bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantification of Inactive Lithium, Solid Carbonate Species, and Lithium Acetylide on Graphite Electrodes after Fast Charging
Authors: McShane Eric J. , Colclasure Andrew M. , Brown David Emory , Konz Zachary M. , Smith Kandler , McCloskey Bryan D.
Published: December 2020

Lithium plating on graphite anodes currently limits the fast charging performance of lithium-ion batteries because plated Li is prone to become electronically isolated from the electrode (referred to as 'inactive Li') or react with electrolyte, both of which contribute to rapid cell capacity fade. To understand the onset and extent of these detrimental processes, it is critical to quantify these sources of capacity loss. In this work, we demonstrate a titration technique to quantify both inactive Li and solid electrolyte interphase (SEI) species (solid carbonates and lithium acetylide, Li2C2) that remain on the graphite electrode after fast charging. We additionally compare electrochemical modeling results with our experimental data to determine the Li plating exchange current density (10 A/m2) and stripping efficiency (65%) of plated Li metal on graphite. Our techniques lay the groundwork for benchmarking proposed Li plating detection techniques and provide an avenue to pursue more comprehensive studies of Li plating on graphite surfaces.
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).
On the Capacitive Nature of Electrodeposited MnO2 Nanostructure
Authors: Ghanim ِAbdulsattar H.
Published: December 2020

One-dimensional array architectures such as nanotubes and nanowires are widely used to enhance the energy storage devices. In this study we are fabricating 3-D structure (Hierarchical) MnO2 nanowire with high surface area, low toxicity, high abundance, low cost, and environmental friendliness in order to increase the power density of supercapacitors. Al with less than 0.21 atom % Cu will be used to form a 3-D porous template during the anodization process. Presence of Cu impurities in an Al ﬁlm introduces horizontal pores interconnecting the vertically aligned pore structure of the anodized aluminium oxide (AAO) template. These hierarchical nanowires show a large specific capacitance of 319 F/g at 5 mV/s compare to regular nanowire and thin film which are around 256 F/g and 219 F/g respectively.
Facile Multivalent Redox Chemistries in Water-in-Bisalt Hydrogel Electrolytes for Hybrid Energy Storage Full Cells
Authors: Park Jae Min , Jana Milan , Nakhanivej Puritut , Park Ho Seok
Published: December 2020

High-capacity electrode materials have been investigated to overcome the low energy density of electrochemical capacitors, but there are still issues arising from the trade-off between charge storage capacity and kinetics, efficiency, and stability. Herein, we describe multivalent sulfur redox chemistry for the high power and energy efficiency of hybrid energy storage full cells, where nitrogenincorporated nanoporous carbon/nanosulfur (N-NC/nS) and lithium manganese oxide are configured into negative and positive electrodes, respectively, using water-in-bisalt (WIBS)-soaked poly(acrylic acid) hydrogel electrolyte. As confirmed by the major contribution of surface redox capacity to the total capacity, low activation energy, high exchange current density, and fast charge transfer, the N-NC/nS achieves facile surface redox kinetics arising from the hierarchical porosity, nanoscale confinement of nS, and high ionic conductivity of WIBS hydrogels. The resulting full cells deliver capacitor-like high power density of 15.7 kW kg−1 , along with an energy density of 30.1 Wh kg−1, 78.7% retention over 2000 cycles, and an energy efficiency of 98%.
Mechanistic Role of Thermal Gradients on Lithium Plating in Li-Ion Batteries
Authors: Fear Conner , Parmananda Mukul , Kabra Venkatesh , Carter Rachel E. , Love Corey T. , Mukherjee Partha P.
Published: December 2020

Unwanted lithium deposition on the surface of graphite particles tends to occur during charging of Li-ion batteries at low temperatures, high rates, and high states of charge. However, the intricacies of the coupled thermal-electrochemical interactions that govern Li plating behavior are yet to be fully uncovered. Thermal inhomogeneity naturally develops during the high rate operation of large-format cells, particularly when active cooling systems are employed; hence, a deeper investigation of the relationship between thermal gradients and Li plating is merited. This study employs a microstructure-aware modeling approach to probe the influences of both in-plane and inter-electrode thermal gradients on Li plating. Both types of thermal gradient were found to cause inhomogeneous current distribution within the electrodes. While inter-electrode gradients resulted in a variation in the Li plating onset point and severity, the Li plating induced by in-plane gradients was nearly the same as for isothermal cases at the same mean temperature. The sensitivity of charging performance to mean temperature and thermal gradient magnitude was analyzed across a range of practical conditions. Electrochemical experiments were performed under applied external thermal gradients to study the effect on plating and cell lifespan in various cell formats, and the electrode degradation was characterized post-mortem. By gaining a fundamental understanding of the Li plating phenomenon, this study aims to assist in the design of electrode structures and cell formats that will reduce the propensity for this mode of degradation.
Welcome Remarks - I01C: Polymer Electrolyte Fuel Cells & Electrolyzers 20 (PEFC&E 20) - Cation-Exchange Membrane Development, Performance and Durability
Authors: Pintauro Peter N.
Published: December 2020

