bluuebunny/crossref_metadata_2025 huggingface dataset:
Proton Conduction Properties of Bzcy and Szcy Perovskites Type Oxides; Addressing the Effect of Dopant Levels and Proton Content
Authors: Leonard Kwati , Lee Young-Sung , Okuyama Yuji , Miyazaki Kuninori , Matsumoto Hiroshige
Published: February 2020

Electrochemical devices based on perovskites-type proton conducting oxides, are gaining wide interest as promising green technologies for hydrogen production and seperation. Interest in this class of materials stems from their lower activation energy for proton transport (typically 0.3-0.6 eV) relative to that for oxide ion conduction, thus making them suitable electrolyes for steam electrolysis cell operation at intermediate temperature. Despite the advances in proton-conducting electrolytes, their development still lag behind the oxygen-ion counterparts. The most prominent limitation being, conductivity, chemical stability, incomplete hydration of the electrolytes, as well as the grain boundary resistance.

In the present contribution, starting from SrZr0.5Ce0.4Y0.1O3-δ, we examined the effects of Ba substitution for Sr and the doping level of Y on the lattice structure, electrical properties, proton content as well as chemical stability of the following compositions A(Zr5/9Ce4/9)1-x
Y
x
O3-
δ
, (A= Ba, Sr and x=0.1, 0.2). Thermo-gravimetric analyses revealed almost similar proton concentration in both SZCY541 and SZCY(54)8/9-2 with a constant Zr/Ce fraction of 5:4. Both samples showed almost comparable proton conductivities in humidified 1% H2 hydrogen. BZCY(54)8/9-2 shows a maximum proton limit of 13.3 mol % compared to only 6.03 mol % for SZCY(54)8/9-2 and retained the highest proton conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600 oC (Fig. 1.) as well as excellent chemical stability under 80 % steam for 200 hours. Ba at A-site provides higher proton mobility than Sr. It is also evident from the data that the bulk and grain boundary contributions on the conductivity were strongly dependent on the A-site host, with the grain boundary response dominating the impedance spectra of the BZCY system relative to the SZCY. However the major difference in conductivity among the compositions originates mostly from the differences in proton concentration levels as well as the magnitude of the grain boundary contribution. This paper discusses these aspects based on experimental results as well as steam electrolysis using SZCY541 and BZCY(54)8/9-2 as electrolytes.

Acknowledgement

This work was supported by the Council for Science, Technology and Innovation　(CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier”(Funding agency: JST)　and by World Premium International Research Center Initiative (WPI), MEXT Japan.

Figure 1
(High Temperature Materials Division Outstanding Achievement Award) A Country Boy Finds Materials Science
Authors: Anderson Harlan U.
Published: February 2020

I am greatly honored to have been chosen by the High Temperature Materials Division of the Electrochemical Society to receive their Outstanding Achievement Award for 2016. 

For this lecture, I will give a brief review of who I am, my career in teaching, my research interests in both insulating and electrical conducting oxides and focus on what I perceive as my major contributions to the world of ceramics (high temperature materials).

Ceramics are well-known for their ability to serve as electrical and thermal insulators, structural components and for corrosion protection. In addition, their unique ability to interact with electric and magnetic fields yields properties that can vary many orders of magnitude. These include the dielectric permittivity, electrical conductivity, piezoelectricity, magnetic susceptibility, and magneto-and electro-optics. With these variety of properties, the use of ceramic components is so vast that it includes most of the devices, which we encounter and use every day.

For example, the electrical insulating properties allow use of materials such as alumina for substrate in integrated circuits as well as high voltage insulators (e.g. computers. spark plugs, TV). Electrical energy storage capabilities have allowed ceramic materials to be integral parts of electronic circuits. Both require active component isolation as well as local power supplies which capacitors provide (e.g. TV, computers, cell phones). High electronic conductivity allows ceramics to be used as electrodes as well as resistors for a wide range of applications. Piezoelectric properties allow ceramics to serve as transducers for many everyday applications (e.g. ultrasonic imaging and smoke detectors]. The ability of zirconia to display high oxygen conductivity has enabled a rapidly growing list of applications such as oxygen sensors (every automobile has one), oxygen separations membranes and electrolytes for solid oxide fuel cells.

All of these applications of ceramics are perfect examples where understanding the structure-property relationships at multiple scale levels were a key necessity for success. Amongst the crystallographic symmetries which have yielded the most varied properties, the perovskite system reigns supreme. I have dedicated my research career to this system and explore the influence of composition and defect structure on both electrical insulating and conducting systems. I first will discuss the properties and characteristics of this unique class of ceramics which allows them to be utilized both as electrical insulators as well as electrical conductors. I will then give some examples in which the properties are tailored to meet requirements of specific applications: capacitors, solid oxide fuel cells, and sensors.
Stability and Performance Investigation of Co-Sputtered Ni Cermet Thin Films at Reduced Temperature
Authors: Lee Yeageun , Yu Wonjong , Lee Yoon Ho , Kim Yusung , Cha Suk Won
Published: February 2020

Thin film solid oxide fuel cells (thin film SOFCs) were introduced to reduce the high operating temperature of traditional SOFCs. By employing thin film techniques such as sputtering, atomic layer deposition, and pulsed laser deposition, less than 1 μm-thick electrolytes have been successfully fabricated and functioned properly. Through these thin film electrolytes, the low ionic conductivity of the electrolyte materials at reduced temperature is compensated by the shortened travel length of the oxygen ions. However, low temperature also leads the poor electrode activity, and this lowered activity has not been fully overcome.

