shows that the mechano-electrochemical measurements prove to agree well with simulation when using non-ideal lithiation-based volume change as opposed to the previously assumed ideal volume change behavior.

The resulting model was used to simulate other mechano-electrochemical phenomena including the effects of anode/cathode capacity ratio and changing pressure/porosity during cell discharge. This mechano-electrochemical model shows promise to help define operational parameters to mitigate negative effects from active material volume change and may act as a tool for developers to reduce the extensive electrochemical and mechanical testing required for the design of promising new batteries.

References

T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, Journal of The Electrochemical Society, 164, E3592 (2017).

T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, Journal of The Electrochemical Society, 164, E3552 (2017).

T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, Journal of The Electrochemical Society, 161, E3297 (2014).

D. J. Pereira, J. W. Weidner and T. R. Garrick, Journal of The Electrochemical Society, 166, A1251 (2019).

D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner, and T. R. Garrick, Journal of The Electrochemical Society, 167, 080515 (2020).

Figure 1. Experimentally measured data and simulations using ideal and non-ideal active material volume change behavior for a NMC/LMO:Graphite pouch cell strain as a function of cell state-of-charge.

Figure 1
Modeling Capacity and Power Fade of Cylindrical NCA-Si Graphite Battery Cell in Electric Vehicles
Authors: Ko Jing Ying , Benavente Fabian Andres , Ekström Henrik , Lindbergh Göran
Published: December 2020

The energy storage device in most electric vehicles today are lithium-ion batteries. Particularly, Tesla electric vehicles uses the lithium ion chemistry of nickel cobalt aluminum oxide (NCA) and graphite electrodes. Their aging and lifetime are critical issues that must be addressed for a successful large-scale commercialization of electrified vehicles. Therefore, the present work focus on the study of possible aging mechanisms that contribute to the capacity fade and impedance increase of NCA and Si-graphite battery cells in a modeling framework. The batteries are subjected to partial cycling at different state-of-charge (SOC) ranges to imitate different driving behaviors. By predicting the aging parameters from separated electrodes through model, it is possible to understand the responsible aging mechanisms in such applications.

The NCA/Si-graphite cylindrical cells were calendar-aged and cycle-aged between SOC of 20-50 %, 35-65 %, 60-90 % and 20-95 % until end of test (EOT) is reached. The cells electrochemical characterization methods include electrochemical impedance spectroscopy (EIS) at 100-cycle interval to measure the impedance behavior and slow cycle discharge to measure the capacity available.

We use two models in analyzing the aging behavior through fitting and validation with experimental data – time-based model for capacity fade and frequency-based model for impedance increase. They are physics-based Doyle-Fuller-Newman (DFN) model, which is based on porous electrode theory. The models account for (electrochemical) aging processes within the electrode. Specifically, the solid-electrolyte interface (SEI) build-up, surface and particle cracking; and electrolyte oxidation on the cathode particle interface. These lead to the loss of lithium inventory (LLI) and loss of active material (LAM), contributing to the capacity fade. The same aging mechanisms are represented in the impedance model in the form of charge transfer resistance, interfacial resistance and diffusion time constant. The challenge in modeling the full cell impedance is the superimposition of aging parameters of roughly the same time constants, making it quite hard for the deconvolution of anode and cathode aging. The deduced aging mechanisms from the modeling work are supported by experimental observation, e.g. scanning electron microscope (SEM). For example, micro-cracks and isolation of particles observed from SEM explain the high possibility of increase in LAM and structural change. Overall, modeling of the battery’s capacity and power fade can deepen our understanding of aging processes, allow lifetime prediction, or optimal battery design.
(Invited) Probing Redox Centers in Oxygen-Redox Electrodes Using Soft X-Ray Spectroscopy
Authors: Okubo Masashi , Yamada Atsuo
Published: December 2020

High-energy-density batteries have been a long-standing target toward sustainability, but the energy density of state-of-the-art lithium-ion batteries is limited in part by the small capacity of positive electrode materials. Although employing the additional oxygen-redox reaction of Li-excess transition-metal oxides is an attractive approach to increase the capacity, an atomic-level understanding of the reaction mechanism has not been established so far. In this talk, using bulk-sensitive resonant inelastic X-ray scattering (RIXS) spectroscopy combined with ab initio computations, we show the presence of a localized oxygen 2p orbital weakly hybridized with transition metal t
2g orbitals that was theoretically predicted to play a key role in oxygen-redox reactions. The ex-situ RIXS spectroscopy also unveils the stabilization mechanism of oxidized phases.

