bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Electro-Epitaxial Deposition of Zn on Cu Substrate by a Combinatorial Substrate Approach
Authors: Fang Guan-Ting , Tung Yun-Chih , Chang Liuwen , Wang Chih-Chieh
Published: December 2024

Zinc ion batteries (ZIBs) offer notable advantages such as low safety concerns, cost-effectiveness and a high theoretical capacity for serving as a large-scale energy storage system. However, the application of ZIBs is hindered by the dendrite growth problem leading to a low column power efficiency and a shorter lifespan. Epitaxial growth of Zn in deposition is a promising strategy to suppress dendrite growth. Existing methods primarily involve modifying the substrate surface to enhance Zn binding or to lower the lattice mismatch. However, these methods add complexity to the processing and inflate cost. Alternatively, this study aims at a simpler strategy of utilizing suitable substrates with high stability in the electrochemical environment and low lattice mismatches with Zn to enhance Zn epitaxy in deposition. It is noted that copper meets the electrochemical stability criterion, and the (111) Cu planes have a low lattice mismatch of 4.1% with the (0001)Zn. In this study, Zn was deposited galvanostatically in a sulfate solutions onto polycrystalline Cu sheets at room temperature using a combinatorial substrate approach. The effects of solution pH, current density and substrate orientation were examined. Electron backscatter diffraction technique was used to analyze the orientation of each substrate grain prior to deposition and the overlaid Zn layer afterwards. Results indicated that the solution pH, current density and substrate orientation all affected significantly on the deposition mode of Zn. At high pHs and an intermediate range of current density, Zn was deposited epitaxially up to a thickness of 10 mm or more. Moreover, the epitaxial growth on the (100) grains was heavily prohibited regardless the deposition condition.
Electroplating Zirconium from Low Temperature Deep Eutectic Solvents
Authors: Stull Jamie A , De Silva Umanga , Janusz Jordyn , Jones Ben
Published: December 2024

High temperature coatings such as zirconium are highly desirable in several applications due to their high melting point, corrosion resistance, and low neutron cross section. As such these materials are commonly used in nuclear reactors and the chemical processing industry. Due to the reduction potential of zirconium typical aqueous electroplating methods are not feasible. Physical deposition methods are possible but are limited to thin coatings (1-5 mm) and difficult for complex geometries and through holes. To achieve thicker conformal coatings molten salt electroplating is commonly employed. This method requires high temperatures (600-700°C) and complex experimental set-up that can accommodate the high temperatures and exclude water and oxygen.

Our team is developing low temperature (80-100°C) electroplating solvents based off deep eutectic chemistry. These solvents are low cost and low hazard. We have explored different deep eutectic solvents (DES) using choline chloride as the hydrogen bond acceptor. The hydrogen bond donor has been varied, ethylene glycol and urea are examples that have been explored. We have completed electrochemical (cyclic voltammetry) and solubility studies of multiple supporting electrolytes (LiF, LiCl, etc.) and zirconium metal salt. Preliminary electroplating results will also be presented.
Electrochemistry of Trivalent Chromium in Ionic-Liquid/Deep Eutectic Solvent-Based Ternary Aqueous Solutions
Authors: Sconyers David J. , Briem Musashi , Curran Daniel J. , Maurer Joshua A.
Published: December 2024

Hexavalent chromium electroplating has come under severe scrutiny, with increasingly strict regulations and plans for complete removal from operations within the US within the next 10 years. Hexavalent chromium poses large risks, as it is a known carcinogen and presents severe occupational and environmental hazards in its use. However, chromium coatings offer many benefits, including excellent wear and corrosion resistance, along with good hardness and adhesion properties. As such, an effective chromium plating alternative for hexavalent-based processes is sorely needed. Trivalent chromium systems represent a promising and safer alternative to existing technologies due to their decreased toxicity. However, fundamental challenges in addressing the thermodynamics and equilibria of chromium’s complex aqueous chemistry have made the successful development of new plating methodologies difficult. Present solutions incorporate a multitude of complexing agents that play unknown roles in stabilizing trivalent chromium itself or its reduced intermediates. An alternative approach is to use ionic liquids/deep eutectic solvents or ionic liquid/deep eutectic solvent and water mixed systems, which have unique physical and chemical characteristics that could support and poise trivalent chromium for effective electrodeposition. Here, we explore the electrochemical profiles of ionic liquid-based trivalent chromium electroplating systems, highlighting the strong dependence of the spectroscopic response and plating behavior on solution water content.
Annealing Phenomena in the Electroformed Invar FMM
Authors: KIM In Gyeong , Lee Jun Ha , Shin Se Eun , Park Yong Bum
Published: December 2024

