bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microfluidic Device for in Situ Observation of Bottom-up Copper Deposition in a TSV-like Structure- Improved Adhesion of Working Electrode Edge
Authors: Zhu Yize , Hayase Masanori 
Published: December 2024

The high performance of modern integrated circuits is now owing to packaging technologies. 3d-packaging using TSVs (Through Silicon Vias) has attracted large attention. Copper electroplating is used for filling conductor into the vias, because extreme bottom-up is available using a combination of additives. Even though extreme bottom-up is available with single addition of leveler without other additives and theoretical model, such as S-NDR model proposed by Moffat and Josell, can predict the filling behavior, still combination of leveler, suppressor and accelerator is generally used in industry and filling mechanism with the combination is not clear yet. To understand the mechanism of copper filling and the function of each additive, we have proposed microfluidic devices. In our previous study, a TSV-like structure was built in a micro channel as shown in figure 1, and real-time observation of copper bottom-up deposition was demonstrated. Though the observation was successful, observation period was limited to short periods of time, because abnormal deposition occurred at mouse of the TSV-like structure.
In this study, we assumed that poor adhesion around the edge of the working electrode on a substrate caused the abnormal deposition, because insufficient adsorption of leveler is expected if the working electrode thin film was floating from the substrate. Then, fabrication process of the working electrode was changed from etching to lift-off patterning technique. Several processes were optimized and abnormal deposition along the edge was successfully suppressed as show in figure 2. Using the lift-off technique, a TSV-like structure was built and electrodeposition was examined. Electrodeposition was started at 30 s after feeding a plating solution containing the leveler. Results are shown in figure 3. No abnormal deposition around the opening of TSV-like structure more than 10 min, and we succeeded in the observation of suppression breakdown inside the via. Further study with various combination of additives will be planned.

Figure 1
The Future of Die-to-Die Copper Interconnects and Epoxy Dielectrics
Authors: Park Junghyun , Dauda Monsuru Olatunji , Bello Mustapha , Flake John C. 
Published: December 2024

Recent Die-to-Die (D2D) interconnects require high data rates operating at high frequencies (> 10 GHz) in multichip packages. Mechanical adhesion was utilized to improve the reliability of traditional packages by increasing interface roughness between epoxy dielectrics and electrochemically deposited copper interconnects. The classical packages, operating at low frequencies below 1 GHz, showed a negligible scattering of electromagnetic waves (S21 < 0.5 dB/m) on the rough surface [1, 2]; however, recent interconnects present considerable degradation in power losses (S21 > 1.0 dB/m) on the rough surface due to skin effect at high frequencies (> 10 GHz) [2]. While previous works have shown the impact of surface roughness on adhesion enhancement, a trade-off between adhesion and power losses has not been precisely considered.
This study investigates the trade-off between reliability and performance. We explore the impact of surface roughness on adhesion and power efficiency of electrochemically deposited copper interconnects at high frequencies up to 18 GHz. Wet etching was performed to modify surface roughness for low-cost production. The root-mean-square roughness (RRMS) is regulated at ~10-100 nm to examine smooth copper-epoxy interfaces for future D2D interconnects. The surface morphology is analyzed by atomic force microscopy (AFM). Adhesion and insertion losses are investigated by peel test and vector network analyzer. A direction for future work is provided to improve chemical adhesion at a smooth copper-epoxy interface. Chemical adhesion is expected to improve the reliability of future multichip packages while maintaining power integrity. For example, surface oxidation and silane coupling agents are discussed to improve chemical adhesion at the smooth interface (< 100 nm RRMS).
REFERENCES:
[1] Lau, J.H., Recent Advances and Trends in Advanced Packaging. IEEE Transactions on Components, Packaging and Manufacturing Technology, 2022. 12(2): p. 228-252.
[2] Gold, G. and K. Helmreich, A physical surface roughness model and its applications. IEEE Transactions on Microwave Theory and Techniques, 2017. 65(10): p. 3720-3732.
(Invited) Processing, Mechanics, and Electrode Structure for All-Solid State LLZO Batteries
Authors: Tucker Mike C , Go Wooseok , Jonson Robert A , Shen Fengyu , Doeff Marca M. 
Published: December 2024