Welcome to I01C: Polymer Electrolyte Fuel Cells & Electrolyzers 20 (PEFC&E 20) - Cation-Exchange Membrane Development, Performance and Durability! Take a moment to listen to welcome remarks from the lead organizer, Peter Pintauro.
(Keynote) Understanding Performance Degradation of Li-Ion Batteries Under Fast Charge Conditions
Authors: Zhang Sheng S.
Published: December 2020

Fast charge is a critical challenge for the electric vehicles in competing with rapid gasoline refueling of the traditional internal combustion engine vehicles. Fast charge not only causes accelerated performance degradation, but also increases safety risk of the Li-ion batteries, which are attributed to a number of physical and chemical processes, such as overheating by Joule heat, Li plating on the graphite anode, structural deterioration of the layered cathode material, and electrolyte depletion. The performance degradation behaves as a decline in the capacity and operating voltage, and it is often accompanied by impedance growth and volumetric swelling of the battery. Owing to the high reactivity of Li metal with electrolyte solvents and its dendritic electrodeposition nature, Li plating has long been considered as the key issue resulting in the accelerated performance degradation and potential safety risk.1, 2 However, our recent work3, 4 shows that in health power-optimized Li-ion cells, Li plating does not occur even when the charging rate is increased to 10C, while the accelerated performance degradation is still present. The above results suggest that there must be other factors triggering the accelerated performance degradation, and that the safety risk by Li plating may be overestimated. In this work, we made a comprehensive survey on the accelerated performance degradation by analyzing the literature and our own results. It is concluded that the accelerated capacity degradation under the fast charge conditions can be ultimately attributed to the loss of cyclable Li+ ions from the limited capacity of the cathode, namely a decrease in the cathode-to-anode (C/A) capacity ratio (or an increase in the negative-to-positive (N/P) capacity ratio, as called elsewhere), and that such a process is always accompanied by the depletion of electrolyte and the resultant impedance growth and volumetric swelling of the battery, as summarized in Fig. 1, though degradation mechanisms in the graphite anode and layered transition metal oxide cathode are fundamentally different. In this presentation, the effect of various factors on the performance degradation of the Li-ion batteries and their correlation with the depletion of electrolyte will be discussed, and several strategies towards enhancing the fast-charging capability of the Li-ion batteries will be presented.

References

A. Tomaszewska, Z. Chu, X. Feng, S. O’Kane, X. Liu, J. Chen, C. Ji, E. Endler, R. Li, L. Liu, Y. Li, S. Zheng, S. Vetterlein, M. Gao, J. Du, M. Parkes, M. Ouyang, M. Marinescu, G. Offer, and B. Wu, eTransportation, 1, 100011 (2019).

H. Zhao, L. Wang, Z. Chen, and X. He, Energies, 12 (20) (2019).

S. S. Zhang, InfoMat, 2, 1606823 (2020). https://doi.org/10.1002/inf2.12058.

S. S. Zhang, ChemElectroChem, 7, 555-560 (2020).

Fig. 1. A summary of the factors leading to accelerated performance degradation of Li-ion batteries under fast charge conditions.

Figure 1
Elucidating the Formation Mechanisms of Fe-N-C Electrocatalysts Using High-Temperature in Situ Characterisation Techniques
Authors: Mufundirwa Albert , Gell Charles E , Yoshioka Satoru , Sugiyama Takeharu , Cunning Benjamin Vaughan , Smid Bretslav , Harrington George Frederick , Sasaki Kazunari , Hayashi Akari , Lyth Stephen Matthew
Published: December 2020

