bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multiscale Simulation of Proton Transport in the Catalyst Layer with Consideration of Ionomer Thickness Distribution
Authors: Matsuda Tomohiro , Kobayashi Koichi , Mabuchi Takuya , Inoue Gen , Tokumasu Takashi 
Published: December 2020

To spread polymer electrolyte fuel cells (PEFCs) widely, which have many advantages, such as low environment load and high energy conversion efficiency, design and optimization of cathode catalyst layers (CLs) are necessary. CLs have inhomogeneous microstructures where Pt catalysts covered with ionomer thin films are supported by carbon particles. Electrons and protons transport to Pt surface through carbon particles and ionomer thin films while oxygen molecules diffuse in void and permeate through ionomer thin film to reach the Pt surface. Therefore, analyzing and understanding of mass transport of proton and oxygen in CLs are important for improving fuel cell performance. However, since an ionomer thin film on the Pt surface has a thickness of about 4 to 10 nm,1 detail understanding of the relationship between the transport mechanism within the nanostructures of ionomers and the fuel cell performance remains an issue. Therefore, we have focused on the analysis of transport phenomena using mesoscale numerical simulations by considering the effects of nanostructures on mass transport obtained from molecular dynamics (MD) simulations. Kobayashi et al.2 have studied the thickness dependence of ionomer thin films on proton transport using MD simulations and introduced these effects into the mesoscale simulations. The authors found that the self-diffusion coefficients of proton (D
H
+) show a peak at the ionomer thickness of 7 nm, in which the value of D
H
+ is almost two times larger than that in the bulk membrane, leading to the high proton conductivity that is 1.6 times larger than the bulk membrane. These results suggest that the influence of ionomer thickness at the nanometer scale on the performance of PEFCs is significant. However, in the mesoscale simulations, the resulting cell performance (i.e., I-V curve) show similar results between the systems with and without consideration of the thickness effects because the thickness distributions obtained from experiments was not sufficiently reproduced using the hydrophilic adhesion model for ionomer distribution in the mesoscale simulation. In this study, we develop a new method to improve the non-uniform ionomer distribution that reproduces the experimental thickness distribution. Furthermore, we take into account the oxygen transport results obtained from MD simulation in the mesoscale simulations to understand the effects of ionomer nanostructures on the oxygen transport at larger scale in CLs and the fuel cell performance.
Reference

Lopez-Haro, M. et al. Three-dimensional analysis of Nafion layers in fuel cell electrodes. Nat. Commun.
5, 1–6 (2014).

Kobayashi, K., Mabuchi, T., Inoue, G. & Tokumasu, T. Nano/Microscale Simulation of Proton Transport in Catalyst Layer. ECS Trans.
92, 515–522 (2019).
(PEFC&E 2nd Place Best Poster Winner) Simulation of Reaction and Mass Transport in PEFC Cathode Catalyst Layer Fabricated by Inkjet Printing Method
Authors: Wei Yuting , Park Kayoung , Inoue Gen , Kimura Naoki , Tsuge Yoshifumi 
Published: December 2020

