bluuebunny/crossref_metadata_2025 huggingface dataset:
Transition Metal Sulfides As Conductive Additives for Sulfur Electrode in Li-S Battery
Authors: Sun Ke , Su Dong , Zhang Qing , Bock David C , Marschilok Amy C , Takeuchi Esther S , Gan Hong
Published: February 2020

Lithium-Sulfur (Li-S) battery has been a hot research topic currently due to its potential of combining high energy density and low cost together.  In this work, we have investigated various transition metal sulfides (CuS, FeS2, TiS2, CoS2) as conductive additive to sulfur electrode in lithium-sulfur (Li-S) battery. We found that all metal sulfides additives enhanced the utilization of sulfur cathode at high rate discharge when compared with a sulfur-carbon composite electrode with equivalent sulfur volumetric loading. Systematic study suggests the reason for the enhancement is the activation of the polysulfide to Li2S2/Li2S conversion process that constitutes the second plateau in Li-S battery discharge. Besides, the results also indicate that the high electronic conductivity of transition metal sulfides could not fully account for the second plateau activation. Instead, it is found that the interaction between polysulfide and metal sulfides is actually helping the nucleation process of Li2S2/Li2S nucleation and deposition, and the level of this interaction also has profound influence on the cycle life and columbic efficiency of sulfur electrodes with transition metal sulfide additives. The results of this study will help to direct the design of non-carbon based conductive fillers for sulfur electrodes and enable the development of high power Li-S batteries.
UCSD ECS Student Chapter: A Burgeoning Local Community in San Diego
Authors: Parikh Pritesh , Liu Haodong , Alvarado Judith , Nguyen Han , Meng Ying Shirley
Published: February 2020

The ECS student chapter at the University of California, San Diego (UCSD) represents a myriad group of students across various disciplines and education level that are involved in promoting electrochemistry science and technology. 

With over 24,000 undergraduate students, 4000 graduate students and 1000 full time faculty, UCSD has a large community that is interested topics ranging from energy storage and conversion to nanocarbons to photonic devices and even energy efficient building systems. The recent announcement of the multi-disciplinary SPEC (Sustainable Power and Energy Conversion) Center and a student run Energy Club provides our ECS local chapter with a unique opportunity to collaborate and educate students about electrochemistry. 

With the support of our faculty advisor, Prof. Shirley Meng and the ECS community at large, we have successfully hosted seminars from both academic and industry connections. Students associated with the UCSD ECS chapter have also had an opportunity to attend and present their work at annual symposium gatherings.  A successful first year of the student chapter, in 2014, enabled us to be featured in the ECS interface magazine. Following into our second year of operations, we are geared for another series of exciting seminars and demonstrations. 

We are very happy to share with you some of previous efforts, ongoing activities and future plans for our local student chapter.

Figure 1
Electroplating Titanium on Conductive and Non-Conductive Substrates
Authors: Parker Margaret
Published: February 2020

Crista Chemical Company LLC’s (3C) goal was to develop a novel, low-cost, industrial method of plating titanium on metallic and nonmetallic materials. Crista Chemical Company achieved this goal by developing an innovative technology of titanium electroplating and receiving a patent for the achievement U.S. Patent No. 9,023,187, and soon to be published ASTM B999-15.  The innovation was ground breaking as before the discovery, titanium electroplating was considered impossible.

Crista Chemical Company’s revolutionary innovation electrodeposits coatings of Titanium and Titanium-zirconium alloys on conductive and non-conductive substrates coated with low, medium, or high phosphate electroless nickel. Two methods of titanium deposition were designed and optimized. One was a conventional electroplating method—which used constant current—and another one was a nanocrystalline electrodeposition (we refer to as the “turbo method”), which uses pulse plating. In both methods electrodeposition of the titanium alloys proceeded from the sulfuric acid solution.

The advantages of the method of plating titanium include a) low cost, b) relatively low number of process steps, thus posing minimal effect on the environment (safer and zero discharge process) and c) very broad application.  Moreover,  Produced materials are characterized by a) light weight, b) high corrosion resistance c) high yield strength, d) wear resistance, e) high resilience, stiffness at room temperature as well as at elevated temperature (e.g. up to 200C). This makes the titanium coating an attractive technology for a variety of industries including: high efficiency batteries, medical applications, biotechnology, aerospace, defense, sports and automotive.
Electrochemical Mechanism Insights from Mott-Schottky Measurements: Application to Europium in Molten Oxide
Authors: Caldwell Andrew Harvey , Allanore Antoine
Published: February 2020

Electrochemical impedance measurements are commonly conducted at a constant direct current (DC) potential while sweeping the frequency of the perturbation. The mainstream plots used to discuss data are then Nyquist and Bode plots, on which fitting curves for the postulated equivalent circuit are represented.

Unfortunately for high temperature electrochemists interested in faradaic reactions in molten electrolytes with a high concentration of electroactive species [1] or a very high conductivity [2], this method rarely provides meaningful results due to data that are often noisy and difficult to interpret at potentials away from the open-circuit potential (OCP).

Methods employing a dynamic sweep of the DC potential at a fixed frequency of perturbation experimentally provide more reliable insight into electrochemical impedance phenomena in molten electrolytes. The archetypical example is alternating current (AC) voltammetry in its various forms, such as sine- or square-wave voltammetry [3][4]. However, most modern potentiostats offer only one means of conducting DC potential sweep impedance measurements, the so-called Mott-Schottky (MS) method. This method is not truly dynamic from a DC potential perspective, and is traditionally used for capacitance measurements and characterization of semi-conductor electrodes.

