bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing Li-Metal Alloy Batteries with High Cyclability and Rate Capability
Authors: Niu Junjie
Published: February 2020

The development of high-energy density and high-power density lithium ion batteries (LIBs) for portable electronics, electric vehicles, and other large-scale energy storage devices over the last decade has led to continual search on new electrode candidates. The cost-effective, chemically stable (safe), and highly conductive metal as anode electrode that is capable of high capacity due to the large Li stoichiometric ratio, has recently stimulated enormous attention. There have been many efforts to increase the capacity using group IV elements Sn, Ge, Pb, Si and Mg, Al, Ga, Zn, and Bi thus far. Sn, another group IV element, is a promising alternative anode material, as its bulk phase is known to have a higher theoretical capacity of 990 mAh/g (Li4.4Sn) compared to 370 mAh/g of commercial graphite. Sn is also less toxic and less expensive, but huge volume changes up to 300% during Li insertion and extraction limit the energy capacity and cycle lifetime in LIBs. In addition to the volume factor, another obstacle lies in the naturally formed oxide layer, which introduces a non-reversible capacity, although some researchers have found that an ultrathin coating on electrodes could enhance the performance of lithium-ion batteries. To maximize the electrochemical performance of Sn, a well-desired configuration that can efficiently prevent the chemo-mechanical failure must be developed.

Here we present a novel sub-100nm Sn nano-cage (Sn-NC) comprising an industrially available, pure metal Sn and a conductive oxide surface (not SnOx). The protection of the rigid oxide surface and the adjustable interspace can prevent the pulverization and oxidation of the metal while supplying a fast Li+/e- pathway. The coin/punch cell assembled using Sn-NCs as anode provides a high capacity (>600 mAh/g) with a long cyclability (>500 cycles) at a high charge/discharge rate. The synthesis of Sn-NCs is scalable thus indicating a potential on industrial commercialization.
Enhanced β"-Alumina Solid Electrolytes for Lower Temperature Operating Planar Sodium Beta-Alumina Batteries (LT-NBBs)
Authors: Lee Younki , Park Yoon-Cheol , Son Sori , Jung Keeyoung
Published: February 2020

The sodium beta-alumina battery (NBB), which employs molten sodium as an anode and sodium-ion conducting β"-alumina as a solid electrolyte, is an attractive device for grid scale energy storage thanks to its long lifetime with negligible self-discharge and potentially low cost by use of naturally abundant elements. Commercialized NBBs, such as sodium sulfur (Na/S) and sodium nickel chloride (Na/NiCl2) batteries, are typically being operated at 280~350oC in order to facilitate ionic conduction through the solid electrolyte. However, this high operation temperature disturb additional cell cost reduction, which is continuously exacted by demanding forecast, since it is difficult to replace conventional expensive sealing technologies (such as glass sealing, thermal compression bonding, electron beam welding and so on) with lower cost substitutes. If the cell operation temperature is lowered down to below 200oC, a wider range of choices for sealing technology can be considered such as inexpensive polymer sealing. Suppressed cell degradation at lower temperatures would be another important benefit.

However, a number of hurdles need to be overcome in order to lower the cell operation temperature. One of the most difficult challenges to make it is an issue regarding the exponential resistance rise of the solid electrolyte with decreased temperature, which can result in substantial performance loss. One can consider that reducing the thickness of the β"-alumina solid electrolyte (BASE) may resolve the issue. However, as the BASE thickness decreases below 1.5~2.0 mm, its flexural strength becomes not acceptable to be used in cell fabrication. Therefore, our target has set to develop a BASE (1) to be thin to compensate the resistance increase at lower temperatures, (2) with enhanced mechanical properties to minimize unwanted cell failure. The target can be achieved by fabricating highly toughened thin composite electrolytes. In this presentation, our on-going efforts on developing thin composite electrolytes made of β"-alumina and oxygen conducting oxides. Results showed that the flexural strength of this novel electrolyte could be greatly increased maintaining its area specific resistivity (ASR) as low as that of a conventional BASE.
Enhancing Electrochemical Performance By Coating Al2O3 on Na0.6Mn0.66Ni0.22Co0.11O2 cathode in Sodium-Ion Batteries
Authors: Nguyen Ngoc Anh , Kim Kyuman , Cho Inseong , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Rechargeable sodium-ion batteries (SIBs) have recently attracted much attention as an alternative electric energy storage device to lithium-ion batteries (LIBs) because of the availability and low cost of sodium. However, the cycle performance of SIBs is not comparable to LIBs due to the side reaction between electrode and electrolyte as well as the structural instability and transition metal dissolution into electrolyte. In order to solve these problems, various surface coating techniques have been used to coat oxides on the cathode active material surface before making the electrode. However, additional coating process causes the price increase, and they have not been applied for SIB cathodes.

Herein, an Al2O3 thin film was directly deposited on the surface of Na0.6Mn0.66Ni0.22Co0.11O2(NaMNCO2) cathode by a radio-frequency magnetron sputtering. Only 4 min coating of Al2O3 upon the NaMNCO2 could improve the specific capacity from 134.6 to 146.4 mA h g-1 in a voltage range of 2.1 to 4.3 V. In addition, the cycle performance was also enhanced to deliver 49.7 mA h g-1 even after 200 cycles. In case of high voltage operation up to 4.5 V, the discharge capacities of pristine and Al2O3-coated electrodes are 150.6 and 160.1 mA h g-1, respectively.

Acknowledgement

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).

References

[1] Y.S. Jung, A.S. Cavanagh, A.C. Dillon, M.D. Groner, S.M. George, S.-H. Lee, J. Electrochem. Soc. 157 (2010) A75.

[2] Y. Huang, J. Chen, F. Cheng, W. Wan, W. Liu, H. Zhou, et al., J. Power Sources. 195 (2010) 8267–8274.

