bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Impedance Spectroscopy of Lithium Plating from Next Generation Electrolytes
Authors: Sacci Robert L , Westover Andrew S , Yu Zhiao , Bao Zhenan
Published: November 2022

The anode-free cells have emerged due to the need to maximize Li metal batteries' energy density. However, anode-free Li batteries suffer from short cycle life because of the lack of Li inventory at the anode. Freshly deposited Li metal anodes usually take hundreds of cycles to reach initial SEI stabilization optimum coulombic efficiency (CE) due to initial SEI stabilization and electrode activation. The anode-free cell design requires high Li metal CE over the whole cycling life, particularly during the initial activation cycles. A holistic approach to electrolyte design, mechanism understanding, and battery engineering is needed to fulfill these requirements. Here, we present a mechanistic study on lithium plating and stripping from next generation electrolytes.

We conducted dynamic impedance spectroscopy (dEIS) to probe the formation and evolution of the SEI during Li plating and stripping on copper current collectors. dEIS superimposes a multisine waveform atop the dc stimulus signal, as shown by the lightly shaded curves in Fig 1 (top left). We applied a sliding window FFT protocol that takes the complex ratio of the measured potential and current signals obtained from Fig 1 (top right) and transforms it into complex impedance. We will discuss two Li platting systems, Lipon (an amorphous ceramic) and a liquid electrolyte with stabilizing additives. We observed drastic changes in the cells' impedance during plating and stripping, Figure 1 (bottom plots). We will show how the passivation layer's impedance continues to evolve during Li cycling and accounts for a significant amount of the overall cell resistance.

The US Department of Energy’s Energy Efficiency and Renewable Energy Vehicles Technologies Office provided funding for this work under the US-German Cooperation on Energy Storage: Lithium-Solid-Electrolyte Interfaces program.

Figure 1
Quantification of Hydrogen Evolution on a Zinc Rotating Disk Electrode in Traditional Alkaline Electrolytes and Acetate-Based Water-in-Salt “Wise” Electrolytes
Authors: Dutta Debayon , Messinger Robert J. , Turney Damon E. , Banerjee Sanjoy , Lambert Timothy N.
Published: November 2022

Rechargeable batteries as energy storage devices for the electric grid are advantageous to bridge the intermittency in the daily energy demand and production by renewable energy sources such as solar microgrids. Another important consideration to satiate this energy landscape is the need for inexpensive, safe, and non-toxic rechargeable battery technology and chemistry. Zinc aqueous (alkaline) batteries are one of the prime candidates that satisfies the aforementioned criterion and has thus warranted a lot of scientific and technological research for commercial applicability. There has been considerable work conducted by the researchers in this field to bolster the cycle life and active material utilization of zinc in alkaline systems. However, zinc is thermodynamically susceptible to hydrogen gas evolution in alkaline solutions as witnessed by its Pourbaix diagram. On a device level, this affects the columbic efficiency due to the deleterious side reaction, which in turn negatively impacts the energy density of the battery. Water-in-salt electrolytes (WiSE) are a recently developed class of electrolytes that directly address this shortcoming of dilute electrolytes due to the modified solvation structure of water which lowers the activity of free water molecules in solution.

In this work, we show a type of non-toxic and cheap acetate-based WiSE that has lower hydrogen gassing rates when compared to traditional alkaline potassium hydroxide-based electrolytes. Specifically, we quantify hydrogen gas evolution at the zinc electrode-electrolyte interface using the rotating disk electrode technique at different overpotentials to show the remarked improvement in gassing observed. At overpotentials of 100, 300 and 500 mV, 27 m (molal) potassium acetate is observed to have gassing rates of up to 16 times less than that of 25 weight percent potassium hydroxide. Using the Koutecky-Levich equation, mass-transfer and kinetic parameters for the hydrogen evolution reaction were also determined. The results establish the applicability of this class of WiSE in reducing gassing on zinc and thus, improving the overall efficiency of zinc-based aqueous batteries.
Improved Electrochemical Performances of Li/CFx-MnO2 Primary Batteries Via the Optimization of Electrolytes
Authors: Cho Jang-Hyeon , Yoo Eunji , Yeo Jae-Seong , Yoon Hyunki , Choi Yusong
Published: November 2022

The lithium(Li) primary batteries have been widely used in power sources for military applications. According to the military standards, the design temperatures for the basic climate category including the mid-altitude areas will include the ambient air temperature range of -32oC through +60oC, considering the operational, storage, and transit conditions of materiel systems. Among a variety of Li primary batteries, lithium/thionyl chloride (Li/SOCl2) primary batteries have been commonly utilized in military applications due to their high energy density, high operating voltage, and competitive cost. However, Li/SOCl2 batteries have serious challenges due to initial voltage delay by lithium chloride passivation layer and possible safety issues by a formation of toxic sulfur-dioxide (SO2) gas and solid sulfur during discharge. To overcome the intrinsic disadvantages of Li/SOCl2 batteries, research into lithium/carbon fluoride-manganese dioxide (Li/CFx-MnO2) batteries has been ramped up for military applications due to their high energy density and good rate capability. In this study, we have focused on an optimization of solvents and Li salts to improve the electrochemical performances of Li/CFx-MnO2 batteries in a wide operating temperature ranges. We have investigated candidate solvents for Li/CFx-MnO2 batteries with different compositions of methyl butyrate (MB) and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as well as conventional solvents including propylene carbonate (PC), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), ethyl acetate (EA), and 1,2-dioxolane (DOL). Moreover, we have investigated the effects of Li salts, lithium perchlorate (LiClO4) and lithium bis(trifluoromethanesulfonyl)imide (LiFSI), on the electrochemical performances in the low and high operating temperatures. Ionic conductivity measurements and differential scanning calorimetry (DSC) analysis were also carried out to investigate the physical properties and stability of electrolyte. This study will provide an opportunity to develop the new electrolyte systems for Li/CFx-MnO2 batteries in a wide operating temperature window.
Nano-Diamond Reinforced Polymer Separators for Energy Dense Lithium-Ion Batteries
Authors: Narla Aashray , Fu Wenbin , Kulaksizoglu Alp , Johnson Billy , Raman Ashwin Sankara , Wang Fujia , Magasinski Alexandre , Kim Doyoub , Jhulki Samik , Yushin Gleb
Published: November 2022