The present work shows a procedure to extract faradaic data from MS data, inspired from the background subtraction method previously proposed for AC-polarography [5].  Nyquist-type representations are derived from the MS data, enabling a connection to mainstream impedance analysis methods. An example of this procedure, an investigation of the electrochemistry of europium ions in molten oxide, is provided.

[1] A. Kisza, Polish J. Chem., 67 [1993] 885-894

[2] B. Savova-Stoynov and Z.B. Stoynov, Journal of Applied Electrochemistry, 17 [1987] 1150-1158

[3] A.M. Bond et al., Anal. Chem., 77 (9) [2005] 186-195

[4] C. Montel, C. Russel and E. Freude E, Glastech Ber, 61, [1988], 59–63

[5] A.M. Bond et al., J.  Electroanal. Chem., 222 (1) [1987] 35-44.
An Active Li-Mn-O Compound for High Energy Density Li-Ion Batteries
Authors: Freire Melanie , Kosova Nina V. , Jordy Christian , Chateigner Daniel , Lebedev Oleg , Maignan Antoine , Pralong Valerie
Published: February 2020

Due to their low weight, high energy densities and long cycle life, the battery scientific community is still trying to develop new high capacity cathodes materials in order to increase the energy density of storage devices [1].

After a composition screening, a new material family has been discovered in the Li-Mn-O system and has been investigated as potential new material for Li-ion batteries to replace conventional NMC materials (LiNi1/3Mn1/3Co1/3O2) [2]. In this study, we report for the first time the synthesis, structural and electrochemical characterizations of a new non-lamellar oxide with the highest capacity observed ever before in the Li-Mn-O system. This new patented [3] material with the composition of Li4Mn2O5 shows a discharge capacity of 300 mAh/g. It is a rock-salt type nanostructured material, prepared by a direct mechanochemical synthesis. The typical crystallite size is about 5-10nm (from Transmission electron microscopy TEM and electron diffraction ED). The ring ED pattern of this individual phase can be indexed on the cubic Fm-3m structure, with a rock-salt cell parameter of a=4.16Å, according to Rietveld refinement.

The electrochemical performances were performed at a C/20 rate, and show a reversible discharge capacity about 300 mAh/g. A gradual increase in the cut-off voltage up to 4.8V activates the material and prevents the electrolyte degradations. During cycling, the derivative curves indicate at least 2 active redox couples [4]: Mn3+/ Mn4+ (around 3.3V), Mn4+/ Mn5+ and/or O2-/ O- (around 4.1V).  In order to have a better insight of lithium deinsertion process, we used magnetic measurements at various charge states. We will show that magnetic measurements are perfect tools to access to the oxidation level of the material, and in agreement with the values obtained after iodometric redox titrations. We will namely show that this material is oxidized up to Mn5+oxidation state with a competition of the oxygen oxidation [4].

In short, in this work are reported the first results of a new electrochemically active compound as positive electrode for Li-ion batteries, with the active participation of both redox centers: Manganese and Oxygen [5].

[1]   B.L. Ellis, et al., Chem. Mater., 2010, 22, 691

[2]   H. Koga, et al., J. Electrochem. Soc., 2013, 160, A786

[3]   Patent FR1258625

[4]   M. Sathiya, et al., Nature Mat., 2013 , 12, 827

[5]   M. Freire et al., Nature Mat. Letters, 2015, 14, DOI : 10.1038/NMAT4479
Positive and Negative Potassium-Ion Electrodes' Behavior in Non-Aqueous Electrolytes
Authors: Vaalma Christoph , Buchholz Daniel , Passerini Stefano
Published: February 2020

Recent concerns about the availability of raw materials for lithium-ion batteries (LIBs) have led to an increased interest in alternative secondary battery technologies. Recently, from about 2010 on, researchers’ attention shifted back to sodium-ion batteries (NIBs) as they offer advantages like the replacement of the copper current collector of the anode by aluminum and low cost and abundant Na-reserves instead of relatively high cost and poorly distributed Li-reserves. These advantages are considerable, since NIBs show a comparable electrochemical performance to LIBs.1

A significant advantage of potassium-ion batteries (KIBs), if compared with NIBs, is the lower potential of K/K+ related to the standard hydrogen electrode (SHE). The standard potentials are reported as −2.71 V for Na/Na+, −2.94 V for K/K+ and −3.04 V for Li/Li+.2 Therefore, in theory, KIBs should deliver cell voltages similar to LIBs and higher than NIBs. Nevertheless, it needs to be considered that the higher radius and increased mass of K-ions result in decreased gravimetric and volumetric energy densities (76 pm and 6.941 g mol-1 for Li+; 100 pm and 22.990 g mol-1 for Na+; 140 pm and 39.098 g mol-1 for K+).2,3 Taking these aspects into account, KIBs could potentially show a combination of the advantages of LIBs and NIBs without suffering of their drawbacks.

With this work we demonstrate as positive and negative K-ion materials, including a K-ion full cell, may show interesting electrochemical performances which are worth to be investigated in greater detail by a wider scientific community.

