bluuebunny/crossref_metadata_2025_split huggingface dataset:
Light-Weight and Corrosion-Resistant Current Collector for Aqueous Li-Ion Batteries
Authors: Gheytani Saman 
Published: February 2020

The use of low-cost and light-weight aluminium as current collectors in aqueous Li-ion batteries with water-based electrolytes is restricted by corrosion reactions caused by the aggressive ions in the aqueous environments. Here we report for the first time using highly corrosion-resistant Al foil with the chromate conversion coating (CCC Al) as current collector for cathodes in aqueous Li-ion batteries. Coating aluminium with chromium compounds is currently the most effective way to inhibit corrosion of aluminium and its alloys. The protection with the CCC is two-fold: (1) an impervious hydrated chromium(III) oxide serving as a physical barrier on the surface and (2) the chromium(VI) ions stored in the coating provide active corrosion protection.
We have experimentally demonstrated that CCC Al foil is resistant to corrosion when used as the current collector of LiMn2O4 electrodes. The cyclability of these electrodes are on par with or better than those observed for electrodes fabricated on stainless steel and titanium substrates. In contrast, electrodes fabricated on untreated Al foil saw serious corrosion of the substrate within the initial 10 cycles. Interestingly, CCC also effectively suppress oxygen evolution reaction at high potentials, leading to improved Coulombic efficiency of up to 99%. The increased overpotential for oxygen evolution was attributed to the occupation of active chemisorption sites and inhibition of electron transfer on the substrate surface by the chromium compounds. These results may open a new insight into the design of high performance and high-stability cathode electrodes for aqueous Li- and Na-ion batteries with a higher cell-level energy density.
Redox Flow Batteries Based on Aqueous Soluble Organics and Mechanistic Diagnostics of Capacity Fading
Authors: Wei Xiaoliang , Wang Wei , Hollas Aaron , Li Bin , Nie Zimin , Vijayakumar Murugesan , Reed David , Sprenkle Vincent 
Published: February 2020

Redox flow batteries have been considered as one of the most promising grid energy storage technologies. The unique cell architecture leads to an important advantage of decoupled energy and power, which offers very flexible designs and excellent scalability to meet different grid applications. State-of-the-art flow batteries based on inorganic redox-active materials (e.g. vanadium) have gained significant momentum and even commercialization offerings. However, the broad market penetration is hampered by limited energy density and/or high cost. This has driven the search for electrochemically active, cost-effective aqueous soluble organics (ASO) to enable competitive flow battery systems. Organic compounds have other advantages of molecular diversity and structural tailorability to enable high solubilities and desirable cell voltages.
Here we report the new development of high-performance ASO flow batteries at Pacific Northwest National Laboratory.1Materials discovery efforts have led to identification of promising ASO candidates, followed by structural tailoring to improve the solubilities, redox activity, and chemical stability. Electrolyte engineering was also carried out to improve the rate performance and cyclability of the ASO flow batteries. Finally, systematic spectroscopic analysis has revealed the mechanisms of capacity fading observed in these ASO flow batteries.

References

1. T. Liu, X. Wei, Z. Nie, V. Sprenkle, W. Wang. Adv. Energy Mater.
2016, 6, 1501449.

Figure 1. The ASO flow battery based on methyl viologen (MV) and 4-hydroxy-TEMPO (TEMPOL). The mechanistic studies of capacity fading will be discussed.

Figure 1
Macromolecular Design Strategies for Long-Lived and Energy Efficient All-Organic Redox-Flow Batteries
Authors: Helms Brett A. , Doris Sean E. , Ward Ashleigh L. , Frischmann Peter D. , Baskin Artem , Prendergast David , Gavvalapalli Nagarjuna , Chenard Etienne , Sevov Christo S. , Moore Jeffrey S 
Published: February 2020

Scalable, low-cost, multi-hour electrochemical energy storage is critical to our efforts seeking to productively integreate renewable energy souces with the grid. Redox-flow batteries offer a solution. However, many suffer from rapid capacity fade and low energy efficiency due to the high permeability of redox-active species across the battery’s membrane. Here I will discuss how macromolecular design, applied to both the membrane and the active materials, uniquely addresses the crossover problem in these cells. In doing so, we identify the minimum size an active material must be to keep it isolated in its intended electrode compartment. We also identify the design rules governing the use of blocking membranes in these cells, particularly with respect to area-specific resistance in flow cells as it is dictated by polymer composition, membrane pore architecture, and electrolyte formulation. I will also discuss early successes in pairing optimized blocking membranes and oligomeric organic active materials in cross-over free redox-flow cells, which bode well for this technology development.
Zinc-Iron Flow Batteries with Common Electrolyte
Authors: Selverston Steven , Savinell Robert F. , Wainright Jesse S. 
Published: February 2020

