bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Simulation of the Primary, Secondary and Tertiary Potential Distribution on Porous Cathode in a Flow-through Packed Bed Reactor. Influence of Thickness, Concentration and Hydrodynamics in Porous Media
Authors: Rivera Fernando Felipe , Nava José Luis 
Published: February 2020

Packed bed electrodes can be used for electrochemical recovery of heavy metals from a variety of industrial and laboratory model solutions. The packed bed electrode forms a porous flow-through (Figure 1) configuration providing large surface area usually depleting the concentration of several metal ions below 0.1 ppm. For design porpoises of these electrodes, it is necessary to study the influence of geometry (cathode thickness), flow rate and concentration on potential distribution.
Numerical simulations of primary, secondary and tertiary current distributions on the porous cathode of a packed bed electrochemical reactor (Figure 1) were calculated. For primary and secondary current distribution, Laplace equations with its respective boundary conditions (constant potential for primary current distribution and charge transfer kinetics described by a Tafel approximation in secondary current distribution) were evaluated using the finite element method. For tertiary current distribution, the influence of hydrodynamics was taken in account, considering Navier-Stokes model with Brinkman extension for porous media. Once Brinkman equations was solved and local velocity distributions were obtained, local mass transfer coefficients were evaluated by means of following relationship:

Kma=cvb

where Km
is local mass transport coefficient, a is the specific area, v is local velocity, c and b are empirical constants taken from literature.
The effects of flow rate, ion concentration, matrix conductivity and thicknes on the distribution of current on porous cathode are analyzed. Results of current distribution obtained by Nava et. al 2008 [1] enable comparisons with the simulations.
References: [1] J.L. Nava, M.T. Oropeza, C. Ponce de León, J. González-García, A.J. Frías-Ferrer. Hydrometallurgy, 91, 2008, 98-103
Magnetic Structure and Properties of NaFePO4 Polymorphs: Antiferromagnetic Ordering and Spin-Flop Transition
Authors: Barpanda Prabeer , Avdeev Maxim , Ling Chris D 
Published: February 2020

In recent years, the cost and sustainability concerns have renewed research efforts on sodium-ion batteries, propelling investigation on various layered oxides and polyanionic family of insertion compounds for low-cost and large-scale cathode applications. These cathode insertion compounds are functional materials, involving redox active 3d transition metals (e.g. Fe/Co/Ni) that are often magnetic in nature. During the Na (de)insertion process involving redox reaction of transition metals and structural alteration, the magnetic magnetic structure/ properties can vary significantly.
We have investigated the magnetic structure and properties of NaFePO4 polyanionic system, which exists in two distinct polymorphs: metastable triphylite and stable maricite. The details of these structures are shown in the figure. Both these polymoprhs undergo antiferromagnetic ordering below 50 K (for triphylite) and 13 K (for maricite). Using the magnetic susceptibility, heat capacity and low temperature neutron powder diffraction, the magnetic structure of these two distinct polymorphs have been solved. The details of these antiferromagnetic structures will be described considering the super- and super-superexchange interactions. In addition, investigating the maricite NaFePO4 polymorph, which consists of edge-sharing FeO6 octahedral chains, we have discovered the occurrence of spin-flop transition below 40 kOe using susceptibility measurement and low-temperature Mossbauer spectroscopy. This spin-flopping (or metamagnetism) phenomenon in maricite NaFePO4 will be described in detail [1-5] to showcase the rich magnetism present in NaFePO4 insertion materials.

References:

P. Barpanda et al, Adv. Energy Mater., 2, 841, 2012.

M. Avdeev et al, Inorg. Chem., 52, 395, 2013.

M. Avdeev et al, Inorg. Chem., 52, 8685, 2013.

M. Avdeev et al, Inorg. Chem., 53, 682, 2014.

M. Avdeev et al, private communication.
Efficient Elimination of Lithium Carbonate/Carboxylates By NiO for Rechargeable Li–O2 Battery
Authors: Hong Misun , Choi Hee Cheul , Byon Hye Ryung 
Published: February 2020

