bluuebunny/crossref_metadata_2025 huggingface dataset:
An Ultra-Low Loading Iridium Electrode for Proton Exchange Membrane Water Electrolyzer
Authors: Kim Hyunki , Han Gyeong Ho , Hong Seokjin , Park Juhae , Ahn Sang Hyun
Published: December 2020

With interest in global warming, hydrogen produced by water electrolysis is a promising candidate for alternative for fossil fuel. For proton exchange membrane water electrolyzer (PEMWE), Ir-based oxide used as an anode which showed high performance for oxygen evolution reaction (OER). However, its high price and scarcity prevent from commercialization. In order to increase the mass activity, various methods have been conducted. In recent, many studies on the electronic structure modified catalyst have been reported and their high OER activity is originated from decreased energy barrier of intermediate for OER. Notwithstanding, it is difficult to facilitate practical application as an anode for PEMWE due to its poor structure for mass transfer at high current range. In general, powder-type of IrOx was used with ionomer solution. On the the hand, self-terminated electrodeposition (SED) facilitates controlling the Ir loading amounts in sub-microgram scale via repeated deposition pulses on Au substrate.In this study, Ir-based electrodes were directly deposited on dendritic Au substrate by SED and subsequent electrochemically (EC) and thermochemically (TC) oxidation process. Metallic Ir nano particles were electrodeposited on Au/carbon paper (Au/CP). Depending on the number of the Ir SED pulses, Ir loading mass and Ir coverage easily controlled. Then the optimized metallic Ir/Au/CP oxidized EC and TC, respectively. The electrochemical surface area (ECSA) and geometric OER activity were measured. The specific OER activities were obtained by normalized the geometric OER activity by ECSA. The oxidation state and changes of phase were investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Through XPS fitting analysis, the Ir valency and electronic structure were investigated. By adjusting the number of the Ir SED pulses and further oxidation process, Ir valency can be changed. Finally, relationship between specific OER activity and Ir valency was investigated. Conclusively, it was confirmed that the specific OER activity was strongly affected by Ir3+/(Ir3++Ir4+).
Membrane-Based Zero Gap CO2 Electrolyzer with Au Cathode Prepared By Electrodeposition
Authors: Kim Junhyeong , Guo Wenwu , Han Gyeong Ho , Oh Jeong Hyun , Yeon Kyurim , Ahn Sang Hyun
Published: December 2020

Electrochemical CO2 conversion has been recognized as a promising technology that can overcome the global warming. Also, the production of useful fuels (e.g. CO, HCOOH, CH4, CH3OH and C2H4) is capable via electrochemical reduction of CO2. It was demonstrated that at least 200 mA cm–2 of partial current density should be required for commercial operation. However, in conventional aqueous system, the CO2 electroreduction was limited to 35 mA cm–2 of current density due to low CO2 solubility into the electrolyte. Furthermore, the diffusion length of CO2 from bulk to catalyst is much longer in H-type cell system causing prevent easy supply of CO2. To overcome these problems, a single cell based on a membrane electrode assembly (MEA) with zero gap between the electrodes was introduced to facilitate CO2 mass transfer to the catalyst surface.

In this study, we investigate the MEA-based CO2 electrolyzer with anion exchange membrane. The electrodeposited Au on gas diffusion electrode (GDL), which exhibits the high CO production selectivity in CO2 electroreduction, was directly used as a cathode of CO2 electrolyzer. The humidified CO2 gas is supplied into cathode to promote the CO2 mass transfer to the catalysts-membrane interfaces. Furthermore, the content of polytetrafluoroethylene on GDL was controlled in order to prevent the product crossover between compartments that is feasible to exhibit stable performance. Compared to conventional H-type cell system, the 2-order magnitude improvement of partial current density was shown in MEA-based zero gap CO2 electrolyzer owing to low ohmic resistance and facile CO2 mass transfer.
Electrochemically Grown Sodium Transition Metal Oxides NaxMO2 (M=Co, Mn, Fe, Ni)
Authors: Patra Arghya , Davis Jerome , Pidaparthy Saran , Karigerasi Manohar H. , Zahiri Beniamin , Kulkarni Ashish Ajit , Caple Michael A. , Shoemaker Daniel P. , Zuo Jian Min , Braun Paul V
Published: December 2020

Electrochemically grown ceramic oxide films have exhibited improved electrochemical, photovoltaic, and catalytic performance. However, product library accessible through conventional aqueous anodic electrolytic deposition of oxides is limited primarily to binary systems and rare examples exist for air and moisture sensitive ternary oxides. Moreover, growth rate, thickness, and functionality of the electrodeposited oxide films are hindered by the solvent of choice, poor reaction kinetics and low temperature of synthesis. Here, we introduce, an intermediate temperature (350oC), dry molten sodium hydroxide mediated binder-free electrodeposition process to grow air and moisture sensitive layered sodium transition metal oxides, NaxMO2 (M=Co, Mn, Ni, Fe), which are conventionally synthesized by solid state reactions at temperatures ≥ 700oC. Albeit the lowest reported synthesis temperature and reaction times, our electrodeposited oxides retain the key structural and electrochemical performance observed in the high temperature bulk synthesized analogues. We demonstrate that tens of microns thick, >75% dense O3 NaxCoO2 and O'3 NaxMnO2 can be deposited at a growth rate of ~5-20 mg/cm2/hr, with near theoretical gravimetric capacity, chemical diffusion coefficient of Na+ ions, and reversible areal capacity in the range ~0.25-0.76 mAh/cm2, which are significantly higher than those reported for binder free sodium cathodes deposited by other techniques. Our method resolves longstanding intrinsic challenges associated with traditional aqueous solution-based electrodeposition of ceramic oxides and opens a general solution chemistry approach for electrochemical processing of hitherto unexplored air and moisture sensitive high valent multinary oxides.
Aggregate-Free Deposition of Highly Organized Nanocomposite Silica Thin Films on Conductive Substrates By Electrochemically Induced Templated Sol-Gel Synthesis
Authors: Vanheusden Genis , Philipsen Harold , Vereecken Philippe M.
Published: December 2020