In the OLED display industry, Invar(Fe-36%Ni) exhibiting anomalous low thermal expansivity is commonly used as a material for the fine metal mask (FMM), which guides the evaporated diode materials through its small holes onto the correct positions of the substrate glass. We are investigated that the coefficient of thermal expansion (CTE) as a function of the alloy composition before and after annealing in the Fe-Ni alloys consisting of the α(BCC) and γ'(FCC)phases fabricated by using an electroforming method. The CTE-composition curve of the electroformed Fe-Ni alloys was measured to be different from that of the pyrometallurgically produced Fe-Ni alloys. The electroformed Invar can perform low CTEs via thermomechanical heat treatment where the a phase and γ′ phase in the as-deposited state are transformed into the γ″(FCC) phase. During annealing of the electroformed Invar, the as-deposited texture with the <110>α//ND + <100>γ′//ND components was changed into the the major <111>//ND and minor <100>//ND components. This texture evolution occurring during annealing has been explained in terms of a combined effect of abnormal grain growth (AGG) and the α → γ″ (or α → γ'→ γ″) phase transformation.
Etidronic Anodizing of Aluminum Alloys: Growth and Properties of Anodic Layers
Authors: Moutarlier Virginie , Daval Jérémy , Brunol Emmanuelle , Viennet Rémy , Ricq Laurence , Hihn Jean-Yves
Published: December 2024

Anodizing is a well-known electrochemical process used to increase the thickness of the natural oxide present on the surface of aluminum alloys. This process is commonly employed to enhance properties such as anticorrosion and hardness. Sulfuric acid is the most frequent used electrolyte for aluminum alloy anodizing, offering significant corrosion resistance. For applications requiring a hard anodic layer, a specialized sulfuric anodizing can be implemented, where the bath temperature is around 0°C. However, when anodizing is necessary at room temperature, Huang et al. [1] have suggested the use a new electrolyte: etidronic acid (HEDP).

The present work focuses on the study of this new hard anodizing process, with etidronic acid. Electrochemical analyses as well as anodic layer characterizations have been performed for various aluminum alloys including 1050, 2024 and 7075 alloys.

The growth of the anodic layer varies depending on the alloy type. Two modes of anodization have been identified: a conventional anodization mode (for 1050 alloy) and a second mode which can be considered as micro-arc anodization (for 2024 et 7075 alloys). These anodization regimes will induce modifications in the thickness, morphology, crystallinity, and hardness of the anodic layers.

[1] H. Huang, J. Qiu, X. Wei, E. Sakai, G. Jiang, H. Wu, T. Komiyama, Ultra-fast fabrication of porous alumina film with excellent wear and corrosion resistance via hard anodizing in etidronic acid, Surface & Coatings Technology 393 (2020)

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(Invited) Binder-Free Sulfur-Carbon Composite Electrodes for High Energy Density Lithium-Sulfur Batteries
Authors: Hwa Yoon , An Yuhui
Published: December 2024

In the scientific mission for sustainable and efficient energy storage solutions, the importance of developing high performance energy storage systems along with environmentally friendly manufacturing technologies has become important. Among various energy storage systems, Lithium-Sulfur (Li/S) batteries are particularly noteworthy for their high theoretical specific energy (2,600 Wh/kg) and cost-effectiveness, traits largely attributable to abundance and favorable properties of sulfur. This positions Li/S batteries as a compelling alternative to the prevalent lithium-ion batteries, setting a new horizon in the pursuit of advanced energy storage solutions. A critical aspect of Li/S battery manufacturing is the fabrication process of sulfur electrodes, traditionally reliant on the slurry casting method with polymer binders like N-Methyl-2-pyrrolidone (NMP), which poses environmental and economic challenges due to the energy-intensive slurry drying and subsequent NMP vapor recovery processes. Although alternatives such as aqueous binders have been explored, they offer limited benefits in reducing the overall environmental impact. Moreover, the use of binders generally increases the resistance of electrodes due to their insulating nature, affecting the electrochemical performance of battery electrodes. Our research marks a significant departure from conventional practices by introducing a novel binder-free and solvent-free approach to fabricate sulfur-carbon composite electrodes. This pioneering method represents a paradigm shift towards green energy technology, addressing both the environmental and economic concerns associated with traditional electrode fabrication. This advancement contributes significantly to reducing the environmental footprint of battery technologies, aligning with the global imperative for cleaner energy solutions. Our comprehensive study focuses on the structural, compositional, and electrochemical characteristics of the binder-free sulfur-carbon electrodes produced through this method. Utilizing advanced spectroscopic and imaging techniques, we examine the mechanisms that underlie the enhanced performance of these electrodes. The investigation reveals critical insights into the morphological and crystalline attributes that promote electrochemical activity, as well as the synergistic interactions between sulfur and carbon in the absence of traditional polymer binder.
(Invited) A Comparative Evaluation of Li, Na, and K-Ion Cathodes
Authors: Ceder Gerbrand
Published: December 2024

Most cathode materials for Li-ion batteries are layered oxides which are isostructural to LiCoO2. Other structures, such as spinels, olivines, and disordered rocksalts, can also be used as high-capacity cathodes. The latter three structures types create less resource issues as they can function with Fe or Mn as active transition metals, but still may suffer from resource issues related to Li-ion availability.