Polymer electrolyte fuel cell (PEFCs) is a potential power source for new-generation automobiles like fuel cell vehicles that run on hydrogen energy, it has been studied a lot for last decades in order to use as the power sources of automotive. The most important characteristics of PEFCs are low operation temperature and quick start and shutdown. However, the properties of PEFCs are still limited due to its high cost and insufficient durability and performance.
Since oxygen reduction reaction (ORR) at the cathode is the dominant reaction in PEFCs, oxygen proton and electron have to be transferred smoothly in porous catalyst layer. Under normal operating conditions, oxygen transfer is the dominant factor of limiting current density, therefore, oxygen transfer must be increased from the gas channel to the Pt surface through various porous media and various components.
On the other hand, inkjet printing has been considered to be an economical and easy scale-up technology for the micro-scale patterning and fabrication as one of the on-demand methods in a variety of field because it allows for the patterning of various ink. In addition, it can reduce the process time, cost and the toxic waste created during the manufacturing process. Also, this method can be easily applied to perform ink composition studies. Especially for fuel cell applications, inkjet printing resolves many of the problems associated with previous methods of catalyst deposition by allowing a uniform distribution of catalyst ink onto the surface of GDL or membrane and by loading a very low amount of catalyst.
So in this research, in order to increase the performance of polymer electrolyte cells, the oxygen diffusion resistance was tested based on the difference of surface of catalyst layer in cathode by using inkjet method. Firstly, we mixed carbon supported Pt catalyst, distilled water and 20wt% Nafion solution and NPA together and then use homogenizer to disperse the liquid, then we got the catalyst ink. The Second step was fabrication of cathode catalyst layer (CCL) by using inkjet method. Third step was to observe the morphology for CCL with catalyst ink, in order to know the length and the height of a drop of ink, we made a sample, and then we took this sample to observe through laser microscope. When we got the basic information about morphology of CCL, we fabricated catalyst layer by inkjet, and took it to do the MEA evaluation and characterization to investigate their electrochemical properties, such as I-V curves, limiting current densities and impedance. And in order to compare with the experimental results, a theoretical model of the 3D structure was also circulated and discussed. From this model and measured data, it was confirmed that the better electrochemical properties results from 3D structure of catalyst layer in cathode.
Fabrication and Evaluation of Lightweight Bipolar Plates for an Direct Ethanol Alkaline Polymeric Electrolyte Membrane Fuel Cell
Authors: Rojo Osorio Santiago , Sanchez Saenz Carlos Ignacio 
Published: December 2020

Increasing awareness of climate change and the dangers of fossil fuels have spurred a need for faster integration of renewable energy sources onto the electrical grid. Direct Ethanol Alkaline Polymeric Electrolyte Membrane Fuel Cells (DE-APEMFC) have been develop as an alternative to this need, specially in Colombia, where the Ethanol Production is bigger than Hydrogen. Besides the operational Temperature make this Technology more attractive to be implemented in the Non Interconnected Zones of the Country. The objective of this study was to create lightweight DE-APEMFC by replacing traditional bipolar plates with combinations of polypropylene (PP), graphite or niquel.
This study involved the fabrication of bipolar plates following a process of electroless coating over polypropylene and the tests to determine their properties in comparison with the DOE Technical Targets for Electrolyte Fuel Cell Components. After bipolar plates testing, qualitative conclusions were made based on the performance of each cell. Then, Fuel cell with be assembled with the developed bipolar plates to determine the effect on the performance measured with polarization curves.The flow channel design was selected from results of previous works where it was determined that for the ethanol serpentine flow field ensure better mass transfer coefficients in the anode, and interdigitated flow field for the cathode ensure better performance for the cell.
Optimization of Mass Transport within Direct Formic Acid Fuel Cell Catalyst Layer via Pore Formers
Authors: Lam Steven , Bixby Meghan Marie , Rice Cynthia A. 
Published: December 2020

Direct formic acid fuel cells (DFAFC) offer a potentially sustainable alternative to the batteries in portable devices due to their higher charge capacity, high efficiency, and smaller size. However, due to the two-phase flow in the anode catalyst layer and the small pore size between agglomerates in the catalyst layer (~20 nm), mass transport limitations plague the performance of the DFAFC. To maximize the performance, the two-phase transport of the reactant (formic acid) and the product (carbon dioxide) must be optimized. The incorporation of a pore forming template during catalyst layer fabrication and subsequent removal can increase the porosity between catalyst/ionomer agglomerates and enhance mass transport into and out of the anode catalyst layer.
In 2002, a 3.4x enhancement in current density at 60°C of 3.4x was reported due to pretreatment with 1M methanol.[1] The methanol swelled the anode catalyst layer thereby enhancing mass transport. This methanol pretreatment was found to be only temporal. In 2012, the addition of the pore forming template lithium carbonate (Li2CO3) has been shown to form ~10 mm voids through the thickness of the ~10 mm catalyst layer after acid leaching out the Li2CO3.[2] The formic acid electrooxidation charge transfer resistance was reduced for 17.5 wt% pore former additions, at the detriment of the catalyst layer’s triple-phase boundaries.
The present study aims to increase the nano-range porosity of the anode catalyst layer to enhance two-phase flow, while maintaining the integrity of the triple-phase boundaries. The alternative templating agent is magnesium oxide (MgO) with an average size of only ~50 nanometers. MgO has been shown to increase mass transport of methanol.[3] The current work shows improved catalytic activity due to the increase in the porosity.

