bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Discharge/Charge Cycles on Inner Structures of Laminated Cells of Lithium Air Batteries By X-Ray CT, SEM/EDS and FIB-SEM/EDS
Authors: Uosaki Kohei , Kimura Shin
Published: July 2022

Lithium-air battery (LAB) is considered to be one of the most promising energy storage devices because of its large theoretical energy density. However, low cyclability caused by battery degradation prevents its practical use.

Here we employed X-ray CT to monitor the structural development of laminated cell of lithium air batteries without dismantling the cells. The results are compared with those of SEM/EDS and FIB-SEM/EDS analyses, which were carried out after dismantling the cells.

Figure 1 shows XCT images of cross section and slice of laminated cell of lithium air battery after several discharge/charge cycles. Each component is well resolved. Figure 2 shows XCT images of cross section of laminated cell of lithium air battery (a) as prepared, and after (b) one, and (c) ten discharge/charge cycles. It is clear lithium became porous even just after one cycle. The porous layer became much thicker after 10 cycles. For detailed understanding of the structure of the porous layer of lithium, the cells were dismantled and were subject to SEM/EDS and FIB-SEM/EDS analyses. Degradation of lithium layer was much less significant if the anode and cathode were separated by solid electrolyte (Ohara). Detailed results and advantages of XCT will discussed.

Figure 1
Voltammetric Analysis of the Ferrocenium/Ferrocene Redox Couple in Litfsi-Acetonitrile Highly Concentrated Electrolyte
Authors: Genereux Simon , Rochefort Dominic
Published: July 2022

Research on electrolytes have a defining role for the progression of current energy storage device and electrocatalysis. For instance, the electrolyte is often a limiting factor in the life span of Li-ions batteries due to slow decomposition at electrodes. Intensive research is therefore ongoing to increase the stability of the electrolyte. One example of such research is on highly concentrated electrolyte (HCE) which are obtained when the number of ions of a salt nears or equals that of the solvent molecules, while maintaining a liquid state. These highly concentrated electrolytes (HCE) or "solvent-in-salt" solutions differ in properties from conventional ones because all solvent molecules are occupying the ion solvation sphere where they are strongly coordinated to the cation. While on the application side, the attention is directed towards their use in batteries or supercapacitors, current research on HCE aims at increasing the fundamental understanding of their properties mostly the transport properties of the Li+ or the formation of the solid electrolyte interface (SEI). Interestingly, there are no reports on the study of heterogeneous electron transfer (ET) in HCE, yet the absence of "free" solvent molecule suggests that ET in HCE might be different from conventional electrolytes because of the importance of solvent reorganization during ET. We therefore investigate the mass transport and ET of dissolved ferrocene (Fc) and with ferrocene terminated self-assemble monolayer, (Fc-SAM). Ferrocene was selected as the redox center for its "ideal" outer shell electron transfer mechanism and well-defined electrochemical properties. To establish the effect of salt concentration, the electrochemical measurements were done in a series of electrolytes composed of Lithium bis(trifluoromethanesulfonyl)imide in acetonitrile with concentrations spanning from diluted (0.3 M) to highly concentrated (4.1 M) solutions. The diffusivity of Fc (Shoup-Szabo) is found to follow the trend with viscosity (η) expected from the Stokes-Einstein relation over the entire concentration range. The ET rate constant k0 variation with η on the other hand diverges from what is expected from a purely adiabatic ET. Possible explanations for deviation involve different dielectric properties, strong coordination of the solvent and particular double-layer structure of HCE, properties that are not fully established. This lack of knowledge highlights the importance of increasing fundamental research on the topic of electrochemistry in HCE.
Membrane-Less Redox Flow Batteries: A Split Biphasic Architecture
Authors: Chakraborty Arunavo , Sepunaru Lior , Menard Gabriel
Published: July 2022

Redox flow batteries (RFBs) are leading contenders for grid-scale energy storage devices. 1. RFBs can be rapidly deployed and demonstrate high durability (>10,000 cycles2), making them appealing for long-term energy storage. Despite these advantages, commercial RFBs are hampered by high capital costs. Ion-selective membranes in RFB cell stacks make up a significant fraction (up to ~37% 3) of the RFB cost – for both new RFBs and expanding existing RFBs. The need for a large membrane area in the cell stacks stems from the cell power capacity (maximum charge-discharge current) being directly dependent on the membrane size.