With Na, almost all transition metals form layered structures, providing less expensive and more resource abundant options for Na-ion cathodes, but typical layered cathodes have a large voltage slope which limits the usable energy density. The voltage slope is even larger when K is used as an intercalant in layered materials. I will discuss the origin of the voltage slope in these materials and evaluate whether better cathode options are available for Na and K-ion batteries.
Origin of Structural Degradation in Li-Rich Layered Oxide Cathode
Authors: Liu Tongchao
Published: December 2024

Li and Mn-rich cathode materials (LMR) that utilize both cation and anion redox can yield substantial increases in battery energy density.1-3 However, even though voltage decay issues cause continuous energy loss and impedes its commercialization, prerequisite driving force for this phenomena are a mystery3-6 Here, with in-situ nanoscale sensitive coherent X-ray diffraction imaging (BCDI) techniques, we reveal that nanostrain and lattice displacement accumulate continuously during cell operation. Evidence unequivocally shows that this effect is the driving force for both structure degradations and oxygen loss that triggers the well-known rapid voltage decay in LMR. By further leveraging micro to macro length characterizations that span atomic structure, primary particle, multi-particle and electrode level, we demonstrate that the heterogeneous nature of LMR cathodes inevitably causes pernicious phase displacement/strain which cannot be eliminated by conventional doping or coating methods. These results affirm that lattice displacement and nano-strain, which represent commonly occurred but less detectable dynamic structure evolutions, play an undeniable role in structure decomposition and voltage fade. With these fundamental discoveries, we propose mesostructural design as a strategy to mitigate lattice displacement and inhomogeneous electrochemical/structural evolutions, thereby achieving stable voltage and capacity profiles. These findings highlight the significance of lattice strain/displacement in causing voltage decay and will inspire a wave of efforts to unlock the potential of the broad-scale commercialization of LMR cathode material.
Ultrafast Deposition of Faceted Lithium Polyhedra By Outpacing SEI Formation
Authors: Yuan Xintong , Li Yuzhang
Published: December 2024

Electrodeposition of lithium (Li) metal is critical for high-energy batteries. However, the simultaneous formation of a surface corrosion film termed the solid electrolyte interphase (SEI) complicates the deposition process, which underpins our poor understanding of Li metal electrodeposition. Here we decouple these two intertwined processes by outpacing SEI formation at ultrafast deposition current densities while also avoiding mass transport limitations. By using cryogenic electron microscopy, we discover the intrinsic deposition morphology of metallic Li to be that of a rhombic dodecahedron, which is surprisingly independent of electrolyte chemistry or current collector substrate. In a coin cell architecture, these rhombic dodecahedra exhibit near point-contact connectivity with the current collector, which can accelerate inactive Li formation. We propose a pulse-current protocol that overcomes this failure mode by leveraging Li rhombic dodecahedra as nucleation seeds, enabling the subsequent growth of dense Li that improves battery performance compared with a baseline. While Li deposition and SEI formation have always been tightly linked in past studies, our experimental approach enables new opportunities to fundamentally understand these processes decoupled from each other and bring about new insights to engineer better batteries.
Thermal Consequences of Lithium Metal Short Circuits
Authors: Schumacher Bret , Sullivan Jon , Alvarez Mia R , Munich Naiara , Marbella Lauren , Steingart Dan
Published: December 2024

Infrequent but catastrophic safety events such as fires and explosions are impeding and in come cases reversing the adoption of lithium ion batteries in dense urban settings. In these events, thermal runaway is often conflated with short-circuiting events through manufacturing defects that cause a pinch short or lithium filament growth during charging and subsequent shorting. We posit that drawing causation from lithium-driven short-circuiting is challenging because the heat produced during this event is poorly understood. We use isothermal microcalorimetry (ITMC) to measure the heat associated with lithium metal short-circuiting in a delithiated LiCoO2 cell when the system is in a thermally unstable state and prone to degassing. We use a custom-built cell design to initiate a controlled lithium metal short and quantify the total energy release of the short in operando. We provide simple energy-mass balances calculations to show that the temperature change during shorting is significantly lower than the temperature needed for thermal reduction and thermal runaway in this system. Finally, we discuss the impact of the observed heat release as these systems are scaled.
Saturation-Based Transport Limitation in Thick Electrodes with Conventional Carbonate Electrolytes
Authors: Hu Kedi , Owen Christopher , West Alan C. , Steingart Dan
Published: December 2024

In electric vehicles, stationary grid storage, and low-power lithium-ion battery (LIB) applications, thick electrodes can minimize inactive material use to increase energy density and decrease costs but face challenges in performance and manufacturability. In thick electrodes, large concentration gradients form across the electrode to push lithium ions through the thickness of the electrode, resulting in large concentration overpotentials that limit capacity utilization at higher rates. It is well understood that lithium-ion depletion at one side of this concentration gradient results in a limiting current for the cell; our models show that for high-power thick electrode systems, salt accumulation at the other side of the concentration gradient exceeds the solubility of conventional carbonate electrolytes used in LIBs. In this study, ~1mm thick dry-pressed lithium iron phosphate (LFP) electrodes were cycled at various current densities to explore precipitation conditions. Thick electrodes become rate-limited in a hexafluorophosphate (PF6)-based carbonate electrolyte; they are able to maintain high capacity utilization (~98% at C/10, ~95% at C/5, ~76% at C/2) in a bis(fluorosulfonyl)imide (FSI)-based electrolyte, which has both higher solubility and diffusivity. Operando acoustics and ex-situ imaging techniques are used to observe the effects and reversibility of precipitation in the PF6 electrolyte system. Lastly, a physics-based model is employed to define saturation-based limiting conditions given the physical electrode thickness, tortuosity, porosity, and electrolyte diffusivity.