LLZO (Li7La3Zr2O12) and related garnet materials are primary candidates for the electrolyte and electrode scaffold of all-solid state lithium batteries. LLZO is a ceramic oxide with a wide voltage stability window, good conductivity at room temperature, and chemical compatibility with a wide variety of electrode active materials. Implementation of LLZO in full cells with high energy density is challenging, however, due to Li loss during sintering, reaction with transition metal cathodes at elevated processing temperatures, high volumetric density that limits cell energy density, brittle mechanical failure, and lithium intrusion into the electrolyte during cell operation at high current density. This presentation will summarize our efforts to address these issues through advancements in processing, mechanical properties, electrode structure, and composite electrode material selection.
To enable high energy density, it is desirable to utilize a thin (<100 μm) LLZO electrolyte layer. High conductivity of the thin electrolyte is maintained by adding sacrificial lithium carbonate, which compensates for lithium evaporation during sintering. Adding MgO prevents abnormal grain growth and maintains the desired fine grain structure, leading to a ~70% increase in fracture strength. Preparing a thin, flexible green ceramic sheet via tapecasting allows the electrolyte to be laminated to a porous LLZO electrode scaffold, or shaped via texturing prior to sintering. Scaffolds are prepared by high shear compaction, phase inversion, freeze tape casting, and other processing techniques based on scalable tape casting. In the case of texturing, surface features are impressed into the green LLZO tape and the additional surface area of the sintered LLZO surface decreases interfacial resistance and increases critical current density from 0.2 to 0.5 mA/cm2.
Utilizing these optimized ceramic fabrication processes, solid state cells are prepared with ~80 μm thick LLZO electrolyte, no added liquid electrolyte, and no exogenous pressure. A catholyte comprising organic ionic plastic crystal and a mixture of lithium salts is melt-processed to achieve good wetting and interfacial contact between the rigid LLZO and NMC cathode active material. This cell design achieves ~180 mAh/g and stable cycling for >100 cycles at room temperature. Efforts to scale up the cell size and improve rate capability will also be discussed.
Understanding the Electrochemistry of Solid-State Lithium-Oxygen Batteries Under Humid Environments
Authors: Lee Jaeheon , McCloskey Bryan D. 
Published: December 2024

Lithium-air batteries (LABs) represent a promising future battery technology due to their high energy density, although several challenges hinder them from achieving their theoretical performance. However, aprotic electrolyte-based LABs face several operational challenges, perhaps with the most severe being the instability of aprotic electrolytes towards reactive O2 species, nucleophilic attack, and auto-oxidation.1,2 Compared with aprotic electrolyte-based LABs, organic-free molten salt LABs showed improved oxygen efficiency but required high temperatures to operate the system.3 Alternatively, inorganic solid state electrolytes could not only enable room temperature and stable performance, but also protect Li metal electrodes from reaction with common air components, such as nitrogen, oxygen, CO2, and H2O.
Recently, a solid state Li-O2 battery was found to form LiOH as the major discharge product when humidity was introduced into the oxygen feed stream.4 Our aim is to understand the influence of humidity on the discharge product composition, as well as the reversibility of the full discharge-charge cycle. To do so, we developed a controlled-humidity Differential Electrochemical gas monitoring system, which controls and monitors humidity in the cell headspace while also tracing overall gas consumption and evolution. We will report on solid-state batteries that employ NASICON-type and garnet-phase ion conductors paired with either carbon or MnO2 cathodes. Our initial results suggest that the discharge product formed is a combination of Li2O2 and LiOH depending on the humidity and cathode composition used. On charge, while oxygen evolution is observed whenever Li2O2 is formed, little O2 evolution is observed from LiOH, suggesting a parasitic reaction involving LiOH and cell components.

