bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Gap Size on Galvanic Corrosion between AA5052 Aluminum-Magnesium Alloy and SS400 Carbon Steel in Aqueous NaCl Solutions
Authors: Ota Kengo , Tada Eiji , Ooi Azusa , Nishikata Atsushi
Published: February 2020

Recently, aluminum alloys (AAs) have been utilized to automobile body parts in order to reduce the weight of the body and improve fuel consumption efficiency. Although some aluminum alloys such as 5000 and 6000 series have relatively good corrosion resistance in atmospheric environments, galvanic corrosion between aluminum alloys and other electroconductive materials is one of the critical issues on automotive application of the aluminum alloys. So far, we have investigated galvanic corrosion between AA5052 aluminum-magnesium alloy and SS400 carbon steel in aqueous NaCl solutions and reported that the galvanic corrosion behavior changes depending on the concentration of NaCl solutions [1]. In this study, effect of gap size between aluminum alloys and steel on galvanic corrosion behavior was investigated in aqueous NaCl solutions.

A galvanic couple used in this study was almost the same as that reported before, which was made of AA5052 Al-Mg alloy (Mg: 2.65, Si: 0. 08, Fe: 0.27, Cu: 0.01, Cr: 0.17, Zn: 0.01, Al: bal. (mass%)) and carbon steel (JIS SS400). The plate of both materials was 10-mm width and 15-mm length and 5-mm thickness. After lead wires were connected to each plate, both plates were embedded together in an epoxy resin. In this study, both plates were placed separately along the surface with gap sizes from 500 um to 10 mm so that a coplaner galvanic couple was prepared. The surface of the galvanic couple was ground with SiC papers up to JIS 2000 grit and rinsed in EtOH. Galvanic corrosion experiments were done for 72 h in aqueous NaCl solutions of various concentrations ranging from 5 mM to 2 M. Galvanic current and corrosion potential of the couple were measured during the immersion in the solutions.

It was found from the results of corrosion potential, galvanic current, and surface observation that galvanic corrosion behavior changes depending on the gap size between AA5052 and SS400 in the NaCl solutions. When the gap size was 10 mm, no corrosion occurred on the SS400 side in all of the test solutions, suggesting that anodic dissolution reaction was dominant on the AA5052 side. However, when the gap size was decreased, the corrosion of the steel occurred in the solutions at lower concentrations, although the aluminum alloy also showed localized corrosion. These results indicated that anodic dissolution reaction was generated on both materials in the smaller gap-size condition with decreasing the NaCl concentrations. In this study, the change in the galvanic corrosion behavior with the gap size was also discussed from the results of change in the solution chemistry and polarization behavior of the materials.

1. K. Ota, E. Tada, A. Ooi, A. Nishikata, ECS meeting abstracts, MA2018-02, 574, 2018.
The Corrosion Behavior of 50-Kg As-Cast Fecrnicomnx Alloys
Authors: Hsu Kuo-Min , Lin Chao-Sung
Published: February 2020

FeCrNiCoMn, one familiar type of high entropy alloys, has drawn much attention due to its interesting mechanical properties at cryogenic temperatures. In this research, the microstructure and corrosion behavior of 50-kg as-cast FeCrNiCoMnx alloys were studied. The X-Ray Diffractometer (XRD) results show that both alloys are single fcc structures. The influence of manganese content on the corrosion behavior of FeCrNiCoMnx was investigated using electrochemical methods in H2SO4 and NaCl solutions. Dendritic structures were observed in each alloy and the interdendritic regions are enriched with manganese and nickel by Energy Dispersive X-ray Spectroscopy (EDS).

The corrosion resistance of FeCrNiCoMnx is improved with decreasing manganese contents in both H2SO4 and NaCl solutions. It was also found that the passive film of central zone acts more active than that of columnar zone in H2SO4 due to the segregation level. Moreover, the onset of pitting in NaCl is related to the manganese content of the FeCrNiCoMnx.

References:

[1] A. Gali et al. Tensile properties of high- and medium-entropy alloys. Intermetallics 39 (2013) 74-78.

[2] Y. F. Kao et al. Electrochemical passive properties of AlxCoCrFeNi (x = 0, 0.25, 0.50, 1.00) alloys in sulfuric acids. Corrosion Science 52 (2010) 1026-1034.

[3] H. Luo et al. Corrosion behavior of an equiatomic CoCrFeMnNi high-entropy alloy compared with 304 stainless steel in sulfuric acid solution.
Corrosion Science 134 (2018) 131–139.

Figure 1
Effect of PBF-SLM Process Parameters on the Electrochemical Behavior of 316L Stainless Steel Parts in Acidic and Chloride Containing Environments
Authors: Murkute Pratik , Pasebani Somayeh , Isgor O. Burkan
Published: February 2020

The powder bed fusion - selective laser melting (PBF-SLM) process parameters such as laser power and laser scan speeds has a prominent effect of the metallurgical and mechanical properties of the printed parts due to high localized temperatures and high cooling rates associated with the PBF-SLM process. This, in turn, affects the electrochemical and corrosion properties and in effect the service life of the parts. This study investigates the effect of PBF-SLM process parameters; laser power and laser scanning speed on the electrochemical and corrosion properties of 316L stainless steel printed cylindrical parts. The parts were printed using laser powers of 100 and 200 W and the laser scan speeds employed were in the range of 100-3000 mm/s. The electrochemical characterization of the parts involved open circuit potential (OCP) monitoring, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and cyclic polarization (CP) using a three-electrode setup. The test electrolyte used for the electrochemical tests were dilute sulphuric acid (pH~2-3) and 3.5 wt.% NaCl aqueous solution (pH~6.5-7) which represented a wide range of applications. In addition, the metallurgical and microstructural aspects of the parts were studies using optical microscopy (OM), scanning electron microscopy (SEM) and X-Ray diffraction (XRD), whereas the mechanical properties were probed using hardness tests.
Electrochemical Changes with Thermal Aging of Duplex Stainless Steels
Authors: Murkute Pratik , Sarfo Kofi Oware , Zhang Yongfeng , Árnadóttir Líney , Tucker Julie , Isgor O. Burkan
Published: February 2020