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Accelerated Solid-State Electrolyte Synthesis via Reaction Equilibria Manipulation
Authors: Garman Kaitlin , Thomas Charlotte Michele , Wang Yangyang , Ban Chunmei
Published: December 2024

Solid-state electrolytes enable the use of a lithium metal anode and offer higher energy density and thermal stability, making all-solid-state batteries (ASSBs) a promising next-generation battery technology. Solid-state synthesis is the main method of synthesizing solid-state electrolytes, such as ceramic garnet-type oxide electrolytes. Solid-state reactions can be challenging due to typically requiring a long time at very high temperatures to allow ion migration and overcome the high activation energy of the forward reaction, making scale-up impractical. Our research focuses on understanding the solid-state reaction mechanisms using a model material, Li6.5La3Zr1.5Ta0.5O12 (LLZTO), renowned for its high lithium-ion conductivity and compatibility with lithium metal anodes. We propose a strategy to manipulate the solid-state reaction equilibrium to expedite LLZTO formation to less than one hour. Operando X-ray diffraction (XRD) and ex-situ XRD were used to study the reaction progress and evolution formation mechanisms. Characterization of composition and electrochemical properties is conducted using inductively coupled plasma optical emission spectroscopy (ICP-OES) and various electrochemical analytical techniques. This presentation aims to elucidate the feasibility of synthesizing LLZTO materials within a shorter timeframe, offering valuable insights for expediting the synthesis of solid-state electrolytes through solid-state reactions.
(Invited) Garnet Electrolyte Material Degradation and Recovery
Authors: Cheng Lei
Published: December 2024

Solid state batteries show advantages in battery safety, energy density and temperature tolerance and therefore are considered promising alternative of Li-ion batteries using organic electrolytic solutions. Solid electrolytes are critical components in solid-state batteries. Among different types of solid electrolyte, oxide based, garnet-type Li7La3Zr2O12 (LLZO) solid electrolytes have been of particular interest due to the combination of good ionic conductivity and chemical stability against metallic lithium. However, these materials exhibit surface degradation when exposed to air and moisture, which adversely impacts their functioning in operating solid state batteries.

In this work, multiple depth-profiling techniques were adopted, and the results revealed that a structural and chemical gradient exists upon LLZO degradation. The degradation mechanism of garnet solid electrolyte is discussed with the focus on the surface and sub-surface of LLZO. Based on the understanding, scalable mitigations are developed to recover the degradation by simple treatment at relatively low temperatures.
(Invited) Achieving Extreme High Ion-Current Densities in Tailored Materials, Structures, and Interfaces
Authors: Wachsman Eric D
Published: December 2024

Oxide-based solid-state batteries have the potential to be a transformational and intrinsically safe energy storage solution due to their non-flammable ceramic electrolyte that enables the use of high-capacity metal anodes and high voltage cathodes for higher energy density over a much wider operating temperature range. However, their progress has been limited due to electrode/electrolyte interfacial issues. In particular for metal anodes concerns over dendrite formation/propagation and the requirement for elevated temperature and high stack pressure are still prevalent. To eliminate these concerns a rational design of tailored materials, 3D structures, and interfaces in metal anodes will be presented. While focus will be on Li-metal anodes we will demonstrate same approach works for Na-metal anodes.

By use of a few nm thin AlOx ALD interfacial layer we were the first to enable Li-metal wetting of LLZO-garnet surface achieving a negligible interfacial ASR of only ~1 Ohm cm2 at room temperature with no applied pressure. Then by fabricating a ~10 mm LLZO dense layer on an extend 3D porous scaffold, with ALD surface modification to enable Li-metal wetting, we were the first to achieve the US DOE VTO Fast Charge goal for Li-metal cycling of 10 mA/cm2 at room temperature with no applied pressure. We subsequently developed a mixed ion and electron conducting (MIEC) garnet composition which when integrated into the 3D porous scaffold structure enabled critical current densities (CCDs) of 100 mA/cm2 and cumulative Li-metal cycling of over 18.5 Ah/cm2 at room temperature with no applied pressure. More recently due to the concern over Li availability we developed higher conductivity NASICON and demonstrated similar stable cycling of Na-metal in 3D structured NASICON achieving CCDs of 30 mA/cm2 at room temperature with no applied pressure.