References

1. N. Yabuuchi, K. Kubota, M. Dahbi, and S. Komaba, Chemical Reviews, 114, 11636–11682 (2014).

2. S. Komaba, T. Hasegawa, M. Dahbi, and K. Kubota, Electrochemistry Communications, 60, 172–175 (2015).

3. M. E. Wieser et al., Pure and Applied Chemistry, 85, 2013 (2013).
Catalytic Deposition of ZnO on Bi2O3 Surface Towards Prolonged Zn-Based Aqueous Rechargeable Battery
Authors: Shin Jaewook , Kumar Rajan , You Jung-Min , Wang Joseph , Meng Ying Shirley
Published: February 2020

Recently, the demand for the large-scale power system has gained much interest due to the increase in energy demand. Scientists recognize load leveling as one of the most crucial aspect in making efficient large-scale power generation. Electrical energy storage (EES) system is most promising type of energy storage systems. Among number of criteria for the large-scale EES, low cost is one of the main focus. To achieve low cost of EES, Zn based aqueous battery should be utilized in the EES, due to the abundance and low cost of Zn and water. However, Zn based aqueous battery suffers from an intrinsic problem. When the Zn is oxidized to ZnO, Zn(OH)4
-2 ion, intermediate phase is formed. This ion is soluble in aqueous electrolyte. When Zn is oxidized, most of the Zn2+ ion detaches from the current collector becoming inactive in the electrochemical process and the battery becomes non-rechargeable. There is a large number reports using Zn electrode in an electrochemical cell. Among them, numerous reports have suggested the use of Bi2O3 as an electrode additive. By simply mixing in the Bi2O3 to the Zn electrode, the electrochemical performance suddenly improves. Thus far in the literature, most explanation for such a phenomenon is improvement in the electrical conductivity. Due to the presence of Bi2O3, a better electrical connection is formed and thus the electrochemical performance is improved. However, electrical conductivity does not have an effect on the intrinsic chemical reaction of Zn oxidation. Here, we have conducted a series of characterizations to understand the mechanistic role of Bi2O3 in the Zn electrode. We have utilized electrochemistry, energy-dispersive X-ray spectroscopy mapping under scanning electron microscope, powder X-ray diffraction (PXRD), Raman spectroscopy, and X-ray photoelectron spectroscopy. Upon oxidizing the Zn electrode, the Bi2O3 surface was covered with ZnO. This ZnO had interactions with the Bi2O3 which was found in PXRD and Raman spectroscopy. We have discovered that the mechanism for the improved performance in the Zn based electrode with the presence of Bi2O3 is due to a surface catalytic deposition of ZnO. With the presence of Bi2O3, Zn oxidation reaction seems to skip the soluble Zn(OH)4
-2 phase formation and directly deposits ZnO onto the surface of Bi2O3. This finding open the way for further optimizing the Zn based electrodes for rechargeable aqueous batteries
The Development of High Capacity V-Based BCC Electrodes for Aqueous Metal Hydride Air Systems
Authors: Weadock Nicholas , Yang Heng , Tan Hongjin , Fultz Brent , Bugga Ratnakumar V
Published: February 2020

The energy density of traditional Ni-MH batteries could be dramatically increased by developing a higher capacity metal hydride alloy.  An even larger increase in energy density for MH-type electrochemical cells would be seen by pairing the high capacity metal hydride with an air cathode to create an MH-air battery.  Vanadium based BCC alloys are a promising choice for high capacity anode materials, and discharge capacities of greater than 450 mAh/g have been reported in the literature for TiV2.1-xCrxNi0.3 alloys.1 The kinetics and power density of these alloys are further improved by reducing the microstructure via rapid solidification.2

Pure vanadium metal forms a dihydride with a total hydrogen content of 4 wt.% or a theoretical electrochemical capacity of 1068 mAh/g.  Practical cycling capacity is limited by the fact that the VH and VH2 phase transitions differ by several orders of magnitude in pressure.3 The plateau pressures of these phase transitions are strongly affected by the composition and lattice parameter of host metal alloy, and the kinetics depend on microstructure and electrode design.  We initially identified a ternary TiVNi alloy4 that delivers close to the theoretical capacity of about 1100 mAh/g by accessing both the monohydride and dihydride phase transitions.  The transitions manifest as two voltage plateaus in the charge/discharge profile of the metal hydride electrode, as seen in the accompanying figure. The difference in voltage plateaus is directly related to the difference in gas phase plateau pressures via the Nernst equation. From the figure we see a difference of ~120mV, corresponding to a 4 – 5 order of magnitude difference in plateau pressure. This alloy has poor cycle life, so Cr is added to prevent corrosion resistance.  We will present results on the effect of composition on the capacity and cycle life of the alloy, and the role that microstructural reduction through rapid solidification and ball milling play on improving the kinetics.

1. H. Inoue, S. Koyama, and E. Higuchi, Electrochimica Acta, 59, 23–31 (2012).

2. H. Tan, N. Weadock, B. Fultz, and R. V. Bugga, Meet. Abstr., MA2015-01, 19–19 (2015).

3. M. Tsukahara et al., J. Alloys Compd., 224, 162–167 (1995).

4. C. Iwakura, W.-K. Choi, R. Miyauchi, and H. Inoue, J. Electrochem. Soc., 147, 2503–2506 (2000).

Figure 1
(Invited) Carbon Nanotubes: Towards an Advanced Material for Energy and Electronic Applications
Authors: Flavel Benjamin S
Published: February 2020

Ever since their discovery, carbon nanotubes (CNTs) have been touted as a material of the future and a lengthy list of possible applications are often cited in the literature.  However, the realization of these applications have so far been hindered by exactly the property which made CNTs so attractive in the first place, namely their varying optical and electronic properties.  In order to become a true advanced material of the future it is necessary to develop techniques to prepare CNTs with defined length, wall number, diameter, electronic and optical property on the large scale.  Furthermore, in addition to simply having large quantities, it is important that strategies for their incorporation into large-area devices are developed.