In this talk, we report our progress on a new RFB layout coined the “split biphasic architecture.” This is a development on membrane-less biphasic RFBs which use mutually immiscible phases for the anolyte and catholyte4. Self-discharge at the anolyte-catholyte interface is a rampant issue in these biphasic RFBs, and we discuss our approach to resolving this issue and increasing Coulombic efficiencies from ~70% to >99%. Further, we will discuss trends in interfacial ion transfer resistance vis-a-vis dependence on the solvents and electrolytes (Hoffmeister series). Building on this fundamental proof-of-concept, we hope to extend the scope of battery chemistry compatible with the split biphasic layout in the future.

(1) Skyllas-Kazacos et al., J. Electrochem. Soc.
2011, 158 (8), R55

(2) Janoschka et. al., Nature
2015, 527 (7576), 78–81

(3) Minke, C.; Kunz, U.; Turek, T., J. Power Sources
2017, 361, 105–114

(4) Molina-Osorio, et. al., Curr.
Opin. Electrochem.
2020, 21, 100–108

Figure 1
Understanding the Effect of Pre-Intercalated Cations on Zn-Ion Storage Mechanism of Layered Birnessite Manganese Oxide for Aqueous Zn-ion Batteries
Authors: Chomkhuntod Praeploy , Sawangphruk Montree
Published: July 2022

With the rapid growth of energy consumption, tremendous research efforts have been dedicated to achieving sustainable and green energy storage systems, owing to environmental concerns. Over the past few years, rechargeable aqueous zinc-ion batteries (ZIBs) have become a compelling alternative to lithium-ion batteries (LIBs). Although LIBs have been successfully commercialized due to their high energy density, their organic-based electrolytes are highly volatile and flammable. Therefore, aqueous Zn-ion batteries have emerged as promising energy storage devices, owing to the benefits of water-based electrolytes such as low-cost, high safety, and high-power density as well as the advantages of zinc metal such as its natural abundance, low redox potential (-0.76 V vs standard hydrogen electrode), and high theoretical capacity (840 mAh g-1). Among cathode materials, birnessite manganese oxide (δ-MnO2) is one of the promising intercalation cathode materials for ZIBs due to its layered structure, which can facilitate H+/Zn2+ diffusion, leading to enhanced rate performance and improved capacity. However, the δ-MnO2 also suffers from some critical drawbacks such as structural phase transformations and collapse of the layered structure, resulting in poor cycling stability. To address these issues, a pre-intercalation strategy has been proved as an effective way to stabilize the layered MnO2 by using various organic polymers and metal cations such as polyaniline, Li+, K+, and Ca2+. In this work, we studied the effect of charge density of pre-intercalated cation on the Zn2+ storage mechanism of the δ-MnO2 in a mild aqueous electrolyte of 1 M ZnSO4. Overall, the results showed that a small amount of highly charged pre-intercalant (Al3+) can efficiently stabilize the layered structure of the δ-MnO2, resulting in more accommodation space for Zn2+ insertion, which can lead to improved capacity for the Al-MnO2 of 210 mAh g-1 at 0.1 A g-1. Apart from high capacity, the Al-MnO2 also exhibits excellent cycling stability with a capacity retention of 84% after 2000cycles at 2 A g-1. This is because highly charged intercalants can induce a reduction of binding energy between Zn2+ and host structure, leading to a highly reversible (de)intercalation of Zn2+ and stable structure of the δ-MnO2 during charge/discharge, which was confirmed by ex-situ XRD and DFT calculations.

KEYWORDS: rechargeable aqueous Zn-ion batteries, birnessite manganese oxide, intercalation
Application-Oriented Analysis of Ageing Processes Using the Example of Li-C Half Cells
Authors: Petit Jan , Brizoti Marquezini Pedro , Joos Martin , Hagen Markus , Tübke Jens
Published: July 2022

Mechanical modifications or harmful side reactions are undesirable ageing effects that can occur during cycling. These phenomena have a negative impact on cell performance and consequently limit cycling stability. The focus here is on investigations of ageing processes such as volume changes and electrolyte decomposition during cycling.

Thickness measurements as well as gas analytical studies of Li-C half cells with a carbonate-based electrolyte are presented. Graphite and Hard Carbon, respectively, were used as carbon materials. The electrolyte applied consists of 1M LiPF6 in EC:DMC (1:1, wt). All investigations were carried out using specially developed multifunctional test setups and accordingly modified test cells.