[3] D. Yuan, W. He, F. Pei, F. Wu, Y. Wu, J. Qian, et al., J. Mater. Chem. A. 1 (2013) 3895.
Thermally Reduced Graphite Oxide for Potassium Ion Battery Anodes
Authors: Jeong Jae Hyang , Pyo Myoungho
Published: February 2020

Among the alkali metals, Li is considered as the best element in terms of the energy density due to the lightest atomic weight and the lowest standard potential. Because of this fundamental advantage, lithium ion batteries (LIBs) are now overwhelmingly used in portable device and transportation markets. In spite of technological settlement, however, the scarcity in reserves and the concomitant rise in cost of lithium urged researchers to shift their interest to other ion sources. Sodium and potassium ions are most promising candidates in that the knowledge accumulated from LIBs researches can be directly applied and the world-wide reserve is almost unlimited. Regarding sodium ion batteries (SIBs), the major current-huddle to commercialization is believed to be a lack of reliable anode materials. Graphite cannot be applied to SIB anodes because the ionic size is not comparable to an interlayer spacing of graphite (This size effect becomes more pronounced when the solvation sheath is considered together.). As a result, graphite can deliver only a small capacity (~35mAh/g) in SIBs. On the contrary, graphite is known to be active for potassium-ion intercalation, showing a reversible capacity of ~230mAh/g (i.e., formation of KC8 at -2.9 V vs SHE). Although K+ ion radius is larger than Na+, weak solvation of K+ makes possible the use of graphite in potassium ion batteries (KIBs). In this work, we studied reduced graphite oxide (rGTO) as a KIB anode. Graphite was mechanically pulverized, chemically oxidized, and finally subjected to a thermal treatment. The graphite oxide was heat-treated at various conditions and the relation between controlled interlayer distances and capability of K+ intercalation/deintercalation was investigated. We controlled d-spacing of rGTO by changing the thermal reduction conditions (heating and cooling rate, maximum temperature, etc.) and established the optimal experimental parameters. We also examined the various types of graphite (MCMB, flake types, etc.). Electrochemical studies revealed that rGTO has superior rate-performance when compared with pristine graphite. Further improvement of reversible capacity and cyclability is underway.
Short and Intermediate Range Ordering in Fast Cation Glasses for Battery Applications
Authors: Kassem Mohammad , Usuki Takeshi , Bychkov Eugene
Published: February 2020

Lithium batteries provide the highest energy density which makes them ideal candidates for future generations of portable electronics (laptops, cellular, tablets, etc.) and hybrid electric vehicles for the time being. However, the increasing demand for lithium batteries will be limited by the fact that lithium is not an abundant material and its cost is expected to increase considerably in the coming years. In contrast, sodium resources are unlimited (fourth most abundant element in Earth’s crust) and from economic point of view, sodium batteries appear as good alternative to lithium devices, particularly for large-scale stationary applications. The ionic conductivity of chalcogenide and chalcohalide glasses is 2 to 3 orders of magnitude higher than that of oxide glasses with the same mobile ion content. This makes chalcogenide systems suitable for applications in power rechargeable systems.

Our studies are focused on the development of new Na+ion-conducting chalcohalide glasses combining sodium halides and sulfide-based glass network. Cation local environment and intermediate-range ordering in glasses are critically important to achieve fast ionic conduction. Usual structural hypothesis related to superionic glasses containing metal halides MY = LiI, NaBr, AgI, etc., implies the absence of chemical interactions between the host glass and metal halide. An expansion of the host network caused by large anions (I, Br) and related increase of the available free volume for fast cations, forming preferential conduction pathways, was considered to be the key parameter for glassy superionics. Nevertheless, recent studies of AgY and CuY crystalline coordination polymers show chemical interaction between metal halide and chalcogenide backbone giving rise to mixed M-centered polyhedra. The polyhedral connectivity was also found to be different, starting from isolated units and dimers and finishing by chains, 2D layers and tubes. Some characteristic types of MY-subnetwork are given in Fig. 1(a,b).

Using pulsed neutron and high-energy x-ray diffraction combined with Reverse Monte Carlo modelling, we examine cation local and intermediate range ordering in two glassy systems containing either silver iodide or sodium halides. Sodium chalcogenide glasses exhibit high ionic conductivity and seem to be promising for battery applications.

Figure 1
Mesoporous Sodium Vanadium Phosphate/Carbon As Efficient Cathode Materials for Rechargeable Sodium-Ion Batteries
Authors: Hung Tai-Feng , Cheng Wei-Jen , Chang Wen-Sheng , Yang Chang-Chung , Kuo Yu-Lin
Published: February 2020

Rechargeable sodium-ion batteries (SIBs) have recently considered as alternative energy storage devices to lithium-ion batteries (LIBs) because of their benefits on material abundance, low cost and electrochemical similarities. In spite of the previously mentioned advantages for SIBs, there still remain challenges to realize the practicalities. In contrast to the smaller lithium cation, for example, the larger radius of sodium cation not only lowers its transportation ability but also causes the more severe structural impact and volume variation of electrode materials during the intercalation/de-intercalation processes. Therefore, searching the electrode materials with excellent structural stability, high reversible capacity, superior rate and cycling performances becomes one of the critical issues.