In our work we address these issues with the use of aqueous gel based sorting techniques to routinely prepare milligram quantities of metallic and semiconducting, single chirality and even double walled carbon nanotubes with defined outer-wall electronic type.  This ‘toolbox’ of available CNTs is then used for the realization of CNT based devices with applications to energy.  For example CNT:Fullerene solar cells, CNT:Si solar cells and CNT based light sensitive elements.  In addition to being of fundamental scientific interest these applications also provide us the opportunity to address the challenges of controlling this 1 D nanomaterial on the macro-scale.  To this end we prepare inks from sorted CNT material and look at strategies to align them in thin films over large areas. 

[1]            K. E. Moore, M. Pfohl, D. D. Tune, F. Hennrich, S. Dehm, V. S. K. Chakradhanula, C. Kuebel, R. Krupke, B. S. Flavel, ACS Nano 9 (2015) 3849-3857.

[2]            D. D. Tune, A. J. Blanch, C. J. Shearer, K. E. Moore, M. Pfohl, J. G. Shapter, B. S Flavel, Applied Materials & Interfaces (2015) 10.1021/acsami.5b08212.

[3]            M. Pfohl, K. Glaser, J. Ludwig, D. D. Tune, S. Dehm, C. Kayser, A. Colsmann, R. Krupke, B. S Flavel, Advanced Energy Materials (2015) 10.1022/aemn.201501345.

[4]            B. S. Flavel, K. E. Moore, M. Pfohl, M. M. Kappes, F. Hennrich, ACS Nano 8 (2014) 1817-1826.
Imaging and Spectroscopy of Carbon Nanotube Optical Reporters to Probe Biological Environments
Authors: Jena Prakrit Vaibhav , Roxbury Daniel , Galassi Thomas Vito , Horoszko Christopher , Budhathoki-Uprety Januka , Harvey Jackson Dean , Heller Daniel A
Published: February 2020

The near-infrared photoluminescence from non-covalently dispersed single-walled carbon nanotubes (SWCNT) is optimally suited to probe distinct classes of biological environments. At the single cell level, DNA-nanotubes enter live cells via endocytosis at 37°C and remain within the endosomal pathway, with their final localization exclusively in the lysosomes. By carefully screening DNA sequences for their sensitivity to lysosomal components accessible to the carbon nanotube, we present a platform to assay changes in the lysosomal environment via a resulting modulation of nanotube fluorescence.
Digitonin Dispersed Carbon Nanotubes to Remove Cholesterol from Serum
Authors: Baker Stefanie L. , Dahl Kris Noel , Islam Mohammad F.
Published: February 2020

High blood cholesterol levels increase the risk of heart disease, which is the leading cause of death in the United States. Current interventions for high cholesterol include pharmaceuticals such as statins, which have considerable negative side effects, and expensive apheresis treatment in severe cases of hypercholesterolemia. To remove cholesterol from serum, we use digitonin bound to single-wall carbon nanotubes (SWCNTs). Digitonin is a nonionic, biological surfactant that specifically binds to cholesterol, but previous studies with digitonin required extensive ultracentrifugation to separate the digitonin/cholesterol complex. We have found that digitonin also has the ability to noncovalently bind to SWCNTs and individually disperse them in water. We characterized SWCNTs-digitonin dispersions using ultraviolet-visible-near infrared (UV-vis-NIR) absorbance, NIR fluorescence, and Raman spectroscopies. Our results show that digitonin dispersed SWCNTs individually in water at any SWCNT:digitonin weight ratio greater than 1:2, and the dispersions remained stable for more than 2 months. SWCNTs provide a structural component and high surface area-to-volume ratio to anchor digitonin molecules while simultaneously binding to cholesterol. We removed any free digitonin from SWCNT-digitonin dispersions and then added them to cholesterol-containing serum. SWCNTs-digitonin agglomerated upon binding to cholesterol within 24 hours while remaining individualized within the agglomerate; SWCNT aggregation state was monitored using the aforementioned spectroscopic techniques. These SWCNTs-digitonin-cholesterol agglomerates, which removed ≈ 46 wt% of serum cholesterol measured using an enzymatic fluorescent assay, could be readily decanted from the remaining serum. We use a thermodynamic model of binding to suggest that digitonin will show similar interactions with other graphitic structures while simultaneously binding to cholesterol, allowing for development of an in-line filter from free-standing graphitic porous structures to remove cholesterol from blood.
(Invited) Growth of Single-Walled Carbon Nanotubes with Specific Structure
Authors: Li Yan , Yang Feng
Published: February 2020

Single-walled carbon nanotubes (SWNTs) present unique structure-dependent properties and the controlled preparation of chemically and structurally pristine SWNTs is a crucial issue for their advanced applications (e.g. nanoelectronics) and has been a great challenge.Epitaxial growth of SWNTs from well-defined seeds has shown to be a promising strategy to control the structure of SWNTs. Inspired by the specificity of enzyme-catalyzed reactions, we realized that only catalysts with unique crystal structure and desired atomic arrangements can act as the structural templates for chirality specific growth of SWNTs, relying on the high selectivity in geometry match between catalysts and SWNTs. We developed a new family of catalysts, tungsten-based intermetallic compounds, which have high melting point and very special crystal structure, to synthesize SWNTs with designed chirality. Using W6Co7 catalysts, (12, 6) SWNTs was directly grown with the purity higher than 92%. The selective growth of (12, 6) tubes is due to a good structural match between the carbon atom arrangement around the nanotube circumference and the metal atom arrangement of (0 0 12) planes in the catalyst. Similarly, (16, 0) SWNT exhibits good structural match to (1 1 6) plane of Co7W6 catalyst. By manipulating the chemical vapor deposition (CVD) conditions, zigzag (16, 0) SWNTs, which are generally known as a kinetically unfavorable species in CVD growth, were obtained at the purity of ~80%. The chirality-specific growth of SWNTs is realized by the cooperation of two factors: the structural match between SWNTs and the catalysts makes the growth of SWNTs with specific chirality thermodynamically favorable; and further manipulation of CVD conditions obtains optimized growth kinetics for SWNTs with this designed chirality. This idea has also been proved to be valid for SWNTs with other chiralities and intermetallic catalysts.