The non-aqueous lithium–oxygen (Li–O2) battery has been extensively investigated by virtue of its remarkably high theoretical energy density. However, the Li–O2 cell has suffered from parasitic side reactions due to superoxide (O2
•−) attack and lithium peroxide (Li2O2) activity to non-aqueous electrolytes and carbon cathodes, which form lithium carbonates (Li2CO3) and carboxylates (RCO2Li, R = H or alkyl). These poor-conducting side products deposited on the cathode increase the recharge potential, which triggers the parasitic side reactions further. Some efforts to employ superoxide-tolerant electrolytes, carbon-free cathodes and cycling with limited depth of discharge have alleviated the side reactions whereas the lithium carbonates/carboxylates inevitably formed are overwhelmingly deposited on the cathode for cycling thus terminating the Li–O2 cell operation rapidly.
Here, we present new approach to promote elimination of lithium carbonate/carboxylates using nanoporous nickel oxide (NiO), which enhances cycling performance and round trip efficiency of Li–O2 battery for cycling. The crystalline nanoporous NiO plates that were homogeneously distributed on the entangled carbon nanotubes (CNT) network via hydrothermal synthesis (NiO/CNT) exhibit striking capacity retention of over 70 cycles at a limited discharge capacity of 1000 mAh gCNT
−1 with a stable recharge potential of 4.1 V vs. Li/Li+ in tetraglyme electrolyte. The role of nanoporous NiO is investigated under the cycling at deep depth of discharge. Unlike the first cycle providing predominant Li2O2, the increasing extent of lithium carbonates/carboxylates for cycling are observed by 1H NMR and FTIR spectroscopies. In particular, the lithium carbonates become a main side product over 10 cycles. Interestingly, the NiO/CNT cathodes reveal disappearance of these side products after every recharge and high capacity retention, which are different from NiO-free CNT cathodes providing the accumulated side products and swift capacity fading. Further analysis using anodic potential sweeps of side products in three-electrode cell demonstrate ~300 mV lower oxidation potential on the NiO/CNT than the NiO-free CNT while negligible influence on the electrolyte oxidation, which implies a promoter of nanoporous NiO to eliminate lithium carbonates/carboxylates. TEM images display that the side products seem to transport along the CNT and make a lump close to the NiO, where the decomposition of side products can be carried out actively. The nanoporous NiO has been very stable during deep cycling, where either chemical or structural change is not observed, which indicates that the NiO can contribute toward stable long-term cycling performance of Li–O2 cell.
High Rechargeable and Efficient Li-O2 Battery Using a Novel Organic Catalyst
Authors: Liu Jia , Renault Stéven , Brandell Daniel , Gustafsson Torbjörn , Edström Kristina , Zhu Jiefang 
Published: February 2020

As an advanced large-scale energy storage and conversion system, the rechargeable non-aqueous Li-O2 battery has recently attracted considerable attention because of its high gravimetric density since it was firstly presented in 1996[1]. In an ideal Li-O2 battery, on discharge, O2 is reduced at the cathode, where it combines with Li+ released from the Li-metal anode to yield Li2O2 (oxygen reduction reaction (ORR), 2 Li+ + O2↑ + 2 e- → Li2O2)). On charge, Li2O2 is converted back to Li+ and O2 (oxygen evolution reaction (OER), Li2O2→2 Li+ + O2↑ + 2 e-))[2]. One of the critical challenges which limit the implementation of Li-O2 batteries is the low round-trip efficiency and poor cyclability resulting from a large over-potential. Although the real effect of catalytic activity is controversial and the mechanism of catalyst is not yet clear, it has been widely accepted that the employment of catalyst can minimize the over-potential of Li-O2 battery. Up to now, a number of materials have been employed as cathode catalysts, such as noble metal (alloy), carbon, transition-metal oxide, showing some improvement.
Herein, a highly reversible and efficient Li-O2 cell using Dilithium (2,5-dilithium-oxy)-terephthalate (Li4C8H2O6) as a novel organic catalyst was reported. The mechanism of the increasing efficiency and cyclability was systematically investigated. In addition, operando synchrotron-based XRD (SR-PXD) as a diagnostic tool that allowed us to probe the dynamics for the degradation of Li2O2 during charging process was employed to further study the real-time kinetics of OER in a Li-O2 cell.
REFERENCES
[1] J. Liu, M. Roberts, R. Younesi, M. Dahbi, K. Edström, T. Gustafsson, J. Zhu, The Journal of Physical Chemistry Letters 4 (2013) 4045-4050.
[2] R. Younesi, S. Urbonaite, K. Edström, M. Hahlin, The Journal of Physical Chemistry C 116 (2012) 20673-20680.
Modified Li-Ion Conducting Ceramic Membrane for Improved Performance in Hybrid Li-Air Battery
Authors: Li Yunfeng , Xing Yangchuan 
Published: February 2020