In this study, we investigated various types of Ni-based cermet films to gain better electrode activity. The cermet films were fabricated by magnetron sputtering. For ion-conducting materials, yttria-stabilized zirconia (YSZ) and scandia-stabilized zirconia (ScSZ) were used. These ion-conducting materials were co-sputtered with Ni. The sputtering power of each material was varied for changing Ni contents of the films. To obtain the Ni contents, we utilized X-ray photoelectron spectroscopy (XPS). Four-point probe measurement was also conducted to verify the degree of Ni percolation of the films. In addition, the surface and cross-sectional images of the films were observed to investigate the microstructure and porosity.

For analyzing the electrochemical performance of the co-sputtered cermet films at reduced temperature, we fabricated several experimental SOFCs. On the one side of the solid electrolyte pellet, the thin cermet anode was deposited, while thin Pt cathode was deposited on the other side of the pellet. Then, the experimental SOFCs were operated at below 500 oC. During the operation, the j-V characteristics and electrochemical impedance spectroscopy (EIS) of the cells were studied. The thermal stability of the cells was also characterized by potentiostatic measurement and the measured data were compared to the cell with pure Ni anode.
(Invited) Investigation on the Selective Exsolved Electro-Catalytic Nanoparticles from Perovskite Oxide Lattices
Authors: Kwon Ohhun , Ju Young-Wan , Kim Guntae
Published: February 2020

Surface decorated electro-catalytic nanoparticles can effectively improve the electrochemical performance of the anode of a solid oxide fuel cell (SOFC). For the anode of SOFC, the electro-catalytic nanoparticles (NPs) have mainly been prepared by chemical depositions such as infiltration. However, it is difficult to control and maintain the morphology of electro-catalyst on the surface due to an agglomeration of catalyst during long-term operation at high temperature. Therefore, an exsolution of electro-catalysts from a host oxide can be considered as an alternative method for high efficient and stable electro-catalyst. Herein, we have investigated a selective exsolution phenomenon of metal NPs from perovskite oxides via a transmission electron microscopy (TEM) and a density functional theory (DFT). Furthermore, an influence of exsolved NPs on electro-catalytic performance of SOFC anode has been studied by various electrochemical tests.
Electrochemical Characteristics of Nickel and Ceria Infiltrated Nano-Structured La0.2Sr0.8TiO3 Anodes for Solid Oxide Fuel Cells By Infiltration
Authors: Lee Min-Jin , Choi Byung Hyun , Ji Mi Jung , Hwang Hae Jin
Published: February 2020

A La-doped SrTiO3 (LST) is an alternative anode material of solid oxide fuel cells (SOFC). The LST has a high electronic conductivity and chemically stable under a reduced atmosphere. In addition, it has excellent carbon deposition resistance and high tolerance of sulfur in hydrocarbon fuels. However, the LST suffers from a low catalytic activity toward the oxygen reduction reaction. Thus, it needs to improve the catalyst activity of the LST anode.

In this study, nickel and gadolia-doped ceria (GDC) infiltrated nano-structured LST anodes were proposed in order to improve the catalytic activity of the LST-based oxide anode. Nano-sized Ni and GDC were homogeneously dispersed in a LST backbone by infiltration. Ni/GDC infiltrated LST showed higher catalytic activity than Ni and GDC infiltrated ones, which means that the synergistic effect can be expected in the Ni/GDC infiltrated LST. It seems that the polarization resistance (Rp) depended on the infiltrated Ni and GDC content and their dispersion state or microstructure. We analyzed the correlation between the microstructure of the infiltrated anode and electrochemical characteristics.
Understanding the Effect of Temperature on the Sulfur Tolerance of a Ca Rich Ferrite SOFC Electrode
Authors: Addo Paul , Ahsen Ali , Buyukaksoy Aligul , Molero-Sánchez Beatriz , Ozturk Osman , Birss Viola
Published: February 2020

Previously, we have shown that a symmetrical La0.3Ca0.7Fe0.7Cr0.3O3-δ (LCFCr) SOFC full cell (LCFCr used at both electrodes) exhibits very good electrochemical performance in H2 and CO at the fuel cell and also has good sulfur tolerance in wet H2 with a low ppm H2S content at 800 oC [1]. In fact, a somewhat enhanced performance of the LCFCr anode towards the hydrogen oxidation reaction was observed under these conditions [1]. However, the effect of temperature, which is known to have a significant impact on the sulfur tolerance of conventional Ni-based anodes [2-6], has not yet been studied. Therefore, in this work, both a symmetrical full cell and a three electrode half cell configuration, using LCFCr for all of the electrodes, were constructed and tested to better understand the sulfur tolerance of this Ca rich ferrite based perovskite in humidified H2 at temperatures ranging from 600-800 oC.