References

S. A. Freunberger et al., Angewandte Chemie - International Edition, 50, 8609–8613 (2011).

J. Lai et al., Angewandte Chemie, 132, 2994–3019 (2020).

V. Giordani et al., J Am Chem Soc, 138, 2656–2663 (2016).

M. Kim et al., Sci Adv, 8 (2022).

Figure
1. Schematic diagram of Solid-State Lithium-Air Batteries under a humid environmen

Figure 1
Electrochemical Looping Using Tungsten Oxide for Electrolytic Hydrogenations
Authors: Sharifi Abdar Payman , Miu Evan V , Hughes Isabella , McKone James 
Published: December 2024

Global R&D associated with the production and utilization of hydrogen has been increasing dramatically to support the global effort to reduce CO2 emissions. Hydrogen can be used as a source of fuel and electricity, and it is also used as a chemical reductant for a host of industrial processes. One of the widely used applications of hydrogen in chemical industries is for hydrogenation reactions like ammonia synthesis and biomass hydrogenation. However, providing hydrogen for these reactions is practically challenging due to the several issues related to the high cost of infrastructure for hydrogen storage and transportation as well as safety concerns. These challenges could be mitigated if the hydrogen equivalents (i.e, protons and electrons) needed for these reactions can be supplied from water without producing H2 gas.
In this study, we introduce the concept of electrochemical looping hydrogenation, in which, instead of producing H2, a solid hydrogen-transfer mediator is used to activate hydrogen through water electrolysis and subsequently deliver it catalytically to a target molecule. Here, tungsten oxide (WO3) plays the role of the mediator due to its ability to reversibly uptake and donate hydrogen atoms. In this process, hydrogen is electrochemically inserted into WO3 to form tungsten oxide hydrogen bronze (HxWO3). The stored hydrogen is then used to drive a chemical hydrogenation reaction via hydrogen de-insertion from HxWO3 and reformation of WO3. For this study, hydrogenation of 4-hydroxy TEMPO (2,2,6,6-tetramethylpiperidine N-oxyl) to 4-hydroxy TEMPO-H was chosen as a model hydrogen acceptor. The results validate proof-of concept for our electrochemical looping system and permit systematic measurements exploring the interplay between interfacial transfer and intra-phase transport of electrons and protons.
Physics-Based Modeling to Elucidate Design Principles for Redox-Mediated Electrochemical Systems
Authors: Matteucci Nicholas J. , Mallia Christopher T. , Brushett Fikile R. 
Published: December 2024

Electrochemical systems are increasingly being developed and deployed as sustainable technologies that support reductions in greenhouse gas emissions across the electric power, transportation, and industrial sectors. However, the need to overcome challenges related to cost, performance, and scalability continues to motivate exploration into alternative material sets and reactor designs that offer new pathways to widespread adoption. Redox-mediated processes, which decouple electrode reactions that activate a soluble mediator from “off-electrode” reactions where the activated mediator exchanges electrons with a solid material, are of growing interest.1,2 Recent literature has illustrated the potential of this approach for increasing the charge-storage capacity of redox flow batteries,2 performing impractical electrochemical processes,3 enhancing selectivity and efficiency of electrochemical separations and recycling,1,4,5 and unlocking spatial and temporal flexibility in electrochemical operations.6 Previously, we have developed and qualitatively validated a model capable of capturing key dynamics observed in redox-mediated flow batteries.7 Grounded in first principles and contextualized by experiments, this model has the potential to rapidly assess tradeoffs and opportunities for redox-mediated systems for applications in energy storage and conversion as well as materials recovery and recycling.
Here, we describe how our model can be used to gain generalizable insights into the design-space for redox-mediated electrochemical processes. By incorporating models for pressure drop in porous media with simulated electrochemical performance, we assess the trade-offs associated with capacity utilization, power output, and parasitic pumping losses. Furthermore, we demonstrate how the model can support constrained optimization to guide the design of a system of known physical parameters. Ultimately, we seek to translate these findings into universal design principles for how electrochemical protocol and solid incorporation can be tuned to develop high-performing redox-mediated systems.

Acknowledgements

N.J.M gratefully acknowledges the NSF Graduate Research Fellowship Program under Grant Number 2141064. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the NSF.

References

Xue et al., Green Chem. 2020, 22 (19): 6288-6309.

