bluuebunny/crossref_metadata_2025 huggingface dataset:
The Metal Gate Cut Process(Part I): Plasma Assistant CD Shrinkage
Authors: Ji Shi-liang , Liu Shaoxiong , Zhang Haiyang
Published: February 2020

The technology of FinFET has led to the continuity of device scaling and enabled the prolongation of Moore’s Law towards the 7 nm and beyond nodes. The gate cut last has been widely adopted since it can provide better SiP/SiGe growth environment, hence yielding the better electrical performance. However, this approach requires more complex process engineering at 3D structure. Both perfect physical structure and good electronic performance are challenging for gate cut last process.

As is well known, the metal gate cut process is the inevitable choice of 5nm FinFET and GAA FinFET, which directly determines the performance of FinFET. At present, the metal gate cut process has suffer the following difficulties: the Critical Dimension of the metal gate is only about ten nanometers, the height is about one hundred nanometers, and the aspect ratio has exceeded the limit of the most advanced etching tool; the metal gate complex composition, including more than 10 kinds of metal and insulation materials; the cut CD is very small, but the profile requirement is very challenging, all the metal layers are vertical, and the same CD is maintained from top to bottom. The bigger challenge is that the line end of metal gate cut is very close to germanium silicon or phosphor silicon. On the other hand, the metal's easy collection of charge and easy conduction will greatly increase the plasma induce damage risk, which needs to be controlled by properly selecting etching conditions.

We will start a series of studies on the above issues and discuss the development direction and research ideas in each aspect. This manuscript will focus on how to use plasma etching technology to shrink CD in the soft mask etching process so as to break through the exposure limit of the immersion lithography. In general, immersion lithography with negative photoresist can not complete less than 40 nm CD, but gate cut, especially metal gate cut CD need as small as 20 nm. This puts forward very high requirements for soft mask etching. On the one hand, etch stop or defect cannot be caused with the large CD shrinkage; on the other hand, the CD should meet the design requirements and the patterning should be complete. We use the CxHyFz as etching gas with the advanced coupled plasma etching tool.We found the high/low bias pulsing scheme can reach balance on all sides, as the CD shrinkage, defect control, pattern transfer, line width roughness, the optimum process window.
Application of Broadband Microwave Metrology to Emerging Integrated Circuit Device Reliability Analyses
Authors: Obeng Yaw S. , Amoah Papa K.
Published: February 2020

Metrology is needed to characterize structure and composition in emerging integrated circuits at the nano-scale. Interconnect technology has been identified as the largest single factor limiting both performance, power, and reliability of emerging devices. The artifacts of interest may be exposed or embedded and may occur at any stage of device fabrication. We are particularly interested in metrology for the accurate understanding and quantification of the reliability issues associated with interconnect metallization in emerging nanoelectronic devices. In this regard, we have developed a suite of broadband microwave (RF)-based metrology techniques to non-destructively identify, measure, and characterize performance-limiting defects in emerging nanoelectronic devices. These RF based metrology tools offer several advantages over the traditional techniques and are uniquely suitable for studying the kinds of problems we are interested in. For example, the traditional low-frequency resistance (RDC) measurements, commonly used for electromigration, are based on changes in the resistance of conductive pathways. So long as there are contiguous electrical paths, the devices under test will not fail the RDC test. In contrast, changes in RF insertion losses offer early prognostics.

In this talk, we describe the application of a suite of broadband microwave-based techniques to the interconnect reliability assessment of integrated circuits. We discuss how microwave propagation characteristics have been used to study the impact of thermal aging on phenomena such as stress-induced failures, electromigration, and corrosion of the interconnects in 3D-ICs. We will also compare the mechanistic insights obtained from the traditional resistance increases in low-frequency direct current to those from high-frequency measurements.
(Invited) Do We Need 3D Metal Structures for Catalysis and Electronics When 2D Metals Are Possible and Perform Better?
Authors: Alamgir Faisal M.
Published: February 2020

This presentation will describe a new material paradigm: contiguous, atomically-thin, epitaxial metal films, one monolayer to several multilayers thick, where the graphene serves as both the growth template for the metal films and also as a ‘chemically transparent’ barrier against catalytic deactivation. In the latter role, graphene does not restrict access of the reactants to the catalyst but blocks the catalyst from dissolution or agglomeration. In other words, a true 2D atomically-thin metal is demonstrated - which the author believes is a first in the scientific community. A fundamental questions we can ask ourselves is whether surface metal atoms rendered in these 2D architectures are as stable as those of their counterparts in bulk. In the Pt/graphene case it is found that the surface atoms exhibit stronger binding than their bulk counterparts, but do so without sacrificing metal-like Fermi level electronic structure. The bulk-like stability of atomically-thin Pt/graphene is possible through a combination of inter-planar Pt-C covalent bonding and inter/intra-planar metallic bonding. It is further shown in a related system that by introducing a single-layer of graphene as an interface between the core and surface metal layers, unwanted surface alloying between the layered metals can be mediated. The room-temperature epitaxial synthesis approach has immediate implications on the science and application of metal catalyst systems that are support-flexible in design. More broadly, however, we reveal a new frontier for the nature of metals themselves, where they can be rendered in 2D films that are single to several atoms thin and are supported on a movable, electronically coupled substrate. Such metal/graphene or graphene/metal architectures will impact not just catalysis, but also electronic, thermoelectric and optical materials
Electrodeposition and Characterization of Ultra-Thin Films As Model Systems for Electrocatalysis
Authors: Berretti Enrico , Giaccherini Andrea , Di Benedetto Francesco , Montegrossi Giordano , Lepore Giovanni Orazio , Puri Alessandro , D'acapito Francesco , Dell'Aquila Vincenzo , Lavacchi Alessandro
Published: February 2020