Pt-free cathode catalysts are attracting increased interest to replace platinum in polymer electrolyte membrane fuel cells (PEFCs). Heat-treated nitrogen-doped carbons decorated with iron have been the most widely studied alternative. However, lack of understanding of the formation of active sites and degradation mechanisms in such catalysts is hindering their progress. Here, we use a nitrogen-doped carbon foam support with optimised porosity, surface area, and conductivity which is then infiltrated with three different iron precursors: iron (II) acetate (FeAc); iron (III) chloride (FeCl3); and iron phthalocyanine (FePc). These are then pyrolyzed to form Fe-N-C-based ORR electrocatalysts. This approach takes advantage of an already optimized conductive, porous, high surface area and temperature-stable support. The stability of the support helps to separate the role of the different iron precursors from other factors in the generation of catalytic active sites. High temperature X-ray absorption fine structure (HT-XAFS) and high temperature X-ray photoelectron spectroscopy (HT-XPS) were employed to study changes in the iron precursors during the synthesis of Fe-N-C electrocatalysts. Furthermore, near ambient pressure XPS (NAP-XPS) and in-situ electrochemical XAFS were performed to study the interaction between the synthesized catalysts and oxygen. These results are then related to the electrochemical activity.
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).
Non-Equilibrium Lattice Heterogeneity As the Unified Kinetic Hurdle of Ni-Rich Layered Cathode for Ultrafast Lithium Ion Batteries
Authors: Wang Jian , Hyun Hyejeong , Seo Sungjae , Lim Jongwoo
Published: December 2020

The significantly reduced capacity at a fast cycling rate is one of the most serious bottlenecks that prevent the large-scale application of Ni-rich layered oxide cathode for electrical vehicle batteries. Figuring out the capacity decline mechanism is crucial to addressing such hurdle and developing ultrafast lithium ion batteries. In this work, with operando synchrotron-based spectroscopy, we captured the formation of non-equilibrium separated phases during the extremely fast cycling of various Ni-rich layered oxides, in contrast to their solid-solution structural evolution pathway at slow cycling rate. Further, such non-equilibrium phase heterogeneity was demonstrated to be an effective capacity retention descriptor for Ni-rich layered oxide cathode: the capacity retention ratio is liner inversely proportional to the lattice heterogeneity at an extremely fast cycling rate (e.g., 10C), regardless of the composition and Ni content. Those detrimental non-equilibrium phase heterogeneity could be eliminated by raising the operation temperature, contributing to much higher lithium ion transport kinetics and better capacity retention during ultrafast cycling
Prelithiated C-Si/SiO
x
Based Negative Electrode for High Power and High Energy Density Lithium-Ion Capacitors
Authors: Chung Dong Jae , Park Eunjun , Jeong Won Joon , Park Min-Sik , Kim Hansu
Published: December 2020

A high-performance lithium ion capacitor (LIC) was developed with activated carbon as the positive electrode and pre-lithiated C-coated Si/SiO
x
nanospheres as the negative electrode for high-power and high-energy density energy storage system. The feasibility of pre-lithiated C-coated Si/SiO
x
was thoroughly examined as an advanced negative electrode for LIC by comparing prelithiated C-coated Si/SiO
x
based LIC with conventional graphite anode based LIC. Under optimized pre-lithiation conditions, the prelithiated C-coated Si/SiO
x
based LIC showed enhanced rate capability and reversible capacity with highly stable cycle performance at a current density of 10 A g-1 up to 1000 cycles. Such improvements may result from the unique physical and chemical properties of C-coated Si/SiO
x
. The detailed prelithiation condition and electrochemical behaviors of both active carbon and C-coated Si/SiO
x
in LIC system will be discussed in the presentation.
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
Effect of Doping and Intercalation on the Performance of Supercapacitors
Authors: Shim Jae-Jin , Mohapatra Debananda , Dhakal Ganesh , Eshetie Kidie Abebaw
Published: December 2020

The constant increase in energy demand and inconsistent supply have attracted significant attention towards sustainable energy storage/conversion devices, such as electrochemical capacitors with high energy densities and power densities. Carbonaceous materials such as graphene, carbon nanotubes, and carbon fibers have been studied for energy storage. Materials based on metal oxides/sulfides have also been studied for electrochemical charge storage. Due to the limitations of these materials in the capacitance, a lot of studies have been done to improve the performance of supercapacitors, such as modification of the physical structure of the electrode materials for higher surface area. Other groups have been trying to modify the chemical nature by doping with different elements and by intercalating with different ions. Herein, the effect of doping of nitrogen and sulfur in carbon and metal oxides/sulfides structure on their charge storage performance are discussed. Intercalation of anions in perovskites and layered double hydroxides is also discussed.