Our preliminary potentiostatic data have shown that, in both the full and half-cell mode in low ppm H2S, the LCFCr electrode exhibits an enhancement in the hydrogen oxidation reaction (HOR) kinetics at 750-800 oC, while between 600 and 700 oC, the LCFCr electrode shows some form of deactivation. For instance, in the three electrode half-cell study at a constant anodic overpotential of 100 mV, the current density of the LCFCr electrode increased by 7-10% with the addition of 9 ppm H2S to 50% humidified H2 in the higher temperature range, while at 600 oC and 650 oC, the current density decreased by 2% and 15%, respectively. This deactivation was found to be fully reversible when H2S was removed from the gas stream, however, indicating that there was no permanent damage to either the electrodes, the interfaces, or the current collectors. Similarly, open circuit impedance data for the symmetrical full cell study showed that the polarization resistance (Rp) decreased from 1.0 to 0.95 Ωcm2 with the addition of 9 ppm H2S to 30% humidified H2 at 800 oC, while at 650 oC, Rp increased from 15.3 to 17.6 Ωcm2. To better understand these results, we are employing various surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), to better understand the interaction between H2S and LCFCr, as well as the type of S species formed, over the full temperature range in low ppm H2S.

References

[1] P. K. Addo, B. Molero-Sánchez, A. Buyukaksoy, S. Paulson and V. Birss, ECS Trans., 66 (2), 219 (2015).

[2] L. Debeeleeck et al, Phys.Chem.Chem.Phys., 16, 9383(2014).

[3] J.-H. Wang, M. Liu, Electrochem. Commun., 9, 2212 (2007).

[4] D.G. Ivey et al, J. Power Sources, 195, 6301 (2010).

[5] C. Bartholomew, Appl. Catal. A: Gen., 212, 17 (2001).
Fabrication of Solid State Ionic Devices Using Additive Manufacturing
Authors: Benavidez Angelica D , Tsui Lok-kun , Cook Adam , Diantonio Christopher , Chavez Tom , Garzon Fernando H
Published: February 2020

The fabrication of solid state ionic devices requires customization of size, shape, geometry, and composition for various components. Traditionally used fabrication methods are tape casting and screen printing. Although these methods are well developed they are difficult, time consuming, and costly to adjust to fit particular device requirements. Sandia National Laboratory has recently developed Robocasting, an additive manufacturing technique that was developed as a method that allows for the adaptation needed to rapidly prototype specialty ceramics in a more economically efficient way.

Robocasting is currently used commercially to produce complex ceramic parts that are used in various applications including catalyst supports and casting filters. The technology has not been developed for the fabrication of ceramic electrochemical devices. While this has worked well for these limited specific needs, this technology has been optimized primarily for alumina based ceramic materials. In order to expand the versatility of this method for solid state ionic devices, powder precursors of solid electrolytes and electrode materials with specific properties must be developed. Tailoring the rheology of the pastes and slurries used in this extrusion method is an important aspect that determines the resolution of the resulting ceramic components. Another challenge is controlling the residual stress and shrinkage through the material properties of various components.

We have applied this additive manufacturing technique to our unique design of gas sensors. These multi-component sensors consist of a yttria-stabilized zirconia substrate onto which a set of three solid electrodes and a porous YSZ electrolyte are deposited. The production method employed involves the direct printing of a suspended powder of the electrode and electrolyte components using Robocasting technology. This allows for the rapid prototyping of these devices. The key to this process is the use of high temperature co-fired ceramics which enables all components to be fired together. The electrodes consist of a platinum counter electrode and lanthanum-strontium-chromite and gold-palladium working electrodes. By taking advantage of the dissimilar electrochemical catalytic activity of these materials, the difference in mixed potential between two electrodes can be used to quantify the concentration and discriminate the type of gas present. These devices are capable of detecting NOx, hydrocarbons, H2, and NH3 at concentrations on the order of parts per million.

Figure 1
Structure Control of Thin Films Via Advanced Electrostatic Spray Coating Technique and Its Application of Fuel Cells
Authors: Shin Dongwook , Lee Sewook , Lee Taejun , Lee Hunhyeong , Park Sangho
Published: February 2020

To enhance overall properties of solid oxide fuel cells (SOFC), fabrication of each components is one of significant part in this field. Among the various coating techniques for fabrication of single cells, the coating method using pre-synthesized powder slurry has been widely used due to the fact that the powder technique is cost effective and easily controllable the process parameters than the other techniques using vacuum system such as RF sputtering, PLD and CVD. However, previous powder processes including tape casting, screen printing and dip coating have a difficulty in formation of 1~5 μm thin films for micro-fuel cells. Also, the microstructures of deposited films are very sensitive to process parameters, therefore, not easy to fabricate appropriate films to each layer in SOFC. So, our suggested deposition method in this work is an electrostatic slurry spray deposition (ESSD) technique which uses electrical energy to atomize and spray solutions same as in electrostatic spray deposition (ESD). The ESSD technique is a method of spraying prepared slurry containing powders with pre-developed crystalline phase, while the conventional ESD is a technique of spraying metal salts dissolved solution and the crystalline phases are developed after deposition by post-heat treatment. Dense and porous films without any cracks and delamination can be easily fabricated by the ESSD. Also, it is very powerful tool to fabricate a layer with composite materials and to control film thickness. In overall, the ESSD is a more advanced deposition technique than the conventional ESD in terms of the controllability of the deposition process and the microstructure of the deposited film, the flexibility in process application, the performance of the obtained film, the diversity of film material, so on.

In this study, the objective is to develop advanced electrostatic slurry spray deposition (ESSD) and its application to SOFC. The key parameters in process includes an applied voltage, a flow-rate and a distance to substrate. Through the optimization of deposition conditions, microstructures are easily fabricated as intended. Firstly, our group has optimized the deposition conditions to form thin films ( < 3 μm) for electrolytes. Also, the several trials such as composition and porosity controlled microstructures for electrodes have been investigated. Furthermore, the effective microstructures such as honeycomb, snowball and nano-fibers have been studied and employed to electrodes in single cells. The overall micro-graphical and electrochemical analysis for fore-mentioned microstructures were carried out to verify the effectiveness of each films formed by ESSD technique.