Among the developed cathode materials, sodium vanadium phosphate/carbon (Na3V2(PO4)3/C) nanocomposites with sodium superionic conductor (NASICON) structure have been regarded as one of the most promising candidates for SIBs owing to the high theoretical energy density (ca. 400 Wh/kg), good thermal stability (450°C) and highly covalent three-dimensional framework with large interstitial channels for fast sodium-ion migration. In the present study, mesoporous Na3V2(PO4)3 nanoparticles with highly sp2-coordinated carbon coatings (meso-Na3V2(PO4)3/C) were successfully synthesized by employing ascorbic acid as both of the reductant and carbon source, followed by calcination at 750°C in an argon atmosphere. The crystalline structure, morphology, surface area, carbon nature and amount were systematically identified by powder X-ray diffractometer, field-emission scanning electron microscope, transmission electron microscope, nitrogen adsorption-desorption technique, Raman microscope and thermogravimetric analyzer, respectively. Given their distinctive mesostructures and continuous sp2-coordinated carbon coatings, the remarkable reversible capacity (98 mAh/g@0.1 A/g), rate capability (63 mAh/g@1 A/g) and capacity retention (76 %@450 cycles@0.4 A/g) were achieved as demonstrated by galvanostatic testing. Consequently, the resultant meso-Na3V2(PO4)3/C were anticipated to function as efficient cathode materials for SIBs. More importantly, it appears to be a facile approach towards mass production of the electrode materials because the inexpensive chemicals and mild conditions were introduced to prepare the precursor powders.

Acknowledgements

We gratefully appreciate the financial support from the Bureau of Energy (BOE), Ministry of Economy Affair (MOEA), Taiwan.
Catalytic Activity Variation with the Crystal Structure Change of PdCu Nanocatalysts for Rechargeable Lithium-Oxygen Batteries
Authors: Park Mihui , Song Kyeongse , Kang Yong-Mook
Published: February 2020

Palladium-copper (Pd-Cu) alloys have two representative crystal structures; one is body-centered cubic (bcc), the other is face-centered cubic (fcc) even though both Pd and Cu originally have fcc crystal structures. The fcc Pd-Cu alloys have disordered structure within which Pd and Cu atoms are positioned randomly in fcc lattice, whereas the bcc Pd-Cu alloys have ordered structure which consists of alternative layers with either Pd or Cu atoms. In order to properly design the optimum Pd-Cu alloys, its physical and chemical characteristics have been extensively controlled.

Pd-Cu alloys have been widely utilized as a catalyst for the hydrogenation of carbonyl compounds, the reduction of nitrates and nitrites in water, the oxidation of formic acid in direct formic acid fuel cell, the membrane for hydrogen separation and so on. In particular, bcc Pd-Cu alloys have occasionally shown superior performance to fcc Pd-Cu alloys. As for the hydrogenation of acetylene, bcc Pd-Cu alloy have better ethylene selectivity than fcc Pd-Cu alloys, because isolated Pd atoms on the surface of bcc Pd-Cu alloys enhance selectivity. Most of bcc Pd-Cu alloys have been synthesized by annealing fcc Pd-Cu alloys for structural transformation and particle growth. Hence, the same size of fcc and bcc Pd-Cu alloys is quite difficult to be obtained because the crystallites larger than 20 nm favour the ordered bcc structure with lower symmetry. Thus, bcc Pd-Cu alloys in nanoscale have been rarely reported, and fcc and bcc Pd-Cu alloys have never been properly compared until now.

In this study, we successfully synthesized fcc and bcc Pd-Cu alloys in nanoscale through a simple polyol process. For the comparison between these in catalytic activity, we adopted fcc and bcc Pd-Cu alloys as cathode catalysts for lithium-oxygen batteries. This work would firstly report the comparison between the catalytic activities of fcc and bcc Pd-Cu alloys in nanoscale.
The Effect of the V2O5 Morphology on the Intercalation Behavior of Na+-Ions
Authors: Seidl Lukas , Martens Sladjana , Stimming Ulrich , Schneider Oliver
Published: February 2020

Na-ion batteries (NIBs) are one of the most promising technologies to replace the costly Li-ion batteries (LIBs), since the latter suffer from a lower Li-abundance, which makes LIBs more expensive.1
,
2 Additionally to the higher Na-abundance, Na does not, in contrast to Li, form an Al-alloy during battery operation, which allows the use of Al-current collectors instead of the costly and heavy weight Cu used in LIBs.3 These advantages on the other hand are balanced by restrictions of the NIBs originating from the larger ionic radius and atomic weight of the Na+-ions.3
,
4

Since V2O5 is a suitable intercalation host material for Na+-ions and it can be structured in a wide morphological variety,5
,
6
,
7
,
8
,
9 the effect of structural properties of V2O5 electrodes on the Na+-intercalation has been studied. For this purpose different V2O5 morphologies, ranging from nanostructures, like single crystalline nanobelts, to microstructures, like solid, hollow or yolk-shell V2O5-spheres, were electrochemically tested as cathode material, considering the impact on e.g. phase transformations, capacity, rate capability, efficiency and cycling stability.

References

1. Yabuuchi, N., Kubota, K., Dahbi, M. & Komaba, S. Research Development on Sodium-Ion Batteries. Chem. Rev.
114, 11636–11682 (2014).

2. Palomares, V. et al. Na-ion batteries, recent advances and present challenges to become low cost energy storage systems. Energy Environ. Sci.
5, 5884 (2012).

3. Slater, M. D., Kim, D., Lee, E. & Johnson, C. S. Sodium-Ion Batteries. Adv. Funct. Mater.
23, 947–958 (2013).

4. Hong, S. Y. et al. Charge carriers in rechargeable batteries: Na ions vs. Li ions. Energy Environ. Sci.
6, 2067 (2013).

5. Tepavcevic, S. et al. Nanostructured bilayered vanadium oxide electrodes for rechargeable sodium-ion batteries. ACS Nano
6, 530–538 (2012).

6. Su, D. & Wang, G. Single Crystalline Bilayered V2O5 Nanobelts for High-Capacity Sodium-Ion Batteries. ACS Nano
7, 11218–11226 (2013).