Figure 1
Fabrication of Flexible Catalysts for Hydrazine Electro-Oxidation
Authors: Zabielaite Ausrine , Šimkūnaitė-Stanynienė Birutė , Šimkūnaitė Dijana , Naruškevičius Leonas , Vaičiūnienė Jūratė , Tamašauskaitė-Tamašiūnaitė Loreta , Norkus Eugenijus
Published: December 2020

In this study, we report a facile electrochemical approach for fabrication of flexible catalysts for the electro-oxidation of hydrazine with the aim to use them as the anode material in direct hydrazine fuel cells (DHFCs). A fiber-shaped cobalt coating has been electroplated on the copper coated polyimide surface (labeled as Cofiber/Cu/PI) using the electrolyte containing CoSO4, NaOH and N-(2-Hydroxyethyl) ethylenediamine. For comparison, the cobalt layer that has the smooth structure has been also electrodeposited on the flexible Cu/PI surface (labeled as Cosmooth/Cu/PI). Additionaly, the fabricated flexible catalysts have been decorated with gold (Au), manganese (Mn) or gold-manganese (AuMn) nanoparticles via electrochemical deposition. The morphology, structure and composition of the fabricated flexible catalysts have been characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and inductively coupled plasma optical emission spectroscopy. The activity of catalysts has been investigated with respect to the electro-oxidation of hydrazine in an alkaline medium using cyclic voltammetry and chrono-techniques.

It was found that the deposition of Au, Mn or AuMn nanoparticles on Cofiber/Cu/PI and Cosmooth/Cu/PI results in significantly enhanced electrocatalytic activity of Cofiber/Cu/PI and Cosmooth/Cu/PI towards the electro-oxidation of hydrazine. Moreover, the prepared flexible catalysts seem to be a promising anode material for DHFCs.
(Invited) Effect of Water Management for Cathode Catalyst Layers Using a Non-Noble Metal Catalyst and a Novel Polymer Electrolyte on Cell Performance Hysteresis in Anion Exchange Membrane Fuel Cells
Authors: Uchida Makoto , Otsuji Kanji , Yokota Naoki , Tryk Donald A. , Kakinuma Katsuyoshi , Miyatake Kenji
Published: December 2020

In this work, we examined the cell performance of membrane-electrode assemblies (MEAs), for anion exchange membrane fuel cells (AEMFCs), using a non-noble metal catalyst and a novel polymer electrolyte. The chemical structure of quaternized poly(arylene perfluoroalkylene), i.e., QPAF-4 (ion exchange capacity: IEC = 2.1 meq g-1) developed in this laboratory1 is shown in Figure 1. Since this membrane is soluble in methanol, it is also suitable for use as an electrode binder. The non-precious metal catalyst cell was loaded with 0.45 mg cm-2 Fe-N-C catalyst supplied by Pajarito Powder on the cathode and 0.20 mgPt cm-2 platinum catalyst on the anode. An MEA in which platinum was loaded (0.20 mgPt cm-2) on both the anode and cathode was prepared for comparison. Pt loaded on carbon black (Pt/CB, TEC10E50E), supplied from TKK Japan, was used as the platinum electrocatalyst.

Figure 2 shows a comparison of Fe-N-C and Pt/CB for their I-V performances at 60 oC, 100% RH, 0 kPag; anode H2 (100 mL/min); cathode O2 (100 mL/min). The cell using the Fe-N-C catalyst exhibited large hysteresis in the I-V curve, i.e., a large difference in potential between increasing and decreasing current. Figure 3 shows a comparison of Fe-N-C and Pt/CB for their I-V performances at 60 oC, 100% RH, 100 kPag; anode H2 (100 mL/min); cathode O2 (100 mL/min). The hysteresis of the I-V performance for the cell using the Fe-N-C cathode decreased with increasing back pressure. The cell exhibited slightly lower open circuit voltage and similar IV performance compared with those using Pt/CB. At the present stage, the loading amount of Fe-N-C catalyst, ionomer content, and porosity of the catalyst layer have not yet been optimized.

We investigated whether the hysteresis originates from the anode or cathode. Based on the results of various I-V measurements, we conclude that the hysteresis is related to water supplied to the cathode using the Fe-N-C catalyst. Further details will be given in this presentation. We found from these results that the water management is essential, due to its requirement for the cathode reaction, for high-performance AEMFCs. Finally, these results demonstrate the viability of the use of low-cost materials such as non-noble metal catalysts for the AEMFC.

Acknowledgement

This project was partly supported by NEDO Japan through funds for the “Advanced Research Program for Energy and Environmental Technologies” and the Japan Society for the Promotion of Science (JSPS) and the Swiss National Science Foundation (SNSF) under the Joint Research Projects (JRPs) program.