Ha, S.; Rice, C.A.; Masel, R.I. and Wieckowski, A., Methanol conditioning for improved performance of formic acid fuel cells. 2002, 112, 655-659.

Bauskar, A.S. and Rice, C.A., Impact of anode catalyst layer porosity on the performance of a direct formic acid fuel cell. 2012, 62, 36-41.

Huang, Q.; Jiang, J.; Chai, J.; Yuan, T.; Zhang, H.; Zou, Z.; Zhang, X. and Yang, H., Construction of porous anode by sacrificial template for a passive direct methanol fuel cell. 2014, 262, 213-218.
Characterizing Electrochemical and Thermal Properties of VDF Blended 3M PFSA Ionomer with Chemically Bonded Polyoxometalate Additives
Authors: Kim ChulOong (Christoph) , Kuo Mei-Chen , Lindell Matthew , Thaler Arne , Jiang Ruichun , Gittleman Craig S , Yandrasits Michael , Herring Andrew M. 
Published: December 2020

Proton exchange membranes (PEMs) are considered as the most promising material for fuel cell automobile applications due to their high proton conductivity and power density. The radical attacks with peroxide formation cause lower durability, which is a major challenge to further commercialize fuel cell vehicles. Cerium and manganese cations and oxides have been implemented as radical scavenging agents to overcome the challenge from radical attacks. However, the additives tend to not stay on the initial location but move during the operation due to migration and diffusion. The migration results in cluster formation and eventually the additives may dissolve and leave the membrane system. Our previous work modifying commercial fluroelastomers with chemically bonded polyoxometalate resulted in a membrane with radical scavenging properties while inhibiting additive clustering. Advancement in PEM durability with additives has implications not only for the light-duty fuel cell vehicles but also for medium and heavy-duty vehicles applications, which would aid the widespread of commercialization of fuel cell vehicles.
This work focuses on characterizing the blended perfluorinated sulfonic acid (PFSA) ionomer membrane with the chemically bound radical scavenger to enhance the durability of the membrane. Proton conductivity of the membrane was characterized under controlled relative humidity and temperature with electrochemical impedance spectroscopy (EIS). Ionic Exchange capacity of two or more proton conductive sites was measured using titration method. Correlation between water uptake and membrane properties is discussed and measuring using dynamic vapor sorption (DVS). Thermal stability was investigated through thermalgravimetric analysis (TGA).
(Invited) Redox-Active Electrolyte Capacitors Based on Modified Ionic Liquids
Authors: Wang Yanyu , Xie Han Jin , Gélinas Bruno , Rochefort Dominic 
Published: December 2020

The use of redox-active species is a very powerful approach to increase the energy density of electrochemical capacitors via the contribution of faradaic charge storage. The redox centers selected for this purpose must provide rapid electron transfer reactions to maintain high charge and discharge rates and be stable in both oxidation states to ensure long cycle life. Transition metal complexes such as ferrocene fulfill these requirements and their electrochemistry is well studied. However, the efficient incorporation of such redox centers in the capacitor is not necessarily straightforward. The dissolution of electroactive compounds is the electrolyte is a simple approach but is strongly dependent on the compound’s solubility. The adsorption of the redox center on the surface of activated carbon may provide a high local concentration but for a limited number of cycles due to gradual losses in the electrolyte. Finally, the covalent binding of redox centers on carbon may restrict the access to micropores, thereby decreasing the double-layer charging.
Our approach to overcome these limitations and provide an efficient utilization of redox-active centers in electrochemical capacitors is to rely on ionic liquids (ILs) structures modified with a redox center. As such, ILs are viewed here as a vehicle for the redox center. Because imidazolium and triflimide structures are very stable, highly miscible in several polar organic solvent and easy to modify, they have been selected to bear ferrocene electroactive groups. The structure of such redox-active ionic liquids (RAIL) are shown in Fig. 1. This contribution will show an overview of the properties of redox-active ionic liquids for energy storage in electrochemical capacitors, how they can be efficiently applied in these devices and, importantly, how they can represent an advantage over the more limited off-the-shelf ionic liquids.