7. Su, D. W., Dou, S. X. & Wang, G. X. Hierarchical orthorhombic V2O5 hollow nanospheres as high performance cathode materials for sodium-ion batteries. J. Mater. Chem. A
2, 11185 (2014).

8. Uchaker, E. et al. Better than crystalline: amorphous vanadium oxide for sodium-ion batteries. J. Mater. Chem. A
2, 18208–18214 (2014).

9. Kim, H., Kim, D. Y., Kim, Y., Lee, S.-S. & Park, K. Na Insertion Mechanisms in Vanadium Oxide Nanotubes for Na-Ion Batteries. ACS Appl. Mater. Interfaces
7, 1477–1485 (2015).
1D Structured Fe-Doped Tunnel Na0.44MnO2 Cathode Material with Excellent High Rate and Long Cycle Life Performance for Sodium Ion Battery Application
Authors: Amedzo-Adore Mawuse , Han Dong-Wook , Yang Junghoon , Kang Yong-Mook
Published: February 2020

Due to concern over the sustainability of Lithium ion battery (LIB) as energy storage system as a result of its limited resources, sodium ion battery (SIB) has been considered as an alternative energy storage system to supplement LIBs, due to the fact that, sodium is abundant and less expensive comparable to lithium. Concentration have been on obtaining the appropriate electrode materials for SIB application. NaxMnO2 has demonstrated its ability as a cathode material in SIB. There are different phases of these materials depending on the amount of Na present. Among these Mn-based cathode materials, tunnel Na0.44MnO2 structure, have received wide attention due to; its large channel which is considered to be suitable for ion insertion/extraction process as a cathode, and structural stability attributed to the formation of MnO5 pyramid and sheets of edge-shared MnO6 octahedral to form a large S-channel. However, these tunnel materials suffer from low initial charge and reversible capacities. Also, they are known to have drawbacks associated with lattice transformation which is attributed to Jahn-Teller distortion and Mn2+ dissolution as a result of disproportionation reaction of Mn3+ into Mn2+ and Mn4+ during repeated cycling. These disadvantages are considered to cause considerable strains in the crystal structure, leading to inferior rate and cycling performance.

To find remedy to the above drawbacks and to enhance electrochemical performance, 1D nanostructured Fe-doped Na0.44MnO2 was adopted. Fe substitution of Mn in the structure, helps to maintain material structural stability by suppressing Mn dissolution during cycling, and also give rise to increase in the operating voltage leading to increase in the energy density of the material. 1D nanostructured materials generally shows better performance as it improves the ion diffusion rate. The above adopted strategies provide improved electrochemical performance with excellent rate capability and long cycle life comparable to pristine tunnel Na0.44MnO2 for SIB application.
Mesoporous RuO2/Fe2O3 Nanofiber As Efficient Electrocatalyst for Lithium Oxygen Batteries
Authors: Huang Zhimei , Shen Yue , Huang Yunhui
Published: February 2020

Recently, great attentions have been paid to the development of Lithium oxygen batteries (LOBs) as for its highest energy density up to 3505 Wh kg-1 than the conventional Lithium ion batteries1,2. However, there still have some obstacles to make it practical application in respect of its sluggish charge transfer between the insulating Li2O2 and electrode surface. Thus, many challenges like high overpotential, poor cycle stability, and low rate capacity exists and limits its applications in life. Many researches have made great progress in the development of the OER catalyst which can promote the dissolution of Li2O2. Among them, RuO2 has been widely investigated due to their high electronic conductivity and superior catalytic activity especially for OER3. Additionally, many metal oxides were also been studied in catalyzing the OER reactions, while Fe-based catalysts that exhibit electrocatalytic activities in fuel cells were seldom studied in Li-O2 batteries. Therefore, in this text, we synthesize mesoporous RuO2/Fe2O3 nanofibers by electrospinning as efficient and cost-effective OER catalyst. The synthetic mesoporous RuO2/Fe2O3 nanofibers has a high surface area which is benefit to the diffusion of oxygen and transfer of ions. The discharge and charge capacity in the first cycle are as high as 5600mAh/g and 5200mAh/g at a current density of 200mA/g with lower charging potential, respectively. In addition, a well cycling performance was achieved when limited capacity of 2000mAh/g due to the unique structure of cathode catalyst which has a high surface area with more reaction sites and enough space for Li2O2 deposition. In this way, the mesoporous RuO2/Fe2O3 nanofibers as a new cathode catalyst shows combined effect in catalyzed the dissolution of Li2O2. Reference:

1. Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J.-M. Nat. Mater.
2012, 11, (1), 19-29.

2. Luntz, A. C.; McCloskey, B. D. Chemical reviews. 2014, 114, (23), 11721-50.

3. Yoon, K. R.; Lee, G. Y.; Jung, J.-W.; Kim, N.-H.; Kim, S. O.; Kim, I.-D. Nano Letters. 2016, 16, (3), 2076-2083.

Figure 1
High-Capacity Na-Excess Positive Electrode Materials; Na3NbO4-NaMnO2 Binary System
Authors: Sato Kei , Yabuuchi Naoaki
Published: February 2020