References

1. H. Ono, T. Kimura, A. Takano, K. Asazawa, J. Miyake, J. Inukai, K. Miyatake, J. Mater. Chem. A, 5, 24804 (2017).

Figure 1
Alternative Mechanistic Considerations: Charactering Multiple Reaction Pathways for the Oxygen Evolution Reaction
Authors: Ha Mai-Anh , Alia Shaun M , Larsen Ross E
Published: December 2020

H2 remains an important chemical precursor in processes such as the Haber-Bosch process to synthesize ammonia and hydrocracking for refining of hydrocarbons and also exists as an alternative fuel for transportation. Currently, 95% of H2 is produced by steam methane reforming, whose byproduct is pollutant CO. Electrolysis is a clean, efficient method run at room temperature to split water into H2and O2. However, electrolysis is not cost-competitive with steam methane reforming, utilizing large amounts of platinum group materials. Computational chemistry can give atomic and electronic levels of understanding of a material by identifying highly active facets of a known material or predicting the catalytic potential of unknown materials. We will model catalysts used in the oxygen evolution reaction, the half-cell reaction requiring the most catalyst and occurring many orders of magnitude slower than the hydrogen evolution reaction. We will focus on the effect of the ensemble: modeling different facets of iridium oxide, characterizing all possible configurations of key reaction intermediates, and incorporating explicit solvation to fully understand the nuances of optimizing a premier catalyst such as IrO2. In particular, we will focus our calculations on two facets: (110), the more thermodynamically stable facet and (001), a potentially more active facet due to the presence of undercoordinated, surface Ir sites. We will compare the reaction profile of the ensemble of key reaction intermediates on the (110) versus the (001) facet and in vacuum versus with solvation. The ensemble of intermediates allows us to explore multiple reaction pathways on the surface that have not been characterized.

Figure 1. A schematic summarizing the different isomers found at each reaction step (TOP) and the reaction profile of the oxygen evolution reaction on the (110) facet of iridium oxide (BOTTOM).

Figure 1
Oxygen Evolution Reaction of NiO Nanowalls with a Three-Dimensional Framework
Authors: Takimoto Daisuke , Hideshima Sho , Sugimoto Wataru
Published: December 2020

It is important to optimize the mass transport of electrons, ions and gases to enhance the catalytic activity and efficiency for electrolysis. We previously reported that nanosheets possess higher electrocatalytic activity compared to nanoparticles.1 This is attributed to the large electrochemically active surface area of nanosheets. However, nanosheets tend to re-stack, leading to poor mass transport and low efficiency. In this study, we propose a new electrocatalyst with a three-dimensional architecture composed of a framework of NiO nanowalls toward oxygen evolution reaction (OER).

Macro porous carbon (MPC) was purchased from Toyo Tanso (CNovel®, Japan) and used as template. MPC was dispersed in 2-methoxyethanol, and nickel acetylacetonate was dissolved in 2-methoxyethanol. The suspension was mixed for 3 days and collected by centrifugation. The obtained powder (MPC@NiO
x
) was dispersed in 2-methoxyethanol. After solvothermal treatment, the solution was centrifuged, and the dried powder was heated in air to yield macro porous NiO (3D-NiO). NiO particles were prepared without the macro porous carbon template. OER activity of the electrocatalysts was investigated using a three-electrode system consisting of a Pt mesh counter electrode and a Ag/AgCl (sat. KCl) reference electrode. 1.0 M KOH (30°C) was used as the electrolyte.

TEM images of 3D-NiO showed a 3D structure constructed by 2D NiO nanowalls with very thin and smooth surface. The structure of 3D-NiO was replicated from the MPC template; MPC was oxidatively removed by calcination at 400°C. The redox peaks at a half peak potential of E
1/2 = 1.49 V vs. RHE were observed in the cyclic voltammograms for 3D-NiO and NiO particles. These redox peaks were attributed to the transformation of b-Ni(OH)2 and b-NiOOH (Ni(OH)2 « NiOOH + H+ + e-).2 The OER current at 1.8 V vs. RHE of 3D-NiO was 15 times larger than that of NiO particles. The onset potential of the OER for 3D-NiO was similar to that for NiO particles, indicating that the OER mechanism was not sensitive to the morphology of NiO. The result strongly indicates that the 3D structure with 2D nanowall is a superior design for OER electrocatalyst. Considering the diffusion path of evolved O2 molecules, the enhanced activity could also be attributed to the meso pore nature of 3D-NiO.

This work was supported by Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Young Scientist (Grant Number 18K14054).

References

D. Takimoto, K. Fukuda, S. Miyasaka, T. Ishida, Y. Ayato, D. Mochizuki, W. Shimizu and W. Sugimoto, Electrocatalysis, 8, 144 (2017).