Aqueous hybrid flow batteries are being developed because of their high performance and low cost relative to other energy storage technologies. Zinc-bromine flow batteries, which use an acidic chemistry, have demonstrated high performance by many groups. However, their application has been limited by the safety concerns regarding bromine toxicity. Zinc-ferricyanide flow batteries, which operates in alkaline environment, have also been widely developed, but there have been reported challenges with the high membrane costs, precipitation of zinc oxides and the possibility of generating toxic gas in the event of electrolyte mixing with acid. In our lab, we are investigating a new type of zinc-iron chloride flow battery operating with the reactions given by:
negative Zn2+ + 2e- → Zn -0.76 V
positive Fe3+ + e- → Fe2+ +0.77 V
cell Zn2+ + 2Fe2+ ↔ Zn + 2Fe3+ 1.53 V
The key to making this work is to use the anomalous codeposition (ACD) of zinc from mixed ZnCl2-FeCl2 electrolytes. This effect prevents iron from electroplating during battery charging, so the negative electrode behaves similar to a normal zinc electrode. As with all-iron flow batteries, this type of flow battery also has an inherent crossover tolerance, which is important for long-term stability as well as operability using inexpensive microporous separators. Here, we report results from three-electrode studies of the anomalous codeposition as well as preliminary flow battery experiments.
Polyacrylonitrile-Based Membranes for Aqueous Redox-Flow Batteries
Authors: Karpushkin Evgeny A. , Klimenko Maria M. , Gvozdik Nataliya A. , Stevenson Keith J , Sergeyev Vladimir G. 
Published: February 2020

Due to several advantages (independent power and energy sizing, long cycle life, fast response, and no self-discharge during storage), redox-flow batteries have been recognized as promising electrochemical energy storage devices. A crucial part of the redox flow-cell is the membrane separating the anolyte and catholyte containers (thus providing for charge carriers conductivity and preventing the cross-mixing of the redox-active components). For example, a membrane for vanadium redox-flow battery (VRB) should be stable against oxidation by VO2
+ cations as well as to reduction by V2+ cations and exhibit high proton conductivity to provide high voltage efficiency of the battery as well as low vanadium permeability to ensure high Coulombic efficiency.
Perfluorinated membranes such as Nafion® are currently the most widely used ion-exchange membranes for VRBs. However, the best-performance membranes recognized so far are generally expensive, and the crossover of vanadium species across the membrane is rather high. Therefore, if a cheaper alternative membrane material is found, the cost efficiency of the battery will be drastically improved.
In this contribution, we demonstrate the applicability of membranes based on polyacrylonitrile (PAN) in redox-flow batteries. Using VBR as a model system, we have shown that microporous PAN membranes provide the desired balance of proton conductivity and vanadium species permeability and are chemically resistant under the VBR operation conditions. The proton conductivity of PAN-based membranes is usually lower than that of Nafion® membranes, but the vanadium ions transport is significantly suppressed. This makes the overall energy efficiency of the VBR cell built using the PAN-based membrane comparable to that determined with Nafion® membranes. It is important to mention that porosity and hydrophilicity of PAN membranes can be easily tuned, enabling facile adjustment of its ion-conducting properties. We have studied the influence of the PAN membranes preparation conditions on their characteristics and elaborated the procedures of the membrane modification by introduction of hydrophilic nanoparticles and by heat treatment.
This work was financially supported by Russian Foundation for Basic Research (project no. 16-33-60185 mol_a_dk) and by Centre for Electrochemical Energy of Skolkovo Institute of Science and Technology.
Determination of Internal Stress of Ni Electroplated Samples in Sulphamate Solutions
Authors: Aykac Busra , Erdogan Metehan , Karakaya Ishak 
Published: February 2020