Yan and Wang, Mat. 2018, 30 (47).

Vardner et al., ChemElectroChem 2022, 9 (24).

Cotty et al., ACS Sustain Chem Eng. 2023, 11(9):3975-3986.

Park et al., ACS Sustain Chem Eng. 2021, 9 (24): 8214-8221.

Wang et al, Joule 2021, 5 (1): 149-165.

Matteucci et al., ECS Meeting Abstracts 2023, MA2023-01 (3), 765.
Investigation of Phosphorus Refining in Hot Metal through Electrochemical Methods
Authors: Lee Sanghoon 
Published: December 2024

This study investigates the enhancement of phosphorus removal from hot metal through electrochemical methods to promote sustainable steel production. It introduces electrolytic refining techniques using molten slag as an electrolyte, aiming to overcome the limitations of chemical refining based on conventional CaO-bearing slag.
The research focused on the application of electric potentials to a CaO-SiO2-Al2O3-MgOsat slag system at a temperature of 1550℃ in a CO gas atmosphere, with voltages ranging from -0.5V to -2.0V. Following the attainment of electrochemical equilibrium, the efficiency of phosphorus removal was determined by quantitatively analyzing phosphorus content in the hot metal.
The results demonstrated that applying external electric potentials significantly enhanced phosphorus removal rates compared to the chemical equilibrium between the molten slag and hot metal. Moreover, the influence of slag basicity on the efficiency of phosphorus removal during the electrolytic refining process was confirmed. Consequently, the correlation between slag basicity and phosphorus electrolytic refining efficiency was discussed in detail, based on the physicochemical and electrical properties of the slag.
Molecular Design of Redox-Copolymers for Selective Electrochemical PGM Recovery
Authors: Kim Hee-Eun , Chung Ching-Hsiu , Elbert Johannes , Su Xiao 
Published: December 2024

Platinum group metals (PGMs) are of vital importance to various industries such as manufacturing, transportation, and energy economy. To secure the supply chain of PGMs, it is important to selectively extract target species from the mining ores and recycle spent automobile catalytic converters or e-waste. However, PGMs are challenging species to separate due to very similar physical and chemical properties and low concentration and complex speciation depending on pH or type of electrolyte used.1 Electrochemical separation is environmentally benign with good modularity and scalability. The development of next-generation electrodes with selective interactions for metal-binding and recovery is critical for innovating sustainable mining processes.
Redox electrodes were also shown to be efficient in controlling the operational voltage windows in aqueous-phase electrochemical systems, by increasing the Faradaic efficiency towards ion-binding and suppressing side reactions that would otherwise increase energetic costs. At the same time, polymer-functionalized electrodes have been shown to facilitate selective electrodeposition and regeneration of metals, thus providing an alternative approach for energy-efficient metal recovery. Redox-active polymers containing ferrocene have shown high selectivity towards anionic species such as metal oxyanions of arsenic and chromium.2 By modulating functional groups of redox polymers, charge-transfer behavior can be changed, and it can also provide new binding sites for target ions. We investigated a series of ferrocene-containing redox polymers to understand the kinetic and equilibrium uptake of PGM chloroanions. Different functional groups such as amide, alkyl, amine, and ester, respectively can modulate different redox potential within metallopolymers due to electron donating or electron withdrawing effects. The effect of these homopolymers was evaluated, with high uptake and regeneration being achieved for a range of PGMs. Going further than individual monomers, PGM-specific ligands were designed and incorporated into redox polymer by copolymerization. By leveraging heteroatom ligands as metal-specific functionality, the selectivity of the redox-copolymers in different pairs of PGM binary mixtures was tuned beyond the original homopolymers. The effect of ligand binding strength, ratio between redox group to ligand, and releasing solution on selectivity and uptake was investigated in detail.
(1) Kim, K.; Candeago, R.; Rim, G.; Raymond, D.; Park, A. H. A.; Su, X. Electrochemical approaches for selective recovery of critical elements in hydrometallurgical processes of complex feedstocks. iScience
2021, 24 (5), 31, Review. DOI: 10.1016/j.isci.2021.102374.
(2) Su, X.; Kushima, A.; Halliday, C.; Zhou, J.; Li, J.; Hatton, T. A. Electrochemically-mediated selective capture of heavy metal chromium and arsenic oxyanions from water. Nat. Commun.
2018, 9 (1), 4701. DOI: 10.1038/s41467-018-07159-0.
Fabrication of Superomniphobic TiAl6V4 Surface for Self-Cleaning and Anti-Biofouling Effect of Medical Devices
Authors: Lee Jeong-Won 
Published: December 2024