The synthesis of ordered nanocomposite or nanoporous silica thin films by template-assisted sol-gel processes offers interesting applications in various fields including catalysis, sensors, membranes and energy. The electrochemically assisted self-assembly method allows the growth of highly ordered vertically aligned nanoporous silica thin films on conductive substrates. This orientation, optimized for high mass-transport capabilities, is difficult to obtain by classical approaches. The method involves submerging the conductive substrate in a pre-hydrolyzed precursor liquid followed by the application of a cathodic potential, thereby causing the electrogeneration of hydroxide ions. The pH increase in the diffusion layer near the electrode surface catalyzes the sol-gel formation and the result is a silica thin film that grows on the conductive substrate. The addition of cetyltrimethylammonium bromide (CTAB) micelle templates leads to the formation of a highly ordered nanostructure.

A fundamental limitation of the method as reported in the literature is that the maximum layer thickness which can be obtained is rather limited due to the formation of aggregate by-products. In our contribution we show that diffusion layer thickness control is essential to obtain aggregate-free layers. Silica formation is catalyzed by OH- formed in the electrode’s diffusion layer, which quickly grows up to hundreds of microns under stationary conditions, thereby leading to composite thin films as well as precipitation of aggregates. By using a rotating disc electrode, the hydrodynamic layer is controlled, enabling aggregate-free film growth over a wide thickness range. Additionally, thin film coatings on high aspect ratio micropillar structures were demonstrated. Parameters such as precursor age, deposition temperature and deposition current were systematically investigated and the deposits were characterized using SEM, ellipsometry, TEM, FT-IR and an electrochemical redox probe. Using these techniques, we demonstrated the controlled growth of aggregate-free, uniform and nanostructured thin films with high mass-transport capabilities and thicknesses of 20 nm up to 15 µm, thereby significantly expanding the range of 50-150 nm as reported in literature. These results are explained using a single hydrodynamic layer model.

Figure 1
High-Speed Electrodeposition of Textured Monolithic Lithiated Transition Metal Oxide Cathodes for High Energy and Fast Charging Li-Ion Batteries.
Authors: Cook John B.
Published: December 2020

Xerion Advanced Battery Corp, founded in 2010, is in the process of commercializing two battery technologies: a) a nanoscale metal foam, produced through electrodeposition, that enables high performance alloy-type active material based electrodes, and b) a single-step electroplating process to manufacture lithiated transition metal oxide (LTMO) cathodes.

Xerion’s process benefits from the combined synthesis and electrode formation in just one step – revolutionizing the current commercial slurry-electrode manufacturing process (>20 steps). Certain LTMO’s can be grown as a monolithic structure up to 500 m thick (~ 5 times thicker than state of the art), while simultaneously controlling the crystalline orientation, porosity, surface area and morphology. Ultra-thick textured electrodes significantly decrease the volume, thickness and weight of the resulting battery without compromising run time or power-density. In addition, the deposition process can be applied onto arbitrary shapes giving way to storage solutions that could be integrated as structural and load bearing components leading to low form-factors, ultra-light weight solutions, and new designs. Safety is also improved because conductive agents are not added to the electrode eliminating secondary conductive pathways, which can prevent hard shorts that lead to disastrous thermal run-away events.

The transformative electroplating process can utilize low purity feedstocks instead of highly purified lithium hydroxides and lithium carbonates to produce highly pure Li-ion battery cathodes at a fraction of the cost. This feedstock flexibility arises from selective solubility and differences in redox potential of the desired material and the undesired impurity phases. While commercial active material manufacturing requires feedstock purity >99.5%, purities as low as 50% have been demonstrated with Xerion’s molten salt process. As a result, cost modeling has shown that cost to manufacture cells using this process is reduced by up to 50% even when using an expensive cathode chemistry like LiCoO2. The single-step manufacturing method that produces safe batteries with high energy, fast charging, and high-power characteristics, while simultaneously reducing the cost, is possible through the innovative technology being brought to the market by Xerion Advanced Battery Corporation.
Synthesis and Electrochemical Properties of Ni-Rich Cathode Material for Lithium-Ion Batteries By Electrospinning
Authors: Nam Yun-Chae , Lee Seon-Jin , Ryu Jin , Hong Tae-Whan , Son Jong Tae
Published: December 2020

Ni-rich cathode material for lithium ion battery have receiving attentions due to low cost, non-toxicity and high energy density. Among them, Li[Ni0.8Co0.15Al0.05]O2 is a promising candidate due to its excellent electrochemical performance. In this study, Li[Ni0.8Co0.15Al0.05]O2 cathode material for lithium ion battery is obtained using electrospinning method. We shortened the diffusion path of Li+ and improved the Li+ diffusion coefficient. Scanning electron microscopy (SEM) revealed that the synthesized material consisted of nanofiber. The surface area of nanofiber was measured by atomic force microscopy (AFM). X-ray Diffractometer (XRD) analysis was carried out to determine the structure of Li[Ni0.8Co0.15Al0.05]O2 nanofiber. Then we analyzed electrochemical properties by electrochemical impedance spectroscopy, charge-discharge test.
A Multimodal Electronic Nose Based on High-Density Flexible Sensor Array of Carbon Nanotubes and Photoactive Macromolecules Hybrid Nanostructures
Authors: Tran Thien-Toan , Park Hyusim , To Dung , Gangadhara Karthik , Brady Jacob , Hart Joseph , Jung Sungyong , Myung Nosang Vincent
Published: December 2020