Figure 1
Li7La3Zr2O12 Interface Modification for Li Dendrite Prevention
Authors: Finsterbusch Martin , Tsai Chih Long , Roddatis Vladimir , Nair Vinod Chandra , Ma Qianli , Uhlenbruck Sven , Heitjans Paul , Guillon Olivier
Published: February 2020

Li metal is the ideal anode for rechargeable batteries due to the lowest native electrochemical potential ( -3.4 V vs. H2), extremely high specific capacity (3860 mA h/g) and low density (0.59 g/cm3). However, the use of metallic Li in a rechargeable battery was not successful until now, due to the difficulty of suppressing the growth of Li dendrites. Theoretical calculations suggest that if the shear modulus of the used electrolyte is more than twice that of metallic Li, ~109 Pa, or the Li-ion transference number tLi+ approaches 1, then the dendrite growth can be suppressed. Therefore, the garnet-structured Li7La3Zr2O12(LLZ) solid-state Li-ion conductor is an ideal material as electrolyte in rechargable batteries because of its unity ionic transference number, high mechanical strength and chemical stability to metallic Li.

However, Li dendrite formation was reported by Ishiguro et al [1,2] for their Nb- and Ta-substituted LLZ with unclear reason. In the presented research, Ta-substituted LLZ samples which are Al-contaminated and Al-free were fabricated by hot pressing as well as a regular sintering process. Samples fabricated by hot pressing have relative densities >99% and total conductivities of ~1 mS/cm at room temperature. During this study, impedance measurements show rapid decrease in total resistances within a couple of hundred seconds, which indicates that the dendrites can be formed even in such a highly dense ceramic in a short time (just like in regularly sintered samples with ~93% relative density). Solid-state NMR demonstrates the presence of metallic Li inside the dense pellets, which is also supported by TEM-EELS result [3]. From these dendrite test results, reasons for the formation of the Li dendrite and options to prevent the formation of Li dendrites by interface modification were derived and will be discussed in this presentation.

[1] Ishiguro et al., J. Electrochem. Soc. 2013, 160, A1690−A1693.

[2] Ishiguro et al., J. Electrochem. Soc. 2014, 161, A668−A674.

[3] Tsai et al., ACS Appl. Mater. Interfaces, 2016, DOI: 10.1021/acsami.6b00831
Effect of Lithium Nitrate (LiNO3) on Lithium Metal Secondary Batteries As a Lithium Metal Stabilizing Electrolyte Additive
Authors: Jin Dahee , Lee Hoogil , Han Taeyeong , Kim Seokwoo , Ryou Myung-Hyun , Lee YongMin
Published: February 2020

To realize the successful implementation of the electric vehicles (EVs), the development of advanced lithium secondary batteries having excellent cycle life, high energy density and high power density with low price is prerequisite. To achieve this goal, the conventional active materials such as LiCoO2 and graphite based on the intercalation chemistry, which are used in the commercialized lithium-ion batteries, should be replaced.

Although lithium metal has been a promising anode material over four decades, it could not fully used in commercialized secondary battery system due to poor cycle life ascribed to the dendrite formation during repeated operation. To solve this problem, we introduced a novel lithium metal stabilizing electrolyte additive, lithium nitrate (LiNiO3).

The effect of LiNiO3 was characterized by scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). The cycle performance of coin cells containing 0.3wt% of LiNiO3 revealed an improved cycle performance even at high voltage (3.0~4.5V vs. Li/Li+, C/2) and the rate capability at high current density. We believe this is attributable to the formation of stable solid electrolyte interphase (SEI) layer on the surface of lithium metal during precycling, resulting smaller resistance.

 

Acknowledgements

This work was supported by the international Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No. 20158510050020).

 

References

 

H. S. Kim. et al. Ionics (2013) 19:1795 – 1802

Jing Guo et al. Electrochemistry Communications 51 (2015) 59–63
High Ionic Conductivity and Moduli Iongels Made with Tetraglyme/Litfsi /Methyl Cellulose for Lithium Batteries
Authors: Chinnam Parameswara Rao , Chereddy Sumanth , Wunder Stephanie
Published: February 2020

The motivation for the development of solid polymer electrolytes (SPEs) arises from their safety advantages over liquid electrolytes. In particular SPEs are non-flammable and avoid the problem of electrolyte leakage, both of which can result in fires/explosions. However, SPEs have lower conductivities at room temperature (RT) compared to those of liquid electrolytes, so there is a need to develop SPE with improved RT conductivities.

Recently, glymes, (CH3−O-(CH2−CH2−O)n−CH3) n=3 or 4, have been studied as solvents for non-aqueous electrolytes because of unique properties such as their solvation power (Lewis basicity), relatively long-lived (stable) solvates, and complex formation in certain molar ratios, [M(glyme)x]+, with alkali metal ions. Li(G3 or G4)][TFSI] is molten at room temperature and can be considered as a representative ionic liquid. It has very low volatility, is nonflammable, and has good oxidative stability.