Application-oriented analysis such as gas analysis, thickness measurements or both combined are suitable methods to define operating parameter, to benchmark and to identify decomposition reactions.In-operando electrochemical dilatometry was conducted to check whether an irreversible increase in thickness occurred. On the corresponding cell configurations, the dilatation was recorded over the entire electrode stack as well as of the separate working electrode only.Furthermore, in-operando MS could be used to detect gaseous substances produced by (electro)chemical processes as a function of the state of charge. With the GC-MS, a post-mortem analysis could be performed to identify the individual substances qualitatively.

Results of the different half cells are shown and can be compared with each other. A detailed relationship can be demonstrated between the change in thickness and the potential curve. Moreover, any emerging Li-plating is clearly detectable. Among others, carbon dioxide, ethane as well as ethene were identified as degradation products of the carbonate-based electrolyte and are formed during the charging process. In addition, possible correlations between gas evolution and thickness changes can be shown.

These analytical studies make an important contribution to get a more detailed insight into ageing processes that take place. The possible combination of in-operando dilatometry with in-operando mass spectrometry opens up new interesting perspectives to analyse cell performance. Finally, the shown results lead to a better understanding and help to develop appropriate countermeasures in order to reduce the negative effects and thus to ensure a higher cycling stability.

This work is supported by the Fraunhofer and Max Planck cooperation program (Germany) in the project “ClusterBatt” with Fraunhofer Institute for Material and Beam Technology IWS, Dresden and Max Planck Institute of Colloids and Interfaces MPIKG, Potsdam.

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(Digital Presentation) Analysis of Thermal Runaway Propagation in Lithium-ion Battery Cells and Modules
Authors: Belt Jeffrey , Sorensen Alexander
Published: July 2022

Lithium-ion battery technology is a critical enabling technology to the advancement of electric propulsion transportation. Cost, Life, Performance, and Safety have been the main impediments for the application of batteries for use in Automotive and Aviation markets. Cost, life, and performance have been improving for the last decade.1 However, safety with respect to thermal runaway propensity continues to be a challenge for both automotive and especially aviation electric propulsion due to the energetic nature of the technology. Complete thermal runaway containment is required to obtain FAA certification for passenger safety for aviation applications. Consequently, an evaluation of the thermal runaway characteristics will be discussed.

Thermal runaway propagation analysis at the cell and module level was performed on a suite of Samsung 30Q 18650 cylindrical cells. Measurements such as cell enthalpy, maximum thermal runaway temperature, and thermal runaway onset and initiation temperatures (shown in Figure 1 & 2) were collected and shown to be consistent by means of accelerated rate calorimetry (ARC). Results for ten 30Q cells are shown in Figure 3. This study showed, using the X-57 module billet as a thermal runaway propagation mitigation strategy, wherein the cell energy was successfully absorbed during a failure event in the module and prevented thermal runaway propagation from between cells.

The results show the 30Q cell average maximum temperature is 375°C and the average initiation temperature is 195°C. The average mass lost was 33.1 grams. The stochastic nature of the results indicates the need to test a larger than normal sample to obtain a good statistical sample. These values become critical design points for the module containment strategy. Module level, cell to cell propagation tests will also be evaluated, showing the fulfillment of the module design strategy to eliminate cell to cell propagation.

References

courtesy of Bloomberg NEF 2021

Figure 1
The Impacts of Electrolyte Composition on Key Performance Metrics of the All-Aqueous Copper Thermally Regenerative Ammonia Battery
Authors: Cross Nicholas R. , Rau Matthew J. , Lvov Serguei N. , Gorski Christopher A. , Logan Bruce E. , Hall Derek M.
Published: July 2022