Li-air battery (LAB) with non-aqueous electrolytes currently has insurmountable technical challenges in both electrolytes and solid lithium oxide products [1-2]. A hybrid Li-air (HyLAB) system has been reported as an alternative approach [3-8]. Such systems use non-aqueous electrolyte in the anode and aqueous electrolyte in the cathode. A Li-ion conducting ceramic membrane (water impermeable) is used to separate the anode and cathode chambers. While such hybrid system can avoid many problems in the aprotic system, unfortunately, the ceramic membrane is not stable in acidic or alkaline electrolytes.
In this presentation, we report our recent work to modify the ceramic membranes. We will demonstrate that by modifying the Li-ion conducting ceramics it is possible to improve its resistance to corrosion and therefore increase the performance of the HyLABs. We will discuss the technical details of the work in this presentation.

References

[1] P.G. Bruce, S.A. Freunberger, L.J. Hardwick, J.-M. Tarascon, Nat. Mater., 11 (2012) 19-29.
[2] G. Girishkumar, B. McCloskey, A.C. Luntz, S. Swanson, W. Wilcke, The Journal of Physical Chemistry Letters, 1 (2010) 2193-2203.
[3] S.J. Visco, E. Nimon, B. Katz, L.D. Jonghe and M. Y. Chu, in The 210th Electrochemical Society Meeting, Cancun, Mexico (2006).
[4] T. Zhang, N. Imanishi, Y. Shimonishi, A. Hirano, Y. Takeda, O. Yamamoto, N. Sammes, Chemical Communications, 46 (2010) 1661-1663.
[5] E. Yoo, H. Zhou, ACS Nano, 5 (2011) 3020-3026.
[6] L. Li, X. Zhao, A. Manthiram, Electrochemistry Communications, 14 (2012) 78-81.
[7] Y. Li, K. Huang and Y. Xing, Electrochimica Acta, 81 (2012) 20.
[8] Y. Li, Z-P. Huang, K. Huang, D. Carnahan, and Y. Xing, Energy & Environmental Science, 6 (2013) 3339.
Characterization and Electrochemical Behaviour of AV4S8 (A=Ga,Ge) Materials as Negative Electrodes of Sodium-Ion Batteries
Authors: Michelet Cédric , Crosnier Olivier , Dupré Nicolas , Guyomard Dominique , Brousse Thierry , Moreau Philippe 
Published: February 2020

Lithium-ion batteries have become essential in recent years. Due to both the difficult access and the cost of the alkaline element, a new field of research concerning sodium-ion batteries has recently emerged. Many compounds have been proposed as positive electrodes for Na-ion batteries. However, since sodium does not intercalate into graphite as much as lithium (1), there is a clear need for high capacity materials for negative electrode materials. Intercalation compounds such as Na2Ti3O7 (2) or NaTi2(PO4)3 (3) or Sb-based compounds (4) come usually with a somehow limited capacity (~ 200-400 mAh.g-1). Here, we present the possible use of a class of chalcogenide materials, AV4S8 (A=Ga,Ge), as a negative electrode in sodium-ion batteries.
The reactivity of AV4S8 with Na leads to a remarkable specific capacity of 800 mAh/g for the first discharge at a C/20 rate (1 complete charge in 20 hours), followed by a reversible reaction associated with a 500 mAh/g capacity retained after 30 cycles.
Many experiments were performed in order to understand the reaction mechanism of sodium with the AV4S8 materials. Electrochemical, in situ X-ray diffraction (Figure 1) and transmission electron microscopy experiments suggest that a smooth conversion mechanism is occurring and that the capacity fade is largely due to reactions with the electrolyte at low potential.
EDX and TEM observations, as well as EELS experiments performed at the vanadium L-edge, indicate that a reduction of the vanadium oxidation state occurs during the discharge process. XAS experiments performed at the Vanadium and Germanium K edges also clearly demonstrate that all the elements are involved during the electrochemical processes.
Synthesis, structural characterization and electrochemical behaviour of AV4S8 will be discussed in details in the presentation. Results obtained on the AV4S8 phases are very promising and demonstrate that this new class of materials is a good candidate as a negative electrode for Na-ion batteries.
References
(1). M. M. Doeff, Y. Ma, S. J. Visco,L. C. De Jonghe, J. Electrochem.Soc. 140, L169 (1993).
(2). P. Senguttuvan, G.l. Rousse, V. Seznec, J.-M. Tarascon, M.R. Palacin, Chemistry of Materials, 23, 4109-4111 (2011).
(3). S.I. Park, I. Gocheva, S. Okada, J.-i. Yamaki, J. Electrochem. Soc. 158, A1067-A1070 (2011).
(4). A. Darwiche, C. Marino, M.T. Sougrati, B. Fraisse, L. Stievano, L. Monconduit, Journal of the American Chemical Society, 134, 20805-20811 (2012).
HOR in Alkaline Membrane Fuel Cells: Hollow Octahedral Electrocatalysts
Authors: Shviro Meital , Polani Shlomi , Zitoun David 
Published: February 2020