These new solid-state compositions integrated into surface modified 3D structures enable previously unheard-of metal-anode cycling rates. Their development and progress toward full cells using these tailored materials, structures, and interfaces will be presented.
The Mechanism of Cu Microvia Pulse-Reverse Electrodeposition in Single Accelerator System
Authors: Seo Huiju , Kim Myung Jun , Kim Jae Jeong
Published: December 2024

As device miniaturization approaches its limits in terms of performance enhancement, the importance of efficiently arranging devices and the technology for connecting each device, known as packaging, is increasing. In packaging, interconnects are used to connect devices, and Cu electrodeposition is widely employed to form these interconnects. To achieve defect-free interconnects, typically three types of additives are used: accelerator, suppressor, and leveler. However, using various additives increased the complexity of electrodeposition bath monitoring system. In the PCB industry, where plating baths are used for periods exceeding six months, the complexity of process management due to the use of various additives becomes further increased.

In this study, Cu microvias used as interconnects on PCB are plated using a SPS single accelerator system, within 60 minutes. To achieve defect-free filling, a pulse-reverse current waveform was introduced instead of direct current. Also, the behavior due to differences in convection was analyzed to suggest a mechanism capable of inducing superfilling. After the reverse time, Cu+ forms on the surface, and due to the Cl- rich surrounding environment, Cu-Cl species covers the surface. This CuCl layer is known to assist the adsorption of SPS, accelerating the electrodeposition process. Inside the vias where convection is weak, CuCl remains, leading to an acceleration effect by SPS. However, outside the vias where strong agitation is present, CuCl with adsorbed SPS is flown away into the bulk, resulting in the acceleration effect being observed only within the inside of the vias. In this study, the presence or absence of an acceleration effect depending on convection was confirmed through electrochemical results, and this has been proposed as the mechanism for single accelerator system superfilling.

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Improving Uniformity of Electroplated Co Thin Film on SOFC Interconnector by Controlling Electrochemical Behavior and Microstructure
Authors: Shin Han-Kyun , Park Hyun , Lee Hyo-Jong , KIM Jung HAN
Published: December 2024

Solid oxide fuel cells (SOFC), a third-generation ultra-clean fuel cell, operate at a higher temperature of 600°C and have high energy conversion efficiency. SOFC is capable of a combined power generation system and produces water as a by-product, therefore is attracting attention as one of the eco-friendly power sources. As the SOFC interconnect material, ferritic stainless steel containing Cr is dominant, however it has the problem of durability which originates from the sublimation of Cr on the interconnect surface during high temperature operation. To suppress the Cr sublimation, research is being extensively conducted and the coating of a thin passivation material is thought as a promising solution. In this study, we selected Co thin film as a passivation layer and developed an electroplating technique where the uniformity of Co thin film in an air channel pattern is controlled using organic additives and current densities. The difference in thickness of electroplated Co thin film according to the position of the pattern were measured. In addition, the microstructure of the Co thin film was observed using an EBSD (electron backscatter diffraction) system, and the corresponding electrochemical behavior was analyzed. The uniformity of the Co thin film improved as the current density decreased, which is the result of the increase of Co ions reaching the bottom of the pattern. Furthermore, the combination of thiourea and saccharin led to the decrease in the grain size, resulting in enhancing the uniformity.
The Adsorption Kinetics of CTA+, Br-, and Ag+ Determining Anisotropic Growth of Gold Nanorods
Authors: Min Yujin , Yoon Seolim , Kim Myung Jun
Published: December 2024

Gold nanorods (AuNRs) have received significant attention due to their tunable plasmonic properties across the visible and near-infrared spectrum, large surface area to volume ratio, and chemical inertness, making them valuable in biomedical engineering and photochemistry. The physical properties of anisotropic AuNRs strongly depend on their aspect ratio, defined as the ratio of length to width. Previous studies have primarily focused on synthetic methods to precisely control the aspect ratio of AuNRs. Among various synthetic routes, the seed-mediated growth method in aqueous solution, comprising nucleation and further growth steps, is considered the best approach to obtain highly uniform AuNRs with a high yield. Notably, the method utilizing Ag+ with cetyltrimethylammonium cation (CTA+) and Br- during the growth step from Au nanoparticle seeds to NRs is the most convenient for controlling the aspect ratio of AuNRs. In this method, Ag+ acts as a key additive for symmetry breaking, ultimately modulating the aspect ratio of AuNRs. Despite advancements in synthetic methods, the underlying mechanism governing the cooperative interaction between additives (CTA+, Br-, and Ag+) and the anisotropic growth of AuNRs remains incompletely understood. Although computational simulations shed light on the detailed chemistry regarding the adsorption of additives, further investigation into the adsorption kinetics and their impact on the reduction of Au complexes is necessary. Due to the lack of information on the detailed chemistry during AuNR growth, synthetic results are sometimes inadequately explained by existing mechanisms. Therefore, this study aims to investigate the effect of CTA+, Br-, and Ag+ on the anisotropic growth of AuNRs. Electrochemical analyses will explore how Ag+ affects the adsorption behavior of CTA+ and Br-. This presentation will introduce the influence of each additive on Au reduction and the formation of suppression layers on AuNR surfaces across varying adsorption and growth durations.
Controlling Surface Morphology of Electrodeposited Sn-Bi through Additives
Authors: Hwang Yoojin , Lee Jeong Ho , Kim Myung Jun
Published: December 2024