Here we report the preparation, ionic conductivity (s), mechanical and thermal properties of iongels made from Li(G4)TFSI and methyl cellulose (MC), in ratios of 90/10, 80/20 and 70/30 Li(G4)TFSI/MC. The ionic conductivity decreases with increase in MC content over the temperature range measured, 10 oC to 90 oC (Figure 1A), while the storage moduli increase with increase in MC content. For 90/10 Li(G4)TFSI/MC at 30 oC , s = 3.78×10-4 S/cm and the storage modulus = 50 MPa(Figure 1B). Thermogravimetric analysis of G4, Li(G4)TFSI, Li(G4)TFSI/MC and MC indicates that iongels are stable until the vaporization of the G4(Figure 2A). DSC data for G4, G4 with TFSI, and G4 with TFSI/MC (Figure 2B ) show that: (i) complexation of Li+ with G4 results in an increase in Tg and a suppression of the melt temperature Tm, and (ii) MC content increases Tg  and decreases conductivity (Figure 1A).

Figure 1A. Log (conductivity) versus 1000/T for Li(G4)TFSI and Li(G4)TFSI/MC gels. Figure 1B. Storage modulus for 90/10 Li(G4)TFSI/MC as a function of temperature

Figure 2A.TGA of G4,Li(G4)TFSI, Li(G4)TFSI/MC and MC Figure 2B. DSC scans (second heating cycle) of Li(G4)TFSI and Li(G4)TFSI/MC

References

(1) Zhou, S.; Kim, D. Polymers for Advanced Technologies
2010, 21, 797.

(2) Henderson, W. A. The Journal of Physical Chemistry B
2006, 110, 13177.

(3) Pappenfus, T. M.; Henderson, W. A.; Owens, B. B.; Mann, K. R.; Smyrl, W. H. Journal of The Electrochemical Society
2004, 151, A209.

Figure 1
Synthesis Characteristics of Garnet-Llzo Materials By Modified Co-Precipitation
Authors: Yang Seung-Hoon , Kim Min-Young , Kim Da-Hye , Kim Kyeong-Joon , Choi Seung-Woo , Noh Tae-Hyoung , Lee Moo-Sung , Kim Ho-Sung
Published: February 2020

Recently, many sorts of lithium batteries have been studied such as all solid and lithium-air batteries etc., for EV and ESS applications. Especially, all solid battery is one of the candidates for a large-sized battery in regard of the safety problem. Garnet-type LLZO electrolyte has good advantages with a high ionic conductivity and electrochemical potential window. However, it is reported that there are difficulties to prepare LLZO(Li7La3Zr2O12) pellets with high relative density. In this study, LLZO material was doped by the different elements of Al by co-precipitation process. Furthermore, we studied the effects of lithium excess concentration of Al-doped LLZO. We investigated not only the change of cubic and tetragonal structure but also electrochemical properties according to the synthesis conditions. As a result, ionic conductivity of Al-doped LLZO material was about 3.1x10-4 S/cm at room temperature, indicating a wide electrochemical window of 0~5.5V. Furthermore, we will introduce the electrochemical properties of unit cell using LLZO material in more detail.
Improved Low-Temperature Performance of Li-Ion Battery of LiCoO2//Graphite By Electrolyte Control
Authors: Pham Hieu Quang , Kim Jae-Hee , Kwon Young-Gil , Hwang Eui-Hyung , Lee Jung-Gyu , Song Seung-Wan
Published: February 2020

For the universal use of electric vehicle and energy storage system applications, Li-ion batteries are required to operate at low temperatures below –10 ○C. Battery performance at low temperatures is however often limited by electrolyte, mainly due to a lowered Li-ion conductivity and a phase change of high melting point component from liquid to solid. In an effort to overcome those drawbacks, researchers have made attempts on electrolyte development mostly by blending several solvents to ternary and quaternary electrolytes,1 and by using functional electrolyte additives.2 Although some improvements were made, challenges for finding new electrolyte component remains and the new electrolyte component has to be practically tested in the Li-ion batteries operated at low temperature. In this presentation, we report a development of new lithium salt as an additive to use in the conventional Li-ion cells of LiCoO2//graphite operated at –20 ○C. Improved low temperature performance by the effects of salt additive and its correlation to surface chemistry would be discussed in the meeting.

 

Acknowledgements

This research was supported by the Korean Ministry of Trade, Industry & Energy (A0022-00725 & R0004645).

References

1. M. C. Smart, B. V. Ratnakumar, L. D. Whitcanack, K. B. Chin, S. Surampudi, H. Croft, D. Tice, R. Staniewicz, J. Power Sources, 119–121, 349 (2003).

2. L. Liao, X. Chenga, Y. Ma, P. Zuo, W. Fang, G. Yin, Y. Gao, Electrochim. Acta, 87, 466, (2013).
Composite Polymer-Ceramic Electrolyte for High-Energy Lithium Secondary Batteries
Authors: Samuthira Pandian Amaresh , Delnick Frank , Dudney Nancy J
Published: February 2020

The demand for high-energy batteries is driving development of high voltage lithium batteries, where the electrolyte must be electrochemically stable and resistant to formation of metallic Li dendrites. Replacing the current liquid electrolytes with a robust solid electrolyte that has high ionic conductivity and good mechanical stability is one path to improve the performance and safety. Polymer electrolyte formed with a dissolved Li ion salt are preferred for their low cost, mechanical flexibility and easy processability, however the low room-temperature conductivity restricts the use of most polymer electrolytes. Composite polymer electrolytes, consisting of a polymer electrolyte containing a dispersed inorganic powder, such as alumina, tend to have high conductivity because the filler impedes crystallization of the polymer.1 Another approach is to disperse powders of a highly conductive ceramic electrolyte, rather than insulating filler, such that both phases in the composite conduct the lithium ions. This permit a high ceramic loading such that the mechanical, transport, and chemical stability can be optimized.2