We have recently explored the binary system of NixPt1-x alloys for HOR in alkaline membrane fuel cells and demonstrated our ability to generate mainly [111] facets in octahedral nanocrystals using colloidal synthesis. [1] In a further experiment, galvanic replacement reaction has been used to introduce a third metal and has been successful in the case of other PGM, while etching part of the Ni. In some cases, the etching process yields hollow octahedral frames (see figure).
The catalysts are characterized by electrochemical measurements in 0.1 mol/L of KOH using cyclic voltammetry and polarization curves on glassy carbon rotating disc electrodes. After screening of the best electro-catalysts, a full characterization is carried out to probe the atomic structure by HRTEM, HAADF and EELS, in parallel with gas adsorption spectroscopy (mainly FTIR of CO species) and calorimetry to determine the nature of surface sites on the catalyst.
[1] Shviro, M.; Zitoun, D. RSC Adv.
2013, 3, 1380;
Recent Progress in Commercial PEM Fuel Cell Stacks
Authors: Kerkhof Wybe , Coolegem Jorg , Smit Mascha 
Published: February 2020

Nedstack produces commercial PEM fuel cell stacks in the range of 2 to 10 kW for stationary applications, including backup power systems for the Telecom industry and energy recovery from byproduct hydrogen in the chlorine industry. Many of our stacks have already been installed in backup and continuous power systems for Telecom worldwide, and have been functioning for a number of years. At the same time, in our 70 kW PEM Power Plant in Delfzijl (Netherlands), which has run for over 40,000 hours, we have shown lifetimes of over 23,000 hours for our XXL stacks under real operational conditions.
An analysis of performance data from operation of Nedstack’s XXL stacks in the Delfzijl PEM power plant, as well as a detailed beginning-of-life and end-of-life characterization, including cyclic voltammetry and electrochemical impedance, will be discussed. Stacks show a steady averaged linear decay rate of only 2.3 mV/1000 hr during operation, resulting in a predicted lifetime of 30,000 hours (for a 10% allowable voltage decay). Based on the results, AST’s were developed for material degradation, which have led to better material selection, as well as an improvement in stack design. These have now led to further improved decay rates, below 2 mV/1000 hr, which corresponds to an expected lifetime of 39,000 hours, based on the assumption of linear decay.Nedstack produces commercial PEM fuel cell stacks in the range of 2 to 10 kW for stationary applications, including backup power systems for the Telecom industry and energy recovery from byproduct hydrogen in the chlorine industry. Many of our stacks have already been installed in backup and continuous power systems for Telecom worldwide, and have been functioning for a number of years. At the same time, in our 70 kW PEM Power Plant facility in Delfzijl (Netherlands), which has run for over 40,000 hours, we have shown lifetimes of over 23,000 hours for our XXL stacks under real operational conditions.
An analysis of performance data from operation of Nedstack’s XXL stacks in the Delfzijl PEM power plant, as well as a detailed beginning-of-life and end-of-life characterization, including cyclic voltammetry and electrochemical impedance, will be discussed. Stacks show a steady averaged linear decay rate of only 2.3 mV/1000 hr during operation, resulting in a predicted lifetime of 30,000 hours (for a 10% allowable voltage decay). Based on the results, AST’s were developed for material degradation, which have led to better material selection, as well as an improvement in stack design. These have now led to further improved decay rates, below 2 mV/1000 hr, which corresponds to an expected lifetime of 39,000 hours, based on the assumption of linear decay.
Design of Highly Durable Electrocatalyst for High-Temperature Polymer Electrolyte Fuel Cell
Authors: Fujigaya Tsuyohiko , Berber Mohamed Reda , Nakashima Naotoshi 
Published: February 2020