M.-S. Kim, T.-S. Hwang and K.-B. Kim, J. Electrochem. Soc., 144, 1537 (1997).
Durability and Performance Limitations in Currently Available Alkaline Exchange Membrane Electrolysis Materials and the Relationship to Total System Cost
Authors: Motz Andrew R , Capuano Christopher , Ayers Katherine E.
Published: December 2020

Anion exchange membrane (AEM) electrolyzers have the potential to reduce the cost of hydrogen generated via. electrolysis through reducing the cost of stack materials, improved electrochemical kinetics, and exhibiting a higher tolerance range for water purity (e.g. brackish and saltwater electrolysis). These potential benefits have resulted in a large amount of research funding, and as a result several commercial AEMs are now available. Additionally, several commercial, AEM specific catalysts are also available.

With the increasing maturity of AEM electrolysis (still in the very early stages), there is a growing need for benchmark performance and durability using only membrane electrode assembly (MEA) materials that are commercially available. Several materials, both polymers and catalysts, will be discussed for both performance and durability under differential pressure. The incumbent technology, proton exchange electrolyzers, typically operate up to 435 psig differential H2 pressure accomplished through a combination of electrolysis and electrochemical compression. To provide a more direct comparison to the current technology, durability will be measured under differential H2 pressure. Additionally, test will be performed to identify presence of electronic shorting or cross-cell leaks, both cell failures that will result in apparent improved performance due to the lower operating voltage.

For industry to adopt AEMs, there must be demonstrated device reliability and projected system cost savings. A techno-economic analysis will be performed to compare AEM and PEM electrolysis in several different scenarios to better understand the state of the technology.
High-Efficiency Reversible Hydroxide Exchange Membrane Fuel Cells
Authors: Yang Fan , Green Zach , Strasser Derek , Shi Wenjuan , Rojas-Carbonell Santiago , Yan Yushan , Xu Hui
Published: December 2020

Reversible fuel cells have advantages over rechargeable batteries due to their high energy density, minimal self-discharge, and low cost. Reversible hydroxide exchange membrane fuel cells (HEMFCs) are attractive due to their ability to work with platinum-group-metal (PGM)-free catalysts. HEMFCs and hydroxide exchange membrane electrolyzers (HEMELs) have been separately studied. However, it remains a challenge to integrate the two into a single reversible cell. The major factors that limit the development of unitized reversible HEMFCs are low performance of bifunctional oxygen catalysts, hydroxide membrane stability, hydroxide ion conductivity and water management. Previous research has been focusing on electrolyte-fed HEMELs 1. However, the corrosive alkaline solution presents material compatibility problems and increases the system and balance of plant (BOP) complexity. For example, the presence of alkaline solutions can increase the complexity of the unitized reversible fuel cell system due to adding extra water purging steps during the transition between electrolyzer mode and fuel cell mode.

In this study, we have developed a pure water-fed reversible HEMFC which makes it possible to use stainless steel to replace the titanium current collectors commonly used in proton exchange membrane electrolyzers (PEMELs) to reduce the manufacturing cost. We have made tremendously progress to make the HEMFC reversible without the addition of alkaline or bicarbonate electrolyte. This is the first reported reversible HEMFC with the highest round trip efficiency (RTE) at an appreciable current density (48% @ 0.5 A/cm2). The reversible test result is shown in Figure 1. In addition to the initial RTE evaluation, we also achieved promising MEA stability. However, a voltage increase was also observed in the initial stage of the durability test which is presumptively attributed to the ionomer wash-out and catalyst layer restructuring. These challenges have been addressed by innovative electrode design.

Acknowledgement: The project is finacially supported by the Department of Energy's HFTO under the Grant DE-EE0008438.

Reference:

Abbasi, R., Setzler, B. P., Lin, S., Wang, J., Zhao, Y., Xu, H., Pivovar, B., Tian, B., Chen, X., Wu, G., Yan, Y., A Roadmap to Low‐Cost Hydrogen with Hydroxide Exchange Membrane Electrolyzers. Mater.2019, 31, 1805876

Figure 1
Considering Two-Phase Flow in Three-Dimensional Computational Fluid Dynamics Simulations of Proton Exchange Membrane Water Electrolysis Devices
Authors: Lopata Joseph Steven , Kang Zhenye , Young James L. , Bender Guido , Weidner John W. , Cho Hyun-Seok , Shimpalee Sirivatch
Published: December 2020

Computational studies are employed to construct our understanding of systems and to reduce the monetary and temporal demands of research and development. Proton exchange membrane water electrolysis (PEMWE) devices, with their intricate two-phase transport phenomena and numerous realizable applications, provide an excellent opportunity to utilize computational fluid dynamics (CFD). Toghyani et al.1 modeled the performance of a high-temperature, vapor-fed PEMWE device using CFD simulations, finding fair agreement with prior experimental studies. For low-temperature electrolysis, Nie and Chen2 used a mixture model to study the flow regimes in liquid-fed channels.