We report a multimodal electronic nose system based on photoactive carbonaceous hybrid nanomaterials for the detection and quantification of gaseous odors. The e-nose system comprises a high-density flexible sensor array, colorimetric and electrical measurement electronics, data acquisition software, and data analysis algorithms. The e-nose system combines the unique advantages of electrical, chemical, and physical properties of single-walled carbon nanotubes (SWNTs) with optical and chemical properties of various classes of organic macrocyclic compounds, such as pyrenes, porphyrins, and phthalocyanines, for multimodal gas sensing. Photoactive macromolecules such as metalloporphyrins and metallophthalocyanines have been previously developed into colorimetric sensors to various gas analytes. Their intrinsically low electrical conductivity prevents direct application of porphyrins and phthalocyanines in chemiresistive sensors. However, when used as a secondary sensing material via functionalization onto SWNTs, which intrinsically lacks chemical selectivity, these macromolecules confer their chemical selectivity and optical properties to the intrinsically semiconducting SWNT channel. This hybrid nanostructure allows both chemiresistive sensing and colorimetric sensing modalities. Another beneficial property of this hybrid nanostructure is the optoelectronic tunability of the nanomaterial to allow for direct modulation of chemical and electrical behaviors leading to tunable gas sensing capability.

Using the high-density array containing 118 individually addressable sensors, over 60 different secondary sensing materials (functionalized onto SWNTs) were investigated, which include chemical derivatives of pyrenes, porphyrins, and phthalocyanines, which have a large variety of side-groups, and metal centers. Additionally, by integrating a large variety of secondary sensing materials into each sensing element of the 118-sensor array, we take advantage of the different chemical and electrical characteristics of each macromolecules which allow for different affinities to specific VOC species to enhance overall selectivity of the e-nose system. The functionality of the multimodal e-nose system was demonstrated to distinguish and quantify various volatile organic compounds (VOCs).
Film Fabrication and Composition Control of Transition Metal Oxide Nanoparticles for Oxygen Evolution Catalysts
Authors: Hong Yun-kun , Park Yoonsu , Kang Hyeri , Ha Don-Hyung
Published: December 2020

Development of highly efficient oxygen evolution reaction (OER) catalysts is necessary for commercial implementation of water electrolysis due to overcome slow kinetics of OER. Noble metal based electrocatalysts such as Ir and Ru demonstrate high performance for OER in acidic media. In contrast, the first-row transition metal oxides such as Ni, Co, and Fe oxides show the high catalytic activity and stability in alkaline media. In this work, the composition of bimetallic metal oxide NPs was tuned and their electrochemical performance was analyzed. Furthermore, the electrophoretic deposition (EPD) technique was utilized for the efficient fabrication of NP thin film electrode. The bimetallic transition metal oxide NPs were synthesized by using Ni(acac)2 as Ni precursor and Fe(acac)3 as Fe precursor, leading to the phase control of bimetallic Ni-Fe oxide NPs. As Fe precursor amount was gradually increased compared to that of Ni, the particle size of Ni-Fe oxide NPs was increased, and the shape of NPs was transformed from spherical to irregular shape. The magnetic property of Ni-Fe oxide NPs was also analyzed by vibrating sample magnetometer. The saturation magnetization (Ms) of bimetallic metal oxide was increased and the magnetic coercivity was decreased when the Fe composition was increased. For the electrochemical analysis for OER, the overpotential of bimetallic metal oxide NPs catalysts was highly influenced by the composition of bimetallic metal oxide NPs. Higher Fe contents than Ni in the NPs led to high performance as OER catalysts. The EPD technique was introduced to manufacture the uniform NP films with improved catalytic activity. The catalyst film formed through EPD technique was prepared under the applied voltage of 500 V for 10 minutes. The film of Ni-Fe oxide NPs was well covered on the substrate of the Ti foil. The overpotential of the bimetallic metal oxide NP film fabricated by EPD was decreased from 510 mV to 400 mV at 10 mA/cm2 compared to the films fabricated by drop casting. These results provide useful insights not only for understanding the catalytic activity of bimetallic metal oxide NPs in OER but also for suggesting the film fabrication method for enhancing the catalytic activity.
Role of Ni, Mn and Co in Layered Rock Salt Cathode Materials for Li-Ion Battery: A DFT Study
Authors: Fujiwara Yoshiya , Morita Yoshiyuki , Ogasa Hiroshi , Fujisaki Fumika , Kushima Akihiro
Published: December 2020