Duplex stainless steels are extensively used in pressurized water reactors (PWR) in the form of welds and castings (pumps, valves, etc.). Long-term thermal aging of duplex stainless steels leads to embrittlement due to α-αʹ phase separation in the ferrite grains and this phase separation results in degradation of the corrosion resistance of these alloys. This study investigated the effect of thermal aging time on the electrochemical and corrosion properties of as-received and thermally aged duplex stainless steels in a range of PWR water chemistries. The duplex stainless steels such as 2101, 2003, 2205 and welded 2101 and 2209, were subjected to electrochemical characterization in the as-received condition or after thermal aging for 100, 1000 and 10,000 hours. The electrochemical characterization constituted of open-circuit potential (OCP) monitoring, electrochemical impedance spectroscopy (EIS), linear polarization spectroscopy (LPR) and cyclic polarization (CP) in near neutral aqueous solutions, containing 2.2-5 ppm Li (LiOH) and 800-2000 ppm B (H3BO3). In addition, to investigate the effect of chlorides on the pitting resistance of these alloys, 1M concentration of chlorides (NaCl) were added to the base solution. The α-αʹ phase separation has been characterized by atom probe tomography, nanoindentation and impact toughness testing. The results indicated degradation in impact toughness and corrosion resistance with increasing aging time and phase separation. Some base cases were further characterized for microstructures and rust analysis using optical microscopy and scanning electron microscopy. The results of this work will be used to benchmark corrosion simulation models.
(Invited) A Review on the Role of Slurry Chemistry on Chemically Modified Thin Film Formation for CMP Applications
Authors: Basim G. Bahar
Published: February 2020

Chemical Mechanical Planarization (CMP) process is currently facing the challenge of planarizing larger scale wafers at an atomic scale precision with superior removal rate selectivity and zero defect focus. While the horizontal dimensions of the processed wafers (x-axis and y-axis as the wafer diameter) extend up to 300 mm, the z-axis has to be planarized to a margin of a couple of hundred nanometers. This requirement highlights the need for fundamental understanding on the surface chemistry of the layers being exposed to the planarization process in terms of their interactions with the CMP slurry chemistry. Once the behavior of the wafer surface is understood at an atomic level, the process control metrics can be tuned accordingly.

This paper reviews the role of slurry chemistry in effectively modifying the top surface films of the various materials including conductors, semiconductors and insulators exposed to CMP operations in semiconductor manufacturing. Metallic films are studied in terms of their corrosion and passivation behavior [1, 2] as well as through a modeling of the energy minimization through a Cahn Hilliard Equation (CHE) approach [3]. Furthermore, formation and selectivity properties of the semiconductor materials including conventional and III-V semiconductors and insulators were investigated [4-5]. Some high-end applications where the nano-scale chemically modified films critical are: Metal CMP applications of the tungsten T-gate transistors, new barrier materials, germanium based high-speed shallow trench isolation transistors and high-power transistors and LED applications where III/V semiconductors, such as GaN, are used.

Ozdemir, Basim, G.B. “Effect of Chemical Mechanical Polishing on Surface Nature of Titanium Implants FT-IR and Wettability Data of Titanium Implants Surface After Chemical Mechanical Polishing Implementation”, Data in Brief, 10, P 20-25, 2017.

Karagoz, A., and Basim, G.B. “Controlling Germanium CMP Selectivity through Slurry Mediation by Surface Active Agents”, ECS Journal of Solid State Science and Technology, CMP Special Issue, 4 (11) P5097-P5104, 2015.

Karagoz, A., Sengul, , Basim, G.B., “A Cahn Hilliard Modeling of Metal Oxide Thin Films for Advanced CMP Applications”, 225th ECS Meeting – Orlando, Florida, USA, May 11-15, 2014, ECS Transactions, 61 (17) 15-20 (2014).

Karagoz, A., Craciun, V., Basim, G.B., “Characterization of Nano-Scale Protective Oxide Films_ Application on Metal Chemical Mechanical Planarization”. ECS Journal of Solid State Science and Technology, 4 (2) P1-P8, 2015.