Traditional polyolefin separators tend to perform poorly against heat-triggering reactions causing potentially catastrophic issues in lithium-ion batteries (LIBs). In this study, we developed a high temperature resistant, flexible, mechanically robust and highly ionically conductive composite separator made from electrochemically stable polymer encased with nanodiamonds (NDs). We systematically study the effect of ND concentration in the polymer matrix of the membrane to improve the thermal, mechanical and electrochemical properties of the composites. When tested in LIB with high-voltage LiNiMnCoO2 (NMC), these novel separators exhibited substantially superior performance when compared with commercial polyolefin separator membranes. These cells exhibited closed-to-theoretical capacity (200mAhg-1
NCM), excellent rate capability and minimal degradation for over 150 cycles. Our study showcased the capability of ND powder as a nano-sized filler materials for the fabrication of composite membranes with superior properties, and opened up the broad possibilities of composite membrane fabrications by varying the polymer composition, micro-structure, nanoparticle surface chemistry and concentrations.
Probing Solvation Thermodynamics of Lithium Battery Electrolytes through Potentiometric Methods
Authors: Kim Sang Cheol , Cui Yi
Published: November 2022

The electrolyte is a principal component of a lithium battery that impacts almost every facet of the battery’s performance. Solvation of lithium ions in electrolyte solution is key to understanding the electrolyte, but our understanding of solvation lags behind its significance. Particularly, estimating solvation free energy has been largely limited to computational simulations. Despite their versatility, simulations can be computationally expensive, and experimental methods to complement simulations are desired.

We have recently introduced a potentiometric technique to probe the relative solvation free energy of lithium ions in battery electrolytes. We devised an electrochemical cell composed of two half-cells, with symmetric electrodes but asymmetric electrolytes. Whereas the open circuit potential of a conventional lithium-ion battery measures the free energy differences of lithium ions in the two electrodes, our experimental setup measures the energy differences of the lithium ions in two different electrolytes. By measuring the cell potential with a reference electrolyte, we can quantitatively characterize lithium ion solvation energy of an electrolyte of interest. The effects of concentration, anion and solvent on solvation energy are explored and verified with simulations. Particularly, we establish a correlation between cell potential (Ecell) and cyclability of high-performance electrolytes for lithium metal anodes. We find that solvents with more negative cell potentials and positive solvation energies—those weakly binding to Li+—lead to improved cycling stability. Weaker solvents are conjectured to have more anion-rich solvation structures that lead to anion-derived solid-electrolyte interphases, a hypothesis supported by cryogenic electron microscopy. It reveals that weaker solvation is correlated to an inorganic anion-derived solid-electrolyte interphase that stabilizes cycling.
Uncovering Molecular Structure – Redox Potential Relationships for Organic Electrode Materials: A Hybrid DFT – Machine Learning Approach
Authors: Allam Omar , Woo Hyun-Myung , Brantley Graham , Kuramshin Robert , Stoichev Zlatomir , Yoon Byung-Jun , Jang Seung Soon
Published: November 2022

Density functional theory and machine learning are used to investigate the structure-electrochemical performance relationships of organic moieties for use in Li-ion batteries. Namely, DFT calculations are performed to predict the redox potential of several novel organic molecules with an accuracy within ~0.1 V of experimental measurements. However, despite its ability to provide valuable insight regarding the electrochemical properties of novel organic molecules, our high efficacy DFT modeling protocol demands significant computational time and is therefore impractical for the vast screening of novel material candidate. As a result, we explore machine learning as a strategy for the accelerated discovery of novel organic materials. More critically, we use machine learning as a method for assessing the various structure-electrochemical relationships which can provide a more general guideline for the design of organic electrode materials. We are employing different learning models, including artificial neural networks, gradient-boosting regression, and kernel methods (such as kernel ridge regression and Gaussian process regression), via three different pipelines with varying sophistication with the aim of generating an advanced ML scheme for the accurate prediction and analysis of electrochemical activity. In addition to incorporating structural fingerprints, we are exploring an active learning framework, namely using the efficient global optimization scheme, to explore the materials space strategically using publicly available datasets. Through this approach, we can discover new electrode materials that could 1) have a higher probability for achieving enhanced electrochemical properties and 2) increase our learning model’s performance by increasing our dataset’s representation of the material space. Additionally, we are implementing a high-throughput virtual screening (HTVS) pipeline which consists of several surrogate learning models with increasing levels of fidelity. The material candidates are pruned at each stage to discard samples that are unlikely to possess a desirable redox potential for cathodic application, and the remaining samples move on to the next model. In this way, only a subset of the original dataset which has a higher probability for lying within the desired redox potential range is pursued using the most computationally expensive model.
Ir Nanoconfined and Doped MnO2 Nanosheets for an Enhanced Electrocatalytic Oxygen Evolution Reaction in Acidic and Basic Medium
Authors: Kakati Uddipana , Strongin Daniel R.
Published: November 2022