The research interest for rechargeable sodium batteries is rapidly growing, especially for the large scale energy storage. Recently, we have reported a new Li-excess positive electrode material, Li3NbO4 – LiMnO2,[1] which effectively utilizes solid-state redox reaction of oxide ions, instead of classical redox of transition metals. The use of Na-excess materials and anion redox is important strategy to further increase the energy density of rechargeable sodium batteries.[2] In this study, Na3NbO4 is targeted as a model material and the possibility of new high-capacity electrode materials with the anion redox is examined. Our trials to synthesize Na3NbO4-NaMnO2 binary system by a conventional solid-state method were, however, failed, and therefore the materials were prepared via a non-equilibrium route.NaMnO2 was prepared by solid-state reaction from Na2CO3 (99.5 %, Wako Pure Chemical Industries, Ltd) and Mn2O3 and Na3NbO4 was prepared from Na2CO3 and Nb2O5 (99.9 %, Wako Pure Chemical Industries, Ltd). Both oxides were used as precursors. A mixture of Na3NbO4 and NaMnO2 was ball-milled using a ZrO2 pot and balls. Figure 1a shows X-ray diffraction patterns of the samples of x = 0.43 in x Na3NbO4 – (1–x) NaMnO2 binary system as a function of milling time. The chemical formula of the sample is reformulated as Na1.3Nb0.3Mn0.4O2. The mixture of Na3NbO4 and NaMnO2changes into cation-disordered rocksalt phase after the mechanical milling for 24 h. SEM images before and after ball-milling (24 h) are also compared in Figure 1b. Particle size are decreased to nano scale with spherical morphology. Moreover, thus prepared sample delivers large reversible capacity which cannot be explained on the basis of redox reaction of the transition metal ions.From these results, we will discuss the possibility of Na-excess positive electrode materials with anion redox for rechargeable Na batteries. References[1] N. Yabuuchi, M. Takeuchi, M. Nakayama, H. Shiiba, M. Ogawa, K. Nakayama, T. Ohta, D. Endo, T. Ozaki, T. Inamasu, K. Sato, and S. Komaba, PNAS, 112, 7650-7655 (2015).[2] P. Rozier, M. Sathiya, A.-R. Paulraj, D. Foix, T. Desaunay, P.-L. Taberna, P. Simon, J.-M. Tarascon, Electrochemistry Communications, 53, 29 (2015). 

Figure 1
An Electrically Rechargeable Al-Air Battery with Aprotic Ionic Liquid Electrolyte
Authors: Bogolowski Nicky , Ngaleu Olivia , Drillet Jean-Francois
Published: February 2020

Because of their higher theoretical energy density, lower toxicity, less expensive electrode materials and non-affinity to thermal runaway like e.g. Li-based systems, metal/air batteries such as Al/air (8040 vs. 2046 Ah L-1for Li) are potential candidates for sustainable energy storage applications. However, large scale commercialisation is hindered by some inherent drawbacks related to the metal electrode such as irreversibility (not electrochemically rechargeable), passivation and parasitic hydrogen evolution as well as low energy efficiency [1]. In this context, recent developments in aprotic room temperature ionic liquids (RTIL) based electrolytes such as 1-Ethyl-3-methylimidazolium (EMIm) chloride + aluminum chloride and 1-Butyl-1-methylpyrrolidinium (BMPyr) open new perspectives for Al deposition/dissolution, especially with respect to suppression of passive layer formation and self-discharge due to hydrogen evolution [2,3]. Most of the ILs, however, are highly viscous and consequently have a very low ionic conductivity that drastically limits reaction kinetics. Other crucial aspects are related to the low surface tension of pure ILs compared to water that commonly hinders 3-phase boundary formation at the gas-diffusion electrode. Development of highly active and stable bi-functional air electrode catalysts is still challenging as well. By nature some catalysts are poor electronic conductors or need distribution/support, requiring the addition of conductive materials such as carbon/graphite. For long-term stability of the gas diffusion electrode, highly corrosion-resistant carbon material is required.

In this work, commercial carbon materials have been tested regarding their stability by means of TGA and electrochemical accelerated degradation tests (ADT) in 7 M KOH. Carbon materials KS6L, C65 and Vulcan showed the highest both thermal and electrochemical stability. La0.7Ca0.3CoO3 (LCCO) and Ba0.5Sr0.5C00.8Fe0.2O3 (BSCF) were synthesized by a sol-gel process and characterized by XRD and SEM. GDE fabrication was performed by calendering a catalyst/carbon/PTFE mixture onto a Ni current collector. LCCO/C and BSCF/C activity and stability for oxygen reduction (ORR) and oxygen evolution (OER) reaction were first evaluated in 7 M KOH under half-cell conditions where 1750 and 2000h operation at 10 mA cm-2 was reached, respectively without any relevant cell potential decay. First experiments with ILs were conducted in a commercial El-Cell setup. Performance of as-prepared perovskite-based GDEs in different ILs was compared with that of a commercial Pt-C one. At a catalyst loading of 1 mg cm-2 for GDE, best results were obtained with Al foil // EMIMCl + ACl3 // Pt-C combination at 50 µAcm-2.

Literature:

[1] Pino, M.; Chacón, J.; Fatás, E.; Ocón, P., J. Power Sources 299 (2015) 195

[2] Zein El Abedin et al., Electrochemistry Communications 12 (2010) 1084

[3] Giridhar, P.; Zein El Abedin, S.; Endres, F., Electrochimica Acta 70 (2012) 210
(Invited) Fluorescent Frequency Domain Oxygen Sensing and Gradient Imaging within Microfluidic Structures
Authors: Grate Jay W , Kelly Ryan , Anheier Norm , Suter Jonathan , Liu Bingwen , Bernstein Hans , Vasdekis Andreas , Schmidt Tom , Ghosh Ruby
Published: February 2020