A significant amount of the potential energy that is generated during energy harvesting worldwide is discarded as waste heat because of inefficient power generation cycles. Much of this wasted power source goes unused because it is trapped as low-grade thermal energy (< 100 °C), which traditional power cycles cannot viably harness. With the advent of electrochemical power systems such as redox flow batteries and fuel cells, researchers are investigating new methods of providing usable electric power from these unused low-grade thermal energy sources. The thermally regenerative ammonia battery (TRAB) is one promising technology in this space, as it operates with the same principles as a flow battery except that TRABs can be recharged using low-grade waste heat instead of electric power. Of the TRAB chemistries proposed, the all-aqueous copper TRAB chemistry is capable of both large power densities and energy densities, and high coulombic efficiencies. In this presentation, we discuss how key performance metrics relevant to power generation from low grade thermal energy sources are strongly influenced by electrolyte composition and battery operating parameters. Manipulating the ammonia to copper ratio demonstrated clear tradeoffs between achievable energy and power capacities. Increasing ligand concentration had a large impact on electroactive species solubility and cell potential differences, which increased the theoretical energy density limit of the battery. Increasing the amount of ammonia relative to dissolved copper raised peak power density, but adversely affected energy density. Moderate increases in discharge current density did not decrease the energy density due to reduced impact of ammonia crossover which appears to be a dominant source of energy loss in TRABs.
(Digital Presentation) Industrial Transition and Methods to Apply Metallic Alloys and Composites By Electrodeposition
Authors: Hall Timothy
Published: July 2022

Faraday Technology Inc. is a research, development and engineering firm developing electrochemical innovations based has pulse/pulse reverse electrolytic principles [1]. With that founding basis Faraday has been able to bridge the gap between academic understanding and small scale demonstration to commercialization of practical components over 30 years of operation.

This presentation will discuss a broad range of alloy and composite deposition programs that have been carried out at Faraday. These include functionally graded NiMo, CeO2 inclusion in NiMo, CrAlY inclusions in NiCo, NiCoCr alloy deposition, and so on. We intend the presentation to give a perspective on the challenges associated with transitioning electrodeposition technologies from coupons to components. We also want to demonstrate the potential to achieve success during these challenging transitions by tuning the electrochemical device and method. Finally, we will try to identify similarities and differences in the observed challenges and ways that many could be overcome either by electrochemical engineering, process developments, or program planning.
(Invited) Temperature Dependence of Electrochemical Gas-Phase Nucleation
Authors: White Henry
Published: July 2022

Classical nucleation theory (CNT) suggests that the rate of electrochemical nucleation of a gas phase, and the structure of the nuclei, are complex functions of numerous temperature-dependent system properties, including the dissolved gas diffusivity, saturation concentration, and the surface tension of the liquid-gas interface. For example, the diffusion coefficient of dissolved gases increases with temperature, whereas the surface tension of the gas/water interface decreases. Very few studies of the temperature dependence of gas phase nucleation have been reported. In this report, we describe electrochemical measurements of the nucleation of H2 and N2 nanobubbles as a function of temperature (20-75 oC). The nucleation rates of single bubble nuclei were determined using the galvanostatic technique of induction time (tind). A total of 560 measurements of tind were performed and the effect of temperature on the pre-exponential factor (Jo), activation energy (EA), nucleus contact angle (θ), and the number of molecules (n) in the nuclei were determined.
(Invited, Digital Presentation) Tuning the Electrodeposition of Actinides in Molten Alkali Halide Salts
Authors: MacInnes Molly M , Pace Kristen A , DiMucci Ida M , Anderson Nickolas H , Stein Benjamin W , Kozimor Stosh , Rocha Francisca R , Jones Zachary R , Mocko Veronika , Batista Enrique R , Eiroa-Lledo Cecilia , Livshits Maksim Y , Wacker Jennifer N , Knope Karah E , Yang Ping
Published: July 2022

Molten salts have found use as solvents in numerous applications including nuclear reactors, batteries, and the extraction and purification of various metals. Unfortunately, understanding of the chemistry of molten salt solutions is limited. In this presentation we explore the use of molten salts as a testbed for understanding both outer and inner coordination sphere effects on dissolved metal ions. The electron transfer reactions available to lanthanides (Eu3+, Sm3+, and Yb3+) and actinides (U3+, U4+, and Th4+) were explored in a series of alkali and alkaline earth halide salts. We present electrochemical data that demonstrate significant shifts in the reduction potentials of these metal ions as a function of the anion and cation identities of the molten salt solvent. We hypothesize that effects on the reduction potential of these metals come from two sources: (1) the primary coordination sphere and (2) the secondary coordination sphere. The influence from the primary coordination sphere is dominated by the degree of covalency in the coordination bonds between the Lnn+ and Ann+ cations and the molten salt anions. The influence of the secondary coordination sphere is dominated by the electron-withdrawing character of the salt cations. EXAFS data and computational results that support these hypotheses are presented. Further, we provide insight into electrodeposition of the An0 metals under these conditions and highlight temperature and molten salt effects that influence these electrodepositions. Specifically, we propose that increased mobility of solid-state atoms at high temperature (> 800°C) influence the properties of electrodeposited metals.
Operando X-Ray Diffraction Nanoimaging of Advanced Cathodes
Authors: Martens Isaac , Vostrov Nikita , Mirolo Marta , Drnec Jakub , Schulli Tobias , Zhu Xiaobo
Published: July 2022

