bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Hydrophobicity Gradients within MPL and MEA on PEM fuel cell performance
Authors: Mohseninia Arezou , Kartouzian Dena , Regnet Fabian , Scholta Joachim , Jörissen Ludwig 
Published: February 2020

The water inventory of PEMFC components strongly influences the performance under two-phase operating conditions. Within this work, the influence of hydrophobicity variation within electrode and microporous layer (MPL) on cell performance will be presented. Different weight percentages of PTFE is used in the catalyst and MPL inks as an additive in order to increase the hydrophobicity. The fabrication method for the membrane electrode assembly (MEA) is based on spraying the catalyst ink onto the membrane and coating MPL ink onto the GDL substrate using a doctor blade method. Fuel cell tests are carried out with a 25 cm² active area single cell at different relative humidities (RH) and oxygen flow rates to investigate the effect of PTFE on the ability of MEA and MPL on water management. Electrochemical impedance spectroscopy is performed as a diagnostic tool to investigate the reaction kinetics and mass transport. In order to assess the wettability of MEAs contact angle measurements were carried out. The materials are characterized by mercury porosimetry and scanning electron microscopy.
Figure 1 shows the performance curve for cell 1 (conventional MEA +Conventional MPL), cell 2( MEA with 5 wt.% PTFE +Conventional MPL) and cell 3 (Conventional MEA+ MPL with 40 wt.% PTFE ) at different relative humidities. At dry conditions (RH=70%) cell 2 has a higher limiting current density compared to the other cells, which could be the indication that the hydrophobic electrode keeps the membrane material in the catalyst layer better hydrated. At over humidified conditions (RH=120%) the limiting current density value has decreased for cell 1 and 2 compared to the standard conditions (RH=100%) as a result of mass transport limitations. On contrary, Cell 3 shows an improved performance in high current density region at humid conditions, illustrating the ability of hydrophobic MPL to prevent the accumulation of liquid water at the interphase of MPL and catalyst layer at cathode side. In the presentation of the ongoing work, additional results, including HFR data will be reported.

Figure 1
Impact of Ionomer Dispersion on PEM Fuel Cell Performance
Authors: Xu Hui , Lei Chao , Kim Yu Seung , More Karren L. 
Published: February 2020

Conventional polymer electrolyte membrane (PEM) fuel cell electrodes using aqueous ionomer dispersion suffer from high manufacturing costs and rapid performance degradation. We have investigated an innovative method of designing fuel cell electrodes to reduce manufacturing costs and extend the lifetime. Our approach to obtaining good fuel cell performance is to; 1) understand ionomer particle morphology in dispersion; 2) investigate the electrode morphology, catalyst, and ionomer binder distributions in the electrodes; 3) evaluate the electrode performance using various electrodes prepared from different dispersing agents.
First, laser diffraction particle size analysis was used to understand the various solvents’ impacts on catalyst ink structure. It can be seen that nPA/H2O and ethylene glycol (EG) solvent systems provide better ink structure, implied by much smaller agglomeration sizes. IPA/H2O and pentanediol based solvent systems exhibit large agglomerations in the ink, which may account for their poor quality. The laser diffraction particle size will be correlated with electrode structure and fuel cell performance later.
Low magnification transmission electron microscopy element mapping was then used to characterize the ionomer distribution in these cathode layers. The best ionomer distribution was found in the EG based sample, with ionomer aggregates <50 nm. The porosity and pore size distribution of the electrode layers were also obtained from transmission electron microscopy image analysis. The EG-based electrode shows the lowest porosity (i.e., 13%). It also contains the smallest pore sizes and the highest number of pores.
The effect of the dispersing agents on initial fuel cell performance was investigated. In this experiment, four ionomer dispersions were used and compared with nPA/H2O and IPA/H2O. All MEAs had a Pt loading of ~0.20 mgPt/cm2. The IPA/H2O baseline shows very low performance especially in the mass transport region, which is probably attributed to its poor coating quality. The ionomer dispersions have shown significant influence on the fuel cell performance, with a general ranking as: nPA/H2O > ethylene glycol > butanediol > pentanediol). The ethylene glycol based sample displays the best performance of all the non-aqueous samples, and its performance is very comparable to the nPA/H2O baseline.
Reaction Mechanism of a Novel IrOx-Based OER Catalyst in Acidic Media
Authors: Cheng Junfang , Yang Jun , Kitano Sho , Cui Xuedong , Ghuman Kulbir , Juhász Gergely , Yamauchi Miho , Nakashima Naotoshi 
Published: February 2020

The oxygen evolution reaction (OER) is of prime importance in multiple energy storage devices [1]. IrOx-based catalysts are thought to be the most promising candidates in acidic media, but have been limited by their high cost. Choosing suitable substrates for such catalysts are effective to reduce the Ir consumption as well as beneficial for the OER performance[2
-
4]. Here, we focus on the catalytic mechanism for a newly synthesized IrOx-based composite material which shows an excellent OER performance in acidic media. The catalytic mechanism has been revealed mainly based on in-situ measurements and DFT calculations. The detail mechanism will de presented at the meeting.