Li-ion battery (LIB) has high energy/power density and long cycle life among other battery systems. LiCoO2(LOC) is a commonly used LIB cathode material which has a layered rock salt structure. To meet environmental needs, especially for the reduction of CO2, electrification of the automotive applications requires high volume of batteries. Here, Co which is a key element of LIB has potential supply risks due to its geological availability and value chains. Although, low-Co and high Ni cathode materials such as LiNiMnCoO2 (NMC) or LiNiCoAlO2 (NCA) have been developed by Edisonian approach, the role of Co in the cathode materials with layered rock salt structure is still not clear. To understand the role of Co, we conducted a comprehensive study with modeling and simulation backed up by the synchrotron X-ray experiment. A series of density functional theory (DFT) calculation was performed using the Vienna Ab initiation Simulation Package (VASP)[1,2] within the projector augmented-wave method and generalized-gradient approximation (GGA). All calculations were performed employing PBE-GGA+U. Change in the charge density distributions and thestructure parameters at different states of charge (SOCs) were calculated for mono-transition-metal oxidessuch as LCO, LiNiO2 (LNO) and LiMnO2 (LMO) as well as ternary-transition material NMC with different composition ratio, ie NMC111, NMC622, NMC811. Figure 1 shows Bader charge analysis[3] result for each elements in LCO, LNO and LMO as a function of the SOC. Detailed analysis with experimental results of XAFS and XRD, and will be discussed in the meeting.

[1] P. E. Blöch, Phys. Rev. B 50, 17953 (1994).

[2] G. Kresse et al., Phys. Rev. B 59, 1758 (1999).

[3] G. Henkelman, A. Arnaldsson, and H. Jónsson, Comput. Mater. Sci. 36, 354-360 (2006)

Figure 1
Hydrothermal Synthesis and the Cathode Properties of Na3MPO4CO3 (M = Fe, Mn, Ni, Co) with Highly Concentrated Aqueous Electrolyte
Authors: Okada Masaki , Chiba Kazuyuki , Matsunaga Osamu , Kobayashi Wataru , Takahara Toshiya , Takahashi Kennichi , Sakamoto Ryo , Okada Shigeto
Published: December 2020

Na-ion batteries (NiBs) have drawn much interest as low cost and low environmental impact power source for large-scale grid storage system, because of the abundant resources of sodium. For the past decades, various iron-based polyanionic compounds have been extensively studied as cathode materials for NiBs. Among the candidate of cathode active materials for NiBs, practical use of iron phosphate such as NaFePO4, Na2FePO4F, and Na3Fe3(PO4)4 [1] or carbonophosphate such as Na3FePO4CO3 [2] is expected from the viewpoint of cost and safety.

Recently, our group confirmed that 17m NaClO4 aqueous electrolyte showed high operating voltage up to 2.78V in both Na and Li systems [3]. By using 17 m NaClO4 aqueous electrolyte, it was found that Na3FePO4CO3 prepared by mechanical ball milling provided an initial discharge capacity of 161 mAh g-1 between -1.2 and 1.3 V with a reference electrode of Ag/AgCl at 2 mA cm-2 [4].

In order to make full use of the resource and cost advantages of carbonophosphate, the raw materials used in the synthesis and the synthesis method are also important. In this presentation, we report the direct synthesis of Na3MPO4CO3 (M = Fe, Mn, Co, Ni) by the hydrothermal method and the cathode properties.

Figure 1 shows charge-discharge profiles of Na3FePO4CO3 obtained by hydrothermal synthesis at 180 ° C for 16 hours using iron sulfate (II) (FeSO4·7H2O), trisodium phosphate (Na3PO4·12H2O), and sodium carbonate (Na2CO3) as raw materials. This hydrothermal synthesis Na3FePO4CO3 delivered initial discharge capacity of 112 mAh g-1.

In the presentation, we will be reported the details of cathode properties of the hydrothermal synthesized Na3MPO4CO3 (M = Fe, Mn, Co, Ni).

References

[1] S. Okada, H. Arai, J. Yamaki, DENKIKAGAKU, 65 (1997) 802.

[2] H. Chen, G. Hautier, G. Ceder, J. Am. Chem. Soc., 134 (2012) 19619.

[3] K. Nakamoto, R. Sakamoto, M. Ito, A. Kitajou, S. Okada, Electrochemistry, 85 (2016) 179.

[4] B. Xie, R. Sakamoto, A. Kitajou, K. Nakamoto, L. Zhao, S. Okada, Y. Fujita, N. Oka, T. Nishida, W. Kobayashi, M. Okada, T. Takahara, Sci. Rep., 10 (2020) 3278.

Figure 1
Effect of Modified Li2MnO3 on Electrochemical Properties of Li-Rich Composite Layered Cathode
Authors: Fung Kuan-Zong , Chang Li-Fu , Tsai Shu-Yi , Tang Jhih-Yu
Published: December 2020

xLi2MnO3-(1-x)LiMO2(M = Mn, Ni, Co, etc.) is a general formula representing composite layered cathode materials. Interestingly, this cathode exhibits surprisingly high reversible capacity and receives great attention for practical applications. Li2MnO3 is known to play an important role of providing extra Li source for stabilizing the layered structure. For single phase Li2MnO3, it shows limited capacity during charging/discharging reaction. Furthermore a characteristic 1st charging plateau corresponding to the extended capacity contribution from oxygen release in Li2MnO3. Accordingly, such oxygen release also causes the formation of oxygen defects (vacancies) and may cause the instability of Li2MnO3. Thus, the performance of Li-rich composite oxides cathode with layered structure is highly influenced by the electrochemical properties of Li2MnO3 Therefore, the main objective of this study is (i) to modify the electronic defects of Li2MnO3 through changing pO2, (ii) to add dopants to introduce more electrons to Li2MnO3 for better conduction, (iii) to assemble and test cells using Li2MnO3 as the cathode and Li metal as the anode, (iv) to characterize and understand the electrochemical properties of Li2MnO3. In this study, Li2MnO3 are prepared using sol gel/solid state reaction processes and treated by dopant addition and reducing atmospheres. Impedance of Li2MnO3 is measured using Electrochemical Impedance Spectroscopy (EIS). XRD analysis and SEM observation are performed for synthesized Li2MnO3 particles. A full cell based on Li/ Li2MnO3 and Li/ 0.5Li2MnO3-0.5LiMO2 using treated Li2MnO3 will be assembled and tested.
(Invited) Thermal, Structural, and Electrochemical Characteristics of Ni-Rich NMCs
Authors: Doeff Marca M
Published: December 2020