Platinum is nowadays considered the best catalyst for many anodic and cathodic reactions in fuel cells. However, its low abundance poses a limit for its usage in such devices. In recent years, much effort has been done to substitute this metal whit more abundant ones, in particular concerning the alcohol electrooxidation process in direct alkaline alcohol fuel cells (DAFC).In this respect, palladium (which shares with platinum a similar catalytic activity towards alcohol electrooxidation) may represent a viable substitute for the anodic compartment in DAFC, but its main limit resides in the deactivation process (oxidation of the metal) that occurs during the cell duty cycle.

Aiming to study this phenomenon, different catalytically active bimetallic Au-Pd electrodes were prepared

by combined Under-Potential Deposition (UPD) of copper and Surface Limited Redox Replacement (SLRR) with Pd, exploiting homemade Au (111) polycrystalline surfaces. This catalytic ultra-thin layers (with different Pd coverages above Au) proved to be robust and reproducible, both morphologically and electrochemically. Moreover, this method enabled the preparation of large, flat and homogeneous surfaces, enabling their use as model surfaces in synchrotron light experiments (performed at the BM-08 line of the ESRF in Grenoble), where a blend between the Grazing Incidence X-ray Absorption Spectroscopy (GIXAS) and the Fixed Energy X-Ray Absorption Spectroscopy (FEXRAV) was exploited. This novel experimental set-up, a grazing Incidence FEXRAV technique (GI-FEXRAV), allowed to follow in operando changes in the speciation of the Pd during voltammetric scans, and thus to disclose its deactivation/dissolution in systems with a very low catalytical load. Finally, with this novel set-up we just sampled the topmost catalytic layer, thus greatly enhancing the capability to study small modifications of the surface.
Enhancing the Hydrogen Evolution Reaction Using Oxide Nanoparticles: Electrodeposited Ni-W-TiO2
Authors: Zhang Yujia , Podlaha Elizabeth J.
Published: February 2020

Electrodeposited tungsten alloys containing nickel are well-known electrocatalysts for the hydrogen evolution reaction (HER), with the added benefit of being corrosion resistant.1 The addition of nano-scale, solid oxide particles in the deposit could serve as a potential strategy to further improve the electrocatalytic properties. In the present study, Ni-W-TiO2 composites were fabricated by electrodeposition with different loadings of TiO2 nanoparticles in the electrolyte. The influence of (1) the titania particles in the electrodeposition electrolyte on the hydrogen evolution side reaction and the metal partial current densities are assessed, and (2) the embedded titania particles in Ni-W on the HER kinetics in an alkaline electrolyte are also examined.

Electrodeposition

A citrate-boric acid electrolyte was used to deposit Ni-W alloys and Ni-W-TiO2 composites onto rotating cylinder electrodes, at a pH of 8. The partial current density ratio of Ni/W was affected by the amount of particles in the electrolyte, explained, in part, by differences in adsorption that governs the metal ion induced codeposition mechanism. The hydrogen evolution side reaction was enhanced during deposition when particles were present.

HER Electrocatalysis

HER kinetic parameters of the electrodeposited Ni-W-TiO2 composites and their alloy counterparts, were examined in 1 M NaOH. The embedded TiO2 improved the HER Tafel slope of the electrocatalyst. To compare the overpotential and the exchange current density the electroactive surface area was characterized using a ferricyanide electrolyte with cyclic voltammetry. Under comparable surface areas and metal composition ratio, there was an improvement in lowering the overpotential with the composites but there was no change in the exchange current density. The addition of TiO2 to a Ni-W matrix to enhance HER serves as a model system that can be adapted to other alloy electrocatalysts.

In both electrodeposition and electrocatalysis, the TiO2 is suspected of altering the adsorption of reaction intermediates.

Reference

Tsyntsaru, H. Cesiulis, M. Donten, J. Sorte, E. Pellicer, and E. J. Podlaha-Murphy, Surface Engineering and Applied Electrochemistry, 48 491 (2012).
(Invited) Electrodeposition As a Versatile Method to Prepare Materials for the Storage and Conversion of Sustainable Energy
Authors: Ispas Adriana , Borisenko Natalia , Wang Dong , Fritz Mathias , Kurniawan Mario , Ivanov Svetlozar , Bund Andreas
Published: February 2020

Sustainable energy carriers such as sun light, wind or biomass will play a crucial role in our future. After converting the energy, one should be able to store it and transport it to places where it is needed most. Therefore, the research on materials for storage systems, such as batteries, supercapacitors and fuel cells is an important aspect. Electrodeposition is a powerful technique for the preparation of such materials.

