bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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
(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.
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
Impedance Analysis of High Capacity Manganese Rich Cathode in Lithium Ion Batteries
Authors: Mao Wen-feng , Fu Yanbao , Battaglia Vince 
Published: February 2020

The high capacity manganese rich (HCMR) cathode material (xLi2MnO3• (1-x)LiMO2, M = Ni, Co, Mn) demonstrates the highest discharge capacity (~250 mAh g-1) along with potential cost reduction and safety enhancement among all the high energy cathode materials considered for lithium ion batteries (LIBs).. However, the practical application of HCMR is prohibited due to, among other things, the high impedence at low states of charge (SOC), as shown in the PITT test in Fig. 1. The purpose of this study is to investigate the source of the high impedence for HCMR cathode materials.
HCMR electrodes were prepared with active material (85 wt%), acetylene black conductive additive (7 wt%), and PVdF binder (8 wt%). The loading of HCMR in the cathode is 1.1 mAh/cm2. 2325 coin cell hardware was used for electrochemical measurements, assembled with Celgard 2400 as separator and lithium metal as counter electrode. EIS tests were performed using a VMP3 electrochemical workstation. The EIS results are shown in Fig. 2, and the results of detailed impedance analysis are shown in Fig. 3. At lower SOCs, the HCMR exhibits a greater diffusion impedance (Rdiff), while the charge transfer impedance (Rct) rises quickly and then decreases. Both sources of resistance are much higher than the ohmic impedance (RL) and the another high-frequency source associated with wither the anode or an SEI on the cathode, (RSEI).
In all, we can conclude that both the solid state ionic diffusion and electrochemical charge transfer offer nearly equal contribution to the high impedance of HCMR at low SOCs (between 3.6 and 3.2 V). Therefore, stratagies that may increase the ionic diffusion coefficient (e.g. chemical doping), decrease the ionic diffusion length, or increase the rate of electrochemical reaction must be adopted to solve the high impedance issue at low SOC. Reducing the particle size would have the effect of simultaneously reducing the solid state transport length and increasing the area for charge transfer, but may come at the expense of increased dissolution of the transition metals (not studied here) from the active material.

Figure 1
An Optimized Carbon Matrix for Negative Lithium-Ion Battery Electrodes Based on Silicon and Carbon
Authors: Ulmann Pirmin A. , Pacheco Sergio B. , Mombelli Eddie , Leone Antonio 
Published: February 2020

Since decades, attempts have been made to incorporate silicon into Li-ion battery anodes in order to improve the energy density beyond the theoretical limit of graphite (372 mAh/g).1 These efforts have frequently been hampered by poor cycling stability resulting from the substantial volume change of silicon during lithiation/de-lithiation cycles. It has recently been demonstrated that careful selection of conductive graphite and carbon black additives leads to significantly reduced aging phenomena in silicon-based composite electrodes.2

Electrochemical results will be presented for an optimized surface-modified carbon matrix that leads to highly favorable cycling stability in combination with commercially available silicon-based active materials. Bulk and surface properties of these composite electrodes will be discussed.

References:

1a) Besenhard, J. O.; Komenda, P.; Paxinos, A.; Wudy, E. Solid State Ionics
1986, 18-19 (2), 823; b) Wilson, A. M.; Dahn, J. R. J. Electrochem. Soc.
1995, 142, 2, 326; c) Son, I. H.; Park, J. H.; Kwon, S.; Park, S.; Rümmeli, M. H.; Bachmatiuk, A.; Song, H. J.; Ku, J.; Choi, J. W.; Choi, J.; Doo, S.; Chang, H. Nature Commun.
2015, 6, 7393.
2a) Du, Z.; Dunlap, R. A.; Obrovac, M. N. J. Electrochem. Soc.
2014, 161 (10), A1698; b) Petibon, R.; Chevrier, V. L.; Aiken, C. P.; Hall, D. S.; Hyatt, S. R.; Shunmugasundaram, R.; Dahn, J. R. J. Electrochem. Soc.
2016, 163 (7), A1146.
Synthesis and Electrochemical Properties of Li2MnO3 Li4Mn5O12 Binary System As Positive Electrode Materials for Lithium Ion Battery
Authors: Okada Masaki 
Published: February 2020