References

Sudayama, et al., M. Okubo & A. Yamada, Energy Environ. Sci., 2020, 13, 1492-1500.

Mortemard de Boisse, et al., M. Okubo & A. Yamada, Nature Commun., 2019, 10, 2185.

Mortemard de Boisse, et al., M. Okubo & A. Yamada, Adv. Energy Mater., 2018, 8, 1800409.
(Invited) Nanoarray Cathode Design for Durable Zn Batteries
Authors: Fan Hong Jin , Tan Hua , Wang Zhe
Published: December 2020

Rechargeable aqueous zinc battery, as a novel promising candidate for grid-scale energy storage, has drawn tremendous attention recently. Our group has been actively working in design nanostructured electrode materials for metal-ion batteries (Na, K, Zn) and electrocatalysts for metal-air batteries. In this talk, I will present our latest results on cathode materials for both Zn-ion battery and Zn-air battery. Specifically, we developed layered ZnOV nanosheets that are directly grown on a 3D graphite current collector. Meanwhile, the anode is also 3D Zn nanosheet array obtained by electro-deposition. As for the Zn-air battery cathode, we employed 3D conductive MOF and Ni-based LDH hybrid materials on conductive carbon support as the electrode both for aqueous alkaline and all-solid-state Zn-battery. The whole material system has a high conductivity, sufficient active sites and low transition energy that render highly reversible redox reaction and inhibition of dendrite formation, as well as extremely soft feature so that it can be appropriate for the application of flexible devices. The all-solid-state Zn-based batteries using CMNC@CC and Zn@CC as the electrodes displays outstanding performance when compared with most of the aqueous oxy/hydroxy or pristine MOFs based energy storage devices.

We appreciate the financial support from Agency for Science, Technology, and Research (A*STAR) by AME Individual Research Grant (A1983c0026) and from Singapore MOE AcRF Tier 2 Grant (MOE2017-T2-1-073).
(Invited) Density Functional Theory Modeling - Machine Learning Approach for Redox Potential of Organic Electrode Materials
Authors: Jang Seung Soon
Published: December 2020

In this talk, we present the first-principles density functional theory modeling of redox properties of various carbon materials, including quinone derivatives, dopamine, and DNA. First, we discuss the contribution of electron affinity of molecules and solvation to redox potential from our density functional theory (DFT) calculations. Second, we discuss the relationship of redox potential with the design of molecular structure. It is found that aromaticity and electron-withdrawing functional groups can be used to tune the redox potential. Especially, the variation of redox potential as a function of Li association is discussed. The conclusion is that we can tune up the redox potential by designing the detailed molecular structure. Next, all these results are used to build up machine learning. We discuss our artificial neural network and other machine learning algorithms regarding its validation and predictability. Through this study, the redox characteristics of carbon materials are systematically investigated using the first-principles computational modeling method, and then utilized via machine learning methods for high-throughput screening process.
Data-Driven Discovery of New Materials for Solid-State Batteries
Authors: Mo Yifei
Published: December 2020

All-solid-state Li-ion battery based on solid electrolytes is a promising next-generation battery technology with high energy density, intrinsic safety, long cycle life, and wide operational temperatures. However, the lack of solid electrolyte materials that satisfy multiple requirements, such as high ionic conductivity, good stability, and interfacial compatibility with the electrode, are impeding the development of this new battery technology. To resolve these materials challenges, we develop and leverage an array of data-driven computation techniques including machine learning to discover and design novel solid-state Li-ion conductors as solid electrolytes for all-solid-state batteries. The data-driven approach enables rapid searching over a large materials space of tens of thousands of materials with highly diverse structures and chemistries. Dozens of novel solid-state conductors are discovered through our data-driven materials search. Our data-driven analyses provide unique insights into the fundamental understanding about solid-state Li-ion conductors beyond traditional physical mechanistic studies. Our study demonstrates a new paradigm of using machine learning techniques for materials discovery that overcome the data-scarcity challenges.

Zhang et al., “Unsupervised Discovery of Solid-State Lithium Ion Conductors”, Nature Communications, 10, 5260 (2019) DOI: 10.1038/s41467-019-13214-1

He et al., “Crystal Structural Framework of Lithium Super-Ionic Conductors”, Advanced Energy Materials 9, 1902078 (2019) DOI: 10.1002/aenm.201902078

Nolan et al., “Computation-Accelerated Design of Materials and Interfaces for All-Solid-State Lithium-Ion Batteries”, Joule, 2, 2016-2046 (2018) DOI: 10.1016/j.joule.2018.08.017
Development of Multivalent Electrolytes with a Wide Electrochemical Window and Their Applications
Authors: Liao Chen , Yang Mengxi , Lau Ka-Cheong , Leon Noel , Kwon Bob Jin , Key Baris , Vaughey John T. , Ingram Brian J.
Published: December 2020