Development of microsensors and microfluidics have proceeded in parallel for a number of decades. The incorporation of chemical sensing within microfluidic structures presents specific challenges, however. As one of the most important electron acceptors in biology, oxygen is of particular interest as a as a factor many processes, down to the pore scale. Microfluidic structures offer unique opportunities to create microenvironments that set up gradients and environmental conditions that are relevant to biomedical or natural biogeochemical systems. Gradients of molecular oxygen are of particular interest due to the fact that many important biological processes either occur at interfaces or are regulated by the flux of oxygen and other resources. Here we describe approaches to sense oxygen concentrations and gradients within microfluidic structures, using localized films of fluorescent oxygen sensing dyes and frequency domain fluorescent lifetime imaging. Of particular interest is to design systems where the fluorescent images also match the microfluidic spatial structure within the device. This is a concern because the simplest conventional approach, sandwiching a polymer film containing an oxygen sensing dye between a cover plate and a structured base plate produces a fluorescent signal across the entire device, including (mostly) areas that have nothing to do with the microfluidic structure. By contrast, we are pursuing approaches where the fluorescent signal is only seen in microchannel areas. Diverse approaches will be contrasted for fabricating and imaging oxygen sensing microfluidic structures, including pore network structures as models for natural systems at the pore scale.
Sensor Based Low Cost Agriculture Monitoring System Using Polymeric Hydrogel
Authors: Kabir M. Hasnat , Ahmed Kumkum , Furukawa Hidemitsu
Published: February 2020

A polymeric super absorbent hydrogels are a kind of gels, obtained by chemically synthesized with hydrophilic polymers in a form of 3D-network structure. This hydrogels have been extensively used in agriculture over the last two decades as an absorbent. The aim of this work is to use the polymeric hydrogel for increasing the water holding properties of growing media such as soil and will develop a low cost system for monitoring. Two types of polymeric hydrogels were prepared and the swelling ratio was determined. Three times higher swelling ratio is observed at DMAA (90 wt%) than that of SMG (30 wt%) even though both samples have the same cross-linker (MBAA). The mechanical and dynamic light scattering results suggest the DMAA based hydrogel is suitable for agriculture. The sensor based monitoring system was developed which indicates the merit of the system.
Effect of Post Deposition Annealing on ALD-ZrO2/SiON Gate Stacks for Advanced CMOS Technology
Authors: Gupta Richa , Vaid Rakesh
Published: February 2020

To meet the existing challenges associated with gate leakage current and scaling beyond 22 nm node, we report the fabrication of 8.46 nm thin ALD-ZrO2 film on silicon substrate with ~ 5.43 nm SiON as interfacial layer. Electrical characterizations such as capacitance-voltage and current-voltage measurements reveal that the post deposition annealing (PDA) of ZrO2 in NH3 ambient results in improving various performance parameters such as leakage current density (92% decrease), effective oxide thickness (~22% decrease) and dielectric constant (~32% increase) when compared to PDA in N2 ambient. The surface roughness for N2 and NH3 annealed ZrO2 samples studied using AFM were found to be 0.4949 nm and 0.1385 nm respectively; thereby showing 72% decrease in surface roughness for NH3 annealed samples. The thicknesses of the grown films were corroborated by Ellipsometry and FESEM while the structural analysis was carried out using FTIR technique. The results demonstrate that post deposition annealing of ZrO2 film in NH3 ambient at 5000 C using rapid thermal processing (RTP) gives reduced EOT (~ 1.7 nm), increased K (~30) along with the suppressed off-state leakage current density (2.1× 10-9 A/cm2) and this performance enhancement is attributed to the effective replacement of oxygen by nitrogen atom to form a thermally stable phase of ZrON. Some of the important results obtained from the present work has been exemplified in the figure below.

Keywords: Post depositionannealing (PDA); Zirconium oxide (ZrO2); leakage current density (J); effective oxide thickness (EOT); high- K dielectrics.

Figure 1
Plasmonic Nanostructures for High-Performance Biosensing Devices
Authors: Xiao Bo , Pradhan Sangram , Santiago Kevin , Rutherford Gugu , Pradhan Aswini K
Published: February 2020

The development and implementation of nanotechnology for biomedical diagnostics and sensing applications have tremendous societal impact. These research directions represent leading edges of the fast-moving development in nanotechnologies with strong insight into the understanding of both fundamental and applied aspects of nanoscience and nanotechnology. We would discuss how nanotechnology has made a tremendous impact, especially in the field of health care. The artificially engineered nanostructures are becoming extremely important due to intricate interplay of light and matter, and produce many useful sensing and energy devices. In that regard, can we make very cost-effective, high throughput nano devices for visual identification of diseases for early stage prevention? We have demonstrated that light transmitted through a nanostructured metal thin film without any apertures can be significantly enhanced. The sensitivity of the resonances to the surrounding medium and the transmission efficiency demonstrate its use for imaging, optical processing, sensing, and point-of-care diagnostic applications. We will discuss the effects of plasmon coupling with the Fano resonances, which enhances the detection sensitivity. We will discuss a cost effective way for the mass production of such diagnostic tools, which may significantly impact the health care for the point-of-care diagnostics.
An Inkjet-Printed Hydrogen Peroxide Sensor on Paper
Authors: Shamkhalichenar Hamed , Choi Jin-Woo
Published: February 2020

This work presents a fully inkjet-printed electrochemical sensor on paper for non-enzymatic detection of hydrogen peroxide. A simple and low cost hydrogen peroxide (H2O2) sensing is desired in biomedical and environmental analysis. Enzyme-based sensors have widely been used but the possible chemical and thermal deformation of enzymes during the fabrication of the sensors may influence the stability and reliability of the sensors [1]. An alternative to enzymatic sensing could be electrocatalytic detection utilizing the electrocatalytic property of silver (Ag) nanoparticles in reducing H2O2[2].

In this work, we utilize the same principle for a fully printed sensor on paper. An ink solution containing multi-walled carbon nanotubes and silver nanoparticles has been developed before printing the electrode patterns on paper. Using an office inkjet printer and the developed ink, an electrochemical sensor has been designed and printed as shown in Figures 1(a) and 1(b). A total of 50 prints were applied to form the electrodes with high conductivity. A hydrophobic barrier formed by a wax has also been patterned to prevent a sample solution reaching from electrical contacts.