Synthesis and Electrochemical Properties of Li2MnO3―Li4Mn5O12 Binary System as Positive Electrode Materials for Lithium Ion Battery
Masaki Okada and Yuya Sakaguchi
Inorganic Materials Research Laboratory, TOSOH CORPORATION
Lithium ion batteries are their high energy density compared with other batteries, progressed recently applied to applications requiring large capacity like for electric power storage system and electric vehicle. The positive electrode materials for a lithium ion battery, lithium metal oxide containing a large amount of rare metallic element such as cobalt or nickel are mainly investigated. Positive electrode material containing a large amount of these rare elements is very difficult to achieve both high energy density and low cost. As a positive electrode material that does not contain a rare metallic element, it is being studied of Li2MnO3 with a layered rock-salt structure. Li2MnO3 shows a large discharge capacity of more than 250mAh/g in the first cycle, but the capacity decreases with charge and discharge cycles. [1-3] In this work, we studied the Li2MnO3―Li4Mn5O12 binary system (Li4/3-4X/5Mn2/3O2-2X/5, 0<X<1) of the positive electrode materials based on Li2MnO3. Li4/3-4X/5Mn2/3O2-2X/5 can be suppressed capacity fading as compared with the conventional Li2MnO3. It may be able to achieve both low cost and high energy density.
Li4/3-4X/5Mn2/3O2-2X/5 was prepared by reacting of mixture of MnCO3･0.5H2O and LiOH･H2O as raw material. The mixture was fired at 400～600ºC for 32h in air stream. Crystal structure and multilayered particle structure were investigated through TEM and N2adsorption-desorption isotherm analysis, respectively. The electrochemical characterization of positive electrode material was performed on CR2032 coin type cells. From the TEM images of the prepared samples, the presence of two crystal phases was observed. In addition, the electron diffraction pattern is attributed to the rock salt and the spinel phase, the possibility of a two-phase coexistence structure of Li2MnO3 and Li4Mn5O12 having a twin structure has been suggested. The initial charge and discharge capacity of Li4/3-4X/5Mn2/3O2-2X/5 was reduced as compared with Li2MnO3, but cycle stability was improved (X=0.36, 170mAh/g@50th, 50mA/g, RT). In additionally, capacity fading is suppressed by magnesium substitution of a part of manganese, the substituted sample showed stable cycling at about 200mAh/g (X=0.36, Mg 8mol %). In the viewpoint of the crystal structure and multilayered particle structure, the effect of the characters on capacity and cycle ability will be discussed.
[1] Denis Y.W. Yu et.al., J. Electrochem. Soc. 2009 156(6) A417-A424

[2] Denis Y.W. Yu et.al. J. Electrochem. Soc. 2010 157(11) A1177-A1182
[3] Denis Y.W. Yu et.al., J. Electrochem. Soc. 2011 158(9) A1015-A1022
Development of a Water Based Process for Stable Conversion Cathodes on the Basis of FeF3
Authors: Pohl Alexander Herald , Faraz Mohammadkazem , Schröder Andreas , Baunach Michael , Schabel Wilhelm , Guda Alexander , Shapovalov Viktor , Soldatov Alexander , Chakravadhanula Venkata Sai Kiran , Kübel Christian , Witte Ralf , Hahn Horst , Diemant Thomas , Behm Rolf Jürgen , Emerich Hermann , Fichtner Maximilian 
Published: February 2020

A facile water based synthesis method for HTB-FeF3/rGO and r-FeF3/rGO composites was developed using FeF3 nanoparticles prepared by ball-milling and aqueous graphene oxide precursor. Electrodes of HTB-FeF3/rGO were cast in ambient air and the calendered electrode shows a stable specific energy of 470 Wh kg–1 (210 mAh g–1, 12 mA g−1) after 100 cycles in the range 4.3–1.3 V with very little capacity fading. The good cycle stability is attributed to the intimate contact of FeF3 nanoparticles with reduced graphene oxide carbon surrounding. Using a combination of in situ XRD, XAS and ex situ Mössbauer spectroscopy, we show that during discharge of HTB-FeF3/rGO composite Li is intercalated fast into the tunnels of the HTB-FeF3 structure up to x = 0.92 Li. The Li intercalation is followed by slow conversion of HTB-LixFeF3 to LiF and Fe nanoparticles below 2.0 V. During charge, the LiF and Fe phases are slowly transformed to amorphous FeF2 and FeF3 phases without reformation of the HTB-FeF3 framework structure. At an elevated temperature of 55 °C a much higher specific energy of 780 Wh kg−1 was obtained.

Figure 1
Synthesis, Characterization and Electrochemical Properties of Germanium@Multiwalled Carbon Nanotubes Composite As Anode in Lithium Ion Batteries
Authors: Goriparti Subrahmanyam , Zaccaria Remo Proietti , Capiglia Claudio 
Published: February 2020

Rechargeable lithium ion batteries have been in use in portable appliances like laptops, cameras and cellular phones due to high gravimetric energy together with long cycle life [1-3]. However, the deployment of lithium ion batteries in applications like hybrid electric vehicles, plug in hybrid electric vehicles and smart grids needs improvements in terms of energy and power densities along with reducing the cost [1-2]. Nanostructured electrode active materials have attracted much attention because of their potential to provide higher energy and power densities than bulk materials. In Particularly anodes such as silicon, germanium, tin, metal oxides and carbonaceous are the most promising materials [2-3].
Germanium (Ge) nanocrystals with size of 5 nm and their composites of multiwalled carbon nanotubes (MWCNTs) were synthesized via solvothermal method. Ge and Ge@MWCNTs have been characterized through X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and Raman spectroscopy. Furthermore, electrochemical studies have been carried out with cyclic voltammetry, galvanostatic charging and discharging test, and impedance spectroscopy. The results show that as prepared Ge-MWCNTs nanocomposite exhibits improved cycling performance with higher capacity retention with respect to pure Ge electrode. In fact, Ge-MWCNTs nanocomposite shown a discharge capacity of 1160 mAh g-1 at current rate of 0.1C after 60 cycles as well as an excellent discharge capacity of 406 mAh g-1 at a current rate of 5C even after 400 cycles.References

1. J. B. Goodenough et. al., J. Am. Chem. Soc., 135 (2013) 1167
2. S.Goriparti et.al., J. Power Sources, 257 (2014) 421
3. S.Goriparti et.al., ACS Appl.
Mater. Interfaces, 7, (2015) 25146

Figure 1