Techniques capable of probing active materials in situ are increasingly needed to link cell performance data with nanostructural evolution inside functional devices. Rapid improvements in spatial and temporal resolution of X-ray nanomicroscopy and high-energy diffraction facilitated by new 4th-gen synchrotrons offer a powerful platform for investigating phase transitions inside advanced cathode materials. We show how the latest methodologies can be used to evaluate the mechanism of phase transitions at the nanoscale, linked to degradation processes inside commercially relevant cells.

"Single crystal" cathode active materials have garnered incredible academic and industrial interest in the past several years. Despite extensive electrochemical performance validation, there remain very few tools capable of evaluating the quality and consistency of these materials. Scanning X-ray nanodiffraction microscopy reveals the hidden microstructure and defects inside nominally single crystal cathode particles established during their fabrication. In situ nanodiffraction imaging provides further insight towards the link between this microstructure and functional properties such as high voltage stability inside individual crystallites during cycling.
(Digital Presentation) HF-Free, Pulse-Reverse Electrochemical Machining of Tantalum
Authors: Moran Andrew , Skinn Brian , Snyder Stephen , Hall Timothy
Published: July 2022

Electrochemical machining (ECM) is a manufacturing technology wherein metal is precisely removed by electrochemical oxidation and dissolution/dispersal into an electrolyte solution. ECM is especially well suited for “difficult to cut” materials (high strength/toughness, work-hardening, etc.) such as high strength steel, chrome-copper alloy (C18200), nickel alloy (IN718), cobalt-chrome alloy (Stellite 25) and tantalum-tungsten alloy (Ta10W) since the material removal process involves no mechanical interaction between the tool and the part. In ECM, an electrochemical cell is established wherein the workpiece is the anode and the tool is the cathode; by relative movement of the shaped tool into the workpiece while applying a suitable electrical voltage, the mirror image of the tool is “copied” into the workpiece. Production of parts with complicated and intricate geometries can thus be achieved in these challenging materials by design of a suitably-shaped tool made from a much more easily-machinable material. Compared to mechanical or thermal machining processes, where metal is removed by cutting or electric discharge/laser machining, respectively, ECM does not suffer from tool wear or result in a thermally damaged surface layer on the workpiece. Additionally, the use of pulse and/or pulse-reverse electrical waveforms can enable successful ECM of even highly passive materials using benign, HF-free electrolytes.

Advanced materials such as refractories (e.g., W, Mo, Ta, and their alloys) provide highly desirable characteristics such as high strength, corrosion resistance, and survivability in extreme environments (high temperature, high chemical reactivity, plasma exposure, etc.). As motivation to adopt these materials has increased, conventional fabrication methods have proven progressively less able to successfully machine workpieces of the myriad needed geometries. ECM is a natural non-conventional fabrication method for these materials and workpieces, for the reasons described above. In this talk, we will present results from a proof-of-concept demonstration of pulse-reverse ECM of linear grooves in flat Ta and Ta10W alloy coupons using benign electrolytes, illustrating the potential for cost-effective, safe, environmentally-friendly fabrication using these exotic materials.
High Power Density Fuel Cell Systems for Portable Electric Generators
Authors: Kruusenberg Ivar , Chadha Kush , Atal Taarini
Published: July 2022