References

1.  Yang, F.; Wang, X.; Zhang, D.; Yang, J.; Da, L.; Xu, Z.; Wei, J.; Wang, J.-Q.; Xu, Z.; Peng, F.; Li, X.; Li, R.; Li, Y.; Li, M.; Bai, X.; Ding, F.; Li, Y., Nature
2014, 510, 522-524.

2.  Yang, F.; Wang, X.; Zhang, D.; Qi, K.; Yang, J.; Xu, Z.; Li, M.; Zhao, X.; Bai, X.; Li, Y.,  J. Am. Chem. Soc.
2015, 137, 8688-8691.
Self-Assembled Monolayers on Ferromagnetic Metals Prepared By an Electrochemical Method
Authors: Parveen Rashida , Schwarzacher Walther , Ovchinnikova Svetlana , Masliy Alexander
Published: February 2020

Self-assembled monolayers on ferromagnetic metals are of interest, both because they can protect the surface from oxidation and because they are of potential use in spintronic devices. We have studied the adsorption of alkanethiols on Ni and Co from aqueous solutions under potential control using a renewable micro-electrode and an electrochemical quartz crystal microbalance. Monolayers of both octanethiol and dodecanethiol have been prepared and characterized. Potential control enables us to maintain the metal surface free of oxide, and initial electrochemical studies show that this method is more effective at blocking Ni dissolution than the standard method of immersion in an ethanolic solution of dodecanethiol as well as giving better protection to the Ni surface against oxidation.
Electrochemical Silver Deposition Onto Pt(111) Surfaces
Authors: Kibler Ludwig A. , Soliman Khaled A. , Plumer Alan , Bringley Eric , Wildi Christopher S. , Mueller Jonathan E. , Jacob Timo
Published: February 2020

The underpotential deposition (upd) of Ag onto Pt(111) produces surface structures exhibiting several interesting structural and electrochemical properties: (i) a contracted pseudomorphic Ag monolayer, (ii) deposition-dissolution hysteresis, (iii) an expanded lattice for the second Ag monolayer, (iv) absence of Hupd, and (v) enhanced H2 evolution activity of Ag overlayers compared with Ag(111).

Related measurements under ultrahigh vacuum conditions reveal similar structural transformations, and DFT calculations indicate that there is a thermodynamic driving force for the migration of the first Ag(111) overlayer deeper into the electrode, upon deposition of the second monolayer. We will discuss adlayer formation and the link between structure formation and reactivity of the resulting surface.
(Invited) Photoelectrochemical Water Splitting with Doped TiO2 Nanotube Arrays: Limits and Water Oxidation Efficiency
Authors: Tsui Lok-kun , Zangari Giovanni
Published: February 2020

While solar energy is one of the few energy sources capable of meeting the world’s energy demands,1 the transient nature of sunlight necessitates the development of technologies to store that energy for on-demand use to supplement photovoltaics.2 Photoelectrochemical solar cells use sunlight to electrolyze water to produce hydrogen as an on-demand fuel, which can then be converted to electricity by a fuel cell. TiO2 nanotubes formed by the anodization of titanium foils in electrolytes containing fluoride ions produce aligned arrays of tube-like structures 70-100 nm in width and tunable length on the order of microns. These structures are a promising architecture for photoelectrochemical applications3 because of their high stability in solution and under irradiation, high surface area, and 1-dimensional charge transport for efficient movement of photogenerated charges. While hundreds of microns long nanotubes in principle may be grown, one major limitation on the performance of TiO2 nanotubes is the presence of defects in the crystal structure which facilitate the recombination of photogenerated electron-hole pairs;4 the best photoelectrochemical performance of TiO2 nanotubes for water splitting has been observed in Nb-doped TiO2 with a length of 7um and an associated photocurrent of 1.0 mA/cm2.5 Electrochemical H or Li doping was demonstrated to passivate the trap states in TiO2 nanotubes, suppressing recombination. This process resulted in up to a 2 fold increase in the photoelectrochemical performance of 1 um long TiO2 nanotubes compared to the undoped samples.6 For long TiO2 nanotubes, a new optimum length of 15 um was achieved, resulting in 1.5 mA/cm2 of photocurrent at 1.0 VSCE under simulated sunlight as seen in Figure 1(c). Photocurrent measurements with and without a hole scavenger did show a high efficiency towards water oxidation. These results demonstrate the ability to produce high performance TiO2 nanotubes for photoelectrochemical solar energy devices using simple electrochemical techniques.

(1) Lewis, N. S.; Nocera, D. G. Proc. Natl. Acad. Sci. U. S. Amer.
2006, 103, 15729.

(2) Cook, T. R.; Dogutan, D. K.; Reece, S. Y.; Surendranath, Y.; Teets, T. S.; Nocera, D. G. Chem. Rev.
2010, 110, 6474.