Ozbek, S., Akbar, W., Basim, G.B. “
Optimized Process Design for GaN Chemical Mechanical Planarization” ECS Journal of Solid State Science and Technology, Special Issue on GaN-Based Electronics for Power, RF, and Rad-Hard Applications, 6-11, P S3084-S3092, 2017.
Holographic Characterization of Contaminants in CMP Slurries
Authors: Cheong Fook Chiong , Lumer Juliana , Odete Mary Ann , Winters Annmarie , Philips Laura A.
Published: February 2020

Holographic Microscopy is used to characterize sub-visible particles in CMP nanoparticles slurries. Results of these studies detect and identify a wide range of different large particle contaminants in nanoparticle slurries. Holographic characterization has the unique ability to measure the composition as well as the size of these contaminants. We will present results demonstrating the ability to detect, count and characterize compact dense agglomerates, loosely packed low-density agglomerates, glass particles, polymeric particles and oil droplets in nanoparticles CMP slurries.
Comparison of Wear with Friction Data in Chemical Mechanical Planarization
Authors: McGowan Christopher , Levert Joseph
Published: February 2020

Optimization of Chemical Mechanical Planarization (CMP) on integrated circuits requires an accurate model of material removal. The current model of polishing is two-body abrasion of particles trapped at the asperity-substrate junction, however, this is not supported by friction measurements. A modified friction model is applied to data collected from a pin-on-disk experiment preformed on a fused silica wafer with various polymer polishing pads, flooded with a silica nanoparticle slurry. Results indicate that the friction arises predominantly in the swept region preceding the asperity contact. We will add to this measurements of the volume of the ware-track, indicating the rate of material removal. Our aim is to develop an Archard style relationship between friction and the material removal rate that is independent of the pad material. The long-term goal of this investigation is to aid in the optimization of CMP for structures of decreasing size.
Electrochemical Evaluations for Barrier CMP Optimization
Authors: Basim G. Bahar , Yagan Rawana
Published: February 2020

Ti/TiN barrier films are used to adhere tungsten films on silicon while limiting the metal diffusion into the transistors. When the contact via layers are planarized through chemical mechanical polishing, it becomes critical to enable 1:1:1 removal rate selectivity of the W/Ti/TiN layers. In this study, electrochemical evaluations were performed to evaluate the passivation rates of these three films in various slurry formulations in terms of the slurry chemistry and the particle concentrations. The results of the electrochemical evaluations were compared to the removal rate selectivity as well as the post planarization surface qualities by using blanked Ti, TiN and W films. Chemical activity during the CMP process was controlled by the addition of hydrogen peroxide into the slurry at different concentrations and the formation of the chemically modified metal-oxide layers were studied through electrochemical passivation and surface topography and wettability responses. Initially, the chemical component of the CMP process was optimized at the fixed slurry abrasive concentration and removal rate selectivity was achieved at 0.2 M oxidizer concentration where ~76 nm/min MRR values were obtained for each film. Afterwards, the mechanical component of the CMP process was varied by changing the slurry abrasive concentration at the optimal oxidizer addition of 0.2 M. Titanium films showed high removal rates attained at 5% solids concentration where TiN achieved similar result at 15% solids loading. On the other hand, tungsten exhibited stable rates among the increasing particles loading. This concludes that the tungsten CMP is more chemically limited by the formation of the tungsten oxide film whereas the TiN film is removed more mechanically by increasing the abrasive concentration. Roughness data affirmed a better surface output at the higher slurry solids loadings since metals such as titanium exhibited micro scratches on the surfaces at the lower concentrations of the abrasive particles. The developed systematic study suggest a methodology for developing optimal CMP configurations for the newly introduced barrier CMP films.
Prediction of Pad Wear Depending on Structural Factors of Diamond Conditioner
Authors: Kim Taesung
Published: February 2020

The conditioning process with diamond conditioners is an important role in maintaining chemical mechanical polishing (CMP) performance constant. The conditioning process maintains the surface roughness of the pad and uniformity of the pad wear, resulting in stable material removal rate (MRR) and low within wafer non-uniformity (WIWNU). The pad uniformity is greatly changed by the mechanical action in the conditioning process, and the action is controlled by three mechanical movements; pad / conditioner rotation, conditioner arm sweep. From these three motions, the pad wear profile can be obtained by accumulating the number of points in the pad mesh containing the coordinates of the diamonds moving at a specific time or distance by the movement of the diamond grit as shown in Fig. 1.

In addition, we tried to confirm the pad profile and wear amount depending on the structural properties of the conditioner, applying the diamond characteristics of the conditioner which directly causes the wear. The structural factors of conditioner that affect conditioning are pattern, pitch, size, number and shape of diamond. These factors were formulated and applied in simulation. Then, pad wear amount was calculated from the indentation depth according to the diamond characteristics, and pad profile by wear rather than profile by line density was proposed. The pad wear amount of simulation results according to the number of diamonds are shown in Fig. 2.

Finally, pad wear can be predictable according to various equipment or process conditions and it is also possible to analyze the effect of the conditioner on pad wear through this research. This work is achieved by approaching the process of conditioning in CMP from the topologic aspects and the program is developed through it. The kinematic motion of individual diamonds is modelized and simulated with structural properties of the conditioner to see how these affects the pad wear and profile.

Figure 1
Electroless Metal Deposition Using Multivalent Metal Ions As Reducing Agents
Authors: Norkus Eugenijus , Tamašauskaitė-Tamašiūnaitė Loreta
Published: February 2020

The possibility and conditions to use lower oxidation state metal ions as reducing agents for autocatalytic electroless metal deposition are discussed.

The theoretical background of such kind reactions is presented in the view of thermodynamics.

Kinetic data on electroless silver, copper, palladium and platinum deposition using Co(II)/Co(III) redox systems with different ligands are presented and discussed.

Ti(III)/Ti(IV) redox systems with different ligands were shown also to be suitable reducing agents for reducing of Pt(IV), Pd(II), Ni(II) and Co(II) to metallic state and formation of continuous metal layer on the surface to be plated.