As industry strives to produce smaller portable devices, one needs also smaller and lighter batteries with a high storage capacity per gram of active material. The commercial graphite anodes are limited to ca. 370 mAh/g, but silicon and C-Si composites have a theoretical storage capacity beyond 1000 mAh/g. Thus, nanostructured Si, such as nanoporous Si layers, ordered arrays of Si (porous) nanopillars produced by using a combination of nanoimprint lithography and metal-assisted chemical etching or silicon thin films deposited from ionic liquids could be used as high-capacity anodes in Li-ions batteries.

Another interesting semiconductor material besides Si is Cu2O. Photo-cathodes from Cu2O can be used to produce hydrogen as a chemical fuel by utilizing direct solar energy and its narrow bandgap of 2.0-2.2 eV that can lead to the theoretical value of solar-to-hydrogen efficiency of 18 %. One can fabricate Cu/Cu2O porous electrodes using the hydrogen bubbles as a dynamic and effective template by electrochemical deposition. These foam electrodes can then be used as photocathodes for water electrolysis under visible light irradiation.

This contribution will discuss recent results from the authors’ labs on developing new anode materials for Li-ion batteries (Si based), new electrodes for electrochemical water splitting (Cu2O based) and for electrocatalysis. Further, approaches using light induced plating for electrical front side contacts of solar cells will be presented.
Wearable Supercapacitor Based on Metal Oxide Grown Carbon Fiber Electrodes
Authors: Sambath Kumar Kowsik , Cherusseri Jayesh , Pandey Deepak , Thomas Jayan
Published: February 2020

Increasing development of wearable consumer electronics necessitates the development of flexible energy storage devices for powering them. Supercapacitor is one such energy storage devices offering light weight, safe operation, good charge/discharge capabilities and high cycle life. Choosing the right current collector substrate play a vital role in developing wearable energy storage devices as it should be easy in integrating to the everyday attire. The present study includes the syntheses and characterizations of flexible and high-performance supercapacitors manufactured with metal oxide grown carbon fiber electrodes. Low-cost transition metal oxides such as manganese oxide and molybdenum oxide with excellent electrochemical properties are used as active electrode materials in our work. The electrode manufacturing process followed is a facile, direct growth electrodeposition process eliminating the need for dead binders typically used in supercapacitors. The electrodes synthesized are characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Asymmetric supercapacitor is fabricated and tested by electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge/discharge measurements. The bending test done on the assembled supercapacitor showing very less capacitance degardation demonstrated its flexible nature at different bending angles. This study demonstarted that fibre supercapacitor presented here is a potential energy storage candidate, which can easily be integrated with wearable electronic devices.
Investigation of the Electrochemical Kinetics of Aluminum Deposition from Ionic Liquids
Authors: Böttcher René , Ispas Adriana , Bund Andreas
Published: February 2020

The electrochemical deposition of a number of reactive metals such as Al, Ta and Nb from ionic liquids (ILs) generated high interest during the last decades. Their deposition from aqueous solutions is not possible since these metals have a rather negative Nernst potential. Non-aqueous media have a broader electrochemical window (> 3 V) and offer new possibilities for industrial applications by electrochemical plating of highly reactive metals.

Due to its excellent properties such as high conductivity and the formation of a dense oxide film, the possible applications of aluminum range from electronics and optics all the way to coatings for corrosion protection and decorative purposes. The negative standard potential of aluminum (-1.66 V vs. SHE) led to the development of non-aqueous electrolytes used in industrial processes (e.g. SIGAL process), which are often based on highly flammable and/or volatile chemicals, leading to high costs and risks for the operator. ILs are non-flammable, have a high solubility for metal salts and there is no hydrogen embrittlement due to their aprotic nature. Furthermore, continuously decreasing prices for ILs make them more interesting for industrial processes.

Aluminum was one of the first metals electrochemically deposited from ILs. There are a lot of reports about the pure metal and its alloys. However, there are some basic knowledge gaps about the electrochemical kinetics of the aluminum deposition from ILs.

This paper will discuss recent results from the authors’ lab on the electrochemical kinetics of the deposition of aluminium from 1-ethyl-3-methyl-imidazolium based ILs. A number of high and low amplitude step experiments completed by cyclic voltammetry and conductivity measurements were employed to shed light on the diffusion, nucleation and charge transfer mechanism of the aluminium deposition.
Throwing Power in Chloroaluminate Ionic Liquids: Effects of Metal Concentration, Additives and Waveform on Aluminum/Aluminum Alloy Deposition on Complex Geometries
Authors: Abbott Joshua G. , Lucas Steve , Li WeiNa , Zhang Weilong
Published: February 2020