In the present study, we chose a traditional polymer electrolyte composed of polyethylene oxide (PEO) as the polymer host and Lithium triflate is the mobile ion conducting salt. The solid electrolyte powder from Ohara® Corporation LIC–GC® was selected for the ceramic component because of its inherent high ionic conductivity and stability against water and heat. With these materials, thin composite membranes were fabricated with reasonable conductivity and stability. A solid-state battery consisting of a thin film cathode, the composite electrolyte membrane and vapor deposited metallic Lithium was evaluated. The results to be presented include ionic conductivity of the membrane, stability against Lithium and preliminary cyclic voltammetry of the battery.

Acknowledgement: This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Advanced Battery Materials Research (BMR) Program.

References:

E. Quartarone, P. Mustarelli, and Aldo Magistris, Solid State Ionics, 110, 1 (1998).

Wyatt E. Tenhaeff and Sergiy Kalnaus, Handbook of Solid State Batteries, 2nd Edition, Nancy Dudney, William West, and Jagjit Nanda, World Scientific, Ch. 7 (2015).

*Corresponding author email: dudneynj@ornl.gov
Electrochemical Behavior of Li4Ti5O12 in Ionic Liquid/Water Bilayer Electrolyte
Authors: Miwa Hiroshi , Fukutsuka Tomokazu , Miyazaki Kohei , Abe Takeshi
Published: February 2020

Introduction

Lithium-ion batteries (LIBs) have been used in portable electronic devices, and recently expected to be used in large-scale energy facilities for electric vehicle or large energy storage systems. Flammable organic solvents were used in LIBs and it threaten the safety of LIBs. Therefore, nonflammable aqueous electrolytes have been investigated[1]. However, its narrow potential windows restrict the use of negative electrodes, which makes it difficult to obtain high voltage. In this study, we utilized stable liquid-liquid interface between water and hydrophobic ionic liquids in order to enhance the negative potential window. The electrochemical behavior of Li4Ti5O12(LTO) thin-film electrode, which cannot be used in aqueous solution, was investigated.

Experimental

LTO thin-film electrodes were prepared on a Pt substrate by a sol-gel method. LTO thin-film electrode was used as a working electrode. The bilayer electrolyte was formed on the working electrode: the upper layer was 1.0 mol dm −3 LiNO3 aqueous solution, and the lower layer was butyltrimethylammonium bis(trifluoromethylsulfonyl)amide (BTMATFSA) containing 1.0 mol kg −1 of lithium bis(trifluoromethylsulfonyl)amide (LiTFSA). The counter electrode was platinum wire and the reference electrode was Ag/AgCl electrode (sat. KCl), and these electrodes were placed in the aqueous solution layer. Cyclic voltammetry was performed. Hereafter, all potentials are referred to as Ag/AgCl.

Results

Figure 1(a) shows the cyclic voltammograms of LTO thin-film electrode in bilayer electrolyte. At volume ratio of ionic liquid:aqueous solution = 3:4, clear redox peaks around ca. −1.33 V were observed. This reaction can be assigned to lithium-ion insertion/extraction into/from LTO. In contrast, Figure 1(b) shows that only large reduction current was observed and the redox peaks of LTO were not detected at volume ratio = 1:29. At this ratio, ionic liquid was miscible with aqueous solution. Thus, the reduction current below 0.9 V can be assigned to the hydrogen evolution reaction from water. These results reveal that bilayer electrolyte with clear interface prevent the hydrogen evolution reaction and enable lithium-ion to insert/extract into/from LTO.

Reference

[1] W. Li, J. R. Dahn, and D. S. Wainwright, Science, 264, 1115 (1994).

Acknowledgment

This work was partially supported by CREST, JST. 

Figure 1
(Invited) CO2 Electrolysis for Syngas Production
Authors: Masel Richard I , Liu Zengcai , Kutz Robert , Sajjad Syed , Yang Hongzhou
Published: February 2020

Economic production of syngas from CO2 and H2O could produce new routes to synthetic fuels. In this paper we will describe recent work on the electrolysis of CO2 in a 5 cm² alkaline electrolyzer using standard Fuel Cell Technologies fuel cell hardware. Previous work had demonstrated CO2 conversion with steady state currents of 50 mA/cm² or less at 3 V. In this paper we find that by optimizing the composition of the membrane and ionomer we can raise the current to 280 mA/cm² at 3V and 600 mA/cm² at 3.25-3.35 V.

Table 1 shows how the performance of the electrolyzer varies with membrane composition for several different membranes using bare silver cathode catalysts, ruthenium anode catalysts and a variety of membranes. In all cases the measurements were done by sandwiching the membrane between two pieces of carbon cloth that were coated with membrane, mounting the resultant MEA in 5 cm² fuel cell hardware, supplying humidified CO2 to the cathode, applying 3 V, waiting 20 minutes to 1 hr for the current to stabilize and recording the current.