Electroplating is a surface modification process that does not alter the bulk properties of the substrate and is conducted for improving the surface appearance, generally increasing the corrosion and wear resistance of the material to be electroplated [1]. There are several metals that can be electroplated such as Ni, Cu, Au, Co, Cd, Zn, etc. or the alloys thereof. Among these metals, Ni is the most commonly preferred one. Through the last five decades, the technology of electroplating of nickel extensively developed into a broad range of industrial coatings for both decorative and functional applications. The annual commercially electroplated nickel is over 150,000 tones worldwide [2] due to the useful properties of Ni as a coating and its versatility.
There are several types of baths based on nickel chloride, nickel sulfate and nickel sulphamate [3] for Ni electroplating. Among these, the advantages of Ni electrodeposition from Ni sulphamate based solutions are low internal stress and high current efficiency (>90%). The functionalities of coatings are affected by internal stress which is a common problem of the electroplating process. The parameters of electrodeposition and additive particles which are insoluble in the bath, in the case of composite coatings [4], change the characteristics of the plating and affect the internal stress of the coatings. The influence of the electrodeposition parameters and their interaction effects on the internal stress of Ni deposits were studied by fractional factorial design. Self-interactions and cross correlations of temperature, pH, current density and bath composition on internal stress were determined by statistical analysis of results obtained from sulphamate baths. It was found that increasing temperature and deposit thickness and decreasing boric acid and chloride ion concentrations resulted in decreasing the internal stress within the parameter ranges covered in this study.
[1] Popov,K.I., Djokic,S.S., Grgur,B.N.(2002), Fundamental Aspects of Electrometallurgy, Kluwer Academic Publishers, pp.1-3
[2] Nickel Plating Handbook. (2014). June 28, 2016, retrieved from; https://www.nickelinstitute.org/~/media/Files/TechnicalLiterature/NPH_141015.ashx
[3] DuRose, A.H. (1997), Nickel Solution Buffers and Limiting Current Density, Surface Finishing, 48-52
[4] Saraloğlu Güler, E., Karakaya, İ. and Konca, E. (2014) Effects of current density, coating thickness, temperature, pH and particle concentration on internal stress during Ni-MoS2 electrocodeposition, Surface Engineering, 30, 109-114.
Electrocapping Gold Nanopores with Porous Manganese Dioxide
Authors: Experton Juliette , Wu Xiaojian (James) , Martin Charles R 
Published: February 2020

Nano- and micropores functionalized with responsive or reactive materials offer defined high rates of mass transport which are beneficial for applications in sensing, nanofluidics and catalysis.1,2 They can also act as model systems for material characterization and fabrication.2,3 However, precisely controlling the functionalization reactions inside such tiny volumes is a challenge. Moreover, it is frequently desired to deposit the material at a specific location within the pore, for example, on the inside wall or just at the opening. When the functionalization requires electrodeposition, achievement of such site specificity is difficult as it necessitates a continuous electrical contact that is exposed only at the desired sites. Bipolar electrochemistry is a powerful tool capable of localized electrodeposition in the absence of an electrical contact.4 It offers a precise way to grow materials on 3D substrates.
In our work, two electrodes are placed on either side of a conductive nanoporous membrane and a potential bias is applied (1-4 V). Redox reactions, one cathodic and one anodic, occur at either end of the nanopore. One reaction is chosen such that it forms a porous material which is selectively electrodeposited at one pore orifice. These capped pores allow the study of the properties of this porous material, such as conductivity, reactivity, stability and surface charge.
Figure 1 shows porous manganese dioxide (MnO2) that was selectively electrodeposited at one end of a pore by bipolar electrochemistry. Manganese oxides are interesting materials for sensing, catalysis, supercapacitor and battery applications.5 Their well-defined porous structures exhibit high specific surface areas and lattices that allow the intercalation of ions, such as lithium. We report on the mechanism of formation and growth rate of these MnO2 structures on gold nanopores as studied by electrochemistry and complementary techniques. We also report electrochemical measurements of the synthesized material, including its permselectivity towards lithium, potassium and sodium ions. Finally, we address the performance of this material for applications in batteries and catalysis.

Xu, Y.; Jin, S.; Xu, H.; Nagai, A.; Jiang, D. Chem. Soc. Rev.
2013, 42, 8012-8031.

Wang, C. M.; Kong, D. L.; Chen, Q.; Xue, J. M. Front. Mater. Sci.
2013, 7(4), 335-349.

Baker, L. A.; Choi, Y.; Martin, C. R. Curr. Nanosci.
2006, 2(3), 243-255.

Fosdick, S. E.; Knust, K. N.; Scida, K.; Crooks, R. M. Angew. Chem. Int. Ed.
2013, 52, 10438-10456.

Brock, S. L.; Duan, N.; Tian, Z. R.; Giraldo, O.; Zhou, H.; Suib, S. L. Chem. Mater.
1998, 10, 2619-2628.