References

[1] A. Grimaud, A. Demortiere, M. Saubanere, W. Dachraoui, M. Duchamp, M. Doublet, J. Tarascon, Nature energy, 2016, 2, 16189.
[2] H. Oh, H. Nong, T. Reier, A. Bergmann, M. Gliech, J. Araújo, E. Willinger, R. Schlögl, D. Teschner, P. Strasser, J. Am. Chem. Soc. 2016, 138, 12552−12563.
[3] E. Oakton, D, Lebedev, M. Povia, D. Abbott, E. Fabbri, A. Fedorov, M. Nachtegaal, C. Copéret, T. Schmidt, ACS Catal. 2017, 7, 2346−2352.
[4] H. Casalongue, M. Ng, S. Kaya, D. Friebel, H. Ogasawara, A. Nilsson, Angew. Chem. Int. Ed. 2014, 53, 7169–7172.
In Situ Structural Determination of Underpotentially Deposited Pd Monolayer on Au(111) Surface
Authors: Masuda Takuya , Wakisaka Yuki , Kondo Toshihiro , Chun Wang-Jae , Takakusagi Satoru , Asakura Kiyotaka , Uosaki Kohei 
Published: February 2020

Ultrathin metal films with well-defined atomic arrangements can be formed on surfaces of single crystal electrodes by underpotential deposition (UPD) technique in which metals can be deposited on a foreign metal substrate at potentials more positive than the reversible potential of the bulk deposition if the interaction between the deposited metal and the foreign metal substrate is stronger than that of the deposited metal itself. The structure of a Pd UPD layer prepared on a Au(111) surface has been studied with an atomic resolution in situ by scanning tunneling microscopy (STM) and surface x-ray scattering (SXS) and it was found that a pseudomorphic Pd monolayer is formed on the Au(111) surface.1-5 In addition, the Pd UPD layer on Au(111) surface is known to exhibit unique catalytic activities for oxygen reduction reaction (ORR).6 In the present work, the geometric and electronic structure of the Pd UPD layer on Au(111) surface during ORR were investigated by in situ XAFS measurements in the polarization dependent total reflection fluorescence (PTRF) configuration.7-12

1) Naohara, S. Ye, K. Uosaki, J. Phys. Chem. B
102, 4366 (1998).
2) Naohara, S. Ye, K. Uosaki, J. Electroanal. Chem.
473, 2 (1999).
3) Takahasi, Y. Hayashi, J. Mizuki, K. Tamura, T. Kondo, H. Naohara, K. Uosaki, Surf. Sci.
461, 213 (2000).
4) Naohara, S. Ye, K. Uosaki, J. Electroanal Chem.
500, 435 (2001).
5) Takahashi, Y. Hayashi, J. Mizuki, K. Tamura, T. Kondo, H. Naohara, K. Uosaki, Surf. Sci.
461, 213 (2000).
6) Naohara, S. Ye, K. Uosaki, Electrochim. Acta,
45, 3305 (2000).
7) W.-J. Chun, K. Asakura, Y. Iwasawa, J. Phys. Chem. B
102, 9006 (1998).
8) Masuda, H. Fukumitsu, S. Takakusagi, W.-J. Chun, T. Kondo, K. Asakura, K. Uosaki, Adv. Mater,
24, 268 (2012).
9) Masuda, K. Uosaki, J. Electron Spectrosc. Relat. Phenom.,
221, 88 (2017).
10) Masuda, Y. Sun, H. Fukumitsu, H. Uehara, S. Takakusagi, W.-J. Chun, T. Kondo, K. Asakura, K. Uosaki, J. Phys. Chem. C,
120, 16200 (2016).
11) Masuda, K. Uosaki, Chapter 6, “Novel In Situ Techniques”, Electrochemical Science for a Sustainable Society A Tribute to J.O’M Bockris, Springer International Publishing, 2017, 147-174.
12) Masuda, T. Kondo, K. Uosaki, Section 5.13, “Solid-Liquid Interfaces”, XAFS Techniques for Catalysts, Nanomaterials, and Surfaces, Springer International Publishing, 2016, 505-525.
Photoelectrochemical Methanol Oxidation on TiN@Au Core-Shell Nanoparticles Supported on TiO2
Authors: Baturina Olga A , Epshteyn Albert , Simpkins Blake 
Published: February 2020