Al deposition from chloroaluminate ionic liquids necessitates the use of consumable anodes and near 100% plating efficiency in order prevent irreversible breakdown of the electrolyte. A significant side effect of this high plating efficiency is poor deposit thickness uniformity across current density gradients. For simple or axisymmetric geometries under ideal plating conditions it is straight forward to mitigate such issues through traditional thieving or shielding. However, as part geometries become more complex, and plating conditions less ideal (i.e. barrel plating of small parts), methods of improving poor throwing power resulting from secondary current density effects become less obvious. Addressing this issue is critical in enabling Al plating technologies to progress commercially. We have explored the effects of metal concentration, additives and plating waveform on deposit thickness uniformity for rack and barrel plated parts of increasing geometric complexity in order to minimize plating thickness distribution and improve throwing power of [AlCl3:EMIMCl] chloroaluminate electrolytes into high aspect ratio features.
Electrochemical Behavior of Cobalt and Samarium Species in an Amide-Type Ionic Liquid
Authors: Manjum Marjanul , Serizawa Nobuyuki , Katayama Yasushi
Published: February 2020

Rare earth-transition metal alloys/nanoparticles (NPs) have drawn intensive significance in a wide range of applications in automobiles, data storage, magnetoelectronic, electromechanical, and electronic devices due to their excellent magneto-crystalline anisotropy. Among them, cobalt (Co)-samarium (Sm) alloys are of great interest. Although there are many reports on the preparation of Co-Sm alloys in different media by different techniques, the electrodeposition of Co-Sm alloys/NPs has not been confirmed in an aprotic ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA), which has high cathodic stability. In the present study, the electrochemical behavior of Co and Sm species was investigated in BMPTFSA at different temperatures.

Co(TFSA)2 and Sm(TFSA)3 were prepared by the reactions of CoCO3 and Sm2O3 with HTFSA, respectively, and dissolved in BMPTFSA 1-3. Electrochemical measurements were conducted with an air-tight cell using glassy carbon (GC) as a working electrode, a Co wire as a counter electrode, and an Ag wire immersed in 0.1 M AgCF3SO3/BMPTFSA as a reference electrode.

Potentiostatic cathodic reduction at –2.5 V on a GC electrode was conducted in BMPTFSA containing 30 mM Co(TFSA)2 and 5 mM Sm(TFSA)3 at 25 and 100 oC. The lower concentration of Sm(III) was preferred than that of Co(II) because of the difference in the diffusion coefficients of Co(II) and Sm(III) ions in BMPTFSA. Deposits on the GC electrode surface were found after electrodeposition. The presence of Co and Sm in the deposits was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy. The deposits were found to be amorphous by X-ray diffraction. In addition, the electrolyte after electrolysis was examined by transmission electron microscopy (TEM). The formation of the NPs with lattice fringes was confirmed by TEM. The spots observed in the electron diffraction image of the NPs could be assigned to (111) and (110) planes of SmCo7. EDX confirmed the presence of Co and Sm in the NPs. Therefore, SmCo7 NPs were considered to be prepared in this ionic liquid.

References

1. Y. Katayama, R Fukui, and T Miura, J. Electrochem. Soc., 154, D534 (2007).

2. Y. Katayama, R Fukui, and T Miura, Electrochemistry,
81, 532 (2013).

3. M. Yamagata, Y. Katayama, and T. Miura, J. Electrochem. Soc., 153, E5 (2006).
In Operando Optical Visualization of Br5
- electrochemistry with a Planar Glass Battery for Zn/Br Flow Batteries
Authors: Wu Yutong , Liu Nian
Published: February 2020

Zn/Br flow batteries are one of the promising technologies for stationary energy storage. Bromine complexing agents have been used to form phase-separated liquid polybromide charging products. However, dynamic and microscopic understandings of the nucleation and growth of the polybromides are limiteddue to the beam-sensitivity and complexity of these compounds and their surrounding electrolytes. In this communication, we report an in operando platform composed of dark field light microscopy and a transparent planar electrochemical cell to dynamically reveal the electrochemical nucleation and formation of polybromides. Using our platform, we confirm the liquid nature, reveal the pinning effect (strong interaction with Pt), memory effect (surface residual), self-discharge of the polybromide product, and discover over-oxidation as a side reaction for ZBB. We also conclude that the electrochemically formed droplets are mainly MEPBr5,rather than previously reported MEPBr3 with in situ Raman spectroscopy. These results provide mechanistic insightsinto the role of ionic liquid complexing agents and Zn/Br battery design. The in operando visualization platform can also be applied to study other unstable or transient products or intermediates in electrochemical reactions in ambient environment.
New Reference Electrodes for Air and Moisture Stable Ionic Liquids
Authors: Horwood Corie , Stadermann Michael
Published: February 2020

The use of room temperature ionic liquids (RTILs) for electrochemical applications such as fuel cells, batteries, dye-sensitized solar cells, and supercapacitors, has gained significant interest over the last decade. Despite the increase in attention, a universal reference electrode for use in RTIL electrochemistry has not been adopted. A stable, easy to prepare, and reproducible reference electrode, analogous to Ag/AgCl reference electrodes for aqueous electrochemistry, is crucial for accurately determining redox potentials as well as for comparing these potentials between RTILs and between research labs.