Notice that the faradaic efficiency for the conversion of CO2 to CO varies from 0 to 95%. While the current varies from 5 to 80 mA/cm². Sustainion™ membranes give higher currents and faradaic efficiency than the others. These results demonstrate that the membrane composition makes a significant difference to the electrolyzer performance.

Figure 1 shows how the polarization curve of the cell varies as we add different amounts of Sustainion™-X5 to the cathode layer in a cell with a Sustainion™-X4 membrane. Notice that one can obtain currents of 1.4 amps (280 mA/cm²) at 3 volts with a Sustainion™-X4 membrane and and Sustainion™-X5 ionomer.

Figure 2 shows a steady state run at 600 mA/cm² using an optimal amount of Sustainion™-X6 in the catalyst layer. Notice that we can maintain 600 mA/cm² at between 3.25 and 3.35 V. By comparison, the closest competitor needed almost 7 V to obtain the same current.

Figure 3 shows a steady state run at 200 mA/cm² using a Sustainion™-X1 membrane and an optimal amount of Sustainion™-X5 in the catalyst layer. Notice that we were able to maintain constant current for over 600 hours. Unfortunately, these runs ended abruptly when the power went off and then surged as it went on. But in runs without Sustainion™-X5 in the catalyst layer and no power surges, stable performance was observed for over 4000 hours.

These results show that the ionomer and membrane can make a substantial difference to the performance of a CO2 electrolyzer.

Acknowledgement

Parts of this work were supported by ARPA-E under contract DE-AR0000345 and by 3M. The opinion are those of the authors and may not reflect the opinions of ARPA-E or 3M.

Figure 1
Fouling Behavior of Negatively Charged Natural Organic Matters to Anion Exchange Membranes in Reverse Electrodialysis
Authors: Kim Da-Eun , Oh Yoontaek , Choi Jang-Uk , Song Chan-Ho , Chae Soryong , Kim Chan-Soo , Jeong Nam-Jo , Kang Moon-Sung , Park Jin-Soo
Published: February 2020

Reverse electrodialysis (RED) represents an energy conversion technology from the salinity difference of concentrated salt solutions (e.g., sea water) and diluted salt solutions (e.g., river water). The RED stack is comprised of an alternating arrangement of cation- and anion-exchange membranes between two electrodes that selectively transfer anions and cations. However, the river water used for the RED may contain natural organic matters (i.e., humic acid and fulvic acid). Thus, electrostatic characteristics of organic matter may lead to membrane surface fouling. The membrane fouling cause increase electrical resistance and the increase of maintenance cost, and a significant decrease in operating performance. In this study, the influence of membrane fouling in RED by commercially available humic acid was investigated experimentally, and adsorption tests, open circuit voltage, stack resistance, and power density were measured at different operation conditions. As a result, it was confirmed that the adsorption of humic acid onto the surface of anion-exchange membranes occurred even though the direction of the electromigration of negatively charged humic acid was toward cation-exchange membranes. The fouling of anion exchange membranes by humic acid was highly influenced by the roughness of the surface of anion-exchange membranes. It was confirmed by isothermal curves (i.e., Frendlich isotherm).

Acknowledgements

This work was supported by the New and Renewable Energy of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, and Republic of Korea (No. 20143030071240).
The Role of Temperature on Salt Removal Using Capacitive Deionization
Authors: Zhang Jiankai , Nazemi Mohammadreza , Leksana Caitlin , Hatzell Marta C.
Published: February 2020

Current technologies utilized for seawater desalination, reverse osmosis (RO) and Membrane distillation (MD), are energy intensive because they operated by separating the main component water (H2O) from the salt (NaCl). Capacitive deionization (CDI), an emerging separations based technology, operates by extracting the minority component (NaCl). CDI is similar to a supercapacitors[1], where ions adsorb to the high surface area activated carbon once an electric potential is applied across the electrochemical cell (ion separation process)[2-5]. However, in place of traditional non-aqueous based electrolytes is a electrolyte comprised of sea, brackish or wastewater.

More recent theoretical based studies have emphasized the role heat transfer has on ion adsorption dynamics within CDI cells[6].Traditional CDI cells operate in a cyclic process where the capacitive electrodes are brought in contact with a concentrated salt solution (e.g. brackish water) and charged. Once the charged electrodes are fully saturated with salt ions, the electrodes are regenerated through discharging the electrodes in a brine solution. Analogous to a P-V diagram for traditional heat engines, the enclosed area of the charge versus voltage represents the energy consumed during this charging-discharging process. Here we explore the effect of temperature on salt removal in a CDI cycle. Experimentally, we use traditional electrochemical characterization methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), to evaluate the capacitance and resistance changes with temperature. Specifically the salt adsorption capacity is shown to decrease from 13.82±1.13, to 6.58±1.01 milligram NaCl/mg carbon as the cell temperature is increased from 25oC to 45oC.

1. Hatzell, K.B., M. Boota, and Y. Gogotsi. Chemical Society Reviews, 2015. 44(23): p. 8664-8687.

2. Porada, S., R. Zhao, A. Van Der Wal, V. Presser, and P. Biesheuvel.Progress in Materials Science, 2013.

3. Hatzell, K.B., M.C. Hatzell, K.M. Cook, M. Boota, G.M. Housel, A. McBride, E.C. Kumbur, and Y. Gogotsi. Environmental science & technology, 2015. 49(5): p. 3040-3047.