Ever since Wenzel and Cassie-Baxter announced their theories with respect to wettability transition with surface roughness, numerous studies on fabricating superhydrophobic surface have been carried out to provide industries with the advantages of the superhydrophobic surfaces such as anti-frosting, water proof, and self-cleaning. In metal industries, several methods have been developed to achieve superhydrophobic surfaces on various metals, including aluminum, copper, and steel. However, the fabricated surfaces only show over 150 of contact angles (CAs) for water (surface tension = 72.0 mN/m at 25 ℃) and do not show excellent repellency to low surface tension oils.
In the past few years, advantages of superomniphobic surfaces have been identified and many efforts are directed toward their practical industrial applications. Superomniphobic surfaces, unlike the superhydrophobic surfaces, show high repellency to low surface tension oils as well as anti-fouling, oil transfer, and oil-water separation properties. A superomniphobic surface is required to have not only a low surface energy but also a specific surface structure, because of which, it is much more difficult to fabricate than a typical superhydrophobic surface. Although a few fabrications of superomniphobic surface on titanium alloy (TiAl6V4) substrates have been reported, they are not superomniphobic to low surface tension oils like hexadecane, or are too far from industrialization because their fabrication relies on difficult methods such as laser micromachining. Further, there has been no report on achieving superomniphobic TiAl6V4 surfaces for hexadecane (surface tension = 27.1 mN/m at 25℃) using a simple method.
In this study, we render TiAl6V4 substrates superomniphobic by acid etching followed by anodization. Each process is analyzed with respect to processing times for obtaining optimal hierarchical microhorn/nanopore structures. The surface structures were then fluorinated by a self-assembled monolayer (SAM) coating, thereby imparting great repellency to low surface tension oils, including hexadecane. The surface morphology of TiAl6V4 in each process and analyses of the surface chemical change are discussed.

Figure 1
Simultaneous Entropic Coefficient Measurement and Multi-Species, Multi-Reaction Modelling
Authors: Wolfe Kody D , Paul Abigail , Magee Regan , Wilczewski Warren , Wichert Nathan , Lowe Jeffrey , Trembly Jason , Staser John A. , Garrick Taylor R. 
Published: December 2024

The multi-species, multi-reaction (MSMR) model is developed through the fitting of pseudo-open circuit voltage (POCV) data acquired by cycling a cell at a sufficiently low rate (C/50).1 By comparing MSMR fitted data taken at various temperatures, both temperature dependence of fitting parameters and thermodynamic data including the state-of-charge (SOC) dependent entropic coefficient (dU/dT), entropy (ΔS), and enthalpy (ΔH) can be gleaned.2 In this presentation, POCV behavior of coal-derived graphite will be discussed and compared to thermodynamic measurements of lithium-intercalation under potentiostatic testing conditions.3 Simultaneously measuring POCV data and determining
thermodynamic parameters has the advantages of minimizing testing time and complexity. The MSMR model’s ability to distinguish minute changes in temperature dependent active material behavior will be highlighted through a comparison of coal-derived graphite and commercially available
synthetic graphite.4 Implications of thermodynamic parameters and temperature dependent behavior on cell and pack level engineering will also be presented.
References:
1. D. R. Baker and M. W. Verbrugge, Journal of The Electrochemical Society, 165, A3952 (2018).
2. T. R. Garrick et al., Journal of The Electrochemical Society, 171, 023502 (2024).
3. J. Sturm et al., Journal of Power Sources, 412, 204–223 (2019).
4. A. Paul et al., Journal of The Electrochemical Society, 171, 039001 (2024)