One of the promising strategies to generate hydrogen for a future hydrogen economy is via electrocatalytic water splitting, where renewable electricity would be used to convert water into hydrogen and oxygen on an electrocatalyst within an electrolyzer. Oxygen evolution reaction (OER), the anodic half-reaction of water splitting is, however, kinetically sluggish and requires four electron-proton transfers making the overall reaction energy-intensive. For the economical production of hydrogen, improving the reaction kinetics in both low and high pH is of utmost necessity by designing an active and stable OER catalyst. Precious metals like Ir, Ru, and their oxides are known to be excellent OER catalysts but their large-scale application is hindered due to their low earth-abundancy. To address this issue, we have synthesized two types of OER catalysts with varying Ir wt.% to achieve a higher OER-activity per mass of Ir in the catalyst: Ir/MnO2, Ir nano-confined in the interlayer of layered MnO2 nanosheets and Ir-doped MnO2 nanosheets. In both acidic and basic environments, Ir/MnO2 exhibited better OER activity than Ir-doped MnO2. In 0.5 M H2SO4, 16.7 wt.% Ir/MnO2 and 17.5 wt.% Ir-doped MnO2 exhibited OER overpotentials (η) of 298 mV and 320 mV, respectively, at a current density of 10 mA cm-2. In 1M KOH electrolyte, 15.4 wt.% Ir/MnO2 and 17.5 wt.% of Ir-doped MnO2 exhibited OER η values of 213 mV and 245mV, respectively at 10 mA cm-2. These overpotentials are ~500 mV lower than the pristine MnO2 nanosheets and ~60-120 mV lower than commercial reference catalysts (20 wt.% Ir/C and IrO2) at both low and high pH conditions, respectively. These synthesized catalysts were able to outperform the commercial materials by exhibiting four times higher OER-activity per mass of Ir, in both acidic and basic media. Hence, this synthetic approach may be a method to achieve enhanced OER activity using a lower mass of Ir. The physical characterization of the materials was carried out with X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS).
(Digital Presentation) Tracking Local pH Changes of Electrodeposited Co-Mo-Based Titania Composites for HER
Authors: Wang Cheng , Podlaha Elizabeth J.
Published: November 2022

Cobalt-molybdenum and cobalt-molybdenum-based phosphides are known hydrogen evolution electrocatalysts in alkaline electrolytes.1 Recently it has been shown that the addition of titania particles to create composite Co-Mo-TiO2 and Co-Mo-P-TiO2 enhances the hydrogen evolution reaction (HER).2 In order to better understand the role of TiO2 in the these composites, the local pH change was characterized during both electrodeposition and HER. The composites were electrodeposited onto a copper mesh working electrode in close vicinity to a flat-bottom pH probe. During electrodeposition from a citrate-boric acid electrolyte, there in an initial drop of pH followed by a pH rise with time that was not influenced by the presence of TiO2. However, there was a significant change in the local pH when TiO2 was present in Co-Mo-based electrocatalyst during the HER process. Without TiO2 particles present in the solid state, the local pH change during electrolysis follows an expected increase with time, while with embedded TiO2 particles in the metal matrix, the local pH initially decreases slightly and remains constant with time. The results suggest that the enhanced HER performance with TiO2 in the alloy composite electrocatalyst is a consequence of the buffering of the local pH.

References

Fan, D. Piron, A. Sleb, P. Paradis, J. Electrochem. Soc.
141, 382-387 (1994); P.R. Zabinski, H. Nemoto, S. Meguro, K. Asami K., Hashimoto K., J. Electrochem. Soc.,
150, C717 (2003); Y.-Y. Ma, C.-X. Wu, X.-J. Feng, H.-Q. Tan, L.-K. Yan, Y. Liu, Z.-H. Kang, E.-B. Wang, Y.-G. Li, Energy Environ. Sci.
10, 788-798 (2017); A. C. Thenuwara, L. Dheer, N. H. Attanayake, Q. Yan, U. V. Waghmare, D. R. Strongin, ChemCatChem.
10, 4832-4837 (2018); X. Chen, Q. Li, Q. Che, Y. Chen, X. Xu, ACS Sustain. Chem. Eng.
7, 2437-2445 (2018).