Multivalent (MV) ion batteries have been under intense scrutiny because the modeling effort predicted that a high Mg2+ diffusion mobility in spinel cathodes and a higher specific energy density can be achieved. Recently new cathodes have been tested against Mg, with novel cathodes such as layered oxides MoO2.8F0.2,1 MgCr2-xVxO4,2 and conversion-type cathodes.3

Previously chloride containing electrolytes4 were dominant in multivalent ion batteries because of their facile deposition and high Coulombic efficiency towards the anode. However, the corrosion issue of Cl- limits their application. Here we report the development of chloride-free multivalent salts with a weakly coordinating anion that shows exceptional electrochemical properties. Moreover, the passivation-free properties of these anions make them efficient in assessing the Mg2+ mobility inside a solid solution electrode. Further development on other multivalent cations will also be demonstrated. Together with cathodes, these electrolyte developments would pave the way for a holistic approach towards high energy density multivalent batteries.

References

T. Incorvati, L. F. Wan, B. Key, D. Zhou, C. Liao, L. Fuoco, M. Holland, H. Wang, D. Prendergast, K. R. Poeppelmeier, Chemistry of Materials 2015, 28, 17-20.

J. Kwon, K.-C. Lau, H. Park, Y. A. Wu, K. L. Hawthorne, H. Li, S. Kim, I. L. Bolotin, T. T. Fister, P. Zapol, R. F. Klie, J. Cabana, C. Liao, S. H. Lapidus, B. Key, J. T. Vaughey, Chemistry of Materials 2019. DOI:10.1021/acs.chemmater.9b04206

Pan, J. Huang, Z. Feng, L. Zeng, M. He, L. Zhang, J. T. Vaughey, M. J. Bedzyk, P. Fenter, Z. Zhang, C. Liao, Advanced Energy Materials 2016, 6.

Pan, J. Huang, N. Sa, S. M. Brombosz, J. T. Vaughey, L. Zhang, A. K. Burrell, Z. Zhang, C. Liao, * Journal of The Electrochemical Society 2016, 163, A1672-A1677.

-C. Lau, T. J. Seguin, E. V. Carino, N. T. Hahn, J. G. Connell, B. J. Ingram, K. A. Persson, K. R. Zavadil, C. Liao, * J. Electrochem. Soc. 2019, 166, A1510-A1519.
A GaAs/Si X-Ray Pixel Detector Based on Low Temperature Covalent Wafer Bonding
Authors: Razek Nasser , Prieto Ivan , Neves Jorge , Le Corre Philippe , von Känel Hans
Published: December 2020

Low temperature wafer bonding of silicon to various materials is a key technology for many applications requiring a low temperature budget, such as monolithic CMOS integrated pixel detectors, optoelectronic devices and high-speed electronics. We present a pixel detector comprising a gallium arsenide (GaAs) absorber wafer bonded to a CMOS readout wafer, both 8-inch in size. The 700 µm thick absorber wafer is semi-insulating (ρ = 5 × 108 Ωcm) whereas the CMOS readout wafer, thinned to 50 µm, has a resistivity of 1 kΩcm, as indicated in Fig. 1a). The oxide-free, covalent bonding process was performed at room temperature and under high vacuum.

The surface preparation combines wet etching of the native oxide on the wafer surfaces with the removal of the hydrogen passivation layer by a low-energy plasma prior to bonding. The infrared (Fig. 1b) and scanning acoustic images (Fig. 1c), 1d)) show that the bonded interface is of high quality (no outgassing, no visible voids). After thermal annealing at 200°C the bond strength proved to be sufficiently strong to permit post-bonding processing, including carrier wafer removal and dicing into individual detector chips.

These first prototype GaAs on Si X-ray detectors fabricated by our novel wafer bonding approach are going to be tested for X-ray imaging in the near future.