Figure 1
Kinetic Pathways of Ionic Transport in Fast Charging Lithium Titanate
Authors: Chen Tina , Zhang Wei , Seo Donghwa , Wu Lijun , Topsakal Mehmet , Zhu Yimei , Lu Deyu , Ceder Gerbrand , Wang Feng 
Published: December 2020

Fast-charging batteries typically employ electrodes capable of accommodating lithium continuously via solid-solution transformation because they have few kinetic barriers apart from Li+ diffusion.[1, 2] One exception is lithium titanate, an anode that can cycle without the Li plating observed in graphite [3] and exhibits extraordinary rate capability seemingly inconsistent with its two-phase reaction and the sluggish diffusion within its endmembers [4]. Through real-time tracking of Li+ local environments during migration using operando electron energy-loss spectroscopy in combination with first-principles calculations, we reveal that the kinetic pathway that enables facile ionic transport in lithium titanate consists of distorted face-sharing Li polyhedra in metastable intermediate states. This study highlights that the rate capability of fast-charging electrodes may be controlled not solely by the intrinsic ionic diffusivity of macroscopic phases, but also by the transport pathways available via kinetically accessible low-energy states. Findings from this study, particularly on the improved kinetics originating from the face-sharing Li motifs in intermediate lithium titanate configurations, may open new directions for designing electrode materials for fast-charging batteries.
References:
[1] H. Liu, F. C. Strobridge, O. J. Borkiewicz, K. M. Wiaderek, K. W. Chapman, P. J. Chupas, C. P. Grey, Capturing metastable structures during high-rate cycling of LiFePO4 nanoparticle electrodes. Science
344, 1252817 (2014).
[2] R. Malik, F. Zhou, G. Ceder, Kinetics of non-equilibrium lithium incorporation in LiFePO4. Nat. Mater.
10, 587-590 (2011).
[3] T.-F. Yi, S.-Y. Yang, Y. Xie, Recent advances of Li4Ti5O12 as a promising next generation anode material for high power lithium-ion batteries. J. Mater. Chem. A
3, 5750-5777 (2015).
Thermodynamics of Spinel-like Cation Partial Ordering in Ultrahigh Power and Energy Density Li-Ion Batteries for Fast-Charging Electric Vehicles
Authors: Yang Julia , Ceder Gerbrand 
Published: December 2020

Recently, a class of new materials exhibiting partial spinel-like cation order, but with excess Li and excess cation content was found to combine very high rate performance with high energy density [1]. Such spinels with a cation to anion ratio higher than 3 are unusual as it requires the face sharing of some tetrahedral and octahedral cations. In this presentation we will report on the ab-initio modeling of the metastable cation arrangements in these lithium manganese oxyfluorides that are responsible for the high-rate performance. The high dimensional configurational space of the materials is described by the cluster-expansion technique and parameterized with multiple hundreds of DFT calculations.
Local, atomic-scale features, such as Li-Mn dumbbell formation, antisite defects, and interstitial defects giving rise to face-sharing cations which are challenging to resolve with state-of-the-art diffraction techniques are possible to directly evaluate in our computational approach. We present a computational analysis on how cation excess in spinel-like materials is accommodated and how local cation perturbations ultimately influence short-range order and bulk Li transport. Our understanding of how features in cation-excess spinel-like Li-Mn-O-F materials influence their high rate capabilities may motivate and accelerate design of other high-performance, fast-charging battery materials.
[1] Ji, H., Wu, J., Cai, Z. et al. Ultrahigh power and energy density in partially ordered lithium-ion cathode materials. Nat Energy 5, 213–221 (2020).
An Artificial Interface By Sol-Gel Chemistry to Open the Window of an Aqueous Supercapacitor
Authors: Olarte Marco , Menu Marie-Joelle , Simon Patrice , Gressier Marie , Taberna Pierre-Louis 
Published: December 2020