Refractory transition metal nitrides such as TiN and ZrN are a new class of plasmonic materials that exhibit plasmonic resonance in the visible and near-infrared regions [1, 2]. The similarity of optical appearance of TiN to gold makes one wonder whether inexpensive and chemically and mechanically robust TiN can replace Au in plasmon-mediated photocatalytic reactions. Prior research [3] has shown that cubic 50 nm TiN nanoparticles supported on TiO2 nanowires provide greater photocurrent enhancement for the photoelectrochemical water splitting compared to spherical Au nanoparticles. This has been attributed to more efficient hot carrier generation by TiN nanoparticles, followed by more efficient collection of hot electrons by TiO2. 50 nm TiN nanoparticles (NPs), however, proved to be inefficient in promoting photocatalytic activity of TiO2 towards methanol oxidation in the visible region [4]. This was likely due to a lack of catalytic activity of the TiN NPs’ surface for CH3OH oxidation.
Here, we explore the plasmon-mediated photocatalytic methanol oxidation on hybrid core-shell nanoparticles consisting of a thin gold shell and TiN core and compare the effect of TiO2-supported TiN@Au nanoparticles to that of Au on the photon-to-electron conversion efficiency.
The TiO2-supported TiN@Au photocatalysts were made by the deposition of a thin Au shell on 20 and 50 nm TiN NPs (PlasmaChem) followed by the dispersion of the TiN@Au NPs onto TiO2 nanoparticle support (Degussa). Electrochemical experiments were conducted in a three-electrode photoelectrochemical cell. The thin films of TiN@Au/TiO2 on FTO-coated glass served as working electrodes (WEs), while platinum foil and Ag/AgCl in 3 M NaCl (BioLogic, Inc) were used as counter and reference electrodes, respectively. LED lights were used as light sources. X-Ray Photoelectron Spectroscopy, Powder X-Ray Diffraction, and high resolution transmission electron microscopy were used for characterization of catalysts surface composition and morphology.
References
[1] G.V. Naik, J.L. Schroeder, X. Ni, A.V. Kildishev, T.D. Sands, A. Boltasseva, Optical Materials Express, 2 (2012) 478.
[2] U. Guler, A. Boltasseva, V.M. Shalaev, Science, 344 (2014) 263.
[3] A. Naldoni, U. Guler, Z.X. Wang, M. Marelli, F. Malara, X.G. Meng, L.V. Besteiro, A.O. Govorov, A.V. Kildishev, A. Boltasseva, V.M. Shalaev, Advanced Optical Materials, 5 (2017).
[4].O.A. Baturina, A. Epshteyn, B. Simpkins. Unpublished results
(Keynote) Conducting Redox Polymer Batteries
Authors: Sjödin Martin , Emanuelsson Rikard , Sterby Mia , Huang Hao , Wang Huan , Strømme Maria 
Published: February 2020

Organic matter based battery materials have attracted large interest due to their inherent ability to provide an environmentally benign alternative to inorganic batteries because such materials can be produced from renewable resources via eco-efficient processes. Conducting redox polymers (CRPs) is an attractive class of materials for organic matter based electrical energy storage. CRPs are composed of a conducting polymer backbone with redox active pendant groups covalently linked to the polymer backbone. The conducting polymer backbone renders the material conductive and, due to the large molecular size, prevents material dissolution thus mastering two of the most significant obstacles in achieving powerful and stable battery materials from organic compounds. The pendant redox group, on the other hand, can provide high charge storage capacities to the material. Combining conducting polymers with high charge storage capacity pendants thus has the possibility to form powerful materials for battery applications provided that the individual properties of the backbone and the redox group can be preserved and operate in synergy in the CRP. This requires careful matching of the redox chemistry of the pendant group and the CP backbone as CPs are only conducting in specific potential regions. In this work design principles for CRPs are outlined and we present results suggesting that CRPs can show semi-metallic electron transport properties and that redox conversion rates on the sub-second time-scale can be accomplished with this type of materials [1]. In addition we present an all-organic proton battery composed of quinone CRPs as both anode and cathode [2].
[1] M. Sterby, et al., Electrochim. Acta, 2017, 235, 356-364
[2] R. Emanuelsson, et al., J. Am. Chem. Soc., 2017, 139 (13), 4828-4834.