Figure 1
(Invited) Hybrid Wafer Bonding – The Fusion of Low Temperature Dielectric and Metal Bonding Technologies
Authors: Farrens Dr. Sharon Nannette
Published: December 2020

There are two driving goals in wafer bonding. One is to use wafer bonding methods to engineer starting materials; to integrate silicon with any other material to enable hetero-device architectures. The second is to continually shrink device footprints by bonding layers of devices vertically. Low temperature wafer bonding combined with advances in CMP (chemical mechanical polishing), temporary bonding, and advanced metrology characterization tools are enabling researchers to achieve these goals. In particular, hybrid bonding, which enables simultaneous bonding of dielectric and metallic regions at an interface has produced extremely high-performance devices and miniaturization of display technologies. This talk will highlight the various requirements for hybrid bonding and critical specifications for implementing complex bonding methods.
Comparing Charge Compensation Mechanisms of Li1.3Nb0.3Mn0.4O2 and Li1.3Nb0.3Fe0.4O2 As Novel Cathode Material
Authors: Zuba Mateusz , Chung Hyeseung , Meng Y. Shirley , Piper Louis F.J. , Lebens-Higgins Zachary , Vinckeviciute Julija
Published: December 2020

Li-rich oxides have generated widespread interest for their use as next generation high energy density Li-ion battery cathodes. Among Li-rich candidates, cation disordered phases are novel lithium intercalation compounds that warrant further fundamental characterization. Here, we compare Li1.3Nb0.3Mn0.4O2 and Li1.3Nb0.3Fe0.4O2 system to explore differences in charge compensation and electrochemical performance. Using Operando XANES/EXAFS measurements examine how the Mn/Fe/Nb local environments and oxidation states change and their effect on electrochemistry. Li1.3Nb0.3Mn0.4O2 displays capacities beyond the traditional transition metal redox (Mn3+/4+), which is considered accessible through oxygen redox. Li1.3Nb0.3Fe0.4O2 exhibits charge capacities at similar potentials to that of anionic redox but our investigations suggest the charge compensation mechanism displays more Fe3+/4+ redox in origin. By using a suite of characterization techniques, we explore the capacity contributions of cation and anionic components in these systems.
Toward High Voltage Mg-Ion Battery Cathode Via a Solid-Solution Cr-Mn Spinel Oxide
Authors: Kwon Bob Jin , Yin Liang , Park Haesun , Parajuli Prakash , Kumar Khagesh , Kim Sanghyeon , Yang Mengxi , Zapol Peter , Liao Chen , Fister Timothy T , Klie Robert F , Cabana Jordi , Lapidus Saul H. , Vaughey John T. , Key Baris
Published: December 2020

The capability of the tailored solid-solution spinel, MgCrMnO4, is evaluated by theoretical and experimental approaches. Lattice Mg2+ in the designed oxide is electrochemically utilized at high potentials in a non-aqueous electrolyte. Complementary evidence supports bulk Mg2+ (de)intercalation throughout the designed oxide frame where strong electrostatic interaction between Mg2+ and O2- exists. Mg/Mn antisite inversion in the spinel is lowered via post-annealing to further improve Mg+2 mobility. Spinel lattice is preserved upon removal of Mg2+ without any phase transformations, denoting structural stability at the charged state at a high potential. In the remagnesiated state, insertion of Mg2+ into interstitial sites in the spinel is detected possibly resulting in partial reversibility which needs to be addressed for structural stability. The observations constitute a first clear path to the development of a practical high voltage Mg-ion cathode using a spinel oxide.
A Viologen-Based Anolyte with a Very Negative Redox Potential for Neutral Aqueous Redox Flow Batteries
Authors: Bahari Meisam , D. Watt Gerald , Harb John N.
Published: December 2020

Redox flow batteries have been recognized as a promising option for energy-storage purposes, mitigating the intermittency of renewable sources of energy such as solar, wind, and hydroelectric power. In particular, aqueous redox flow batteries (ARFBs) are very attractive owing to high conductivity, relatively low cost, and safe nature of aqueous electrolytes. Performance of ARFBs can be further improved with developing new electroactive species. Viologens are a group of organic compounds with great tunability, making them appealing for flow battery applications. In this study, a viologen-based electroactive compound called MMV is proposed with the potential of improving performance of aqueous flow batteries.

The potential of MMV as an anolyte was investigated for developing a neutral aqueous flow battery. MMV required a simple synthesis procedure with inexpensive starting materials, resulting in a low cost. MMV showed solubility of almost 3 M that is relatively high compared to other organic electroactive compounds, such as quinones, especially in neutral electrolytes. The electrochemical reaction of MMV involved the transfer of one electron at fast kinetics. Additionally, MMV demonstrated a redox potential of -1.05 V vs. SCE that is one of the most negative redox potentials reported for organic electroactive species under neutral conditions. These characteristics indicated that MMV is a promising anolyte candidate. Such a very negative redox potential and high solubility provide MMV the potential to significantly improve performance of a flow battery in terms of capacity, energy density, and cell potential. Despite these interesting properties, MMV exhibited a poor cycling performance. MMV underwent irreversible reactions at elevated concentrations. Signs of dimerization and also precipitation were observed during cycling. The irreversible reactions led to a high capacity fade rate (2.1%/cycle). Approaches to improve the cycling performance include synthesizing MMV-derivatives that possess a higher charge compared to that of MMV to possibly limit the extent of both dimerization and precipitation.
(Invited) Intercalation-Type Cathode Materials for Nonaqueous Calcium-Ion Batteries
Authors: Hong Seung-Tae
Published: December 2020