To improve energy densities of lithium-ion batteries meant for vehicle applications, the battery community is increasingly turning to Ni-rich NMC cathode materials. These materials, with compositions LiNixMnyCozO2: x+y+z≈1, x>y, are particularly attractive because they have higher practical capacities than NMC formulations where the Ni and Mn contents are matched. However, this comes at the expense of lower thermal stability of delithiated (charged) materials and shorter cycle lives. Utilizing a number of surface and bulk sensitive synchrotron techniques, our group has studied the thermal properties of fully and partially chemically delithiated NMC-622 and NMC-811 as a function of lithium content and temperature. As expected, changes in the bulk structures are observed at lower temperatures for compositions with lower Li and/or higher Ni content. As the temperature increases, phase conversion generally progresses as follows:

Layered--> disordered-->LiMn2O4-type spinel-->M3O4-type spinel-->MO rock salt

Several of these bulk reactions are associated with progressive reduction of Ni and Co with concomitant loss of oxygen. Interestingly, bulk-sensitive hard XAS and surface-sensitive soft XAS experiments suggest that, in some cases, apparent metal oxidation initially occurs close to the temperatures at which phase changes occur, rather than reduction. This can be explained in part by temperature-induced changes in M-O bond covalency, which act as a portent that a bulk reaction is about to occur. Lithium migration from one region in a particle to another may also explain discrepancies between surface and bulk metal oxidation states. In addition to lithium migration, Ni migration has been directly observed in heated particles using in situ synchrotron nanotomography. Full field X-ray spectromicroscopy also reveals considerable heterogeneity in the distribution of metal oxidation states as samples are heated, with reduction and, by inference, bulk phase change, occurring sooner in smaller primary particles than in larger ones. These observations suggest that strategies such as particle size and morphology engineering may help to improve the thermal characteristics of Ni-rich NMCs.
Estimation of Kinetic Parameters of Additives By Semi-Analytical Solution
Authors: De Shuvodeep , Huang Qiang
Published: December 2020

The electrodeposition of Cu and other metals is an essential step in the interconnect fabrication, 3-D integration, and various packaging technologies. Such electrodeposition processes are enabled by a group of organic additives. Furthermore, strong agitation is often used to expedite the electrodeposition rate when the processing time becomes critical for large features, which however introduces non-uniform mass transport within a single feature and between different features. A numerical description of how organic additives behave in conjunction with external flow at various feature geometry and dimensions is a challenging task, but much needed for chemistry and process development. Among the various requirements, the additive behavior or their electrochemical impacts on Cu deposition needs to be precisely described.

This talk reports an effort to obtain the numerical parameters that describe the additive behaviors during Cu deposition on rotating disc electrodes (RDE). A one-dimensional semi-analytical model is developed for Cu electrodeposition from a two-component additive system. The steady-state mass transport differential equations of each chemical species, including diffusion and convection, are solved analytically at different potentials, while the boundary conditions at the RDE surface are coupled with each other through the surface coverages of adsorbed species. The steady state of such surface coverage results from a dynamic equilibrium between three co-existing processes, adsorption, desorption and incorporation (consumption), namely,

Adsorption Rate – Desorption Rate – Consumption Rate = 0

A set of solutions, including the concentration profile of each species in electrolyte as well as the surface coverage of each adsorbate, can be obtained at a fixed potential. The equations are first solved considering only the suppressor for a range of over-potential. It was found that, for a specific range of voltages and kinetic parameters, multiple non-trivial solutions of surface coverage exist. In other words, multiple steady states exist at a same applied potential. As shown in Figure 1, this translates to a S-shaped negative differential resistance (NDR) feature in cyclic voltammogram (CV), consistent with experimental observation reported in literature. The numerically calculated NDR region was found sensitive to the additive concentration and therefore extremely useful in determining the electrochemical parameters using multiple experimental datasets with different concentrations. The swarm optimization algorithm used for parameter fitting and the correlation between multiple numerical solutions with the NDR region will be discussed in details in the talk.

Figure 1
A Study on Void-Free Filling of a High-Aspect-Ratio Though-Silicon Via
Authors: Jin SangHoon , Lee Woon-Young , Lee Dong-Ryul , Jo Yugeun , Lee Min-Hyung
Published: December 2020

The void-free filling of high-aspect-ratio through silicon via (TSV) is one of the technical challenges for 3D integration. We suggest the seed step-coverage enhancement process (SSEP) for void-free filling of a high-aspect-ratio through-silicon via (TSV) because the Cu seed layer deposited usually by physical vapor deposition (PVD) shows the poor step coverage inside the TSV. The SSEP was performed by means of electroplating using an alkaline pyrophosphate solution after the deposition of the Cu seed layer. After the SSEP, in order to fill the TSV without void using a Cu electroplating, we suggest the optimization of the functional groups of levelers in the Cu electroplating solution. In this research, step-coverage enhancement was successfully achieved through optimization of the molar ratio of pyrophosphate ions to Cu ions in the plating solution and the current density. And then, we investigated the TSV filling performance dependent on the functional groups of levelers such as amines, imines, pyridines and pyrrolidones. As the result, it was determined that TSV filling performance was strongly affected by functional group of leveler. Only amines can succeed to fill a TSV without void under high speed electroplating of 1.3ASD. This result proves that the leveler can inhibit the faster electroplating at the upper edge of TSV effectively even at the high current density.