Figure 1
Characterization of Ni Filled Luminescent Porous Silicon By Optical and Magnetic Methods
Authors: Granitzer Petra , Rumpf Klemens , Reissner Michael , Poelt Peter 
Published: February 2020

Porous silicon (PSi) gained by electrochemical etching of a silicon wafer can be fabricated with various morphologies ranging from pore diameters of a few nanometers to tens of micrometers. In the nanoporous regime the material offers a branched structure with pore diameters of 2 – 5 nm. Such microporous silicon (IUPAC notation) is known to emit light in the visible regime since 1990 and is still under investigation [1].
The aim of this work is to combine luminescent porous silicon with a ferromagnetic metal (Ni) to influence on the one hand the photoluminescence by the presence of metal deposits and on the other hand the optical properties by an external magnetic field. The porous silicon samples are fabricated by anodization of moderately doped p-type silicon in an aqueous hydrofluoric acid solution under a constant current density of 10 mA/cm2 for 20 minutes. The metal deposition within these small pores is challenging but succeeded. First the optical properties of the luminescent PSi are investigated, second Ni is electrochemically deposited in the porous silicon sample under cathodic conditions and subsequently the nanocomposite specimens are characterized optically and magnetically. Furthermore the structural characterization of the samples is carried out by SEM and TEM.
Photoluminescence spectra of bare porous silicon show a maximum around 620 nm whereas in the case of Ni filled samples the peak is blue-shifted to around 580 nm and the luminescence intensity is increased. Concerning the magnetic properties of the nanocomposite the embedded Ni structures are superparamagnetic from the size of the pore diameters but due to the branched morphology the achieved deposits are interconnected and thus do not offer necessarily a superparamagnetic behavior. Field dependent magnetization measurements with the magnetic field applied perpendicular to the sample surface show a low coercivity of about 200 Oe and a squareness (magnetic remanence/saturation magnetization) of about 0.2 which is indicative for a film like behavior due to the interconnected Ni structures (figure 1). Temperature dependent magnetization measurements give no hint for a superparamagnetic behavior.
The optical characterization of luminescent PSi with respect to photoluminescence intensity and decay times compared with Ni filled samples is discussed in detail as well as the corresponding magnetic properties of the nanocomposites. Furthermore the influence of a magnetic field on the optical properties is elucidated. The presented systems give not only rise to optoelectronics but also to magneto optical integrated devices.
[1] J. Joo, T. Defforge, A. Loni, D. Kim, Z.Y. Li, M.J. Sailor, G. Gautier, L.T. Canham, Appl. Phys. Lett. 108, 153111 (2016).
Figure 1: Field dependent magnetization curve of microporous silicon filled with Ni.

Figure 1
Effects of Pulse-Reverse Currents on Nickel Deposited from Sulphamate Solutions
Authors: Çetinöz Bilgehan , Erdogan Metehan , Aras Mustafa Serdal , Karakaya Ishak 
Published: February 2020

Electroplating is widely used in many fields for decorative and engineering purposes. Nickel is mostly used for engineering applications beacause of its enchanced mechanical properties such as low internal stress and high corrosion and erosion resistance. It was reported that the use of pulse or pulse reverse currents instead of direct current produced homogenous deposits of better surface finish [1,2]. Nickel sulphamate bath was used in this study to attain better mechanical properties, lower internal stresses and good surface quality. The effects of pulse reverse current (PRC) method on the hardness, microstructure and roughness of the deposits were investigated and compared with direct current (DC) plating. In PRC electroplating, current value is alternated between anodic and cathodic currents to provide higher ion concentrations near electrodes compared to DC plating. In this way, the increased nucleation rate and the number of grains per unit area leads to a decrease in grain size [1]. In addition, the homogenity of the deposits can be improved and the growth of the planes can be controlled by the use of PRC coating [3]. In the design of experiments, special emphasis was given to the ratio of the anodic and cathodic current densities. Scanning electron microscopy (SEM) analyses, roughness measurements and vickers hardness tests were used to characterize the deposits. The results of selected DC and PRC deposits can be seen in Figure 1.
References
[1] Chandrasekar, M.S. and Pushpavanam, M. (2008) ‘Pulse and pulse reverse plating—Conceptual, advantages and applications’, Electrochimica Acta, 53(8), pp. 3313–3322.
[2] Arslan, B., Demirci, G., Karakaya, İ. and Erdoğan, M. (2015) ‘Formation of gold-plated electroformed copper structures’, Advances in Materials and Processing Technologies, 1(3-4), pp. 384–393.
[3] El-Sherik, A.M., Erb, U. and Page, J. (1997) ‘Microstructural evolution in pulse plated nickel electrodeposits’, Surface and Coatings Technology, 88(1-3), pp. 70–78.