Calcium-ion batteries (CIBs) represent a promising alternative to the current lithium-ion batteries (LIBs). Calcium ions can transfer two electrons per ion. Thus, in principle, the capacity of a host material can double due to the divalency of calcium, provided the host material can release and accept the transferred electrons. The final battery product is expected to be cost-effective, owing to the earth-abundance of calcium reserves. The redox potential of calcium is close to that of lithium, enabling a high cell voltage. The larger ionic radius of calcium (1.0 Å) compared to those of other divalent ions (0.60–0.74 Å) could be a disadvantage because a narrow diffusion pathway sufficient for smaller ions will not allow the passage of larger Ca ions. However, the larger ionic radius ensures a lower effective intercalant-ion charge density, which can be rather advantageous for the diffusion in the host materials as well as in the electrolytes.

Recent discoveries of reversible plating or alloying of calcium provoked considerable interest in calcium-based rechargeable batteries. Theoretical calculations also predict that the energy barriers for Ca diffusion are lower than other multivalent ions in some structures, and the development of positive materials are anticipated. However, only a few cathode materials have been reported so far, only to exhibit low energy-storage capability and poor cyclability. In this talk, the synthesis, structural and electrochemical properties of new cathode materials for nonaqueous CIBs will be presented, which were recently developed in our group. Some examples include NASICON-type NaV2(PO4)3, FeV3O9∙1.2H2O, Ca0.13MoO3·(H2O)0.41. These stimulating discoveries will lead to the development of new strategies for obtaining high energy density CIBs.
(Invited) Characterization of ALD in Semiconductor Device Fabrication
Authors: van der Heide Paul
Published: December 2020

The CMOS industry continues to push the boundaries of what is possible. Indeed, today’s manufacturing can be described as atomic level engineering, with an example lying in the use of Atomic Layer Deposition (ALD). The development and fabrication (fundamental R&D through to manufacturing) of highly repeatable structures required by the semiconductor industry also necessitates the use of state-of-the-art materials characterization (“if you can’t see it, you can’t develop it”) and process control capabilities (“if you can’t see it, you can’t control it”). This talk will cover the more commonly used materials characterization capabilities used within the industry. This includes, but not limited to: Transmission Electron Microscopy, Atomic Force Microscopy, and X-ray Photoelectron Spectroscopy. Following this, the use of Secondary Ion Mass Spectrometry (SIMS) in the form of Self Focusing SIMS (SF-SIMS), in area selective ALD R&D will be demonstrated.
Near-Room-Temperature Soft Plasma Pulsed Deposition of SiCxNy from 1,3,5-tri(isopropyl)cyclotrisilazane
Authors: Goff Jonathan , Brick Chad , Kaloyeros Alain , Arkles Barry
Published: December 2020

The silicon-nitrogen material system, primarily in the form of silicon nitride (SiNx) and silicon silicon carbo-nitride (SiNxCy) (where 0<x<1.33 and 0<y<1) continues to witness tremendous research and development interest. This interest is driven by its highly desirable combination of physical, mechanical, electrical, and optoelectronic properties, making it one of the most useful materials in integrated circuitry (IC) applications. However, the drive towards more complex and smaller IC and hetero-device structures is significantly challenging established SiNx deposition methodologies. Low thermal exposure during fabrication of the device structures is becoming essential due to the complexity and thermally fragile nature of these structures, where temperature changes can induce undesirable reactions within substructures. Furthermore, with the thickness of films approaching atomic dimensions, thermally-induced migration, in addition to electromigration, can significantly alter film properties and performance. Another consideration is the desire to move towards more flexible substrates, such as plastic or polymer substrates, which typically cannot withstand the same process temperatures as traditional substrates, such as Si or GaN. Given these emerging thermal budget limitations, work by the present investigators has focused on the development and optimization of a remote plasma-activated ALD and/or pulsed CVD process for SiNxCy at exceptionally low temperatures as protective coatings on thermally and chemically fragile substrates such as polymers and plastics. In this presentation, results are presented for low temperature remote plasma-activated pulsed CVD (P-CVD) SiNxCy using 1,3,5-triisopropylcyclotrisilazane (C9H27Si3N3, TICZ) as source precursor. This presentation will provide the following: (i) the process window for deposition of SiNxCy through the P-CVD decomposition of TICZ as a single-source precursor without a co-reactant and using ammonia (NH3) as co-reactant; (ii) the lowest deposition temperature that can be achieved using this process; (iii) the chemical, compositional, morphological, and structural properties of the resulting films as function of processing parameters, with particular emphasis on film composition, density, etch rate, and structure (amorphous versus crystalline); (iv) the effects of the process on thermally and chemically fragile substrates, such as polymers and plastics; and (v) how to deposit good quality SiNxCy while maintaining the structural and chemical integrity of such substrates, including in particular at the film-substrate interface? The instantaneous growth of the SiNxCy film on multiple types of substrates during the remote plasma pulse of the P-CVD process was observed by in-situ, real-time, ellipsometry (an example is provided in Figure 1) and the resulting films were further analyzed by XPS and wet etch rate studies.