We employed a CFD model to simulate a PEMWE device, exploring the viability of isothermal and non-isothermal mixture models for a liquid-fed cell. The flow rate was altered to study the change in cell temperature and performance, and the model results were compared to experimental data. Additionally, bulk properties of the porous transport layer at the anode were altered to examine performance effects; such effects were expected to be virtually non-existent in light of experimental observations.3,4 The results demonstrate when a continuum assumption is best utilized to predict electrolysis efficiency.

References:

S. Toghyani, E. Afshari, and E. Baniasadi, Journal of Thermal Analysis and Calorimetry, 135, 1911–1919 (2019).

J. Nie and Y. Chen, International Journal of Hydrogen Energy, 35, 3183–3197 (2010).

T. Schuler, T. J. Schmidt, and F. N. Büchi, Journal of The Electrochemical Society, 166, F555–F565 (2019).

J. Lopata et al., Journal of The Electrochemical Society, 167, 064507 (2020).

Figure 1
Active and Stable Bifunctional Oxygen Electrocatalysts and Catalyst Layers for Unitized Regenerative Fuel Cells
Authors: Rhodes Christopher P. , Godinez-Salomon Fernando , Albiter Luis
Published: December 2020

Proton exchange membrane unitized regenerative fuel cells (PEM-URFCs) that can function in both fuel cell and electrolysis modes provide potential weight and cost advantages over discrete systems; however, improved catalysts and catalyst layers are needed to improve performance and stability. PEM-URFCs require bifunctional oxygen electrocatalysts that facilitate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and significant challenges remain to increase catalyst activity, reduce precious metal loading, and obtain long-term stability over the wide potential voltage ranges that occur switching between fuel cell and electrolyzer modes. We have recently shown that bimetallic nanoframes, formed from thermal treatment of noble-metal decorated nanosheets, provide bifunctional oxygen electrocatalysts with significantly higher activity compared with monometallic structures, evaluated using a rotating disk electrode configuration.1 The nanostructured bimetallic alloys utilize noble metal-non-noble transition metal interactions to alter the surface electronic structure, and the unsupported nanostructure provides a carbon-free matrix with three-dimensional accessibility to the catalytically active sites. In addition to design of the catalytically active site, the catalyst layer has important influences on mass transfer and flooding within PEM-URFCs. From our preliminary evaluations, the oxygen catalyst nanostructure, catalyst loading, and catalyst layer composition have significant effects on the performance of PEM-URFC membrane electrode assemblies (MEAs) that operate in both fuel cell and electrolyzer modes.

References

Godínez-Salomón, F.; Albiter, L.; Mendoza-Cruz, R.; Rhodes, C.P. Bimetallic Two-dimensional Nanoframes: High Activity Acidic Bifunctional Oxygen Reduction and Evolution Electrocatalysts, ACS Applied Energy Materials
,
2020,
3, 2404-2421.
http://dx.doi.org/10.1021/acsaem.9b02051
Welcome Remarks - I01Z: Polymer Electrolyte Fuel Cells & Electrolyzers 20 (PEFC&E 20) - Invited Talks
Authors: Swider-Lyons Karen
Published: December 2020

Welcome to I01Z: Polymer Electrolyte Fuel Cells & Electrolyzers 20 (PEFC&E 20) - Invited Talks! Take a moment to listen to welcome remarks from the lead organizer, Karen Swider-Lyons.
(Invited) Electrochemical Li Nucleation, Growth, and Dissolution in Oxide Solid Electrolyte Systems
Authors: Motoyama Munekazu , Kitagawa Mizuki , Hirota Masaharu , Yamamoto Takayuki , Iriyama Yasutoshi
Published: December 2020

A great deal of attention has been paid to all-solid-state-lithium battery, which can theoretically achieve a higher energy density than Li ion batteries. One of the key technologies to achieve a high energy density for all-solid-state-lithium battery is to realize highly reversible Li metal anode free from the short-circuiting of solid-state electrolyte (SE).