Establishing robust electrical connections between chips is crucial in semiconductor packaging structures to manufacture high-performance electronics. Microbumps and low-temperature solders have become preferred alternatives to conventional metal wiring processes, aiming to enhance electronics integration. Microbumps, typically made of Cu for its low electrical resistivity, play a vital role in facilitating efficient electrical connections. Meanwhile, a commonly used solder material is Sn-Ag. However, traditional thermo-compression (TC) bonding utilizing Cu pillars and Sn-Ag solder typically requires temperatures around 230-250°C, raising concerns about stability in the bonding system. The high temperatures involved in the bonding process can lead to wafer warpage due to the different thermal expansion coefficients of front and backside wafer, resulting in the misalignment of bonding wafers that significantly impact yield management and electronic performance. This limitation is one of the hurdles for the fabrication of sub-micrometer pitch interconnections using microbumps and solder. Hence, reducing bonding temperature is imperative, and low melting temperature solder materials like Sn-Bi offer a solution. Sn-58 wt% Bi, for instance, boasts a promising melting temperature of approximately 139°C, significantly lower than Sn-3.5 wt% Ag (~221°C). Despite its potential advantages, the electrodeposition process for Sn-Bi is still in its developmental stages compared to Sn-Ag. To mitigate defects at the bonding interphase, it is crucial to develop an electrodeposition technique capable of producing smooth Sn-Bi films with uniform distributions of Sn and Bi atoms. This study aims to investigate the impact of various additives on manipulating the surface morphology of Sn-Bi films, exploring the effects of electrolyte composition, current density, and the type and concentration of additives on Sn-Bi electrodeposition.
(Invited) Cu-Cu Bonding in Semiconductor Packaging: Utilizing Texture Control for Enhanced Performance
Authors: Han Haneul , Yoon Sanghwa , Yoo Bongyoung
Published: December 2024

The rapid development of IT markets, including big data, AI, 5G, IoT, smart automotive, and datacenters, has led to an increase in demand for advanced packaging solutions. With the IC density doubling through the shrinking of feature sizes, significant improvements in IC device performance have been achieved. This continuous scaling of feature sizes has prompted changes in packaging technology, with three-dimensional die stacking technologies like through-silicon vias (TSVs) and microbumps emerging as crucial innovations.

However, traditional microbumps suffer from issues such as the Kirkendall effect, side wetting, and solder depletion, which compromise both mechanical and electrical properties. Innovative solutions are thus essential to address these challenges effectively. Cu to Cu bonding eliminates the formation of intermetallic compounds, mitigating the problems associated with microbumps. Additionally, Cu to Cu bonding offers superior electrical properties compared to microbumps, further enhancing its appeal.

In particular, semiconductor devices requiring high-density packaging, like high bandwidth memory (HBM), have spurred interest in hybrid bonding. Additionally, the growing need for 3D interconnects in advanced packaging is becoming increasingly apparent.

To this end, research is focusing on next-generation microbumps, particularly Cu-Cu bonding, as an alternative solution. Understanding the internal characteristics of Cu is crucial for promoting diffusion between Cu atoms at lower temperatures. Thus, nanotwinned Cu with a (111) preferred orientation has garnered significant research attention as a material that promotes diffusion between copper atoms, particularly in Cu-Cu bonding processes. However, research is lacking on the optimal grain orientation for the bonding process.

By controlling crystal orientation through plating parameter adjustments, Cu films with three principal preferred orientations have been achieved. These films exhibit distinct mechanical properties based on their preferred orientation, with (111) preferred Cu showing the highest hardness due to the significant presence of nanotwins.

In summary, advancements in 3D interconnect technologies, particularly in Cu-Cu bonding, hold promise for addressing the challenges in advanced packaging. By employing innovative solutions and exploring new materials and techniques, the semiconductor industry can continue to meet the evolving demands of the IT market while ensuring the reliability and performance of semiconductor devices.
(Invited) Mechanics of Materials in All Solid-State Lithium Metal Batteries
Authors: Warren Roseanne
Published: December 2024

All solid-state lithium metal batteries (ASSLBs) with ceramic solid electrolyte and lithium metal anode are promising candidates for next-generation, high energy density batteries. Unlike conventional lithium-ion batteries with liquid electrolyte, ASSLBs present a ceramic-metal interface at the anode that is prone to various mechanical failure modes, including: non-uniform plating causing cracks in the solid electrolyte and the anode current collector; non-uniform stripping creating gaps between anode and electrolyte; and cracking and void formation leading to dendrite growth, short-circuits and capacity loss. As such, the mechanical properties of the ceramic solid electrolyte, lithium metal, and anode current collector are critical parameters affecting cell performance.