Reference

[1] H. Ling, H. Cao, Y Guo, H. Yu, M. Li and D. Mao, International Conference on Electronic Packaging Technology & High Density Packaging (2009) 860-862.

[2] K. Zou, H. Ling, Q. Li, H. Cao, X. Yu, M. Li and D. Mao, International Conference on Electronic Packaging Technology & High Density Packaging (2009) 103-106.

[3] L. Ma, H. Ling, M. Li, J. Sun, X. Yu and Y. Li, 14th International Conference on Electronic Packaging Technology (2013) 356-359

[4] R. Beica, C. Sharbono and Tom Ritzdorf, Electronic Components and Technology Conference (2008) 577-583
Electroless Deposition of Pure Cobalt Film for Realizing Low Resistivity LSI Interconnection
Authors: Morita Kosei , Saida Ryota , Matsudaira Taro , Shimizu Tomohiro , Ito Takeshi , Shingubara Shoso
Published: December 2020

With a scaling trend of LSI interconnection, effective resistivity of Cu/barrier metal interconnect is expected to increase due to increasing electron scattering due to ultrafine dimension smaller than electron mean free path. Therefore, the trend is to substitute Co metal liner for Cu when the line width of LSI interconnect is 10 nm or less. While Chemical Vapor Deposition (CVD) or electrodeposition are discussed as formation method of Co mainly, we introduced electroless deposition (ELD) method. In electroless deposition of Co using Dimethylamine Borane (DMAB), B was incorporated in Co film, and the electric resistivity of the film after heat treatment (400℃ in vacuum, 30 minutes) was 68 µΩ∙cm. In this report, we introduced hydrazine monohydrate as a reducing agent for the purpose of forming ELD pure Co film.

ELD Co bath contains cobalt chloride hexahydrate (CoCl2∙6H2O) as metal ion source and hydrazine monohydrate (N2H4∙H2O) as a reducing agent. In addition, some complexing agents were added to prevent Co hydroxide precipitation. Plating bath pH was adjusted to about 12.3 and the CVD-Co film (thickness: 20 nm) on SiO2 and Si was used as substrate for Co deposition. Obtained Co plated film were observed and analyzed by Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS) and X-Ray Diffraction (XRD). Furthermore, Co plating film was heat-treated at 400℃ in vacuum, and the electrical resistivity of Co film before and after the heat-treatment was measured by four-terminal method.

The deposition rate of ELD cobalt bath was about 19 nm/min, and this cobalt film consisted of columnar crystals (Figure 1). If the film surface is rough, it may cause void formation during electroless Co plating in fine via. Regarding the properties of Co film, impurities derived from the reducing agent were not detected from XPS spectral analysis. Co film with few impurities leads to low resistivity because the probability of electron impurity scattering decrease. However, the resistivity of obtained and heat-treated Co film is 53 µΩ∙cm. It is necessary to form the smooth Co film to reduce the electrical resistivity.

Figure 1
Electrochemical Synthesis of Nanostructured Rhodium Deposits from Carbamide-Chloride Melts
Authors: Buryak Mykola I , Kozin Valentin F. , Blyznyuk Antonina V. , Kochetova Svetlana
Published: December 2020

It has been found by spectroscopy and electrochemical voltammetry that when rhodium is anodically dissolved in a carbamide-chloride melt, [Rh(NH3)4Cl2]+ complexes of D4h symmetry are formed, which are electroactive. The electrochemical behavior of rhodium in a carbamide-chloride melt under stationary and nonstationary electrolysis conditions has been studied. It has been found that the reduction of Rh(III) complexes at the cathode is controlled by the stage involving the formation of a passive film on anodic polarization.
Pulsed Current Vs. Organic Additives on Electrodeposition from Zincate Bath
Authors: Rauch Jeanne-Marie , Gigandet Marie-Pierre , Rolet Jason , Hihn Jean-Yves
Published: December 2020

Among the various zinc electroplating baths, alkaline zincate solution has gained a wider range of applications thanks to its simple bath composition, good dispersion and efficient coverage ability. Nevertheless, alkaline zincate solution cannot be used as such and it is necessary to introduce additives to control the process performances [1]. Otherwise, efficiency is extremely low, and the properties of the coatings are disappointing. Additives can modify the crystal growth and therefore the structural and mechanical properties, the corrosion resistance, and the appearance of coatings [2]. In the absence of additives, the main problem is low efficiency, resulting from the competition between dihydrogen production and the reduction of the metallic species present in the bath.

Therefore, pulsed currents constitute an attractive way to eliminate the need for organic additives by significantly improving the Faradic yield. In this study, the influence of various pulsed current sequences versus the addition of organic additives is observed in the characteristics of the coatings as well as in the process execution. A key point in the determination of the pulse sequence is the study of the transient curves with a zincate bath. This allows for the identification of the most influential parameters on dihydrogen production, with direct consequences on the process mechanisms.