Electrochemical work in RTILs often rely on quasi-reference electrodes (QREs),1 such as Ag or Pt wire, which must be calibrated by the addition of a redox couple (e.g. ferrocene/ferrocenium) after each electrochemical measurement. These quasi-reference electrodes are difficult to reproduce, likely due to the quality of the wire used and the presence of surface adsorbates. Furthermore, they have been known to exhibit potential drift during use, with 10s to 100s of mV drift often observed. Ferrocene is added after the experiment, however this one-point calibration of the QRE does not necessarily apply throughout the entire experiment, as the QRE may drift during the measurement.2

We report on reference electrodes designed for use in ionic liquids, which exhibit stable potential over several months of experimental use. One successful example is based on a silver wire coated with silver sulfide.3 The reference electrode potential is determined by the concentrations of Ag+ and S2
−, which are established by the solubility of the Ag2S coating on the Ag wire. Our reference electrode can be prepared and used in a normal air atmosphere, and does not need to be assembled and used in a glovebox, or protected from light. The reference electrode has been characterized by voltammetry measurements of ferrocene and cobaltocenium hexafluorophosphate, and was found to slowly drift to more positive potentials at a rate of <1 mV/day for five RTILs investigated over the course of 2+ months.

Funding was provided by Lawrence Livermore National Laboratory Directed Research and Development (LDRD) Grant 17-ERD-047. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. IM release LLNL-ABS-748348.

(1) Electrochemical aspects of ionic liquids, 2nd ed.; Ohno, H., Ed.; John Wiley & Sons Inc., 2011.

(2) Torriero, A. A. J.; Sunarso, J.; Howlett, P. C. Electrochim. Acta
2012, 82, 60–68.

(3) Horwood, C.; Stadermann, M. Electrochem. commun.
2018, 88, 105–108.
(Carl Wagner Memorial Award of the Electrochemical Society) Mathematical Modeling of Electrochemical Systems
Authors: Weidner John W.
Published: February 2020

In order to understand and accurately predict the behavior of electrochemical materials, devices, and systems, it is necessary to develop sophisticated mathematical models that consider, for example, transport processes, electrochemical phenomena, thermal and mechanical stresses, and structural changes during operation. This insight aids in the design and operation of electrochemical systems for a particular application. This talk will review some of the mathematical models that we have developed to predict the behavior of electrochemically active materials, fuel cells, electrolyzers, and batteries. In particularly, I will discuss the mathematical models we have developed to better understand the effect of volume change on the behavior of batteries. There are many models in the literature that can predict the electrochemical performance of batteries (e.g., voltage versus time) under a variety of operating (e.g., current) and design (e.g., electrode thickness) conditions. However, existing models do not consider how stresses can build up in the system as the expanding porous electrode is being constrained by the battery casing. Here I show predictions of the dimensional and porosity changes in a porous electrode caused by volume changes in the active material during intercalation (e.g., lithium into carbon or silicon). Porosity and dimensional changes in an electrode significantly affect the resistance of the battery during cycling. In addition, volume changes generate stresses in the electrode, which can lead to premature failure of the battery. Material conservation equations are coupled with the mechanical properties of the porous electrode to derive governing relations that link dimensional and porosity changes to stresses that occur during the intercalation process. The stress-strain relationships used in this model, which are needed to predict porosity and dimensional changes, have been established by examining the similarities between thermal rock expansion (e.g., the exchange of thermal energy with the rock) and electrode expansion due to intercalation.
Stacked Additively Manufactured Electrochemical Cell for Reduction of Carbon Dioxide to Ethylene
Authors: Ball Keiran , Tacon Christopher , Reeve Sam , Perry Samuel Charles , Ponce de Leon Carlos
Published: February 2020

An additively-manufactured two-cell stack is presented for the reduction of carbon dioxide to ethylene, forming part of a Horizon 2020 funded project, CO2EXIDE, which aims to recycle carbon dioxide in order to reduce greenhouse gas emissions1.

In this work we present a new compact flow field design, which allows for an easily expandable cell stack through the manufacture of additional identical bi-polar flow fields2. The flow fields are manufactured from 316L stainless steel using the 3D printing technique – Direct Metal Laser Sintering (DMLS). This allows them to simultaneously act as the flow fields and current collectors. The DMLS technology enables complex internal pipework, shown in figure 1, which allows a compact cell with no external pipework.

Our cell design is built around a membrane electrode assembly (MEA) (see figure 2), where CO2 is reduced at the cathode and water is oxidised at the anode3. The cathode is made from a copper nanoparticle catalyst, which is deposited onto a carbon gas diffusion layer. A nickel mesh is used as a catalyst for the anodic reaction. The flow fields were designed and optimised using the ANSYS Fluent 19.1 software in order to maximise residence time within the cell and ensure a similar pressure drop on each side of the MEA, which are essential to provide high reaction selectivity and to avoid pressure driven fluid transport across the proton exchange membrane respectively. Designing the flow field in this way allowed us to optimise our cell for both high ethylene yield and a long working life time (see figure 3 for the flow field pattern).