Figure 1
A Rational Balance Design of Ionic Liquid Based Electrolyte for Advanced Li-S Batteries
Authors: Lu Hai , Chen Zhen , Du Huiling , Zhang Kai 
Published: February 2020

Lithium-sulfur (Li-S) battery has attracted worldwide attentions by virtue of high theoretical energy density, abundant material source and good environmental friendliness. However, the dissolution and shuttle of the intermediate polysulfides always result in low sulfur utilization, bad cycle stability and severe self-discharge issue.
It is well known that room temperature ionic liquids (ILs) can reduce polysulfide dissolution owing to weak donor ability and delay polysulfide migration due to high viscosity. But high viscosity is a double-edged sword, which can also hinder the transport of Li ion, casing low capacity deliver and weak rate capability. Various low-viscous ethers (DME, DOL, TEGDME) has been attempted to cooperate with the IL, but most of them have a relatively high donor number and hence polysulfide dissolution is reversely promoted unavoidably.
Here, we put forward the introduction of linear fluorinated ethers (LFEs) in the IL-based electrolyte as co-solvent. By adding moderate content of LFEs into the IL, the increased capacity and improved rate capability are demonstrated. On the one hand, LFEs own relatively lower viscosity compared to ILs and hence improve the ion conduction in the electrolyte. On the other hand, they serve to minimize polysulfide dissolution due to low solvation ability. Besides, these F-contained solvents stabilize SEI on Li anode as well. However, the binary system consisting of IL and LFE leads to low active material utilization instead, despite high coulombic efficiency (CE, close to 100%) and stable cycle is obtained. In other words, excessive restriction to polysulfide dissolution is not necessary for the improvement of cell performance. In contrast, the ternary system consisting of IL, LFE and ordinary ether (such as DOL) contributes to more reversible capacity, although the CE value (~90%) is a bit lower than those binary or pure IL cases (Fig.1 as an example). Therefore, it should be emphasized that a rational balance design between the polysulfide dissolution and shuttle suppression is more significant for constructing advanced Li-S batteries.
Fig. 1 (a) Discharge capacities and (b) coulombic efficiencies of Li-S batteries in various electrolytes during cycling

Reference:

Lu, K. Zhang, Y. Yuan, et al, Electrochim. Acta, 2015, 161, 55-62

Lu, Y. Yuan, K. Zhang, et al, J. Electrochem. Soc., 2015, 162, A1460-A1465

Lu, Z. Chen, H. Du, et al, Ionics, DOI: 10.1007/s11581-018-2814-x

Acknowledgment:

This work was supported by the Natural Science Foundation of China (No. 51604221, 51372197 and 51574288), the Key Innovation Team of Shaanxi Province (2014KCT-04).

Figure 1
Key Features in the Manufacturing Process of Ultra-Thick Electrodes for High Energy Lithium Ion Batteries
Authors: Heider Emanuel , Hoffmann Alice , Kremer Lea Sophie , Dreer Christian , Pfeifer Claudia , Diehm Ralf , Kumberg Jana , Schabel Wilhelm , Wohlfahrt-Mehrens Margret 
Published: February 2020

Energy density is one of the key challenges in the development of advanced lithium ion batteries for many applications. To address this issue, a considerable number of studies have been conducted on high capacity cathode materials1–3. Another approach, covered in this contribution, is reducing the amount of passive material in the cell via increasing the mass loading of the electrodes4,5. These ultra-thick electrodes, however, suffer from certain drawbacks like a low rate capability4–7, reduced adhesion and flexibility or crack formation8.
Numerous investigations on the development of electrodes for lithium ion batteries have been performed using preparation techniques typical for lab scale. In common studies, the electrochemical and mechanical properties of an electrode are attributed to mass loading, porosity and the distribution of passive materials in the binder-network9.
This study considers manufacturing procedures for NMC cathodes highly relevant to industrial production. A strong influence of the manufacturing process especially on the morphology and electrochemical performance of ultra-thick electrodes was observed.
As an example, ultra-thick electrodes with an areal capacity of 8 mAhcm-2 were prepared in pilot scale, yielding a significantly higher capacity than state of the art cathodes7,10.
It is demonstrated that the mixing strategy used for slurry preparation significantly alters the distribution of materials and the morphology of the electrode, consequently also influencing adhesion strength and flexibility. These properties are likewise strongly affected by the applied drying procedure. By an optimized mixing and drying procedure, crack-free, ultra-thick electrodes were obtained even in pilot scale. These electrodes, manufactured by the optimized process, show significantly higher flexibility, which is very important for roll-to-roll processing.
Scanning electron microscopy revealed the strong effect of the manufacturing process on the morphology of the material distribution within the electrode composite. Electrochemical measurements and impedance spectroscopy furthermore showed the decisive influence of electrode morphology on rate capability and Li+ transport properties.
As a result, only by applying an improved mixing process, the areal discharge capacity of ultra-thick cathodes at 1 C was increased by more than 50% compared to a common procedure.