By knowing the τD i.e. diffusion time preceding hydrogen reduction, it is possible to design pulse sequences with limited gas production. This is confirmed by mass spectrometry measurements which quantify the total dihydrogen production for each pulse sequence. Fig 1.

The coating’s characterization consists in SEM analysis topographic pictures and preferential orientations and grain sizes determined through XRD. Results confirm the interest of pulsed currents versus organic additives for zincate baths.

[1] J. L. Ortiz-Aparicio, Y. Meas, G. Trejo, R. Ortega, T. W. Chapman, et E. Chainet, « Effects of organic additives on zinc electrodeposition from alkaline electrolytes », J Appl Electrochem, vol. 43, no 3, p. 289-300, mars 2013, doi: 10.1007/s10800-012-0518-x.

[2] L. Yuan, Z. Ding, S. Liu, W. Shu, et Y. He, « Effects of additives on zinc electrodeposition from alkaline zincate solution », Transactions of Nonferrous Metals Society of China, vol. 27, no 7, p. 1656-1664, juill. 2017, doi: 10.1016/S1003-6326(17)60188-2.

Figure 1
Refractory Metal Speciation and Electrochemistry in Novel Deep Eutectic Solvents: Progress Towards Electrodeposition
Authors: Maurer Joshua A. , Frater Theodore E.
Published: December 2020

Deep eutectic solvents offer a broad landscape of benign, inexpensive electrodeposition solvents with tunable electrochemical properties. However, the combinatorial nature of binary deep eutectics makes the number of possible solvents very large, and thus solvent-specific fundamental electrochemical properties of even common solvated metal species, much less refractory metals, are severely underpopulated in the body of literature. Additionally, fundamental questions remain unanswered about the effect of electroplating additives on the speciation of solvated metal complexes in these inherently multicomponent solvents, and the ensuing connection between complex speciation and metal reduction potentials. Here we discuss previously undescribed fundamental electrochemical properties of solvated Niobium in various novel, predominantly choline chloride based, deep eutectic solvents, with and without additives, and the resulting implications for the pursuit of refractory metal electrodeposition.
Electrodeposition of Void-Free Nanostructured Aluminum from AlCl3–Diglyme Electrolyte
Authors: Zhang Zelei , Kitada Atsushi , Fukami Kazuhiro , Murase Kuniaki
Published: December 2020

Since Al has a lower redox potential (–1.68 V vs. SHE), the use of aqueous baths fails to electrodeposit less noble Al. The development of AlCl3–based nonaqueous electrolytes attracts intense interest in the field of Al and its alloys electrodeposition. In our previous studies on AlCl3–glyme electrolytes, AlCl3–G2 has been successfully used for Al and Al–CNTs electrodeposition.

The nature properties of AlCl3–G2 electrolyte will be influenced by amount of AlCl3. AlCl3–G2 electrolyte has been investigated via NMR, Raman, ionic conductivity, dynamic viscosity and cyclic voltammetry. AlCl3–G2 electrolyte contains ionic complex ([AlCl2(G2)2]+ and AlCl4
–) and neutral molecule (AlCl3·G2 and G2). Increasing the molar ratio (x) of AlCl3 from 0.1 to 0.2 and 0.4, the dynamic equilibrium towards the direction of forming ionic species. The AlCl3–G2 electrolyte with x = 0.4 has a lower conductivity (2.6 mS cm–1) than that of molar ratio x = 0.2 at 25oC, due to an increased viscosity (15.2 mPa s). However, it exhibits the best ionicity and can be used to electrodeposit void-free Al deposit with smooth appearance. As shown in Figure 1(a) and (b), the Al deposit from x = 0.4 electrolytes is accumulated by fine particles, giving rise to a compact and smooth surface with metallic luster. In contract, x = 0.2 electrolyte gives a flake-like Al deposit (Figure 1(e) and (f)), resulting in a rough surface with black appearance. In addition, adjacent Al flakes grow at a certain angle indicated by the yellow arrows shown in Figure 1(h), thus, the voids pointed by green circle are remained in the deposits during the continuous electrodeposition.

The corrosion behaviour of Al deposits have been compared using EIS and cyclic polarization techniques. The corrosion behaviour shows a strong dependence on the crystalline size, orientation and compactness. Al deposit obtained from x = 0.4 electrolyte has a trait of nanosized crystalline (about 30 nm), <200> preferential crystal face and a compact microstructure. It accounts for an improved resistance to free corrosion and pitting corrosion in 3.5 wt% NaCl aqueous solution. By contrast, the preferential crystal faces are <111> and <220> for Al deposits obtained from x = 0.1 and 0.2, respectively. Besides, Al deposits from x = 0.1 and 0.2 have a much loose structure compared to that from x = 0.4, thereby leading to a more negative E
corr and E
pit.

Figure 1
Comparison of Ni-Rich Li[Ni1
−x−YCoxAly]O2(NCA) Cathodes for Lithium-Ion Batteries Depending on Extent of Microcracks
Authors: Park Nam-Yung , Nam Gyeong Won , Sun Yang-Kook
Published: December 2020

Ni-rich layered cathode materials Li[Ni1
−
x
−
yCoxMy]O2 (M = Al and Mn are denoted as NCA and NCM, respectively) are typical cathodes for the batteries of electric vehicles (EVs). In particular, Tesla, one of the most promising EVs producers, uses the Panasonic NCA cathode in its Model S. For the wide adoption of EVs, driving range need to be raised by the increase in energy density of lithium ion batteries (LIBs). However, developing LIBs which have high energy density with stable cycle life is mainly hampered by the cathode materials.