The developed sensor was tested with different concentrations of hydrogen peroxide samples. A custom-made potentiostat circuit was used for testing the sensor. Step voltammetry was used by measure the current response after applying -0.3 V to the working electrode. Figure 1(c) shows preliminary results of the sensor response demonstrating that the working electrode current increased with the concentration of H2O2.

In summary, a fully inkjet-printed hydrogen peroxide sensor has been demonstrated and its preliminary results have been obtained. The sensor design is currently under optimization to achieve a lower detection limit and high sensitivity.

References

[1] M. Song, S. Hwang, and D. Whang, “Non-enzymatic electrochemical CuO nanoflowers sensor for hydrogen peroxide detection,” Talanta, vol. 80, no. 5, pp. 1648-1652, 2010.

[2] W. Zhao, H. Wang, X. Qin, X. Wang, Z. Zhao, Z. Miao, L. Chen, M. Shan, Y. Fang, and Q. Chen, “A novel nonenzymatic hydrogen peroxide sensor based on multi-wall carbon nanotube/silver nanoparticle nanohybrids modified gold electrode,” Talanta, vol. 80, no. 2, pp. 1029-1033, 2009.

Figure 1. Inkjet-printed hydrogen peroxide sensor: (a) the sensor design with working, counter, and reference electrodes all formed with inkjet printing; (b) a picture of the printed sensor on paper, and (c) preliminary results of the developed sensor.

Figure 1
a Study on Degradation of Ni-YSZ Anode Materials in Terms of Redox Stability for Solid Oxide Fuel Cells
Authors: Park Jae-Woo , Park Yoon-Tae , Lee Sang-Hun , Lee Ki-Tae
Published: February 2020

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Introduction

Solid oxide fuel cells (SOFCs) have lately attracted considerable attention as the source of new energy considering environmental pollution and exhaustion of underground resources. Nickel-yttria stabilized zirconia (Ni-YSZ) cermet has been used as an anode material for SOFCs for more than 20 years. Although Ni-YSZ has various advantages such as high catalytic activity for H2 oxidation and methane reforming, stability in reducing atmosphere, high electrical conductivity, it exhibits various types of degradations such as poor redox stability, sulfur poisoning, carbon deposition. Ni-YSZ anode still suffers from exposure to oxidizing condition caused by sudden interruption of fuel or sealing problem like leakage. When exposed in oxidizing atmosphere, Ni-YSZ experiences significant volume change due to the oxidation of Ni to NiO, which causes internal cracks and consequent destruction of the cell. In this study, the redox stability of Ni-YSZ cermet according to various conditions such as porosity, pore size distribution, and composition has been studied systematically.

 

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Experimental

NiO-YSZ composite powders have been prepared by mixing of commercial NiO (High purity chemicals, 99.97%), 8YSZ (TZ-8YS: 8 mol% Y2O3-stabilized ZrO2, 99.9% Tosoh, Japan) and PMMA as a pore former. The NiO-YSZ bulk samples were fabricated by the typical die compaction method and sintering at 1450 °C for 4 h in air. The sintered NiO-YSZ samples were reduced at 800 °C for 3 h in H2 in order to make Ni-YSZ. The phase change was confirmed by the X-ray diffraction (XRD). The morphology of Ni-YSZ was investigated by scanning electron microscopy (SEM). Degree of oxidation (D.o.O) of Ni was calculated from thermogravimetric analysis (TGA) data. The amount of volume change of Ni powders during oxidation was measured using a helium pycnometer. The both porosity and pore size distribution of Ni-YSZ bulk samples were analyzed with mercury porosimeter. The linear length change of Ni-YZ during oxidation was measured using dilatometer.

 

▪
Results and Discussion

If we know both temperature and time of exposure in oxidizing atmosphere, we can predict the D.o.O of Ni at a certain condition using the D.o.O equation obtained from TGA data. The percentage weight gain per specific surface area can explain the oxidation kinetics of the Ni-YSZ anode supports, which obeys a multi-stage parabolic law expressed by Kp. Kp can be expressed by Kp1 and Kp2. Kp1 and Kp2 correspond to fast oxidation reaction at early oxidation stage and slow oxidation reaction at the next oxidation stage, respectively. The volume change of Ni-YSZ caused by oxidation can be the result of two competing factors: expansion caused by NiO formation and shrinkage caused by continuous sintering of both Ni and NiO. Ni-YSZ cermet with high porosity showed higher tolerance to the cumulative length change due to providing the more relaxation space.
A Study on Contamination Control of Fume By Analyzation of Air Current
Authors: Lee Sunghoon , Kim Byungsu , Park Segeun , Choi Sanghyun , Yoon Taeyang
Published: February 2020

Fume is major pollution source which is occurred after etch process. [1] Fig. 1 is shown how fume is exhausted after etch process. And wafer stay in buffer during exhausting. At this time, this fume is absorbed with surface of wafer or remained on surface of wafer. Additionally, this fume combines with atmospheric moisture in air. And it is changed to particle the diameter of this particle is less than 1um. So, this fume often make serious wafer defect. For these reasons, if we cannot control this fume, product quality and wafer yield is seriously decreased. Moreover, it makes productivity issues because we spend a lot of time for fume removal process of defected equipments like fig 1. So, our paper proposes several optimization methods for ‘out buffer system’.

Firstly, several gases stay in exhaust system like fig 2(a). This analysis is use aero-dynamics simulation for traditional exhaust systems. This result of simulation is shown some gas stay in system. This gas is normally changed to fume. For reducing this remained gas, we change diameter of vacuum line like fig 4. It shows our final optimized system. Major optimization of systems that the diameter of vacuum line is changed from 200 Ø to 100 Ø. To choose this optimized diameter, we use Bernoulli's theorem [2]. Fig 3 shows that two output vacuum lines are connected to same direct line. So there are different pressures in vacuum line. This is the reason why turbulence flow occurred. To find optimal diameter of this exhaust pipe line, we use Bernoulli's theorem simulation with various test design. Finally we found a optimal structure of vacuum line.