The morphology of metal layers deposited using above-mentioned reducing agents was characterized by means of Field Emission Scanning Electron Microscopy (FESEM). Kinetics of metal deposition rate was investigated by means of the gravimetry or Electrochemical Quartz Crystal Microgravimetry (EQCM).
Hybrid Electrodeposition and Characteristics of Ag-Graphene Composite Films on Cu Sheets Toward High-Performance Electric Connectors
Authors: Sakaida Shizuka , Kure-Chu Song-Zhu Shochiku , Hihara Takehiko , Yashiro Hitoshi
Published: February 2020

Recently, silver (Ag) plating for automotive connector has been attracted extensively attention due to the fast progress of HEV/EV system and as a promising candidate material to substitute the costive gold (Au) plating. The Ag plating film possesses the highest conductivity among the metals and excellent corrosion resistance next to Au plating. However, Ag plating suffers a low wear resistance problem because of the soft nature of Ag metal (~80 Hv). Because an oxidation film is difficult to form on silver surface, the corrosion resistance is good. More serious problem of Ag plating is that an adhesion phenomenon often occurs during sliding wear actions as terminal mating materials, because an oxidation film is difficult to form on Ag surface owing to the good corrosion resistance as a noble metal. To solve those problems, many studies focused on fabricate hard Ag plating by adding some alloy elements like Co, Sb, and Se or adding graphite powder into Ag plating films, which improved wear resistance but sacrificed electric conductivity.

Here, we propose a new Ag-graphene electro-plating film, with the graphene functioning as solid lubricant and electric component, which may reinforce the wear resistance while without lowering its electric conductivity. The Ag-graphene composite films were fabricated on Cu sheets by a hybrid electrodeposition method, i.e., combining electrodeposition of Ag and electrophoric deposition of graphene nano-flakes, in a non-cyanate plating bath. The graphene nano-flakes were prepared by an electrochemical peeling method from a graphite material. The microstructures, chemical composition, and crystalline structure of the anodized specimens before and after annealed were investigated FE-SEM (EDS), XRD, GD-OES, FT-IR, and Raman spectroscopy. Moreover, the electric resistance meter and wear resistance were also investigated, compared to commercial Ag plating as reference.

Figs. 1a and 1b show the surface FE-SEM images of as-electrodeposited pure Ag and Ag-graphene films respectively. It can be seen that, except for the featured Ag nano-particles, some blurry films can be observed on the Ag film in Fig. 1b. The EDS analysis result in Fig.1c demonstrates a strong C peak, indicating the co-deposition of carbon clearly. Moreover, the inclusion of graphene in Ag films were also confirmed by Raman spectra and XRD measurements. The electric resistance of Ag-graphene composite films was equivalent to the commercial Ag films, and the detail results will be reported on the meeting.

Figure 1
Electrochemical Investigation of the Cu2+ → Cu1+ Reduction Reaction in Ethaline Deep Eutectic Solvent
Authors: Steinberg Katherine , Shen Dai , Shaheen Nora , Akolkar Rohan
Published: February 2020

Deep eutectic solvents (DES) are inexpensive, non-flammable, biodegradable, and possess good electrochemical stability. Therefore, they are gaining attention as potential next-generation electrolytes for electrochemical applications such as energy storage and electrodeposition. For use in these applications, knowledge of the transport and electrochemical kinetics properties when using DES electrolytes is critically important. However, accurate measurements of these properties using traditional electrochemical methods such as cyclic voltammetry (CV) and polarization on RDE can be quite challenging in DES systems. Specifically, the highly viscous and thus poorly conducting DES electrolytes cause excessive ohmic polarization rendering the current distribution on the RDE to be highly non-uniform. Furthermore, during unsteady-state measurements such as CV, ohmic electrolyte resistance introduces non-linear changes in the surface potential thereby complicating quantitative CV analysis. In this talk, we will discuss such issues using the well-known Cu2+ + e ↔ Cu1+ reaction in a 1:2 choline chloride – ethylene glycol (ethaline) model DES system. We will present guidelines to circumvent pitfalls so as to obtain reliable transport and kinetics data [1]. Of these recommendations, we will focus on the importance of real-time compensation during CV and the use of electrode configurations, such as microelectrodes, which provide uniform secondary current distribution. Finally, we will report on our efforts to obtain accurate measurements of the kinetics parameters (exchange current density, charge transfer coefficients) associated with Cu2+ + e ↔ Cu1+ reaction. Mechanistic aspects of the Cu2+ + e ↔ Cu1+ reaction which lead to its sluggish electrochemical kinetics in DES media will also be discussed.

D. Shen, K. Steinberg, and R. Akolkar, J. Electrochem.
Soc., 165, E808 (2018).
(Industrial Electrochemistry and Electrochemical Engineering Division Student Achievement Award Address) Fundamental Understanding on Cell Performance Enhancement of Flow Batteries with Serpentine Flow Field Structures
Authors: Ke Xinyou , Savinell Robert F. , Wainright Jesse S.
Published: February 2020

Redox flow batteries are being considered for medium and large-scale stationary energy storage applications. In addition to storing energy by the intermittent resources, such as tide, wind and solar energy, the electrochemical flow battery systems could impact electricity generation and grid effectiveness by supporting energy storage for peaking shaving, load leveling and emergency back up [1,2]. In recent years, flow field designs, such as a serpentine flow field, evolved from proton exchange membrane (PEM) fuel cell have been experimentally demonstrated to deliver improved cell performance and boost cell capacity [3] as compared to flow batteries without flow field designs. However, the mechanisms causing enhanced higher limiting current density with serpentine flow field designs have not been fully understood. In this presentation, I will introduce a concept of maximum current density associated with the stoichiometric availability of the pressure-driven electrolyte flow penetrating into the porous carbon electrode from the from the serpentine flow channel [4-6]. Our three-dimensional model demonstrates that this maximum current density concept can explain the observed limiting current density achieved in a flow battery with a serpentine flow field structure [7]. We hope this fundamental understanding can contribute to a better elucidation of the mechanism on limiting the electrochemical performance and further optimization of flow batteries.