Wang, H.K. Bilan, E.J. Podlaha, J. Electrochem. Soc.
166, F661-F669 (2109); C. Wang, E. J. Podlaha, J. Electrochem. Soc,
167, 132502 (1~4) (2020).
Electrodeposition of Three-Dimensional Au Nanowire Networks and Their Application As Catalysts for Methanol Electro-Oxidation
Authors: Li Mohan , Ulrich Nils , Schubert Ina , Trautmann Christina , Toimil Molares Maria Eugenia
Published: November 2022

In this talk we will first present the synthesis of free-standing, stable gold nanowire network with controlled morphology and geometry by ion-track technology and electrodeposition. Etched ion-track membranes with interconnected nanochannels are produced by sequential GeV heavy ion irradiation of polymer foils from four directions, and subsequent etching and enlargment of the created ion-tracks. Au nanowire networks with three different nanowire diameters are synthesized by potentiostatic electrodeposition in the templates. Nanowire growth rate and homogeneity are tuned by varying the deposition potential. The electrochemical surface area was determined for each sample by CV analysis of surface oxide reduction reaction charge transfer. We will also discuss the catalytic performance of these Au nanowire networks towards methanol electro-oxidation, acting as an electrode in a half-cell setup. High current density and high catalytic activity were recorded. The Au nanowire networks provided up to 200 times higher peak current density than a flat Au electrode, along with excellent long term cyclability, which the current density drops only 5% over 200 CV cycles. SEM studies of the morphology and crystallinity of the nanowires before and after the methanol oxidation reaction will also be presented in the talk.

Figure 1. (a) SEM image of Au nanowire network, (b) Cyclic Voltammograms recorded for a of Au nanowire network in 0.1 M KOH with (solid line) and without (dash line) 1 M MeOH.

Figure 1
Electrochemical Synthesis of Ammonia from Nitrate on Preferentially Oriented Cu2 O
Authors: Anastasiadou Dimitra , Hensen Emiel J.M. , Costa Figueiredo Marta
Published: November 2022

Electrochemistry-based processes to produce ammonia have recently gained widespread interest by the scientific community because they provide a way to reduce the high carbon emissions currently associated with ammonia production. Global NH3 demand is expected to rise since it is included in various energy scenarios as a possible green transportation fuel and storage medium of renewable electricity involving fuel cells.1 Several electrochemical and hybrid electrochemical processes with plasma integration are currently being investigated to produce NH3 via different nitrogen sources, such as N2, NO3
-/NO2
- or NO. The utilization of NO3
- from wastewater sources can be valuable for the environmental and health issues associated with NO3
- contamination. Additionally, NO3
- electroreduction in aqueous media is an attractive approach to investigate the catalysis due to its high solubility and the low dissociation energy needed to break the N=O bond. Cu and Cu-based materials have extensively been studied for NH3 production through NO3
- electroreduction. Earlier studies on Cu single crystals2 in alkaline media showed that Cu (100) performs better than Cu (111) in reducing the NO2
- intermediate to hydroxylamine, which is believed to be the precursor to NH3. On the contrary, recent density functional theory calculations3 showed that a Cu−Cu couple with 2.57 Å distance serves as a catalytic center, leading to the conclusion that Cu (111) is the most active surface termination. In this work, preferentially oriented Cu2O crystals with (111), (100), and (110) terminations were obtained via electrodeposition and evaluated for their performance in NO3
- electroreduction to NH3 (Figure 1). To understand which oxidation state of Cu represents the active phase, the samples were investigated by in-situ Raman spectroscopy. According to a recent study, the active phase was a combination of Cu and Cu+.4 Our results point to the immediate reduction of remaining Cu+ species during application of -0.3V vs. Ag/AgCl and formation of Cu(OH)2 at more negative potentials. The presence of Cu(OH)2 was also apparent from ex-situ XPS and UV-Vis analysis. Moreover, post-reaction XRD analysis showed a retainment of the crystal orientation on the reduced Cu surfaces. All the nanostructured catalysts were active for NO3
- reduction and produced NH3 with faradaic efficiencies above 40%. Cu2O (111) was the most efficient for NH3 synthesis reaching a faradaic efficiency of up to 99%.

1 D. Anastasiadou, Electrochem. Sci. Adv.,submitted.

2 E. Pérez-Gallent, Electrochim. Acta, 2017, 227, 77–84.

3 T. Hu, ACS Catal., 2021, 11, 14417–14427.

4 Y. Wang, Angew. Chemie Int. Ed., 2020, 59, 5350–5354.

Figure 1
The Influence of Graphene on the Electrodeposition of Metals
Authors: Wright Salem Clay , Saini Sonakshi , Raman Tejas K , Tian Mengkun , Shetty Pralav , McDowell Matthew T
Published: November 2022

Electrodeposition of metals with controlled crystallography and grain structure is critical for applications including batteries, electronic circuit fabrication, and industrial coating processes. For metal-anode-based batteries in particular, it is important to understand how the electrode surface affects the crystallography of electrodeposited metals. Graphene and other 2D materials have recently been shown to exhibit strong effects on metal crystallography during electrodeposition, but it is unclear the extent to which graphene is affecting epitaxy, and further understanding of the 3D metal/2D material interface is crucial for advancing interfacial electrodeposition control. In this work, we study the influence of graphene and the underlying Cu substrate on the crystal structure and morphology of electrodeposited metals. Based on extensive electrochemical testing and electron backscatter diffraction (EBSD), we find that the orientation of the substrate underneath graphene (usually copper) exerts a controlling crystallographic influence on the electrodeposited metal overlayer, rather than the graphene layer itself. Further transmission electron microscopy (TEM) and Raman spectroscopy investigations are used to probe the nature of the interface and the graphene layer. These findings are important because they show that graphene can potentially be used as an interlayer to enable high-quality remote epitaxy between a variety of metals that normally exhibit inhibited epitaxy because of surface oxide layers.
The Electrochemical Deposition of Pd and Cucl Films on Graphene
Authors: Drexler Matthew N , Alamgir Faisal M.
Published: November 2022