This talk will explore the mechanical properties of interest for ASSLBs and their influence on cell charge-discharge behavior. Methods of characterization of these properties across length scales will be discussed, including recent work on instrumented indentation testing (nanoindentation, scanning electron microscopy with in-situ picoindentation) and a novel in-situ straining technique with transmission electron microscopy. The ability to influence mechanical properties of the anode-solid electrolyte interface through changes in process parameters will also be described. Overall, the methods and results presented here will provide a picture of the role of mechanics in ASSLBs and highlight pathways to greater understanding.
(Invited) Strategy and Interfacial Design for High-Rate & Hig-Areal-Capacity Sulfur Cathodes in All-Solid-State Li-S Batteries
Authors: Yang Yong
Published: December 2024

All solid-state lithium-sulfur batteries (ASSLSBs) have attracted significant attention due to their enhanced safety and superior energy density. However, the considerable electrolyte decomposition and volume change during cycling poses some challenges, resulting in electrochemical-mechanical degradation. To address this issue, polypyrrole (PPy) is coated on a nitrogen-doped carbon nanotube (NCNT) network to exhibit suitable conductivity and compatibility with sulfide electrolyte. Functionally, PPy@NCNT provides a continuous and conductive pathway, reducing the tortuosity of charge transport. Mechanically, operando pressure measurements and atomic force microscopy (AFM) tests are conducted, demonstrating that the flexible and viscoelastic structure of PPy@NCNT can alleviate local stress. The axial pressure on the cathode can be reduced by 11% with a sulfur area capacity of 3 mg cm-2 at 30°C. At a high areal mass loading of 4.5 mg cm−2, a high areal capacity of 6 mAh cm−2 (1348 mAh g-1, 1C=1675 mA g-1) is achieved at 0.1C, maintaining stability over 300 cycles at 0.2C. Remarkably, it can achieve an areal capacity of over 8.8 mAh cm-2 and stable cycling even at 60°C. This study, being the first to regulate mechano-electrochemical action in ASSLSBs with flexible conducting polymer, highlighted the significance of integrating a continuous and elastic network into solid-state conversion-type cathodes. In addition, atomic layer deposition（ALD）-derived lithium phosphorus oxide is applied to the surface of carbon/sulfur particles to enhance the interfacial stability of the sulfur cathode and improve the electrochemical performance of ASSLSBs. The coating layer can inhibit electrolyte decomposition and improve interfacial stability by blocking electron conduction between carbon and electrolyte. Moreover, it not only serves as an ion-conducting layer to facilitate Li+ transport but also acts as a stress buffer layer to alleviate contact failure. The assembled ASSLSBs with sulfide electrolyte exhibit initial specific capacity of 1322 mAh g-1 at 0.2 C and capacity retention of 86.4% after 300 cycles. Furthermore, ASSLSBs maintain reversible capacity of 645 mAh g-1 at 0.5 A g-1 after 1000 cycles。 Finally，some new results about understanding of failure processes of Li metal anode in all-solid-state battery will be also presented.
(Invited) Designing a Safe and Sustainable Future: Sodium Ion and All-Solid-State Batteries
Authors: Yao Yan
Published: December 2024

In this presentation, I will present the key challenges confronting all-solid sodium batteries, and how soft organic redox materials could enable intimate interfacial contact with solid electrolytes under low operating pressure. Additionally, we developed an oxysulfide glass electrolyte that forms a thin, dense, self-limiting interphase against Na metal and exhibits a fully dense glass microstructure. I will also discuss the role of Na-ion electrolyte additives for stabilizing hard carbon anodes.
(Invited) Materials Development and Their Integration for High Energy and Long Cycle Life Solid-State Li Metal Batteries
Authors: Kim Haegyum
Published: December 2024

All solid-state Li metal batteries are future of the energy storage because of their high energy and safety. In past years, several highly conductive solid-state electrolytes have been developed, which makes the solid-state battery system more appealing. Nevertheless, several important challenges remain to be addressed before any all solid-state Li metal batteries can be competitive and outperform the existing Li-ion batteries. In this presentation, I will provide an overview of solid-state battery programs at Lawrence Berkeley National Laboratory which are supported by the U. S. Department of Energy’s Vehicle Technologies Office (VTO), and discuss the important challenges in the solid-state Li metal batteries as well as our recent progress in the materials development and their integration in the solid-state Li metal batteries.
Lattice Oxygen-Catalyzed Bismuth-Cerium Oxyhydroxide Anode for Anion Exchange Membrane Water Electrolyzers
Authors: Jo Seunghwan , Shin Ki Hoon , Hong John , Sohn Jung Inn
Published: December 2024

The lattice oxygen involvement in the oxygen evolution reaction provides an efficient reaction pathway. However, the structural and electrochemical stabilities are crucial to activate lattice oxygen while minimizing material deformations and ion elution. Herein, a heterostructure Bi/BiCeOOH containing abundant under-coordinated oxygen atoms is prepared by an electrochemical deposition method. The reduction potential difference between Bi and Ce generates partially reduced Bi nanoparticles and surrounding under-coordinated oxygen atoms in BiCeOOH. The lattice oxygen is activated and stabilized when the metal–oxygen covalency increases, and the oxophilic Ce maintains the Bi nanoparticles with surrounding under-coordinated oxygen atoms by preventing over-oxidation of Bi during the oxygen evolution reaction. Bi/BiCeOOH-based anion exchange membrane water electrolyzer exhibits a low cell voltage of 1.79 V and long-term stability with only a 2.2% voltage increase for 100 h at a high practical current density of 1.0 A cm−2.
Electrochemical Studies of Tricosafluorododecanoic Acid (TCFDA) and Perfluoroundecanoic Acid (PFUDA)
Authors: McGhee Saniya , Ridgeway Madison , Workie Bizuneh
Published: December 2024