Acknowledgement

This work was partially supported by the “all-iron flow battery” project with a grant number of DE-AR0000352 funded by the program of the Advanced Research Projects Agency-Energy (ARPA-E) of the Department of Energy (DOE) of the United States. I (XK) would like to acknowledge the late Professor Joseph M. Prahl, who was my advisor and inspirational mentor.

References

[1] A.Z. Weber, M.M. Mench, J.P. Meyers, P.N. Ross, J.T. Gostick and Q. Liu, J. Appl. Electrochem., 41: 1137-1164, 2011

[2] X. Ke, J.M. Prahl, J.I.D. Alexander, J.S. Wainright, T.A. Zawodzinski and R.F. Savinell, Chem. Soc. Rev., DOI: 10.1039/C8CS00072G, 2018

[3] D.S. Aaron, Q. Liu, Z. Tang, G.M. Grim, A.B. Papandrew, A. Turhan, T.A. Zawodzinski, J. Power Sources, 206: 450-453, 2012

[4] X. Ke, J.I.D. Alexander, J.M. Prahl and R.F. Savinell, J. Power Sources, 270: 646-657, 2014

[5] X. Ke, J.I.D. Alexander, J.M. Prahl and R.F. Savinell, J. Power Sources, 288: 308-313, 2015

[6] X. Ke, J.M. Prahl, J.I.D. Alexander and R.F. Savinell, Electrochim. Acta, 223: 124-134, 2017

[7] X. Ke, J.M. Prahl, J.I.D. Alexander and R.F. Savinell, J. Power Sources, 384: 295-302, 2018
A Study of Dark TiO2 Coating on Pure Titanium By Micro Arc Oxidation
Authors: Hong Yu-Fang , Lee Howard , Lin Hsin-Chih
Published: February 2020

Dark TiO2 coatings on Titanium have attracted scientific interest due to their extensive applications such as decorative architectures and optical equipment for solar collectors. Several methods have been reported to prepare successfully the dark TiO2 coatings, such as conventional anodizing, cathodic polarizing, and micro arc oxidation (MAO). It is well known that MAO is a new technique for generating surface oxide coatings on valve metals and alloys, including Titanium, Aluminum and Magnesium. Actually, MAO technique has several advantages for surface coating, such as strong adhesion, high hardness, superior wear and corrosion resistance. However, the dark TiO2 coatings on Titanium prepared by MAO are still seldom reported.

The present study investigated the dark TiO2 coating on pure Titanium by MAO technique. For the MAO process, a bipolar pulsed power supply with appropriate electrical parameters, and a phosphate-based electrolyte with vanadium compound as colorant were used. Experimental results indicated the MAO coatings on pure Titanium are mainly composed of TiO2. These MAO coatings exhibit homogeneous dark color and good surface protection, including the corrosion and wear resistance. In this study, the effects of electrical parameters and various electrolytes on the dark TiO2 coatings will also be systematically discussed, including the surface morphology, microstructure and property of wear and corrosion resistance.
Revealing of Solid Electrolyte Interphases during Electrochemical Deposition and Dissolution of Sodium
Authors: Zeng Zhiyuan
Published: February 2020

We report in situ study of electrochemical deposition of Na in an electrochemical liquid cell with an unprecedented resolution using transmission electron microscopy (TEM). Our observation reveals that sodium metal deposits are granular with SEI layer on each grain. Variations of SEI thickness introduce local growth rate difference thus unique morphology of nanograin deposits. As SEI is thickened, the newly deposited Na is found at the base of deposits close to the electrodes while dissolution on the top of deposits occurs simultaneously. Such in situ characterization of electrochemical deposition and dissolution of sodium provide critical insights on sodium batteries performance and degradation mechanisms.
Room Temperature Solid-State Lithium Polymer Battery with Polyionic Liquid Pentablock Terpolymer Electrolyte
Authors: Chen Tzu-Ling , Sun Rui , Willis Carl , Morgan Brian , Beyer Frederick , Elabd Yossef A
Published: February 2020

Lithium ion batteries are currently the leading commercial technology for portable electronic devices and electric vehicles. However, new solid polymer electrolytes (SPEs) that comprehensively possess the preferred properties of high ion conductivity, high electrochemical stability, robust mechanical properties, flexibility, and good film forming properties, are required to improve the safety and lifetime of lithium ion batteries. Although diblock copolymers have been explored as SPEs and can potentially provide the orthogonal properties of high ion conduction and high mechanical strength simultaneously in a solid-state material, there are limitations to diblock copolymer-salt mixture systems, such as a limited set of morphologies, and a lack of means to achieve simultaneous combination of more than two properties (e.g., conductivity, strength, flexibility). Compared to diblock copolymers, multiblock polymers involve more than two polymer chemistries and therefore enable the possibility to conjoin many of the desired properties, such as high ion conductivity, mechanical strength, flexibility, good film forming properties, processability, and high electrochemical stability all into a single materials platform. In this study, a lithium ion conducting polyionic liquid pentablock terpolymer (PILPTP) was investigated as a solid polymer electrolyte (SPE) for lithium ion batteries.The morphology, chemical, thermal, mechanical, and electrochemical properties were examined as function of ionic liquid composition, cation chemistry, and film processing conditions. Coin cell Li4Ti5O12/SPE/LiCoO2batteries were fabricated with the lithium ion conducting PILPTP as the SPE and room temperature battery performance was demonstrated at high capacity and high cycle life. Overall, this work suggests, for the first time, that lithium conducting polyionic liquid multiblock polymers can be promising electrolyte candidates for developing safe and high performing room temperature solid-state lithium ion batteries.
Improving Cell Resistance and Cycle Life with Solvate/Thiophosphate Hybrid Electrolytes in Lithium Batteries
Authors: Gewirth Andrew A. , Philip Maria
Published: February 2020