Surface limited redox replacement (SLRR) is an electrochemical technique for depositing metal films monolayers in thickness, typically on other metals. As interest in graphene as a highly conductive, chemically resistant support for metal nanoparticles has risen, some have sought to apply this deposition technique to graphene as an electrochemical alternative to other chemical or vacuum-based deposition techniques. To better understand the nature of the interactions between the metal and graphene, our group has used this technique to deposit Pt on graphene to observe the structure of Pt and its epitaxy with the substrate. We have previously found that Pt prefers to bind to the bridge sites of graphene, preferring to form a simple-cubic-like structure and producing a slight lattice compression. We sought to expand on this study by observing the interactions of Pd with graphene.

Pd was deposited on graphene using Cu-mediated SLRR, however, most Cu-mediated SLRR is performed with CuSO4 or Cu(ClO4)2 dissolved in H2SO4 or HClO4. This does not necessarily produce a strong Cu underpotential deposition feature on graphene, so HCl was used as the electrolyte instead. This produced a substantially more pronounced underpotential deposition feature, but cyclic voltammograms in this solution do not appear to agree with typical Cu-S-Cl Pourbaix diagram.

This also resulted in two different types of structures, primarily Cu-containing films and primarily Pd-containing nanoparticles. The films were always found in the presence of the particles, but the particles did not always have accompanying films. A structural analysis of the particles determined that they preferred to interface with graphene along the (110) planes of Pd and have a slight elongation along the [001] direction of about 1.6% when oriented such that their columns were visible in the scanning transmission electron microscope. Based on an analysis of their orientation, this alignment and elongation appear to be the result of Pd minimizing its interfacial strain with graphene. A structural and compositional analysis of the films determined them to be CuCl, and they prefer to interface with graphene along their (111) plane, although the reason for this particular orientation is unclear as there is weaker evidence for a correlation between the alignment of the graphene and the films.
Characterization of Protective Coatings on Stainless Steel Bipolar Plates for PEM Electrolyzers
Authors: Leimbach Martin , Kurniawan Mario , Zimmermann Christoph Philipp , Höß Christian Elieser , Fritz Mathias , Bund Andreas
Published: November 2022

Hydrogen production by electrolysis offers significant advantages over established and more common processes such as steam reforming with regard to CO2 emissions, in particular through the use of electrical energy from renewable sources and the establishment of a decentralized supply structure. The advantages of PEM (proton exchange membrane) electrolysis include high power density, scalability, and the high purity of the produced hydrogen. However, so far the manufacturing of the PEM electrolyzers is realized only on small scale, which makes the widespread use difficult and is a main cost driver for electrolyzer systems.

In the scope of the publically funded lead project H2Giga, a series of manufacturing processes are developed for industrial scale-up production of PEM electrolyzer components, in particular the bipolar plates (BPP) and the porous transport layers (PTL). Base materials like stainless steel are used that can be processed at a low cost but need protective coatings to withstand the highly corrosive conditions during electrolysis, especially at the anode side of each cell.

In our approach, these coatings are produced by electroplating, and their protective properties are investigated by electrochemical and surface characterization techniques. Precious metals (e.g. gold, platinum) are promising due their good stability at high anodic potentials and low pH values. However, nickel alloys, especially tin-nickel, could offer a cost-effective alternative. An improved stability of the tin-nickel alloy is observed above +1.5 V vs. NHE which can be attributed to the formation of an oxide layer. The coating systems showing the best results are investigated further in a multi-cell stack setup.
Electrochemical Reduction of Iron Oxide - Produced from Iron Combustion - for the Valorization of Iron Fuel Cycle
Authors: Majid Akmal Irfan , Tang Yali , Finotello Giulia , van der Schaaf John , Deen Niels Gerbrand
Published: November 2022

Iron is a prospective candidate for energy carriers in the energy transition era with high energy density. In this concept, energy is released by the combustion of iron powder whilst the solid product - iron oxide - can be collected and reduced back to metallic iron, forming a recyclable iron fuel cycle. The electrochemical technique is considered to be a suitable reduction method as it has attractive aspects including low electric energy consumption, low temperature, direct usage of renewable energy, and a short process chain. In this study, the performance of iron electrodeposition is investigated using an electrolysis cell containing a suspension of micron-sized combusted iron powder in aqueous NaOH (50%wt, 18 M) at a temperature of 110°C. The parallel plate electrolyzer used in these experiments consists of a stainless-steel plate (cathode) and a nickel gauze (anode). The effects imposed by varying current density, iron oxide composition, and iron oxide particle diameter on Faradaic efficiency and reduced iron yield are evaluated. Additional experiments using a rotating disc electrode (RDE) are also conducted to determine the system's diffusion coefficient under different operating conditions. Generally, cathodic deposition of metallic iron is successfully achieved and the morphology of the deposited iron depends on the operation conditions including the current density and heterogeneity of the flow system. The obtained results open new perspectives for efficient and cost-effective iron production/regeneration.