Many of oxide SEs such as Li7La3Zr2O12 (LLZ) are mechanically hard materials with shear moduli on the order of 102 GPa. So, it had been believed that an oxide SE could act as a separator to prevent Li dendrite growth from the anode side through the SE. However, short-circuiting events have been found to still occur even with the SE. Figure 1 shows voltage transients during Li plating/stripping cycles at various current densities using Li/Ta-doped LLZ (LLZT)/Li symmetric cells 1. Short-circuiting events occurred in any cells, but it was found that the cycling stability significantly depended on the surface treatment. SiC-polishing removed surface Li2CO3 and LiOH from LLZT samples but simultaneously created thin damage layers on the surface. This damage layer was electrochemically inactive. Hence, LLZT etched in a 1.0 mol dm−3 aqueous solution exihbited the longest cycling stability because damge layers were removed from the surface during the etching.

Many researchers have put a lot of effort into controlling the Li plating/stripping processes in solid-state battery, but there is still a lack of fundamental understanding of electrochemical Li deposition and dissolution in solid-state electrolyte systems. I will present the results of our recent studies on Li plating/stripping reactions at “Li-free” interface as well as Li/SE interface 2,3.

Acknowledgement

This work was in part supported by JSPS KAKENHI Grant Number JP19H05813 (Grant-in-Aid for Scientific Research on Innovative Areas “Interface IONICS”).

References

[1] M. Motoyama et al., “The Active Interface of Ta-Doped Li7La3Zr2O12 for Li Plating/ Stripping Revealed by Acid Aqueous Etching ”, ACS Appl. Energy Mater.,
2, 6720 (2019).

[2] M. Motoyama et al., “Modeling the Nucleation and Growth of Li at Metal Current Collector/LiPON Interfaces”, J. Electrochem. Soc.,
162, A7067 (2015).

[3] M. Motoyama et al., “In Situ Scanning Electron Microscope Observations of Li Plating/Stripping Reactions with Pt Current Collectors on LiPON Electrolyte”, J. Electrochem. Soc.,
165, A1338 (2018).

Fig. 1. (Left) Voltage transients during galvanostatic cycling of Li plating/stripping with various LLZT samples: (top) #3000-polished, (middle) #400-polsihed, (bottom) 5m-HCl-etched. (Right) Optical images of molten Li in contact with LLZT samples prepared by each polishing or etching condition on the left-hand-side figure.

Figure 1
Solid Oxide Fuel Cell Development at Pacific Northwest National Laboratory
Authors: Hardy John S , Chou Yeong-Shyung , Choi Jung Pyung , Kirby Brent , Meinhardt Kerry , Whyatt Greg A , Davis James M , Fischer Christopher M , Lowrey Caleb A , Coyle Christopher A , Bonnett Jeff F , Canfield Nathan L , Droubay Timothy C , Xu Zhijie , Karri Naveen K , Bao Jie , Nguyen Ba N , Wang Dewei , Koeppel Brian J
Published: December 2020

Pacific Northwest National Laboratory (PNNL), a U.S. Department of Energy (DOE) laboratory, is working with government agencies and industrial collaborators to accelerate the commercialization of SOFC power systems for distributed and central power applications. This presentation will highlight recent progress in work being performed for the US DOE Office of Fossil Energy’s Solid Oxide Fuel Cell program. Topics to be covered include effects of contaminants and their mitigation on electrode performance; investigating volatility from cathode materials; improved cell materials; Co-free protective interconnect/BOP coatings development; and design, fabrication, validation of an SOFC stack test platform; and modeling tools to evaluate and optimize SOFC stack and system performance.
Controlling Porosity By Freeze Casting in Tubular Solid Oxide Fuel Cell Anode Supports
Authors: Emley Benjamin , Yao Yan
Published: December 2020

Solid oxide fuel cells (SOFCs) have the ability to demonstrate high energy conversion efficiency with commercially available fuels over a wide array of power applications. In order to achieve commercial viability, the cost and durability of the technology require significant improvements. Here we report high performance of a tubular solid oxide fuel cell utilizing a freeze-casting process to form the anode support. In our full-cell demonstration, we employed a standard nickel cermet anode with a standard lanthanum strontium manganite perovskite cathode to show the effect of a novel pore structure within the supporting anode. When evaluated with 30 vol% H2 as the fuel at 800 oC, a decrease of concentration polarization was achieved by increasing the porosity which enabled a 42% increase in the electrochemical performance from 0.35 to 0.50 W/cm2. Controlling porosity within the SOFC active layers is highly desirable for improving the electrochemical performance which can both affect the overall cost and durability of the system. Here we show how freeze casting allows for fine tuning of the aligned porosity within the tubular, anode support of the SOFC with simple adjustments in the solids/water ratio in the casting slurries. Permeation measurements of the anode structures support these findings and show how future improvements can be made by further optimization of the anode interface between the bulk anode and the electrolyte.