(3) Tsui, L. -k.; Zangari, G. J. Electrochem. Soc.
2014, 161, D3066

(4) Tsui, L.; Zangari, G. Electrochim. Acta
2014, 121, 203.

(5) Das, C.; Roy, P.; Yang, M.; Jha, H.; Schmuki, P. Nanoscale
2011, 3, 3094.

(6) Tsui, L.; Saito, M.; Homma, T.; Zangari, G. J. Mater. Chem. A
2015, 3, 360.
Highly Glossy Copper Foil Electrodeposition Used As a Negative Electrode of Lithium Batteries
Authors: Yen Chih-Han , Hsu Chia-Fu , Dow Wei-Ping , Hwang Kuen-Yuen , Chou Jui-Chang , Cheng Kuei-Sen , Hwang Huei-Fang
Published: February 2020

Lithium batteries have been an attractive power source for electronic product applications nowadays. The negative electrode material in the lithium battery dominates its discharge-recharge cycles and affects battery performance. Electrodeposited (ED) copper foils with excellent electrical characteristics and a low cost would be a promising candidate to replace rolled copper foils. However, ED copper foils decrease retention rate of capacity when they were used as the negative electrode material of a lithium battery. Therefore, an ED copper foil with a smooth surface on both sides has been developed for the lithium battery fabrication. In this work, 8μm thick ED copper foils were fabricated in a jet flow plating bath at a high temperature and a high current density (i.e., above 30 ASD). The surface roughness (Rz) of both mat and shiny sides is less than 2 μm. To smoothen the shiny side of the ED copper foil, a novel surface modification treatment of cathode were developed. With the pretreatment of the cathodic surface, the shiny side of the ED copper foil exhibited a smooth surface with gloss higher than 350 and a low roughness (i.e., Rz < 2 μm). For the mat side of copper foil, its gloss was higher than 500 and the roughness (Rz) was lower than 1 μm. The copper plating bath contained chloride ions, an accelerator, a suppressor and a leveler. ED copper foils were successfully fabricated with smooth surfaces on mat and shiny sides. As a consequence, large scale ED copper foils (>100 cm2) with very low roughness were fabricated, the ED nucleation was studied and the surface morphologies, roughness and structure orientation of these ED copper foils were characterized by SEM, AFM and XRD, respectively.
Sn-Cu Alloy Microtubes for Li-Ion Battery Anode Prepared By Electroless Plating
Authors: Fujiwara Yutaka , Ikeda Shingo , Takahashi Masanari , Kobayashi Yasuyuki
Published: February 2020

Graphite is generally used for the anode of Li-ion batteries. One of the disadvantages of graphite anode is its small specific charge of 372 mAh/g for lithiation and delithiation. Sn-based materials have been studied as the anode materials alternative to graphite, because Sn has relatively large specific charge of 994 mAh/g. However, the significant volume change (300% expansion) during lithiation is a serious disadvantage of Sn anode causing the pulverization of the anode.

To overcome the limitation of Sn-based anode due to the large volume changes, one approach is reducing the particle size of the anode materials. In this regard, varieties of nanostructures and micro 3D architectures of Sn-based materials have been proposed to accommodate the expansion. Sn alloys with the inactive elements such as Cu have also been studied because the alloying elements are expected to buffer the volume change.

We propose here the novel and facile processes to prepare the micro architectures of Sn-Cu alloys for the high performance Li-ion battery anode. Cu6Sn5 microtubes are prepared by electroless deposition of Cu and Sn on a polyethylene terephthalate (PET) nonwoven fabric, and their performances as the Li-ion battery anode are evaluated.

Preparation of Sn-Cu alloy microtubes

PET nonwoven fabrics were hydrophilized by dipping in an O3 saturated 1M HNO3. Pd catalysts were adsorbed on every fiber of 12 micrometers in diameter, and Cu was subsequently deposited from a conventional electroless plating bath. Sn was deposited on the Cu-coated fibers by the contact immersion processes (1). In the contact immersion processes, the Cu-coated fabric was dipped in a Sn2+–citrate solution, and was electrically contacted to metallic Sn dipped in the same solution. Sn was deposited on Cu at underpotentials, and diffused into the Cu substrate to form the intermetallic phase, Cu6Sn5, without annealing. We obtained the Cu (1500-nm thick) / Cu6Sn5 (200-nm thick) bilayer microtubes which completely coat the PET fibers as shown in Fig. 1.

Charge-discharge Cycling

Charge-discharge characteristics of the Sn-Cu microtube fabric anodes were evaluated in a two electrode flat type cell using a Li foil as the counter and reference electrode and a 1M LiPF6 solution in 1:1 EC/DEC as the electrolyte. Measurements were carried out at a constant current corresponding to the C-rate of 0.5 over the range of 0.001-2.0 V vs. Li/Li+.

Charge-discharge capacity vs. cycle number plots showed that the capacities of the microtube anode were stable at around 850 mAh/g-Sn during the first 50 cycles. This is as high as 85% of the specific charge of Sn. The coulombic efficiencies were also high, exceeding 95%, during the 50cycles.

Reference

(1)Y. Fujiwara, Thin Solid Films, 425, 121 (2003).