The finished assembly (see figure 4) was analysed for its ability to selectively reduce CO2 to ethylene. CO2 was flowed over the cathode at varying flow rates, and the outflow gas was collected for ex situ analysis by gas chromatography. This design is promising for the future development of CO2 as a carbon source for ethylene, as the stackable design makes this assembly more easily scalable for large scale operations.

[1] CO2EXIDE, “CO2EXIDE - CO2-based electrosynthesis of ethylene oxide,” 2018. [Online]. Available: http://www.co2exide.eu/. [Accessed 12 March 2019].

[2] O'Neil, Glen D.; Ahmed, Shakir; Halloran, Kevin; Janusz, Jordyn N.; Rodriguez, Alexandra; Terrero Rodriguez, Irina M. Single-step fabrication of electrochemical flow cells utilizing multi-material 3D printing. Electrochemistry Communications 99 (2019) 56-60.

[3] DeWulf, D.W.; Jin, T.; Bard, A.J. Electrochemical and Surface Studies of Carbon Dioxide Reduction to Methane and Ethylene at Copper Electrodes in Aqueous Solutions. Journal of the Electrochemical Society. 136(6) (1989) 1686-1691.

Figure 1
Developing Platinum Group Metal Free Catalysts with Multiple Metal Centers for the Oxygen Reduction Reaction in Acid
Authors: Jiao Li , Liu Ershuai , LaRochelle Richard Lynne , Mukerjee Sanjeev , Jia Qingying
Published: February 2020

Remarkable advancement of Platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) in acidic media makes it potentially feasible as an alternate to Pt-based catalysts in polymer electrolyte fuel cells (PEMFCs). The current leading PGM-free catalysts are composed of single transition metal atoms embedded in microporous nitrogen-doped carbon matrix (M-N-C). The commercialization of M-N-C catalysts in PEMFCs has been impeded by the insufficient activity and particularly durability. The limited ORR performance is likely owing to the single metal center configuration that causes low active site density, undesired O2 binding configuration and energy toward the metal center, etc. These inherent limitations of M-N-C catalysts motivate us to move toward Mx-N-C with multiple metal center (MMC) sites.

On account of this, herein a multidentate ligand platform is utilized to prepare a series of bimetallic coordination complexes. These complexes were then used as the metal precursors to produce Mx-N-C with MMC sites by incorporating them into microporous nitrogen-doped carbon matrix via both pyrolysis and surface deposition approaches without breaking the pre-existing multiple nuclear structure. The formation of MMC sites is supported by multiple characterizations. The high ORR activity achieved is tentatively related to MMC sites that promotes the desorption of oxygen adsorbates and suppress the site-blocking effect at elevated potentials. Further improvement, however, is limited by the low concentration of MMC sites. densification of MMC sites is undergoing.

Acknowledgement

This work was supported by the US Department of Energy under award number DE-EE0008416. The authors declare no competing financial interests. MRCAT operations are supported by the Department of Energy and the MRCAT member institution. This research used resources of the Advanced Photon Source, a DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
(Invited) Recycling of Used Li-Ion Batteries By Innovative Electrodialysis Using New Lithium Ionic Conductor Membrane
Authors: Hoshino Tsuyoshi
Published: February 2020

As a means of addressing global warming, the world is increasingly turning to the use of Li-ion batteries in electric vehicles and as storage batteries in the home; therefore, there is a growing need for Li. I have developed a method for the recovery of Li from used Li-ion batteries using a Li ionic conductor functioning as a Li-ion separation membrane (LISM).

This innovative method involves the use of an LISM whereby only Li ions in a solution of used Li-ion batteries permeate from the positive electrode side to the negative electrode side during electrodialysis; the other ions, including Co, Al, and F, do not permeate the membrane. Li0.29La0.57TiO3 was selected as the LISM. The positive side of the dialysis cell was filled with used Li-ion battery solution. Then the negative side was filled with distilled water. The applied dialysis voltage was 5 V, and electrode area was 16 cm2. The Li recovery ratio increased with electrodialysis time. Then, Co, Al, and F were not permeated (Fig.1).

Measurements of the Li ion concentration at the negative electrode side as a function of dialysis duration showed that the Li recovery ratio increased to approximately 90% after 72 h. Moreover, other ions in the seawater did not permeate the LISM. With both ends of the LISM bound with a negative and positive electrode, hydrated Li ion was transformed to Li ion only because Li ion can permeate through the LISM [1].

After electrodialysis, CO2 gas was bubbled in the Li recovery water to produce lithium carbonate (Li2CO3) as a raw material for Li-ion batteries. The Li2CO3 deposition was easily generated by the reaction of CO2 gas and the Li recovery solution as a lithium hydroxide (LiOH) solution (Fig.2). Moreover, the purity of Li2CO3 is up to 99.99%.

This new method for recycling Li-ion batteries shows good energy efficiency and is easily scalable. Thus, this electrodialysis method is suitable for the recycling of Li from used Li-ion batteries.