Phosphoric acid-doped polybenzimidazoles (denoted PA-doped PBIs) have been considered as the most promising substitutive polyelectrolytes and the PEFC employing PA-doped PBIs not only in PEM but also in the catalyst layers (Cat-L) have been developed for high temperature operation. However, recent studies have revealed that leaching of liquid PA from PEM1) and Cat-L2) causes inhomogeneous PA distribution that results in deterioration of PEFC performance during long-term operation.
In this study, in order to prevent acid leaching from the high temperature PEFC system, we used poly(vinylphosphonic acid) (PVPA) in place of PA because PVPA is a polymeric acid and is stably bound to the PBIs via multipoint acid-base reactions. We fabricated a novel electrocatalyst for Cat-L assembled with carbon nanotubes (CNTs), PVPA-doped PBI and platinum (Pt) nanoparticles as an electron-conducting supporting material, electrolyte and metal catalyst, respectively. Bottom-up assembly of nanometer-thick PVPA-doped PBI layer around CNTs is expected to serve as an effective proton conduction pathway via the Grotthuss mechanism. The doping stability of PVPA in addition to the PEFC activity and durability were studied.
We tested the durability of the PVPA-doped MEA by following the protocol proposed by the Fuel Cell Commercialization Conference of Japan (FCCJ)3). As a comparison, the durability of a PA-non-doped MEA (MWNT/PyPBI/Pt electrocatalyst doped with leached PA) was tested. Dramatic drop of the cell voltage was observed for PA-non-doped MEA, while PVPA-doped MEA shows slight decrease (Fig. 1). Such high durability of PVPA-doped MEA shows an extended stability of PEM against degradation, and also shows a continuous connection of the proton path in the Cat-L4).

References

1) Y. Oono, T. Fukuda, A. Sounai, and M. Hori, J. Power Sources 195, 1007-1014 (2010).
2) Y. Oono, A. Sounai, and M. Hori, J. Power Sources 189, 943-949 (2009).
3) A. Ohma, K. Shinohara, A. Iiyama, T. Yoshida, and A. Daimaru, ECS Transactions 41, 775-784 (2011).
4) M. R. Berber, T. Fujigaya, K. Sasaki, and N. Nakashima, Sci. Rep. 3, (2013).
Synthesis of Reduced Graphene Oxides-Supported Binary Catalysts and Its Electrocatalytic Activity
Authors: Jeevagan Arockiam John , Gunji Takao , Hashimoto Masanari , Kaneko Shingo , Tanaka Manabu , Matsumoto Futoshi 
Published: February 2020

Proton exchange membrane fuel cells (PEMFCs) have attracted wide attention beacause of their high energy efficiency and environmental freindliness.1 Noble nanoparticles (Pt, Pd) based binary alloys nanoparticles supported on carbon black were widely used in PEMFCs. Highly dispersed Pt based nanoparticles on Vulcan carbon (VC), carbon nanotubes (CNTs),carbon fibres exhibit enhanced electrocatalytic activites in PEMFCs. Recently, graphene nanosheets have been studied extensively as catalyst supports for PEMFCs owing to its high surface area, electrical conductivity and specific thermal/chemical stability.2 Graphene exhibit a unique structure of two-dimensional sp2-bonded carbon atoms with one-atom thickness and possess large surface area and higher electrical conductivity when compared to CNTs.3 But, the efficient immobilization of Pt nanoparticles on graphene surface remains a big challenge. Additionaly, It has been reported that chemical reduction of exfoliated graphene oxide (GO) could act as effective catalyst supporter because of their oxygen-containing functional groups which act as the binding sites for Pt nanoparticles on GO surfaces.4Herein, we demonstrate that, a one-pot synthesis of binary alloy catalyst under alkaline conditions.
Figure 1 shows the pXRD pattern (A) and TEM image (B) of Pt/RGO catalyst. The peaks between 30 and 90 can be indexed to Pt crystals of face-centered cubic structure (fcc). In TEM image, the Pt NPs are showed monodispersity and homogeneity on the RGO support catalyst. The details about the synthesis, characterization and catalytic activity of catalysts would be discussed in the presentation.

References

1. R. Wang, C. Xu, X. Bi and Y. Ding, Energy Environ.

Sci., 5, 5281, (2012).
2. R.H. Baughman, A.A. Zakhidov and W.A. de Heer,
Science, 297, 787, (2002).
3. Y.B. Zhang, Y.W. Tan, H.L. Stormer and P.Kim,

Nature, 438, 197, (2005).
4. B. Seger and P.V. Kamat, J. Phys. Chem. C, 113,
7990, (2009).