Per- and polyfluoroalkyl compounds (PFCs) are anthropogenic industrial chemicals widely used in applications like surface coatings, surfactants, and flame retardants. These compounds have become emerging contaminants due to their persistence and resistance to degradation in the environment. PFCs are known for their environmental stability, which allows them to remain in air, water, and soil for extended periods. As a result, they have been detected globally in water, soil, wildlife, and even in human bodies. Their recalcitrant nature poses a significant environmental concern.

One potential solution for mitigating PFC contamination involves their decomposition through oxidation or reduction methods. Cyclic voltammetry (CV) studies have shown that certain per- and poly-fluoroalkyl substances (PFAS), such as Tricosafluorododecanoic Acid (TCFDA) and Perfluoroundecanoic Acid (PFUDA), are reducible. These studies were conducted in acetonitrile (CH3CN) with tetrabutylammonium hexafluorophosphate (TBAHFP) as the supporting electrolyte. CV experiments were performed with a 5.00 mM solution of TCFDA and PFUDA over a voltage range from 1.20 V to -1.20 V, using platinum as the working electrode and Ag/AgCl, KCl (satd.) as the reference electrode. The results indicated similar major cathodic and anodic peaks for both compounds, though the peaks showed variations in potential and height.

In addition to CV studies, exhaustive electrolysis of TCFDA and PFUDA in TBAHFP–CH3CN confirmed the decomposition of these compounds, producing new intermediate compounds. The findings from this research provide valuable information that could contribute to the development of electrochemical methods for decomposing PFAS, particularly TCFDA and PFUDA, in wastewater. This approach could offer a promising treatment strategy to reduce the environmental persistence and impact of these compounds.
Electrifying Industrial Hydrogen Peroxide Production
Authors: Xi Dawei , Wu Yuheng , Li Yuli , Aziz Michael J.
Published: December 2024

Current hydrogen peroxide (H2O2) production is dominantly made through thermocatalytic anthraquinone autoxidation (t-AO) method at industrial scale. Incumbent anthraquinone hydrogenation involves pressurized hydrogen input and requires palladium-based catalysts that can over-reduce anthraquinone to non-reactive molecules. A considerable amount of energy is associated with the distillation and transportation of H2O2, which could be avoided with decentralized electrochemical H2O2 production methods. We developed an interfacial hydrogen atom transfer reaction between an aqueous and a nonaqueous phase to realize an electrochemical AO process (e-AO), avoiding undesired over-reduction side-reactions. The ambient aqueous electrochemical process enables us to produce H2O2 with a Faradaic efficiency about 80% under high current densities (> 200 mA cm−2). The system can be free of hydrogen gas and noble metal. The H2O2 produced this way can be at high concentration (> 10%) and free of electrolyte. This method can facilitate the electrification and decentralization of H2O2 production and reduce the major waste associated with the decomposition of anthraquinone molecules. The electrochemically obtained non-aqueous peroxide can also be directly used in organic synthesis of other high-value chemicals.

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Kinetic and Potential Modeling of the Electrolysis Cell for Nitrate Reduction Reaction to Ammonia
Authors: Ahmadi Maryam , Nazemi Mohammadreza (Reza)
Published: December 2024

Electrochemical nitrate reduction reaction (NO3
-RR) is a potential renewable pathway to produce green ammonia. Excessive nitrate concentration in wastewater (>10 mg) threatens human health and contributes to eutrophication in agricultural applications. Furthermore, the burgeoning ammonia market, with an annual growth rate of USD 14.2 billion, necessitates green infrastructures to compete with the carbon-intensive Haber Bosch process with economic feasibility. The design of catalytic materials that aim to enhance the kinetics of nitrate reduction reactions is well-established in the literature. These catalytic materials present high catalyst activity, Faradaic efficiency (>90%), and durability for this reaction. The objective of our study is to conduct both computational study and eco-analysis to optimize the energy efficiency of the electrolysis system and evaluate its future economic potential. This can bridge the gap between the laboratory–scale electrolysis and industrial-scale units. In our modeling, we studied the effect of pH, membrane, conductivity, buffer solution, competing reactions, and kinetics of electrodes to find the potential losses and their origins in the electrolysis cell and calculate the final cell voltage for industrial applications. The primary sources of potential losses identified in these cells include Nernstian loss resulting from the pH difference between the boundary layer and bulk, ohmic loss due to solution resistance, and overpotentials required for activating the reaction. We established a computational platform for both laminar flows, where bubble evolution at the cathode and anode surfaces was not considered, and a bubbly flow model, which accounts for the effect of bubble evolution on liquid velocity and consequently pH distribution. The results of our study demonstrate close agreement with experimental findings.

Figure 1