Fig.1 Schematic of Li recovery from Li-ion battery solution using the proposed electrodialysis.

Fig.2 Production of High-purity Li2CO3 by CO2 bubbling method.

[1] T. Hoshino, Desalination, 359, 59-63 (2015).

Figure 1
Dissolution of Rare Earth Elements from Nd Magnet Scraps Using Gas Electrodes in Molten Chlorides
Authors: Konishi Hirokazu , Koizumi Yuichiro
Published: February 2020

Here we study the dissolution of rare earth elements from Nd magnet scraps using Cl2 or O2 gas electrodes in order to achieve new rare earth recycle process. The anodic polarization of Nd magnet scraps and cathodic polarization of O2 gas electrodes were investigated in molten LiCl-KCl systems at 723 K. The anodic polarization was carried out by potentiostatic electrolysis of Nd magnet scraps electrode from 0.69-2.39 V(vs. Li+/Li) at every 0.050 V interval. The large anodic current was observed at 1.80-2.00 V due to anodic reaction of dissolution of rare earth elements. On the other hand, the cathodic polarization was carried out by potentiostatic electrolysis of O2 gas electrode using porous Ni from 1.20-2.30 V at every 0.10 V interval in a molten LiCl-KCl added Li2O(0.50 mol%) system. The large cathodic current was observed from 1.40-1.90 V due to cathodic reaction from O2 to O2-. It was possible to dissolve rare earth elements selectively from Nd magnet scraps using O2 gas electrodes.
Road Salt Reduction from Source Water Using 3-Compartment Borohydride/ Hydrogen Peroxide Desalination Cell
Authors: Hamilton Shawn Nicholas , Bassi Amarjeet , Karamanev Dimitri
Published: February 2020

The road salt that is applied to sidewalks, driveways, roads and parking lots makes its way to our local waterways killing freshwater biotas as well as decreasing structures working life through increasing corrosion rates. Recycling road salt is essential to reduce the ever-increasing amounts used in Quebec and Ontario, Canada. Using electrochemical desalination cells is investigated to regenerate the salt. The optimization includes solvent selection, establishing a compact design and increasing the removal rate with as little energy requirement as possible. This paper reports the optimum combined conditions obtained so far. In a 2-compartment cell, Direct Borohydride Fuel Cell (DBFC), based on sodium borohydride (NaBH4) and hydrogen peroxide provided better current and power densities in comparison to Direct Methanol Fuel Cell (DMFC), based on methanol and peroxide. This agrees with several review papers comparing these two fuel cell types. For further testing NaBH4 was substituted with potassium borohydride (KBH4) in a 3-compartment cell, t producing a highly-desalinated effluent. The sodium ions (Na+) and chloride ions (Cl-) were 98.7% and 99.2% removed, respectively. The maximum open circuit voltage (OCV) is 1.49 V, but quickly drops to 1.23 V. Future work includes incorporation of microbes (mixed culture) in the anodic compartment against a variation of several microalgae species in the cathodic compartment such as Desulfovibrio vulgaris, Geobacter sulfurreducens and Shewanella putrefaciens.
(Keynote) Solid State Ionics; Applying What I Learned from Bob Huggins to Advancing Electrochemical Energy Conversion and Storage
Authors: Wachsman Eric D.
Published: February 2020

Research in functional materials has progressed from those materials exhibiting structural to electronic functionality. The study of ion conducting ceramics ushers in a new era of "chemically functional materials." This chemical functionality arises out of the defect equilibria of these materials, and results in the ability to transport chemical species and actively participate in chemical reactions at their surface. Moreover, this chemical functionality provides a promise for the future whereby the harnessing of our natural hydrocarbon energy resources can shift from inefficient and polluting combustion - mechanical methods to direct electrochemical conversion.

The unique properties of these materials and their applications will be described. The focus will be on the application of ion conducting ceramics to energy conversion and storage, chemical sensors, chemical separation and conversion, and life support systems. Results presented will include development of record high conductivity electrolytes, record high power density solid oxide fuel cells, solid-state Li-batteries, NOx/CO species selective solid-state sensors, high yield membrane reactors, and regenerative life support systems that reduce CO2 to O2 and solid C.
(Invited) Electrochemical Energy Harvesting Systems from a Mechanical Perspective
Authors: Lee Seok Woo
Published: February 2020

Electrochemistry is playing very important role of energy storage, sensing, manufacturing systems, etc. In contrast, it has gotten less attention in the field of energy harvesting. However, electrochemical system has lots of potential of various energy harvesting applications from large scale to miniaturized scale because of its cost-effective electrode materials and simple configuration. In this talk, I will discuss how electrochemical system can be applied various energy harvesting systems with a mechanical perspective. In the first part of the talk, the electrochemical thermodynamic cycle for thermal energy harvesting will be introduced. By utilizing novel electrode materials, this system can achieve very high efficiencies at low temperature ranges. In the second part of the talk, we suggest an electrochemical kinetic energy harvesting using selective ion sweeping on the supercapacitor electrode and ion hosting battery electrode. Shaking a hybrid cell consisting of supercapacitor electrode and battery electrode induces ion sweeping on supercapacitor by the electrolyte flow inside the cell and generates electricity. This method can obtain continuous current with slow decaying, i.e.) non-peak energy, which can be efficiently used in low frequency kinetic energy harvesting.
Side-View Operando microscopy of Graphite Anodes to Understand Kinetic Hysteresis
Authors: Kang Sujin , Yeom Su Jeong , Lee Hyun-Wook
Published: February 2020