Solid electrolytes (SEs) have become a practical option for lithium ion and lithium metal batteries due to their improved safety over commercially available ionic liquids. The most promising of the SEs are the thiophosphates whose excellent ionic conductivities at room temperature are comparable to those of the commercially-utilized ionic liquids. Hybrid solid-liquid electrolytes exhibit higher ionic conductivities than their bare solid electrolyte counterparts due to decreased grain boundary resistance, enhanced interfacial contact with electrodes, and decreased degradation at the interface. In this study, we add lithium bis(triflouromethane sulfonyl)imide (LiTFSI) and a highly fluorinated ether (HFE) solvate electrolyte to the surface of Li7P3S11 (LPS) and Li10GeP2S12 (LGPS) pellets and evaluate their overall cell resistance in Li-Li symmetric cells relative to their bare Li/SE/Li counterparts. Time-resolved electrochemical impedance spectroscopy (EIS) shows an order of magnitude lower cell resistance for the LGPS-solvate than for the bare LGPS. Cyclic voltammetry (CV) of the bare and hybrid SE cells shows an order of magnitude higher current density for the LGPS-solvate cell over the bare LGPS. Interestingly, hybrid electrolytes made by combining HFE-modified solvates and SE exhibit all the benefits of the interlayer modified SEs, without the necessity of pellet manufacture. This study suggests that solvates can be used to improve the cell resistance and current density of solid electrolytes by altering the grain boundary structures and the interphase between electrode and electrolyte.
Iron Controllable Lithium into Lithiotropic Carbon Fiber Fabric: A Novel Li Metal Anode with Improved Cyclability and Dendrite Suppression
Authors: Niu Junjie , Chen Xi , Lv Yingying , Shang Mingwei
Published: February 2020

The Department of Energy (DoE) announced the >500 Wh/Kg even 600 Wh/Kg target of the energy density for next-generation lithium-ion batteries in the incoming 3-5 years, to meet the rapidly growing market in electrical vehicles (EVs) and portable electronic devices. In order to reach this goal, Li metal, is considered as the most promising candidate as anode (Xu, Energy Environ Sci 2014). However, the dendrite forming, low Coulombic efficiency, and unstable solid electrolyte interphase (SEI) pose big challenges in applying Li metal in batteries (Chandrashekar, Nat Mater 2012).

Herewe report a novel, single-side Li-infused carbon fiber fabric (LiCFF) with a controllable, minimized Li loading, which shows a highly reversible plating/stripping with a low overpotential of less than 50 mV (Li foil: >1.0 V over 50 cycles) in symmetric cells up to >3000 cycles (>6000 hours) (Energy Environ Sci, under review). Full cell batteries using the LiCFF as ‘all-in-one’ anode without additional slurry-making process and nickel-manganese-cobalt oxide (NMC) as cathode exhibit an improved capacity retention when compared with Li foil: 32% at 0.5 C and 119% at 1.0 C capacity improved after 100 cycles. In parallel, the mossy/dendritic Li on the LiCFF was largely suppressed, which was confirmed using in-situobservations of Li plating/striping in a capillary cell. The stable, uniform deposition of a thin, controllable Li layer on CFF using a facile ironing method lead to form a reversible, dendrite-free Li metal electrode, which enables practical applications in Li-metal based batteries such as Li-S, Li-O2, and Li-transition metals.
Investigation on Solvent and Surface Modification Effects for Li Metal Anodes
Authors: Liu Hao-Wen , Weng Yu-Ting , Wu Nae-Lih
Published: February 2020

Li metal anode is strongly considered to be one of the most promising candidates for high-energy Li-ion batteries. However, lithium dendrite growth, which could cause short-circuit and low Coulombic efficiency (CE), is one of the key issues for realizing practical applications of Li anode technologies. Various strategies have been proposed to suppress Li dendrite formation. In order to understand the Li dendrite formation and suppression behaviors for Li plating, we carried out extensive study on the effects of solvent and surface coating on the electrochemical behaviors of the Li metal anodes. Carbonate solvents having various components with/without additives have been employed for Li plating and stripping on Cu substrate. Polymeric coatings on Cu have also been tested for their effects on the morphology of Li deposition and SEI analysis. In particular, extensive real-time optical microscopy imaging and post mortem SEM analyses are carried out in conjunction with electrochemical characterizations to reveal the underlying mechanisms for the resulting effects.