4. Ren, C.E., K.B. Hatzell, M. Alhabeb, Z. Ling, K.A. Mahmoud, and Y. Gogotsi. The journal of physical chemistry letters, 2015. 6(20): p. 4026-4031.

5. Hatzell, K.B., E. Iwama, A. Ferris, B. Daffos, K. Urita, T. Tzedakis, F. Chauvet, P.-L. Taberna, Y. Gogotsi, and P. Simon. Electrochemistry Communications, 2014. 43: p. 18-21.

6. Janssen, M., A. Härtel, and R. Van Roij. Physical review letters, 2014. 113(26): p. 268501.
Novel Strategies for Preparing Highly Luminescent Gold Nanoclusters
Authors: Pyo Kyunglim , Yoon Sook Young , Lee Dongil
Published: February 2020

Quantum-sized gold nanoclusters with high photo-luminescence properties have been one of the briskly studied materials for their applications in light emitting display, biomedical imaging, optical sensors and more. Also atomically precise gold nanoclusters with well-defined core shell structures have bright prospects to achieve high luminescence quantum efficiency. In this presentation, we present the novel strategies for enhancing the luminescence of water soluble Au22SG18 via ion-pairing bulk tetraoctylammonium (TOA) cations and covalent attachment of small aromatic chromophores to glutathione. TOA was ion-paired to glutathione by phase transferring the water soluble Au22SG18 to the organic solvent under pH 9. TOA ion-paired Au22 showed a massive increase in the luminescence (Q.Y. ~60 %) due to the enhanced rigidity of the gold-ligand shell, which was also shown in the PL lifetime and steady state luminescence under the solvent freezing point. Furthermore, the small aromatic chromophores, such as pyrene, was covalently attached by EDC/NHS coupling reaction which enhanced the luminescence of water soluble Au22 by more than 8 times. Compared to the result from TOA-Au22, the enhancement was on account to the increased rigidity of the gold-ligand shell from the functionalized aromatics as well as the fluorescence resonance energy transfer (FRET) phenomenon from pyrene to Au22. Steady-state and femtosecond time-resolved fluorescence measurements of each Au22 and pyrene functionalized Au22 (Au22-Py) was taken, for the calculation of energy transfer efficiency, which was 20 %. However, the ultrafast transient absorption result suggested the possibility of charge transfer occurring from Au22 to pyrene hindering the energy transfer phenomenon. In order to enhance the energy transfer contribution instead of the charge transfer, TOA was ion-paired to the gold-ligand shell on Au22-Py followed by a 21 fold luminescence enhancement. These strategies for adjusting the gold-ligand shell of the nanoclusters, opens up a new way for preparing highly luminescent gold nanoclusters in water that can be used for luminescent display applications and biological imaging.
(Invited) Foldable Circuits and Organic Electronic Devices Based on Solution-Processed Graphene Composites and Inkjet Printing
Authors: Chin Byung Doo , Jo Sung Min
Published: February 2020

A facile and cost-effective strategy for foldable and flexible electronics is solution process, such as inkjet printing, of graphene-based materials, which will be also useful for application with large area or ultra-thin form factor. In this presentation, graphene ink and graphene/silver nanowire (AgNW) paste were formulated and printed on the surface-treated flexible/foldable substrates, including plastic or functionalized paper. Circuits of the graphene nano-plates, prepared on the paper substrate by simple transfer printing, showed a very small change in the conductance under various folding angles, retaining more than 90% of initial conductance after repeated cycles [1]. Moreover, compared with electrodes formed by neat graphene, graphene/AgNW circuit showed superior performance both for sheet resistivity as well as folding stability. For the inside (−180◦) and outside (+180◦) folding angle condition, the circuits revealed much smaller change in conductance, maintaining the electronic path on foldable paper.

Due to the lack of transparency for most paper-based substrate, top-emitting organic light emitting diode (TOLED) was employed, where its light emitting behavior and efficiency were investigated in terms of the multilayer surface composition on paper and functionality. TOLED on paper was prepared by thermal evaporation or printing of several organic layers onto the reflective anode, where the interconnecting graphene/AgNW circuit supplied the bias voltage and current. Electrical and luminous properties of TOLED were dependent upon the applied bias voltage driven by graphene/AgNW electrodes [2].

Solution-phase direct exfoliation of neat graphene is favorable for maintain higher conductivity of printed patterns [3]. We have dispersed graphene nano-platelets in methanol, with 0.5wt% polymeric surfactant (such as triton X-100). Improved uniformity and printability of graphene-based ink materials and their patterns were evaluated using the commercial inkjet/simple nozzle printing. Tiny droplets of graphene or graphene-AgNW composite solution ink could be jetted onto a fast-moving substrate to produce 100μm-width pristine line patterns. Pattern uniformity and resolution were further controllable by the adjusting of the surface tension via ink formulation as well as modification of functional surface of paper substrates. Organic thin film transistor with various patterns/channel length of graphene-base electrodes were fabricated for the evaluation of printed graphene circuits.

References

[1] W. J. Hyun, O O. Park, B. D. Chin, Adv. Mater., 2013, 25, 4729-4734

[2] S.M. Jo, D. G. Yoon, R. Bail, B. D. Chin, ECS J. Sol. Sta. Sci. and Tech.
2016, 5, R3185-R3190

[3] E. B. Secor, P. L. Prabhumirashi, K. Puntambekar, M. L. Geier, M. C. Hersam, J. Phys. Chem. Lett.
2013, 4, 1347-1351