Figure 1
Novel Alkyl Aluminum Coating Method for Lithium Ion Batteries Cathode Materials
Authors: Aoki Masahiro , Takemoto Yujin , Futagoishi Tsukasa , Inaba Koichirou , Nakajima Nami , Haraguti Tomohiro , Sakai Kentaro 
Published: February 2020

Lithium ion batteries (LIBs) have high energy density compared with other batteries. However, LIBs require more energy density since mobile devices become high performance.
In order to increase the energy density of LIBs, it is effective that increase of the charge-discharge operating voltage. However, increasing voltage simultaneously induced the decomposition of electrolyte in LIBs and deteriorate safety and durability of batteries.
Coating positive electrode materials with the metal oxide has been developed as the effective techniques for improving the safety and durability of LIBs (1-3).
It was well known that the coating methods with metal oxide protect the surface from chemical reaction with the electrolyte. On the other hands, coating with a metal oxide leads to an increase in interfacial resistance.
We have been developing the Al materials for coating based on partially hydrolyzed alkyl aluminum wet process technology.
The partially hydrolyzed alkyl aluminum coated on LiCoO2 active material exhibited a capacity retention of 85.6% after 500 charge-discharge cycles in the 3.0-4.35V (vs. Li/Li+) range. In contrast, the bare LiCoO2 active material displayed only a 9.6% capacity retention.
The coating process with partially hydrolyzed alkyl aluminum can formed thin film on active materials in contrast to the sol-gel process.
Therefore, this process does not cause an increase in interfacial resistance.
In this presentation, we will report several battery characteristics using coating method with partially hydrolyzed alkyl aluminum.

H.-J. Kweon, J. Park, J. Seo, G. Kim, B. Jung, and H. S. Lim Journal of Power Sources, 126, 156 (2004).

J. Cho, Y. Kim, T.-J. Kim, and B. Park, Angewante Chemie International Edition, 18, 3367 (2001).

Y. S. Jung, A. S. Cavanagh, A. C. Dillon, M. D. Groner, S. M. George, and S.-H. Lee, Journal of Electrochemical Society, 157(1), A75 (2010).
Fabrication and Electrochemical Studies of Ncm Cathode Active Material with Nano-Grade Materials for All-Solid State Batteries
Authors: Park Sang-Jun , Yang Seung-Hoon , Kim Min-Young , Jung Ha-Young , Ban Hee-Jung , Song Young-Woog , Jeon Se-Hyeon , Nam Su-jeong , Kim Ho-Sung , Han Jong-Hun , Kim Yoong-Ahm 
Published: February 2020

Recently, all-solid state batteries (ASSBs) are studied using hybrid solid electrolyte and composite cathode by wet process. NCM materials is suitable for high voltage and capacity of ASSBs. However, since the ASSBs are used under high-temperature (60~80°C), the initial capacity is lower than that of the liquid type lithium ion battery, and the discharge capacity tends to decrease according to the charge/discharge cycle.
In order to improve the thermal properties and the electrochemical reactivity of the NCM material, the surface was coated with nanoparticles of LFP or LMO material using liquid dispersion method. The surface of the active materials was observed by SEM and TEM analysis, and the lattice parameter was analyzed by XRD and Rietveld analysis. Furthermore, the coated NCM active materials were mixed with garnet LLZO, a polymeric binder, and a conductive material to prepare a cathode by a wet process. A 2032 coin cell was fabricated using Garnet LLZO composite solid electrolyte sheet (SE) as a solid electrolyte and Li-metal as anode to evaluate electrochemical characteristics. The characteristics of charge/discharge cycle of ASSBs will be described in more detail.