Figure 1
Polypropylene Carbonate Based Solid Polymer Electrolytes for Lithium Ion Batteries
Authors: LaCoste Jed , Campo Nicholas , Ardoin Sydney , He Zizhou , Guo Hui , Fei Ling
Published: February 2020

Lithium ion batteries are promising as energy storage devices because of their high energy density; however, current technology for lithium ion batteries is not safe for large scale applications and general use. Traditional lithium ion batteries utilize an organic liquid electrolyte to transport lithium ions between electrodes. Organic liquids used in lithium ion batteries, such as diethyl carbonate, are highly flammable and volatile. Safety becomes an issue when the battery heats from charging, discharging, or if the battery shorts circuits due to dendrite formation in the cell; when this happens, the battery can potentially ignite. For this project, the research focus is developing novel solid polymer electrolytes for lithium ion batteries. Polypropylene carbonate (PPC), a copolymer of propylene oxide and carbon dioxide, has emerged as a promising candidate for solid polymer electrolytes (SPE) because of its good chemical stability, ionic conductivity, low flammability, as well as environmental friendliness. A versatile air-controlled electrospray technique is used to directly deposit PPC based electrolyte on cathodes with a selected range of thickness. Directing casting electrolyte films on electrode can greatly enhance the interface contact and lower ion transfer resistance. The composition of the SPE can be simply controlled by tuning the polymer solution. The thickness can be controlled by either the deposition time or flow rate.

Several tests are to be performed to characterize the electrolyte material as well as battery performance. These tests include cyclic voltammetry, Fourier Transform Infrared Spectroscopy, AC Impedance Spectroscopy, and Scanning Electron Microscopy. The impact of solid electrolyte film on lithium dendrite formation are also monitored and analyzed.
Phase Inversion Strategy to Flexible Freestanding Electrodes: Critical Coupling of Binders and Electrolytes for High Performance Li-S Battery
Authors: Wahyudi Wandi , Chao Zhen , Kumar Pushpendra , Li Mengliu , Wu Yingqiang , Hedhili Mohammed N. , Cavallo Luigi , Li Lain-Jong , Ming Jun , Anthopoulos Thomas D.
Published: February 2020

Development of flexible and freestanding electrode is fascinating for lithium-sulfur (Li-S) batteries to enable higher gravimetric energy density and wider potential applications. However, the lithium polysulfides shuttle effect remains challenging and leads to a severe capacity fading. Here, we study the sulfur cathode prepared via phase inversion method with polyethersulfone (PES) polymeric binder and the coupling strategy of the electrode with polysulfide-modified electrolyte to enhance the cells performance. The flexible/freestanding electrode was successfully prepared by the efficient and straight forward method, even it is possible for massive production of electrodes with various size. The resultant polymeric networks in the electrode can effectively trap the soluble polysulfides owing to the higher hydrophilicity and stronger affinity of PES than that with the routine polyvinylidene fluoride (PVDF) binder. Furthermore, we show a two-fold enhancement of the cell performance by coupling the electrode with polysulfide-modified electrolyte, giving an improved capacity of 1141 mAh g-1, lower polarization of 192 mV and more stable capacity retention with 100% Coulombic efficiency over 100 cycles at 0.25C. The advantages of favored strategy are further demonstrated in lithium-ion sulfur full battery with lithiated graphite anode, which demonstrates much improved performance than those previously reported. This work successfully introduces an efficient strategy for flexible/freestanding electrodes and enlightens the importance of coupling strategy to enhance the performances of Li-S batteries.

Figure 1. (a) Digital photographs of the as-prepared composite via phase inversion method. (b) Cycle performance of half-cells using 2-layer PES-CNT-S and PVDF-CNT-S cathodes with polysulfide(PS)-free electrolyte and polysulfide(PS)-modified electrolyte at 0.25C.

REFERENCES

W. Wahyudi, Z. Cao, P. Kumar, M. Li, Y. Wu, M. N. Hedhili, T. D. Anthopoulos, L. Cavallo, L. J. Li, J. Ming, Adv. Funct. Mater., 2018, 28 (34), 1802244.

Ming, Z. Cao, W. Wahyudi, M. Li, P. Kumar, Y. Wu, J. Y. Hwang, M. N. Hedhili, L. Cavallo, Y. K. Sun, L. J. Li, ACS Energy Lett., 2018, 3 (2), 335-340.

Wang, Z. Cao, G. A. Elia, Y. Wu, W. Wahyudi, E. Abou-Hamad, A. H. Emwas, L. Cavallo, L. J. Li, J. Ming, ACS Energy Lett., 2018, 3 (12), 2899-2907.

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Experiment and Modeling of Electrochemical Performance of Lithium-Sulfur Batteries with Varying Carbon to Sulfur Ratios
Authors: Koenig Gary , Michaelis Charles , Erisen Nisa , Eroglu Damla
Published: February 2020

Lithium-sulfur batteries have attracted much research interest due to their high theoretical energy density and low cost raw materials. While the electrodes are comprised of readily available materials, the processes that occur within the cell are complex and the electrochemical performance of these batteries is very sensitive to a number of cell processing parameters. In this poster, a simple electrochemical model will be presented and will be used to predict, with quantitative agreement, the electrochemical properties of lithium-sulfur cathodes with varying carbon to sulfur ratios. The experimental polarization was accurately captured by the model, including a transition in the capacity and polarization at higher sulfur loading. In addition, a transition in the electrode morphology – from well dispersed to aggregated sulfur at the surface – will be reflected in the change in a critical model parameter demonstrating the sensitivity and functionality of even this simple model in predicting complex behavior in the lithium-sulfur cells.
Ionic Liquid-Based Electrolytes for High-Voltage Li-Ion Batteries
Authors: Liu Qian , Jiang Wei , Li Ying , Pupek Krzysztof Z. , Piernas-Muñoz María José , Bloom Ira , Zhang Zhengcheng
Published: February 2020

The lithium-ion battery (LIB) with high energy density is highly demanded for electric vehicle application. To increase the energy density of LIB, one popular approach is to elevate the operation potential of the cathode or the voltage of the cell. However, at high potentials or high voltages, the state-of-the-art (SOA) organic carbonate-based electrolytes tend to be oxidatively decomposed at the cathode surface causing gassing issue, low Coulombic efficiency, transition metal ion dissolution and rapid capacity fade of the full cell. In this presentation, we studied the piperidinium-based ionic liquids as an electrolyte candidate for high-voltage lithium-ion battery due to their low melting point, low vapor wide electrochemical window, nonflammability and low/non-volatile merits.