Figure 1
Immersed Interface and Diffuse-Domain Approach for Current-Potential Distributions and Electrodeposition Problems
Authors: Jang Taejin , Mishra Lubhani , Subramaniam Akshay , Uppaluri Maitri , Subramanian Venkat R.
Published: November 2022

Several numerical approaches are being developed to solve the moving boundary models which predict the morphological evolution of the electrode surface during electrodeposition. Despite these significant research efforts over a broad range of materials, scales, and purposes, the prediction of the shape evolution of the electrodes over time is still a challenging problem. One needs to solve these moving boundary problems, as the potential and current distributions within the cell get affected by the geometry.1-2

In this work, we will demonstrate a recently developed numerical framework based on the diffused domain approach using phase-field models for two classical example, Hull cell and copper deposition in trenches.3 The original model equation was carefully reformulated as a diffuse-domain/immerse domain approach for steady state current-potential distribution problems.4-5 Then the shape change problem is cast as a transient phase-field problem to predict the shape changes of the electrode during electrodeposition. A comparative analysis has also been performed for the efficiency, accuracy, speed, and convergence of the present solutions for the Hull cell with other available numerical and even analytical methods. It can be stated that the present phase-field model is robust and efficient for predicting the shape changes of the electrode over time without oscillations.

Acknowledgments

This research was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy (DoE) through the Advanced Battery Materials Research Program (Battery500 Consortium)

References

V. R. Subramanian, and R. E. White, J. Electrochem. Soc, 149(10) C498 (2002).

R. Alkire, T. Bergh, and R. L. Sani, J. Electrochem. Soc., 125, 1981 (1978).

T. Jang, L. Mishra, S. A. Roberts, A. Subramaniam, M. Uppaluri, M. P. Gururajan, J. Zhang, and V. R. Subramanian, “BattPhase – A convergent, non-oscillatory, efficient algorithm and code for predicting shape changes in lithium metal batteries using phase-field models – 1. Secondary Current Distribution,” ECSarXiv (2022), doi:10.1149/osf.io/k2vu6

C. S. Peskin, Acta Numer., 11, 479 (2003).

X. Li, J. Lowengrub, A. Ratz and A. Voigt, Commun. Math. Sci., 7, 81 (2009).
Electrodeposition of Transition Metal Alloy Films for Magnetic Thermometry
Authors: Rus Eric , de Lima Corrêa Eduardo , Dennis Cindi L , Moffat Thomas P
Published: November 2022

As part of an effort to develop methodology for magnetism-based thermometry, the present work seeks to develop materials and structures with temperature-dependent magnetic properties providing optimal sensitivity near room temperature, leveraging previous work which demonstrated compositional control of alloy films by varying the deposition potential. We will discuss deposition and characterization of these films with an emphasis on factors affecting their temperature-dependent magnetic properties, namely the effects of deposition potential and the presence of boric acid. A series of electrodeposited platinum nickel alloy films was characterized by superconducting quantum interference device vibrating sample magnetometry (SQUID VSM), and it was found that films deposited at more reducing potentials (those with higher nickel content) had predominantly ferromagnetic behavior, while films deposited at more positive potentials showed behavior with ferromagnetic and paramagnetic contributions. Depositions at more reducing potentials in the presence of boric acid proceeded with lower Coulombic efficiency and resulted in films with higher oxygen content and diminished magnetization relative to depositions in the absence of boric acid.
Electrodeposition of Ni-Fe Alloy in Presence of Complexing Agent
Authors: Park Jung-Joon , Seo Jinmyeong , Yoon Sanghwa , Yoo Bongyoung
Published: November 2022

The nickel-iron alloys have been widely used for versatile soft magnetic applications and electro-magnetic applications due to their magnetic properties for a long time. Also, it has been discovered that Ni-Fe alloy near 36 wt% Ni shows almost zero thermal expansion composition(CTE) in a wide temperature range (~150 ℃). The phenomenon showing low CTE in a specific composition is called the Invar effect. Due to the Invar effect, Invar alloys are used for temperature-sensitive applications such as oscillators and fiber-optic package parts. Invar alloy films are used for fine metal masks, an essential part of OLED fabrication. The invar film currently in use is fabricated using the pyrometallurgy method, more than 20um thick. However, miniaturization and high performance of the products require the thinner thickness of the Invar film, around 10um thick which shows the need for a bottom-up fabrication process of invar film. There are various methodologies to fabricate thin films, such as thermal evaporation, sputtering, CVD, and electrodeposition. Most fabricating processes are the vacuum process, a high-cost and non-continuous process. On the other hand, electrodeposition is a non-vacuum process, relatively low-cost, large-scale, and continuous process.

Despite these advantages, there are some obstacles to gaining the Invar thin film by electrodeposition, such as anomalous deposition, composition uniformity, and higher CTE of electrodeposited Invar film. There are researches[1-3] about electrodeposited Ni-Fe thin films in the aspect of CTE, magnetic properties, crystal structures, etc. However, very few researchers have seen the effect of complexing agents other than specific complexing agents such as boric acid and ascorbic acid. In addition, Ni-Fe electrodeposition shows very different results depending on temperature and agitation, but no research confirms the effect on various complexing agents under the same condition.