Devices with high power density which can store energy with a fast rate charge-discharge, the supercapacitors are suitable in different applications where high power is needed. That because it stores charge by fast surface process, i.e. ion adsorption of an electrolyte into the electrochemical double layer at the electrode/electrolyte interface. Nevertheless, in order to extend their autonomy beyond few seconds, its energy density has to be increased. For this aspect, in recent years many teams around the world have set up different strategies as a combination of a carbon electrode with a faradic type electrode (battery electrode or pseudocapacitive) or through the development of new active materials, including the development of new electrolytes. The main significant achievements are more on the active material side. Even though some works have been successful in increasing the cell voltage, thanks to the use of new ionic liquids, they are still room for improvement regarding the increase of the cell voltage.
To address this point, we have targeted to obtain an aqueous-based high voltage supercapacitor. Our strategy consists in using an Artificial Interface (AI) by depositing an ionogel onto a carbon electrode, the AI is composed of an inorganic matrix and an ionic liquid, in order to form a passivation layer at the electrode/electrolyte interface; a better electrochemical and thermal stability of this interface is thus expected. The AI has got to be electronically insulating but ionic conductive, limiting or even preventing the transfer of electronic charge to the electrode / electrolyte interface.1,2

First things first, the study have been carried out on glassy carbon where AI has been deposited and the linear sweep voltammetry tests in an aqueous electrolyte based on EMI+ HSO4
- and H2SO4 indicate, in both cases, an increase in the potential window: the onset potential for water reduction is shifted toward more cathodic potentials. Going further, tests in the presence of a redox probe (Ferri-Ferro potassium cyanide) demonstrate the absence of electron transfer at the electrode/electrolyte interface. On the other hand, it appears, thanks to measurements carried out by electrochemical impedance spectroscopy, since within the AI is embedded EMI+ TFSI-, better ionic conduction is obtained when the electrolyte is made of EMI+ HSO4
-, sharing the same cation than the one of AI. As we will be showing, a better transference number is achieved for EMI+ cations than for H+ still further works are needed to improve the selectivity of the AI to improve its stability over cycling.
1. Z. H. Zhang et al., Sci. Rep., 8, 1–12 (2018).
2. M. D. Elola and J. Rodriguez, J. Phys. Chem. C, 123, 3622–3633 (2019).
Fast Charging Hybrid Battery-Capacitor Based on Electrochemically-Intercalated Ni-Graphite
Authors: Mandler Daniel , Mukherjee Debdyuti , Schoetz Theresa , Geuli Ori , Hao Qingli , Yen Hung-Ju 
Published: December 2020

The electrochemical intercalation of Ni(II) as a redox-spacer between graphite sheets is demonstrated as an efficient way to produce a fast-charging aqueous hybrid battery-capacitor (Scheme). The approach is based on the electrochemical exfoliation of free-standing graphite sheets and the intercalation of Ni(II) by a single step. This is accomplished by applying a negative potential to graphite in an isopropyl alcohol solution consisting of Ni(II), leading to an increase of the electrode’s active area and prevents the restacking of the graphene sheets. The fabricated hybrid electrodes demonstrate a specific capacity of 84 mAh g−1 at high charge-discharge rates of 30-300 mA (7.5-75 C rates) in aqueous solution. The performance of an asymmetric full cell, consisting of the hybrid electrode and an activated carbon electrode, delivers a specific energy of 96 Wh kg-1 and exceptionally high specific power of 6.2 kW kg-1 at 300 mA (45 C) charge-discharge rate. The hybrid electrode and the full cell were cycled over 10,000 times under very fast very fast cycling conditions with minimal decrease in performance. The intercalation of Ni(II) into the layers is confirmed by cross-section electron microscopy and electrochemistry.
The outstanding storage performance of this system is attributed to the redox reaction of the intercalated Ni(II) inside the graphite layers, which have an additional capacitive contribution, combining the advantages of battery and capacitor in one material. Furthermore, the very efficient charge transfer stems from the proximity of the redox to the highly conductive graphite.

Figure 1