Figure 1
(Invited) Atomic Layer Deposited Amorphous Igzo Semiconductor with Vertical Composition Engineering for High Mobility Field Effect Transistor
Authors: Sheng Jiazhen , Hong Tae-Hyun , Jeong Hyun-Jun , Park Jin-Seong
Published: December 2020

Amorphous oxide semiconductors have been widely studied for the potential use in flat-panel displays such as active matrix liquid crystal display (LCD) and Organic light emitting didoes (OLEDs). Since reporting amorphous InGaZnO semiconductor thin film transistor (TFT) in 2003 & 2004, many multi-component oxide semiconductors have been intensively investigated and developed by physical vapor deposition (PVD) method. Very recently, the sputtered InGaZnO TFTs are already adopted in mass-production to fabricate AMOLED TVs. Also, semiconductor industries have looked at metal oxide semiconductor thin films as an alternative Si channel layer because this semiconductor exhibited extremely low-off current level (below 10-18A/um). It is the unique property to decrease power consumption for various semiconductor devices. However, there remain several problems such as enhancing field effect mobility, composition uniformity, bias-temperature stability, and p-type oxide semiconductor in order to go further for the future device applications.

In this talk, I will introduce various oxide semiconductor materials with atomic layer deposition (ALD) methods. Unlike PVD, ALD method has unique properties, including controlling atomic-level-thickness, manipulating atomic-level-composition control, and depositing impurity-free & uniform films. The key materials such In2O3, ZnO, SnO2, and Ga2O3 will be summarized and then I will show the combinatorial research works in terms of amorphous InGaZnO semiconductor thin film transistors. Generally, electrical properties of amorphous oxide semiconductors are strongly dependent on each element composition. The indium (In) rich InGaZnO exhibited a high mobility of 50cm2/V.sec. However, the In-rich InGaZnO TFTs have the demerit of negative threshold voltage owing to intrinsically high carrier density. I will present that In-rich IGZO TFTs with vertical stacked InOx, ZnOx and GaOx atomic layers show excellent performances such as saturation mobility of ~ 74cm cm2/V.sec, threshold voltage of -1.3V, on/off ratio of 8.9 × 108, subthreshold swing of 0.26V/decade, and hysteresis of 0.2V, while keeping a reasonable carrier density of ~1017 cm-3. Flexible ALD InGaZnO TFTs on polymer substrates were also discussed depending on gate insulator materials, in terms of device performances. ALD technique will be a very promising candidate to improve oxide semiconductor materials as well as various device applications (Display & Semiconductor Industry) because it has not only unique nano-growth mechanism but also ultimate uniform property.
(Invited) In-Situ and Combinatorial Techniques for Spatial ALD
Authors: Musselman Kevin P , Alshehri Abdullah , Mistry Kissan , Jones Alexander , Loke Jhi Yong , Nguyen Viet Huong , Muñoz-Rojas David
Published: December 2020

Atmospheric-pressure spatial atomic layer deposition (AP-SALD) and chemical vapor deposition (AP-CVD) have been developed in recent years as scalable techniques for the rapid deposition of oxide thin films on different substrates for a variety of applications. The atmospheric nature of these techniques facilitates the integration of characterization tools and the modification of the experimental setup to produce novel materials. Here we report in-situ electrical and optical characterization methods that have been developed for our AP-SALD/CVD system, as well as new techniques to deposit oxide films with nanoscale thickness gradients. The in-situ electrical measurements are enabled by a custom-designed, flexible printed circuit board substrate and the optical measurements are performed via reflectometry techniques. The thickness, resistance, and optical constants of prototypical AP-SALD films (ZnO and Al2O3) were monitored during depositions, providing insight into film nucleation and growth. The nanoscale thickness gradient films facilitate combinatorial high-throughput screening of devices, where a multitude of devices with varying film thicknesses can be fabricated on a single substrate. This combinatorial approach was applied to study the role of Al2O3 film thickness as an insulating layer in quantum-tunneling metal-insulator-metal diodes and as an encapsulation layer in metal halide perovskite solar cells.
(Invited) Investigations into Molecular Layer Deposition of Conjugated Amine Polymers
Authors: Young Matthias J , Wyatt Quinton K , Gettler Ryan C , Paranamana Nikhila , White Tommi A , He Xiaoqing
Published: December 2020