In this study, we synthesized Ni-Fe alloy thin film by electrodeposition in the presence of various complexing agents with different functional groups (amine, carboxyl, alcohol, etc.) such as glycolic acid, malonic acid, ethylenediamine, etc. on 20um stainless 304 foil substrates. The electrodeposition was conducted under the aqueous acidic bath(pH 2) at 55℃. Electrochemical studies were conducted to set appropriate potential and current density for electrodeposition. The thin film was characterized by SEM, EDS, XRD, and copper strip tests to observe the difference in composition, surface morphology, phase, and internal stress.
Electrodeposited Conifex Magnetic Films with Low Magnetic Losses for Power Applications
Authors: Solanki Dhaivat , Aleksov Aleksandar , Brankovic Stanko
Published: November 2022

Electromagnetic induction is essential for functioning of the analog circuits used in cell phones, MEMS devices and other power related electronics. In order to meet the demand of higher efficiency and minimum magnetic losses in packaging industry, we have developed solution chemistry1
,
2 for electrodeposition of CoNiFeX (X=S,O,P,B,V) thin films (thickness=500 nm) with high magnetic moment (HMM) and >500 permeability at >500 MHz frequency; >100μΩ-cm resistivity; >1.5 T magnetic moment. The CoNiFeX alloys are fully compatible with existing manufacturing concepts in semiconductor industry. Direct current (DC) and pulse current3 (PC) deposition methods for CoNiFeX alloys is employed to demonstrate control over BCC/FCC crystal structure by tuning transport conditions during electrodeposition. The structure of CoNiFeX alloys is characterized with average grain size of 15-20 nm which consequently yields coercivity values of CoNiFeX alloy films between 8-15 Oe at 500 nm thickness. CoNiFe alloys produced by DC and PC deposition have magnetic moment of 1.8 T, which is optimized to 2.2 T with addition of X (X=S,O,P,B,V) as additives4. More than 100% increase in the resistivity of deposited CoNiFe alloys is demonstrated with controlled concentration of additives and Fe3+ ions as oxide precipitating agent5 without reduction in magnetic properties. All samples exhibit shiny surface finish and low stress. Thin film inductor devices are fabricated with CoNiFeX alloys to test magnetic properties at >500 MHz frequency, which would be discussed with testing data.

Brankovic, S. R., Vasiljevic, N., Klemmer, T. J. & Johns, E. C. Influence of additive adsorption on properties of pulse deposited CoFeNi alloys. Journal of the Electrochemical Society
152, C196 (2005).

Brankovic, S. R., Sendur, K. & Klemmer, T. J. Magnetic Materials, Processes, and Devices VII and Electrodeposition of Alloys. in Proceedings of the International Symposia
2002, 269 (Electrochemical Society, 2003).

Puippe, J.-C. & Leaman, F. Theory and practice of pulse plating. (Amer Electroplaters Soc, 1986).

Djokić, S. S. Electrodeposition of amorphous alloys based on the iron group of metals. Journal of the Electrochemical Society
146, 1824 (1999).

George, J. et al. Oxide/hydroxide incorporation into electrodeposited CoFe alloys—Consequences for magnetic softness. Electrochimica Acta
110, 411–417 (2013).
Innovative Processes for a Low Impact in the Electroplating of Stainless Steel
Authors: Giurlani Walter , Biffoli Fabio , Pappaianni Giulio , Mariani Elena , Meoli Arianna , Dini Tommaso , Pizzetti Federico , Innocenti Massimo
Published: November 2022

Steel is a cheap renewable material with many interesting properties but its presence in the electroplating sector is very limited due to adhesion difficulties. Stainless steel contains approximately 10.5% chromium, which forms a surface oxide layer that passivates the steel, making it resistant to corrosion [1]. It is the presence of this surface oxide film that makes it difficult to electroplate steel. The aim of electroplating steel is to refine it by depositing nobler metals of the desired color, such as ruthenium and gold.

The activation of steel involves the remotion of the oxide layer. The main method of electroplating stainless steel is generally through the deposition of nickel, but the intensive use of nickel baths makes these processes inappropriate for the sustainability paths taken by the electroplating industry. Even when nickel-based galvanizing processes are not used, it is possible that steel objects do not pass the nickel release test. This is because the steel itself contains nickel, so the removal of the surface oxide layer during the electroplating process may facilitate the release of nickel.

The nickel release mechanism is not yet fully clear but bring to allergenic issues in the final product [2]. We performed a systematic study electroplating various metals and alloys on steel to evaluate which one performed better as barrier against the release of nickel and shed light on this issue.

The steel substrate was characterized microscopically and spectroscopically before and after the release test. The amount of nickel was evaluated in the solution that simulates human sweat to evaluate its release in µm·cm-2·week-1 according to the standard EN 1811:2015.

The authors acknowledge Regione Toscana POR CreO FESR 2014-2020 – azione 1.1.5 sub-azione a1 – Bando 1 “Progetti Strategici di ricerca e sviluppo” which made possible the projects “A.C.A.L. 4.0” (CUP 3553.04032020.158000165_1385), “A.M.P.E.R.E.” (CUP 3553.04032020.158000223_1538), “GIGA 4.0” (CUP 3553.04032020.158000105_1242) and “GoodGalv” (3647.04032020.157000060).

References

[1] Olsson, C. O. A.; Landolt, D. Passive films on stainless steels—chemistry, structure and growth. Electrochim. Acta. 2003, 48, 1093-1104, doi:10.1016/S0013-4686(02)00841-1.