Figure 1
(Invited) Electrodeposited Carbon Nanotube Ropes, Decorated with Electrodeposited Pd Nanoparticles for Fast, Sensitive, and Wide-Range, H2 Sensors
Authors: Penner Reginald , Li Xiaowei 
Published: February 2020

Hydrogen (H2) gas sensors that are sensitive, rapid-responding, stable, selective, compact, and inexpensive are needed to support the operation of fuel cell-electric automobiles. Palladium absorbs hydrogen to form a hydride (PdHx
) with x saturating at 0.67 and since 1869 it has been known that the electrical resistivity of this hydride increases linearly with x by a factor of 1.8 – 1.9 over the range from x = 0 to 0.67. This property of PdHx was first exploited for hydrogen sensing by Hughes and Schubert in 1992. As hydrogen gas sensors, Pd thin film resistors are elegant in their simplicity and cheap, but they are much too slow. One solution is to use a Pd nanowire as a resistive H2 sensor instead of a film. In this talk, we describe a second approach involving palladium (Pd) nanoparticle (NP)-decorated carbon nanotube (CNT) ropes (or CNT@PdNP). In the devices we prepare here, the Pd NPs have a mean diameter below 6 nm and are highly dispersed on the CNT surfaces. Both the Pd NPs and the CNT ropes are prepared by pulsed electrodeposition methods. Such CNT@PdNP ropes produce a relative resistance change 20 - 30 times larger than is observed at single, pure Pd nanowires. Thus, CNT@PdNP rope sensors improve upon all H2 sensing metrics (speed, dynamic range, and limit- of-detection), relative to single Pd nanowires which heretofore have defined the state- of-the-art in H2 sensing performance. Specifically, response and recovery times in air at [H2] ≈ 50 ppm are one sixth of those produced by single Pd nanowires with cross- sectional dimensions of 40 × 100 nm Pd. The LODH2 is <10 ppm versus 300 ppm, and the dynamic range (10 ppm – 4%) is nearly twice that afforded by the Pd nanowire. CNT@PdNP rope sensors are prepared by the dielectrophoretic deposition of a single semiconducting CNT rope followed by the electrodeposition of Pd nanoparticles with mean diameters ranging from 4.5 (± 1) nm to 5.8 (± 3) nm. The diminutive mean diameter and the high degree of diameter monodispersity for the deposited Pd nanoparticles are distinguishing features of the CNT@PdNP rope sensors described here, relative to prior work on similar systems.

Figure 1
(Invited) Engineering Surface Structures and Energetics of α-Fe2O3 and p-Si for Efficient Solar Water Splitting
Authors: Shen Shaohua 
Published: February 2020

Solar hydrogen conversion via photoelectrochemical water splitting is an important technology for energy and environment sustainability. Since the pioneering work of Fujishima and Honda in 1972, tremendous research on semiconductor-based photoelectrochemical water splitting has yielded better understanding of the processes as well as encouraging development of high efficiency photoelectrodes for solar hydrogen generation. In this talk, some recent progresses in heterostructures of α-Fe2O3and p-Si for photoelectrochemical solar water splitting in our group will be introduced.
Given the narrow band gap enabling excellent optical absorption, increased charge carrier density and accelerated surface oxidation reaction kinetics become the key points for improved photoelectrochemical performances for water splitting over α-Fe2O3 photoanodes. By engineering the surface structures of α-Fe2O3 nanorods with AgxFe2-xO3, TiO2 and HfO2overlayers, the surface charge recombination was greatly inhibited and the surface water oxidation kinetics were efficiently accelerated, resulting in remarkable enhancement in PEC water splitting performances.
p-Si has captured intensive attentions for solar hydrogen conversion due to its high natural abundance and narrow band gap (~1.1 eV). However, the slow charge-transfer kinetics at the p-Si/electrolyte interface lead to large overpotentials for hydrogen evolution and electrocatalysts are always necessary. Recently, we successfully engineered the surface energetics of p-Si with n-WO3 overlayer and Ni molecular complexes, which gave rise to a great anodic shift of up to 300 mV in onset potential for photocathodic water reduction.