Conjugated amine polymers (CAPs) such as polyaniline and polypyrrole have high electrical conductivities (>500 S/cm), high specific capacities (>500 F/g), and are one of few known material classes containing redox-active sites for binding negatively-charged anions. These properties make CAPs appealing for a range of electrochemical applications including semiconductor devices, energy storage devices, sensors, and electrochemical separation processes. Unfortunately, existing synthesis routes for CAPs rely on rapid chemical or electrochemical oxidation reactions that provide limited control over the molecular structure and thickness of CAPs. This restricts the ability to use CAPs to address technological needs. In this report, we describe ongoing research in our group to deposit conformal CAP films with molecular-scale control of thickness and composition using sequential and self-limiting gas-phase surface reactions. Our approach is in line with established molecular layer deposition (MLD) techniques, and uses an oxidant as one of the MLD precursors in so-called oxidative molecular layer deposition (oMLD). Using select examples, we reveal new insights into oMLD growth behavior, characterize the molecular structures of the oMLD CAP films, and connect structural differences under varying deposition conditions with electrical and electrochemical properties of the films. The insights we report enable the deposition of electrically conductive and redox-active CAP films conformally onto high-surface area samples, opening new avenues to enable advanced electrochemical technologies based on ultrathin and conformal CAP films.
Effect of microgroove structures on the fluid dynamics and film conformality in spatial atomic layer deposition of Al2O3
Authors: Li Zoushuang , Li Xiaobo , Cao Kun , Chen Rong
Published: December 2020

With the development of semiconductors, efficient ultrathin coatings on large areas is of great significance to the commercial needs for the encapsulation of materials with micro- or nano-structures. Spatial Atomic Layer Deposition (ALD) is an emerging high throughput and economic technique which can deposit nano-scale films on substrates with different topographies. However, the complex fluid dynamics and diffusion kinetics in the spatial ALD system bring great challenge to the investigation and optimization of the film conformality. In this work, a two-dimensional model coupling Computational Fluid Dynamics (CFD) coupled with chemical kinetics details is built to investigate the hydrodynamics and film growth characteristics in spatial ALD system with different substrates. The effects of the microgroove structures and the microgroove heights on the velocity flow fields and the conformality of alumina films are studied, as shown in the Figure. With numerical simulations, our results show that higher aspect ratio of groove structure leads to more vortex flow at the corner of the microstructures. The motion of the substrates exacerbates the formation of vortex, which will definitely cause the precursor intermixing. Besides, the conformality of the alumina film decreases as the aspect ratio of microgroove structures increases. In order to ensure the self-limited ALD reaction and improve the film conformality, process parameters of total gap size, separate gas flow rate, the carrier gas flow rate as well as the motion velocity of the substrate are investigated. It is found that low carrier gas flow rate can not only reduce the chemical vapor deposition (CVD) growth, but also increase precursor utilization. This work is important for the packaging of micro structure devices and is rather instructive to the further design of spatial ALD system.

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Advanced Electron Microscopy of Multi-Valent Cathode Materials
Authors: Parajuli Prakash , Kwon Bob Jin , Kim Sanghyeon , Vaughey John T. , Key Baris , Cabana Jordi , Klie Robert F
Published: December 2020