The general strategy for increasing the reversible capacity of NCM and NCA cathodes is to increase the relative Ni fraction in their composition. However, it is well acknowledged that increasing the Ni composition in NCM cathodes leads to the deterioration in both cycling performance and thermal stability.1 The fast capacity fading of Ni-rich NCM cathode is mostly attributed to the H2–H3 phase transition at the charged state, inducing an anisotropic lattice volume change generating internal microcracks in the particles.2 The extent of microcrack, which is a crucial factor dictating a performance of cathode material, increases as Ni fraction increases. Similar to NCM cathodes, Ni-rich NCA cathodes are also supposed to suffer from capacity fading and thermal instability problems owing to microcracks. To apply Ni-rich NCA cathodes in high-energy batteries for EVs, it is important to establish the capacity-cycling stability-thermal stability relationship depending on the extent of microcracks.

Based on the results in NCM cathodes, we investigated the comparative study of NCA cathodes whose Ni fraction are 80%, 88%, and 95% to assess their cycling stability and to determine the capacity limit that can be attained by Ni-rich NCA cathodes without substantial sacrifice of the cycling stability. In addition, The extent of microcracks during charging and discharging was focused to identify the capacity-fading mechanism of these Ni-rich NCA cathodes. The results can provide the technical and scientific basis for further material development of these cathodes.

Reference
s

1. H.-J. Noh, S. Youn, C. S. Yoon and Y.-K. Sun, J. Power Sources, 2013, 233, 121.

2. H.-H. Ryu, K.-J. Park, C. S. Yoon and Y.-K. Sun, Chem. Mater. 2018, 30, 1155.
Understanding Non-Uniformities in 3D Lithium-Ion Battery Electrode Architectures
Authors: Hung Chih-Hsuan , Allu Srikanth , Cobb Corie Lynn
Published: December 2020

Conventional Lithium-ion intercalation batteries that are composed of planar cathode, separator, and anode layers have an intrinsic trade-off between energy density and power density. While thick electrodes allow for more active material loading and higher energy densities, thick electrodes lengthen ion transport pathways and limit power performance. Conversely, thin electrodes have fast ion transport at the cost of reduced material loading which leads to lower energy densities. Three-dimensional (3D) batteries can potentially mitigate this power and energy trade-off through electrode architecture. Unlike planar electrodes, 3D batteries have unique and integrated electrode architectures that can modify ion transport pathways in three-dimensions on a micron to millimeter scale. These architectures may be locally imbalanced in material loading, leading to nonuniform current density and local depletion of the electrode or electrolyte material. These nonuniformities can terminate a discharge or charge cycle prematurely. Although many 3D battery architectures have been proposed to date, few comparative modeling studies have been conducted for these architectures to understand their relative performance gains.

In this presentation, we will investigate the impact of 3D electrode architecture on current density uniformity and material lithiation at different discharge rates in several 3D batteries. Our batteries are simulated using the software CAEBAT: AMPERES
1
, which provides a 3D electrochemical model on the continuum level using volume-averaging techniques. 3D batteries with different parameterizations and geometries of interdigitated anode and cathode electrodes are studied. In addition, the effects of current collector placement, material loading, and electrode feature shapes are also presented.

1. Allu, S., Kalnaus, S., Simunovic, S., Nanda, J., Turner, J. A., and Pannala, S., J. Power Sources, 325, 42 (2016)
Electrodeposition of Cadmium Selenide on Silicon to Integrate the Semiconductors Properties
Authors: Giurlani Walter , Vizza Martina , Fabbri Lorenzo , Marcantelli Patrick , Martinuzzi Stefano , Lo Faro Maria Josè , Irrera Alessia , Innocenti Massimo
Published: December 2020

Monocrystalline silicon has been considered for years among the materials at the base of the macro and micro-electronics industry. At the bulk state silicon is an intrinsic semiconductor whose conductive properties can be easily modulated by using doping agents. This feature combined with high availability and accessible production costs makes it particularly suitable for many applications based on semiconductor technology. With the development of vacuum deposition techniques, it has been possible to create systems that integrate monocrystalline silicon with other materials of technological interest, thus allowing the realization of highly performing devices. However, the use of these techniques is limited by special working conditions and very expensive instruments. An alternative to these techniques is the electrodeposition from aqueous solution. Studies on the deposition of materials of technological interest on gold and silver have been known for several years now. In this work we use the electrodeposition technique, with all the advantages it brings both in terms of costs and deposition quality, on monocrystalline 100 n-type silicon. The study dealt with the co-deposition and alternate deposition of the semiconductor cadmium selenide (CdSe) [1]. First of all, we carried out the electrochemical characterization of the precursors on the substrate to find the optimal conditions (pH and concentrations) for the deposition, then the deposition was performed using two different approaches: co-deposition (both the precursors present in the same solution) and charge controlled alternate deposition of the two components. Finally, deposits were characterized spectroscopically and microscopically: we found that, with the electrochemical method, we obtained to the formation of micro-clusters of CdSe on n-Si. The present study funded by the PRIN Project (“Progetti di Ricerca di Rilevante Interesse Nazionale”), “Novel Multilayered and Micro-Machined Electrode Nano-Architectures for Electrocatalytic Applications (Fuel Cells and Electrolyzers)”, grant number 2017YH9MRK.

References:

[1] Giurlani, W. et al. Electrodeposition of Nanoparticles and Continuous Film of CdSe on n-Si (100). Nanomaterials 9, 1504 (2019). 10.3390/nano9101504.