[2] Yuan, J.P.; Li, W.; Wang, C.; Ma, C.Y.; Chen, L.X.; Chen, D.D. Nickel release rate of several nickel-containing stainless steels for jewelries. J. Iron Steel Res. Int.
2015, 22, 72-77, doi: 10.1016/S1006-706X(15)60012-7.
Insights and Applications of Composite Electroplating
Authors: Fransaer Jan
Published: November 2022

Composite electroplating is the process of particle incorporation during the electrolytic deposition of metal. This process produces composite films consisting of a metallic matrix containing a dispersion of small particles. The advantages of composite electrodeposition over other coating methods are the uniformity of deposition even for complex shapes, the strong adhesion to the substrate, reduction of waste compared to dipping or spraying techniques, low levels of contamination, the ability to produce functionally-gradient material and to continuously process parts. In addition, this process avoids the problems associated with high temperature or vacuum processing.

There are many contradictory experimental results in literature concerning the effects of the electrocodeposition process variables on particle incorporation. The effects of some of the process variables also vary for different particle-electrolyte combinations and cell configurations. Some of the reported contradictions are a direct consequence of incomparable hydrodynamics. The bulk of experimental electrocodeposition research has been conducted using a vertical parallel plate electrode set-up. In this configuration, the particles are maintained in suspension by either stirring the solution, vibrating a perforated plate at the bottom of the cell, bubbling gas, or pumping the suspension through the cell, all of which result in uncontrollable, and hence incomparable hydrodynamics. Other contradictions are due to the fact that the process parameters were evaluated only for a narrow range of experimental parameters and to differences in particle size and purity.

This talk discusses the experimental results and mathematical modeling of electrocodeposition of particles in a metallic matrix. The effects of several key parameters, such as current density, particle loading, electrolyte composition, particle surface charge and polarity, on particle incorporation in electrodeposited composite coatings were studied and modeled. All experiments were done utilizing rotating disk electrodes over a wide range of experimental conditions in which the incorporation behavior changes appreciably, yielding reproducible data for better interpretation of process effects and modeling. These studies were combined with colloidal probe AFM experiments and process archeology using pulse plating which helped to understand the codeposition mechanism.
Superconformal Deposition for Building 3D Circuitry
Authors: Moffat Thomas P , Braun Trevor Michael , Raciti David , Josell Daniel
Published: November 2022

State of the art manufacturing of microelectronics involves the electrodeposition of copper for fabricating on-chip interconnects, through-silicon-vias for chip stacking, and high density printed circuit boards. This lecture will present a selection of highlights related to superconformal electrodeposition of Cu ranging from its history to its impact on processing of microelectronic circuitry and, more generally, the understanding of additive effects in electrodeposition. The story begins in the mid-20th century with the formal discovery of the effectiveness of plating additives in yielding smooth surfaces i.e. brighteners and levelers, before pivoting to the IBM paradigm changing introduction of complex 3-D Damascene Cu superfilling for on-chip interconnects in 1997. The role of electroanalytical, metallurgical, and surface science measurements along with insights, and modeling to develop a mechanistic understanding of morphological and microstructural evolution during trench and via filling will be detailed. The lessons learned and their extension to other chemical systems and applications will be discussed along with the challenges that lie ahead.
Hull Cell Investigation of Ni-Mo and Ni-Mo-O Electrodeposits from Ammonium Citrate Baths
Authors: To Dung T. , Myung Nosang V.
Published: November 2022

Among different Ni-based alloys, Ni-Mo is well-known for the excellent corrosion resistance which makes them a potential alternative for the electroplated chromium. In addition, Ni-Mo alloys have been used as substrates for various purposes and as hydrogen evolution reaction electrocatalyst owing to their good mechanical strength and electrocatalytic activities. Each application requires distinct material properties of Ni-Mo alloys (e.g., composition, morphology, and crystallinity). Therefore, tunability of the material properties of Ni-Mo alloys become important to facilitate them for applications. Synthesis of Ni-Mo alloys has been achieved by various methods (e.g., e-beam evaporation, sputtering, and arc melting); however, high cost and time consumption, especially harsh synthesis conditions, limit the range of studied parameters. Hull cell, an electrodeposition technique, becomes a promising means for the high throughput investigation of synthesis parameters. Similar to other efficient electrodeposition techniques, Hull cell not only provides the tunability of morphology and composition, but also requires a simple setup and near ambient operating conditions. Ni-Mo alloys are electrodeposited via induced co-deposition, implying the dependent reduction of Ni and Mo. Therefore, complexing agent (e.g., citrate ions) is required to control the relative reduction rates of Ni and Mo and consequently tune the material properties via the complexation and the reduction reactions. The complexation between metal precursors and complexing agents generates many different species. Only chemically active species participate in the reduction reactions at the interface of electrolyte and electrode. Thereby, it is necessary to study the distribution of species after complexation to maximize the fraction of chemically active species for Ni-Mo co-deposition. In this work, effects of various synthesis parameters on the formation of Ni-Mo alloys and Ni-Mo-O composites were investigated using Hull cell. Firstly, the fraction of complex species at equilibrium is simulated using material balance with the assistance of MATLAB to understand the complexation of metals and complexing agents as well as predict the solution compositions which maximize the chemically active species for reduction reactions. Also, the effect of various synthesis parameters (e.g., complexing agents (ammonium-to-citrate ratio), Ni/Mo precursor ratio, pH) are experimentally studied and correlated with simulated data to elucidate the deposition mechanism as well as determine the conditions for the transition from Ni-Mo alloys to Ni-Mo-O composites.