Figure 1
Systematic Characterization of a SOFC Short Stack in Multiple Operation Modes
Authors: McPhail Stephen J. , Conti Bruno , Graziadio Marco
Published: February 2020

A series of SOC (Solid Oxide Cell) short stacks from identical production batches was operated in 3 different modes for the systematic assessment of performance according to experimental protocols being harmonized across 7 institutes in Europe and Asia. The operation modes were:

Solid oxide fuel cell (SOFC) operation under electrical current profiles and thermal cycling conditions for stationary applications (micro-chp and distributed power generation) and mobile application (SOFC-APU).

Solid oxide electrolysis (SOEC) operation under dynamic current profiles for H2 production in a power to gas system.

Combined SOFC/SOEC operation for electricity storage in a power-to-gas-to-power system.

Each of these cases includes both steady state and dynamic operations. The measurements carried out were current-voltage curves, electrochemical impedance spectroscopy and galvanostatic performance, each executed according to agreed and fully developed protocols. These will be established and experimentally validated. The test modules and programs will consider all relevant operating conditions of the complete SOC test system, e.g. input gases, pressure levels, temperatures, current loads, voltage level, mechanical loads, dynamic transients etc. In order to systematically study these effects, a sound understanding of the interaction of the test object with the test bench shall be developed. It needs to include test bench specifications (e.g. temporal resolution of sensor signals or time constants associated to actuators) and the associated limits to the data analysis. Analysis of the short stack response allowed us to map different parameters with the aim to systematically investigate performance dependency in all the operation modes considered, including:

Power density versus current density, fuel utilization, gas phase composition;

Efficiency versus temperature, inlet pressure, fuel utilization or gas phase composition

Degradation versus time

The outcome of the campaign is a clearer assessment of SOC performance dependencies as well as a set of harmonized, rigorous, easy-to-understand and user-friendly procedures for univocal testing of SOC stacks in representative application areas of SOC. Preliminary results underline good performance and repeatability of the tested stacks, strong dependence on gas (H2 and air) inlet temperature, strong instability effects in SOEC modes due to high steam contents and imperfect steam supply etc. The test results will lead to recommendations on test procedure execution and instrument specifications for the benefit of reliable characterization of SOC stacks in multiple, application-representative modes.
(Invited) Chloride and SPS Reaction
Authors: Hoang Ha Van , Kondo Kazuo
Published: February 2020

Three-dimension integration using TSVs has brought to a sharp improvement in every aspect of the packaging industry, and also the performance of integrated systems. For several decades of research and development, the TSV technology is currently mature for fabrication. The fulfilled TSVs in copper electrodeposition is typically based on the role of additives which classify into three categories: accelerator, inhibitor and leveler. Accelerator, inhibitor, and leveler contain specific function groups which are sulfonate, ether, and ammonium group, respectively. The interaction of Clˉ, additives, and cuprous was investigated using chronoamperometry, cyclic voltammetric stripping (CVS). Electrolyte baths contained 200g/L of CuSO4.5H2O, 25g/L of H2SO4, and additive concentrations were varied in experiments. In electrodeposition experiments, wafers were placed on a rotating disk electrode rotated at 1000rpm, and applied a pulse reverse current.

Kinetic behavior of the electrodeposition with/without Clˉ and SPS was determined. The reaction rate constant of the first step in the copper electrodeposition increased from 5.50E-7m/s to 2.42E-6m/s and that of the second step reduced from 7.50E-3m/s to 3.50E-3m/s in the presence of Clˉ with SPS. That contributed to the acceleration of areas where Clˉ with SPS occupied. The significant difference of anodic and cathodic areas of CVSs when added PEG, SPS and leveler confirmed the formation of the transition states which were cuprous and its complexes. The formation of a V-shape deposition or a super bottom up filing was controlled by the leveler concentration that explained the competitive inhibition on the TSV wall of PEG and leveler.
(Invited) Copper Plating and Its Application in Advanced Packaging
Authors: Wei Lingyun , Thorseth Matthew , Scalisi Mark , Prange Jonathan P , Lee Inho , Lee Yil-Hak , Kim yoon Joo , Lefebvre Mark , Calvert Jeffrey , Tachikawa Wataru
Published: February 2020

Conventional acid electroplated copper is being widely used in semiconductor industries from back-end-of-the-line (BEOL) interconnects to advanced packaging applications such as copper pillar, redistribution layer (RDL) copper and Through Silicon Via ( TSV) because of low cost, easy manufacturing process and high throughput[1-3]. Industry trends towards higher performance semiconductor devices with increased interconnect density have created significant materials challenges for advanced electronics packaging metallization processes. Copper pillar becomes a transformative technology replacing traditional C4 (controlled collapse chip connection) bumps to meet new performance demands. Copper pillar chemistry requires innovative organic additives in order to meet challenges such as flat pillar shape, void-free intermetallic interface after reflow with solder, fast plating speed, high purity deposits and excellent uniformity. Copper plating baths may contain at least one or three of the additives: accelerator, suppressor, and leveler. Accelerator is usually used to enhance plating rate (depolarization agent) just as its name indicates, while suppressor and leveler are polarization agents that inhibit the plating locally. Although all the additives can be defined as either polarization or depolarization agents, depending on the electrochemical response, the function of each additive could be very different depending on the application. In this talk, the additive function in three different electroplating applications, Dual Damascene, TSV, and copper pillar, will be compared. Then we will introduce the development of Dow Electronic Materials’ next-generation copper pillar chemistry. Additives, current density and process impact on plating performance will be discussed.