It is of utmost importance to develop light weight fuel cell stacks and find the ways to integrate these to light weight and low temperature fuel cell systems. In order to meet the future energy demands non-polluting, compact, transportation and portable applications are required. Current energy systems have lower power density (kW/kg) resulting in optimized power only at higher overall weight. Systems with higher power density demands higher initial setup costs. Low temperature PEMFC, on other hand offers various advantages but fails to provide the required output without exceeding the weight of the fuel cell stack and thereby fuel cell systems. A fuel cell system consists of a fuel cell stack, compressed gas in cylinder, pressure relief valves, regulators, water pump, sensors and cvm. A fuel cell stack is the main component consisting of one of the devices with maximum weight and cost contribution. In such case, developing a system with stack having higher power density reduces overall weight and increases power density (kW/kg). PowerUP Energy Technologies has developed light weight fuel cell stack to achieve higher power density. Experiments considering flow field designs, recirculation strategy, different anode configuration has been a subject of study. Dead-end anode, closed cathode configuration of fuel cell stack further improves fuel utilization. Recirculation line of hydrogen if further added can improve in overall fuel utilization. Counter flow arrangement for reactant distribution further removes the necessity of humidifying the gases. This result in removal of humidifiers and thereby reducing the weight of the fuel cell system in total. Portable fuel cell systems have flexibility for ease in transportation and stationery solutions. Furthermore, lighter fuel cell stacks add advantage for higher output power at lower overall weights. This stack developed is further optimized with improved flow field designs and design of manifold. These fuel cell stacks are used in PowerUP’s portable fuel cell electric generators that are more efficient and sustainable than the currently used fossil fuel based solutions.
(Electronics and Photonics Division Award) The Impact of Defects on the Performance of Semiconductor Devices and Materials
Authors: Simoen Eddy , Takakura K. , Hsu Brent , Claeys Cor
Published: July 2022

Since the early days of the semiconductor industry, defect control has been key to the successful development of devices and circuits. It requires a thorough understanding of their formation and the impact on the electrical material parameters. This has only been possible by the invention of powerful structural, chemical and electrical characterization tools, with the device itself perhaps as the most sensitive probe. This evolution was paralleled by the development of ab initio calculation methods, based on Density Functional Theory and more recently, also TCAD tools allowing more and more refined modelling of the impact of defects on the electrical characteristics of devices.

The implementation of other materials than Si and SiO2 in CMOS through the hetero-epitaxial growth on a silicon substrate for example, has renewed the interest in defect engineering during the last two decades, leading to single-defect analysis methods like Random Telegraph Noise (RTN) [1] or novel growth schemes like Aspect Ratio Trapping (ART) [2] for the removal of extended defects from the device active regions.

In this presentation, some state-of-the-art analysis techniques will be highlighted, including Deep Level Transient Spectroscopy (DLTS) [3], Generation-Recombination (GR) noise and RTN spectroscopy [1,4] and p-n diode lifetime analysis [5]. These methods will be applied to several case studies. As shown in Fig. 1, threading extended defects impact the recombination lifetime of lowly-doped n-type In0.47Ga0.53As starting from a density of a few 107 cm-2. Likewise, it will be demonstrated that the GR noise observed in GaN-on-Si MOSHEMTs (Fig. 2) most likely originates from threading dislocations [6]. It is concluded that when hetero-epitaxial layers can be grown with a sufficiently low defect density, their impact will be more on the variability of the electrical parameters rather than on the effective values. In addition, the position of the defect with respect to strategic nodes like a p-n junction or depletion region largely determines its electrical impact, as has been validated by TCAD simulations.

References

[1] E. Simoen and C. Claeys, “Random Telegraph Signals in Semiconductor Devices”, The Institute of Physics, Bristol, UK (2016).

[2] J. Z. Li et al., Appl.
Phys. Lett., 91, p. 021114 (2007).

[3] E. Simoen, J. Lauwaert and H. Vrielinck, Semiconductors and Semimetals, Eds. L. Romano, V. Privitera and C. Jagadish, 91, pp. 205-250, Elsevier 2015.

[4] D. Boudier et al., Solid-St.
Electron., 128, pp. 102-108 (2017).

[5] Po-Chun (Brent) Hsu et al., J. Phys. D: Appl.
Phys., 52, p. 485102 (2019).

[6] K. Takakura et al., IEEE Trans. Electron Devices, 67, pp. 3062-3068 (2020).

Figure 1
(Invited) Water Electrolyzers for Green Hydrogen Production - a Tutorial on Catalyst and Electrode Development for Next Generation Devices
Authors: Carmo Marcelo , Capuano Christopher , Ayers Katherine E.
Published: July 2022

Green hydrogen generation via electrolysis is at the forefront of international debates, with an unprecedent momentum within hydrogen technology. Various countries have already released their hydrogen strategy documents, recognizing the high propositional value of hydrogen as energy commodity of the future. Significant growth in water electrolysis has therefore occurred in recent years,` with the largest 20MW PEM electrolyzer being deployed for Iberdrola by NEL Hydrogen in Spain in 2021.