When doped with various amount of lithium fluorosulfonylimide salt (LiFSI), the piperidinium-FSI- based ionic liquid showed much improved cycling performance in the NMC532/Li cells at voltages higher than 4.5 V compared with the SOA electrolyte - 1.2 M LiPF6 EC/EMC (3/7 wt.). The feasibility as a practical electrolyte for the next generation LIB was evaluated by its physical properties and electrochemical stability on both cathode and anode. Furthermore, Raman spectroscopy and molecular dynamic simulations (MD) were conducted shedding light on the sophisticated 3D-network structure containing piperidinium cation, FSI- and Li+ species at various LiFSI concentrations.
Structure and Electrochemistry of LiV3O8 Thin Film Electrode: Effect of Diffusion Rate and Concentration on Cell Polarization
Authors: Zhang Yiman , Marschilok Amy C. , Takeuchi Kenneth J , Kercher Andrew , Takeuchi Esther S , Dudney Nancy J.
Published: February 2020

Electrochemistry of lithium trivanadate (LiV3O8, LVO) has been extensively studied due to its large capacity and high rate capability. The material undergoes both insertion/extraction and phase transform reactions during discharge and charge in a Li-ion battery. However, the rate limiting factors of the material are unclear over the cycling window of 2.0 -3.8 V. In this work, LVO thin films are fabricated from RF magnetron sputtering and annealed at different temperatures of 260, 350, 400 and 500°C. Crystallinity, crystallite size and preferred orientation of the thin films are analyzed by x-ray diffraction. All solid-state thin film batteries are fabricated with LVO cathodes annealed at different temperatures of 260, 350 and 400°C. The electrochemical properties are investigated at two different test temperatures to compare the rate limiting process for discharge and charge. AC impedance is applied on the 260 and 350°C cells to characterize the voltage dependence of the diffusion coefficient during both discharge and charge. Our work correlates the cell polarization with both the diffusion coefficient and the Li+ concentration, showing that these parameters play different roles in the insertion and phase transform reactions, and shows the structural dependence of these parameters.

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A Study of Particle Size Effect on the Voltage Behavior of LixNi0.5Mn1.5O4 Electrode
Authors: Xie Yuanyuan
Published: February 2020

Lithium nickel manganese oxide (LNMO, LixNi0.5Mn1.5O4) is an attractive high potential cathode material for rechargeable lithium ion batteries to meet toady’s pressing need of high energy density. One of the main issues faced by LNMO electrode is that its voltage could be invariant with state of charge in charge and discharge operations of battery. This is believed to be originated from its two consecutive phase transition processes during cycling. In this study, a mathematical model is developed to understand the voltage behavior of LNMO electrode in the charge and discharge process by coupling phase transition process with lithium transport process. Effect of electrode particle size on the phase distribution and stability is simulated by the developed model. Results indicate that the voltage behavior of electrode in the charge and discharge can be significantly influenced by different LNMO particle size. Further, electrode with mixed size particles is also investigated by the developed model. Through comparison, limitations of current existing models on predicting LNMO electrode voltage behavior as well as their underlying reasons are discussed based on the modeling results.
Mixed Mode Growth Model for the Solid Electrolyte Interface (SEI)
Authors: Kamyab Niloofar , Weidner John W. , White Ralph E.
Published: February 2020

A mixed mode solid electrolyte interphase (SEI) growth model is presented that includes both the influence of the kinetics of the solvent reduction reaction at the SEI/electrode interface and diffusion of the solvent through the SEI layer. The governing equations are solved numerically to predict the solvent concentration profile, the SEI layer thickness, and the capacity loss. Capacity loss predictions are fitted to two sets of experimental data from the literature. The high quality of the fits demonstrates that the mixed mode model provides a useful description of the capacity loss in the cell due to the growth of the SEI layer on the anode under constant voltage storage condition. Also, analytical expressions are presented for SEI growth for both the combined kinetics/diffusion mode (mixed mode model) and the limit of a fast solvent reduction reaction (diffusion limited mode model) as a function of cell characteristics.
Computational Insights to Charge Transfer Kinetics at the Cathode/Electrolyte Interface
Authors: Li Yunsong
Published: February 2020

The charge transfer reaction is the fundamental reaction for rechargeable batteries. The energy landscape of this reaction depicts the equilibrium and kinetics of the electrochemical process. Many transition metal oxide surfaces in a high oxidation state have been found to be unstable against common Li-ion electrolytes. It undergoes a spontaneous reduction upon immersion in the electrolyte in open circuit. This process involves the reduction of the cathode surface and degradation of the electrolyte to form a cathode electrolyte interphase (CEI), forming a complex cathode/CEI/electrolyte interface. However, the mechanism of this interaction remains unclear. In this work, a modeling framework was developed to predict the energy landscape of the charge transfer reaction at a LiCoO2/LiF/EC-electrolyte interface, with combined density functional theory (DFT) and molecular dynamics (MD) calculations. The energy profile of this reaction was simulated under different voltage. The mechanism of the interaction between LiCoO2 and EC-electrolyte would be discussed.