Recent progress in the field of scanning/transmission electron microscopy (S/TEM) has resulted in intense electron probes providing an ultra-high spatial (e.g. sub-Å) and energy (3 meV) resolution, with a previously unattainable signal-to-noise ratio. Furthermore, the STEM-based methods: direct imaging of both heavy and light elements, and both the energy-dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies are becoming the most promising characterization tools for battery materials, providing an unprecedented opportunity to probe the evolution of structure and electronic state of the cathodes following their electrochemical activity. The current talk will focus on the electron microscopy characterization of various materials that are considered as potential cathodes for the multivalent batteries, including transition metal (TM) oxides and polyanionic compounds. Materials were characterized using aberration-corrected JEOL JEM-ARM200CF, equipped with a cold field emission and operated at 200 kV, in pristine, cycled, and in-situ irradiated phases exploring their structure, chemistry, and electronic states. The in-situ technique mimics the electrochemical cell and allows for single-particle tracking of the dynamic processes occurring upon oxygen loss from the material providing helpful knowledge to further strengthen the understanding of the electrochemical activity of the cathodes. Several imaging modes, including high/low angle annular dark field (H/LAADF) and annular bright field (ABF), in conjunction with EELS/EDX, were used extensively for the analysis. Various parameters such as TM valence, phase transition, oxygen deficiency, and multivalent ion intercalation will be discussed.
Microstructual and Chemical Analysis of Surface Treated Metal Foam Anode for Li Rechargeable Battery
Authors: Ahn Tae-Young , Choi Yu Song , Kim Jiyoun , Cho Jang-Hyeon
Published: December 2020

As the amount of power consumed by electronic products increases, a lot of studies focused on high capacity and miniaturization of batteries. In order to overcome the low capacity of carbon anode in Li rechargeable battery, researches on the development of high capacity anode material have been conducted. In particularly, it has been reported that pure lithium was adopted for high capacity of Li ion battery due to its light in weight and excellent theoretical capacity. However, when pure lithium is used, the capacity decreases rapidly as charging and discharging proceeded, which is reported to be formation of dendrite on the Li surface during charging/discharging. In order to suppress the growth of dendrite during charging/discharging, several researches have been focused on the Li impregnated metal foam for Li rechargeable battery. However, due to the poor wettability between metal foam and pure Li, adhesive materials had to be deposited by using expensive processes such as chemical vapor deposition to impregnate the Li into metal foam.

In this study we focus on the heat treatment effect on the microstructure and Li-impregnation property of Ni metal foam. We oxidized the metal foam in a high temperature(500-900oC) for 5 min using the furnace to improve the wettability between the Lithium and Ni metal foam. Heat treated metal foam was dip into melted Li at 400 oC in a glove box. As a result, the rate of Li-impregnation in the heat treated metal foam was more than 10 times faster than that of the untreated Ni metal foam. The surface of heat treated Ni metal foam was characterized using transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy(EDS). Figure. 1 shows the TEM image of the untreated and heat treated Ni metal foam surface. It reveals that an additional layer having a thickness of 200 nm was observed in the heat treated Ni foam. The additional layer was identified as polycrystalline NiOx by EDS and selected area diffraction pattern (SADP). It is believed that formation of NiOx was greatly contribute to improvement of the impregnation characteristics. In addition, the impregnation characteristics of Ni alloy foam will be discussed in this presentation.

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(Invited) Theory of Silicon-Based Light Emitting
Authors: Luo Jun-Wei
Published: December 2020

The indirect band gap preclude the silicon from making light-emitting devices, which is, however, a quest for exploration of large-scale integration of both electronic and photonic devices on a single microchip. Why silicon and germanium are both indirect band gap and most of group III-V and all group II-VI semiconductors are direct band gap is a long standing puzzle. In this talk, I will first present our recently developed unified theory, based on occupied d orbitals in cations, for explaining why diamond, Si, Ge, and Al-containing group III-V semiconductors have indirect band gap, and the remaining group III-V and II-VI semiconductors, except GaP, have direct band gap. This theory also unravels that it is impossible to make allotropes of Si and compounds consisting by Si mixed together with other elements high efficient direct bandgap light emitting. Interface and quantum confinement in low-dimensional Si nanostructures are two knobs to relax the momentum conservation law of optical transition. Our theory confirms that the light emission efficiency of Si quantum dots increases exponentially as reducing dot size, but its highest reachable efficiently is still two orders of magnitude smaller than that of direct bandgap InP and GaAs. Fortunately, we discovered that Si/Ge magic sequence superlattices exhibit orders more efficient at emission light than their existing counterpart records and approach more than 10% brightness of real direct gap materials, such as GaAs. Furthermore, regarding the direct bandgap is only 140 meV above the indirect bandgap in Germanium (Ge), it is well established that a tiny (1-2%) extensile strain could render an indirect-to-direct bandgap transition and makes it direct bandgap. However, there is no feasible way to create such extensive strain on Ge since the lattice parameter of Ge is even 4.3% larger than Si. We propose insert external atoms into interstitial sites of Ge, which grows on Si substrate through SiGe buffer layer, to induce an effective tensile uniaxial strain on Ge, a new pathway toward direct band gap Ge. Because our proposed scheme is highly compatible with CMOS fabrication process, our presented new pathway would be a solution for on-chip lasers.