REFERENCE

1. Effects of reactant rotational excitation on reactivity: Perspectives from the sudden limit B Jiang, J Li, H Guo - The Journal of chemical physics, 2014 - scitation.aip.org

2. Department of Mathematics, Hoseo University, Chungnam 336-795, Korea *School of Mechanical Engineering

Figure 1
An Assessment of Copper Electrodeposition into Bakky-Pepar Consisted of Single-Walled Carbon Nanotube
Authors: Kirihata Kyohei , Arai Susumu , Katada Arinobu , Hirota Mitsuhito , Uejima Mitsugu
Published: February 2020

Introduction

Copper has many useful properties, such as high electrical conductivity, good thermal conductivity and ductility, resulting in the widespread use of copper plating in an electronics industry. Single-walled carbon nanotubes (SWCNTs) also exhibit attractive characteristics, including stable electrical resistance in the presence of high currents, superior thermal conductivity and good field emission properties, and so have a wide range of applications. Cu/SWCNT composites are also expected to exhibit excellent electrical and thermal conductivities. In the present research, we attempted to fabricate a novel Cu/SWCNT composite by copper deposition into Bakky-paper consisted of SWCNTs.

Experimental

Bakky-paper (SWCNT sheet) with a thickness in the range of 30 to 40 mm (Zeon Co.) was used as the cathode, and copper electrodeposition was performed on both sides under galvanostatic conditions with an immersed surface area of 2 cm2(= 1 cm × 1 cm × 2). Copper containing phosphorous as anodes were placed at both sides of the cathode, and then copper deposition was carried out with or without additives. The additives were polyethylene glycol (PEG), chloride ions, bis(3-sulfopropyl) disulfide (SPS) and Janus green B (JGB). The surfaces and cross-sectional morphologies of the composites obtained by the electrodeposition were observed by a field emission scanning electron microscopy (FE-SEM). The effects of plasma pretreatment of the Bakky-paper (SWCNT sheet) on microstructure and copper deposition were also examined.

 

Results and Discussion

Figure 1 compares cross-sectional SEM images of Cu/SWCNT composites prepared by two kinds of electrodeposition bath. Figure 1(a) displays the composite prepared in a bath without additives. It is clear that copper plating proceeded only on Bakky-paper surface. This is the reason why the plating liquid could not penetrate the sheet. In contrast, the use of various additives in the plating bath (100 ppm PEG + 50 ppm Cl- + 2 ppm SPS + 2 ppm JGB) resulted in copious copper deposition within the sheet structure (Figure 1(b)). Electrodeposition under these conditions also generated numerous voids in the Cu/SWCNT composite and greatly increased the thickness of the SWCNT sheet. The application of the Cu/SWCNT composite-film would be effective for the development of electronics devices.

Figure 1
Solid Oxide Photo-electrochemistry with Oxides “Breathing” upon UV Light and Solar Cells Operating at 400°C
Authors: Fleig Juergen , Walch Gregor , Opitz Alexander Karl , Kubicek Markus , Brunauer Georg Christoph , Rotter Bernhard , Ponweiser Karl
Published: February 2020

Photo-electrochemistry is largely based on aqueous electrolytes. However, the efficiency and/or materials stability in such cells is still not sufficient for widespread application. This raises the question whether solid electrolyte based systems may also be an option. Very little is known on the realizability of all solid state photo-electrochemical cells based on oxide ion conductors; UV light was shown to accelerate oxygen incorporation into SrTiO3 [1] and a theoretical model of a solid state photo-electrochemical cell including a mixed conducting electrode was described in Ref. [2]. Here, we present experiments of two novel approaches to solid oxide photo-electrochemical cells.

SrTiO3 with Pt current collector was used as an electrode on an oxide ion conductor (YSZ). Upon UV light, cell voltages in the 200 mV range result at ca. 400°C. Oxygen incorporation of the illuminated SrTiO3, i.e. a kind of “breathing” of the electrode, modifies the voltage and an EMF remains even after switching off the light. Two effects take place: a photo-voltage develops, which is coupled to the external circuit via a solid electrolyte, and a battery-type (Nernst) voltage builds up upon illumination. The latter reflects the oxygen chemical potential difference induced by the “breathing” of the oxide and corresponds to a kind of light driven-battery charging.

A second approach makes use of a high temperature solar cell which consists of a Sr-doped LaCrO3 thin film on a SrTiO3 single crystal. This heterojunction leads to photo-voltages as high as 900 mV at 400°C [3]. The photon induced driving force was then used to pump oxygen from low to high oxygen partial pressures and thus to chemically store photon energy [3]. In the corresponding solid oxide photo-electrochemical cell, the bottom electrode of the oxide solar cell (Sr-doped LaFeO3) was employed as the top electrode of a zirconia based solid electrochemical cell. By short circuiting the outer electrodes of this oxide hetero-structure electrochemical oxygen pumping became possible.

[1] X. Ye, J. Melas-Kyriazi, Z. A. Feng, N. A. Melosh, W. C. Chueh, Phys. Chem. Chem. Phys. 2013, 15, 15459-15469.

[2] R. Merkle, R.A. De Souza, J. Maier, Angew. Chem. Int. Ed. 2001, 40, 2126-2129

[3] G. C. Brunauer, B. Rotter, G. Walch, A. K. Opitz, G. Ponweiser, J. Summhammer, J. Fleig, Adv. Funct. Mat. 26 (2016) 120-128