Operando imaging analysis has emerged as a promising characterization tool for the observation of nanoscale processes; chemical synthesis, electrochemical reaction, and physical interaction of various materials. For past a decade, operando microscopy tools have contributed to understanding the lithiation or sodiation behaviors in battery materials for discovering new electrode materials with high performance and identifying the fundamental failure mechanisms that prevent a prolonged cycle life. Among the candidates, graphite anodes have the most promise to apply for lithium-ion batteries, but also have scientific challenges to retain their kinetics upon repeated charge and discharge cycles. To develop a better design of the electrodes, understanding graphite anodes with direct observation has created a high interest. Although such demands lead to extensive studies about operando imaging techniques, the observation is mostly limited for a single particle or a particular position of the electrodes.

In this regard, we have demonstrated side-view operando optical microscopy on graphite anodes by a change of color during electrochemical lithiation. Since the color of graphite changes owing to the different bandgap during lithiation and delithiation processes, operando optical microscopy enables to analyze the kinetics of charge and discharge behaviors. In addition, our cell configuration has the manifold advantages of applying and adjusting liquid electrolytes which is similar to commercial cells as a practical application and offering the investigation of the electrode side view. The side-view observation of an electrode level is found that microscale spatial variations in rate and composition control the insertion and desertion to understand the kinetics through the whole electrode. Our results allow for a better fundamental understanding of kinetics in battery materials.
(Invited) Garnet-Based Advanced Solid-State Batteries
Authors: Hu Liangbing
Published: February 2020

I will start by giving an overview of active research activities in my research group located at University of Maryland Energy Research Center, including wood materials toward sustainability, 3000K high temperature materials and processing (Science2018), wood nanotechnologies (
Nature
2018), beyond-Li ion batteries (solid state, Na-ion). Then I will focus on our recent development on
garnet
-based solid-state Li-metal batteries including interface engineering to improve the wetting between Li metal anode and Garnet solid-state electrolyte (Nature Materials 2016; Science Advances 2017); Garnet based 3D Li ion conductive framework (bilayer, trilayer) toward high energy density Li-S batteries (EES 2017); Garnet nanofiber based flexible, hybrid electrolyte with a high Li ion conductivity (PNAS 2016), and In-situ neutron depth profiling technique in understanding Li-garnet and CNT-garnet interfaces (JACS 2016).
Sustainable Electrochemical Conversion of Lignin to Renewable Chemicals with Simultaneous Hydrogen Production Via a Continuous Flow Electrochemical Reactor
Authors: Ghahremani Raziyeh , Staser John A.
Published: February 2020

Lignin is the most abundant renewable source of aromatic compounds which can be utilized to generate fuels, chemicals, and polymers, however, due to the lack of an efficient lignin conversion process, it is usually burned as a low-grade fuel in the pulp and paper industry [1,2]. The key issue for commercial application of lignin is to develop an efficient depolymerization process to produce lower molecular weight aromatic compounds at relatively low cost. Several methods including photocatalytic degradation, hydrogenolysis, thermolysis, oxidation, biodegradation, and electrocatalytic degradation have been used to convert lignin to other value-added chemicals. Among them, electrochemical valorization of lignin is likely a promising method for commercial application due to occurring in moderate reaction conditions. Lead dioxide is one of the common active catalysts for electrochemical lignin oxidation [3]. However, due to the toxicity of lead which causes environmental and health issues, developing the lead-free electrocatalysts is greatly needed. Accordingly, we investigated the rate of lignin conversion and hydrogen production on different lead-free electrocatalysts developed in this study using a flow electrochemical reactor. Gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography (HPLC), and fourier transform infrared spectroscopy (FTIR) were employed to evaluate molecular weight distribution of lignin and characterize the functional groups.

References

[1] R. Ghahremani, J.A. Staser, Electrochemical oxidation of lignin for the production of value-added chemicals on Ni-Co bimetallic electrocatalysts, Holzforschung. 0 (2018). doi:10.1515/hf-2018-0041.

[2] T.K.F. Dier, D. Rauber, D. Durneata, R. Hempelmann, D.A. Volmer, Sustainable Electrochemical Depolymerization of Lignin in Reusable Ionic Liquids, Sci. Rep. 7 (2017) 5041. doi:10.1038/s41598-017-05316-x.

[3] P. Cai, H. Fan, S. Cao, J. Qi, S. Zhang, G. Li, Electrochemical conversion of corn stover lignin to biomass-based chemicals between Cu/NiMoCo cathode and Pb/PbO2 anode in alkali solution, Electrochimica Acta. 264 (2018) 128–139. doi:10.1016/j.electacta.2018.01.111.