E. Reddington, M. Thorseth, Y. Qin, J. Woertink, R. Farrell, M. Scalisi, E. Banelis, P. Lopez-Montesinos, B. Sherzer, Z. Baumer, W. Tachikawa, J. dong, M. Lefebvre, J. Calvert, International Wafer Level Packaging Conference (IWLPC), 2014, San Jose

T. P. Moffat, D. Wheeler, M.D. Edelstein, D. Josell, IBM J. RES. & DEV. 49, 2005, 19-36

M. Thorseth, M. Scalisi, I. Lee, S. Park, Y. Lee, J. Prange, M. Imanari, M. Lefebvre, J. Calvert, 12th International Microelectronics Assembly and Packaging Society (IMAPS), 2016, Arizona
Room Temperature Synthesized Hybrid Open Frameworks for Li-Ion Battery Cathodes
Authors: Abdulrahman Shahul Hameed , Al-Qaradawi Siham Y. , Deniz Erhan , Reddy M.V.
Published: February 2020

Li-ion batteries (LIBs) have been the most promising battery technology owing to their large energy density, environmental friendliness and design flexibility. LIBs have been dominating the rechargeable battery market fue to their advantages and they found application in various electonic gadgets. Large scale utilization of LIBs is anticipated in the near future for efficient utilization of renewable energy as there is gap between energy supply and demand. As solar radiation is available during daytime, the peak energy demand is at night. In addition, LIBs are expected to push forward the production of eco-friendly transportation such as electric vehicles (EVs) and hybrid electric vehicles (HEVs). Transformation from conventional vehicles to EVs are mainly hindered by the high upfront price of the EVs which are mainly due to the high cost of the battery packs used to power these vehicles. Hence, cost reduction of LIBs is one of the major strategies to bring forth the EVs to compete in the market with their gasoline counterparts. In our attempt to produce cheaper high-performance cathode materials for LIBs, a Graphene/MOPOF (Metal Organophosphate Open Framework) [1-3] nanocomposite with ~4 V of operation has been developed by a cost effective room temperature synthesis that does not require any expensive post-synthetic treatments at high temperature in inert atmospheres like Ar/Ar-H2. These open frameworks has a layered structure with each layer made of metal phosphate cross-linked by oxalate. Presence of alkali ions in the interlayer space with a redox system helpes in the reversible extraction of them, making it a feasible cathode material. Though the pristine material undergoes reversible lithium storage, there was capacity fading. Enhanced lithium cycling with minimal capacity fading was witnessed with the graphene nanocomposite owing to the increased electronic conductivity and enhanced Li diffusivity. Stable reversible capacity of ~100 mAh g-1 were obtained.

Refereces

A. Shahul Hameed, M. V. Reddy, M. Nagarathinam, Tomče Runčevski, Robert E Dinnebier, Stefan Adams, B. V. R. Chowdari and Jagadese J. Vittal, Sci. Rep., 2015, 5, 16270. 

A. Shahul Hameed, M. Nagarathinam, Martin Schreyer, M. V. Reddy, B. V. R. Chowdari and Jagadese J. Vittal, J. Mater. Chem. A, 2013, 1, 5721-5726.

M. Nagarathinam, K. Saravanan, E. J. H. Phua, M. V. Reddy,B. V. R. Chowdari and J. J. Vittal, Angew. Chem., Int. Ed.,
2012, 51, 5866–5870.
Light-Assisted Delithiation of Nano-LiFePO4 for Photo-Rechargeable Li-Ion Batteries
Authors: Paolella Andrea , Faure Cyril , Demopoulos George P. , Zaghib Karim
Published: February 2020

We describe a new device able to photo-oxidize LiFePO4 nanocrystals to FePO4 in the presence of a N719-Ruthenium-dye using a three-electrode system. Under Open Circuit Voltage (OCV) the LiFePO4 nanoparticles spontaneously delithiated and converted to heterosite FePO4 with the assistance of the ruthenium-dye (see Figure 1). Our results can open interesting perspectives to solar rechargeable battery field.

Figure 1

: a-c) XRD pattern and HRTEM of LiFePO4 nanocrystals, b-d) XRD pattern and HRTEM image of FePO4 nanocrystals, e) Charging of LiFePO4 by N719 dye in presence of the light followed by an open circuit voltage (OCV)

Figure 1
Electrochemical-Acoustic Investigation of Current Density Distribution in Lithium-Ion Batteries
Authors: Hsieh Andrew , Davies Greg , Wang Michael , Steingart Daniel A
Published: February 2020

The combination of Ohmic losses, transport phenomena, and reaction kinetics make scaling batteries up from lab-scale to commercially-relevant sizes a non-trivial endeavor. As the size of cells increases, manufacturing difficulties such as well-dispersed slurries, even electrode coatings over large areas, and proper electrolyte filling add additional levels of complexity. A particular difficulty for large format cells is current density distribution: inhomogeneities in current density across the electrode area leads to an uneven distribution of electrochemical reactions. This leads to suboptimal utilization of active material during operation, especially at higher charge-discharge rates. This has been shown in operando with synchrotron and neutron sources, however such techniques are not widely available, nor are they scalable or portable for widespread in-field use. Furthermore, electrical measurements only provide electrode-averaged abstractions of physical state, and AC impedance measurements interrupt normal operation. Here, we show that electrochemical-acoustic analysis is an excellent alternative to incumbent methods. Acoustic analysis can directly measure the physical and structural state of the battery, in real-time and with good spatial resolution. This is possible because the local behavior of sound in a battery is sensitive to the spatial differences in physical state (i.e., extent of reaction) that arise from the current density distribution. We present evidence from LCO pouch cells with a range of sizes, and demonstrate the utility of electrochemical-acoustic analysis as a scalable way to monitor the performance and utilization of large-format cells.