This project shows how commercial polymer electrolyte membrane (PEM) electrolysis has reached scales of several hundred kg/day, providing a relevant pathway for industrial scale hydrogen generation. PEM electrolyzers also have tremendous potential for continuing cost reduction, leveraging system and manufacturing scaling laws as well as leveraging advancements in nanomaterials, advanced manufacturing tools, and both in-situ and ex-situ analysis tools. Order of magnitude improvements in some of the highest cost elements have already been achieved, including by NEL Hydrogen. Many of the technology elements such as PFSA membranes, iridium electrodes, porous transport layers, etc. are known, but still need to be refined and validated in a manufacturing environment at scale, including modifications in materials and novel yet economical methods of fabrication. At the same time, classic KOH based alkaline electrolyzers (AEL) are showing renewed promise, as diaphragm structure has advanced and understanding of electrode processing has developed. The basic environment of the alkaline electrolysis cell enables a broader range of materials and the potential to eliminate the highest cost materials such as platinum group metals and commercially pure titanium from the stack.

However, for both AEL and PEM, complex interactions at the electrode level exist which need to be considered in catalyst and membrane/diaphragm development. First, the liquid electrolyte environment used for catalyst activity screening, where all the catalyst surface is accessible to the reactant is often not comparable to a complex, 3-dimensional, ionomer-based electrode. Therefore, in the same way that future alkaline electrode/diaphragm structures might resemble PEM catalyst coated membranes, novel PGM-free components still ought to show durability profiles similar to those shown by AEL stacks. This talk will describe some of the complex interactions that need to be considered, typical operating requirements, and stages of development where relevant conditions should be introduced.
(Invited) Electrolysis in the Canadian Context
Authors: Girard François
Published: July 2022

Electrolysis is seen by many as the ultimate solution for producing hydrogen with zero emission, assuming the electricity source to be without emission itself. Obviously this depends the context existing in each specific region of the world. This paper will focus on the Canadian context, its electrical generation characteristics, its Hydrogen strategy elements and examine what it would take to ensure the viability of electrolysis in this context. The discussion will bring those considerations down to technical R&D challenges to consider for electrolysis of the future. Lessons learned from R&D in Proton Exchange Membrane fuel cells will be included in the discussion.
(Invited, Digital Presentation) Regulating the Dynamic Surface Reconstruction of a Layered Cobalt Oxide Electrocatalyst for Water Oxidation
Authors: Wang Jian
Published: July 2022

Water electrolysis conditions accelerate the dissolution and corrosion of electrocatalysts, changing their surface and/or bulk composition/structure from the original states. This dynamic reconstruction process redefines the catalytically active species. However, rational control of the in-situ surface reconstruction for electrocatalysts is tremendously challenging. Here, we proposed a novel redox-tuning method to precisely modulate the surface reconstruction and to favor the water oxidation activity. For a category of layered transition metal oxide (AMO2: A = alkaline metal, M = transition metal), redox of transition metal during the alkaline OER was in-situ tuned to engineer the catalyst leaching potential, manipulate the cation leaching amount, and redirect the dynamic catalyst reconstruction. Specifically, Cl doping lowered the cobalt valence state of LiCoO2 and the further OER potential for its in-situ cobalt oxidation triggering Li leaching. Operando XAFS and DFT calculations confirmed that such modulation bypassed the less favorable surface reconstruction by forming Li1-xCo2O4-type spinel structure, transforming the surface of LiCoO1.8Cl0.2 into a more catalytically-active (oxy)hydroxide phase. The proposed method could be potentially generalized to manipulate the surface reconstruction of other pre-catalysts.

References

1. Wang, J.; Gao, Y.; Kong, H.; Kim, J.; Choi, S.; Ciucci, F.; Hao, Y.; Yang, S.; Shao, Z.; Lim, J., Non-precious-metal catalysts for alkaline water electrolysis: operando characterizations, theoretical calculations, and recent advances. Chemical Society Reviews 2020, (49), 9154-9196.

2. Wang, J.; Kim, S.-J.; Liu, J.; Gao, Y.; Choi, S.; Han, J.; Shin, H.; Jo, S.; Kim, J.; Ciucci, F.; Kim, H.; Li, Q.; Yang, W.; Long, X.; Yang, S.; Cho, S.-P.; Chae, K. H.; Kim, M. G.; Kim, H.; Lim, J., Redirecting dynamic surface restructuring of a layered transition metal oxide catalyst for superior water oxidation. Nature Catalysis
2021,
4 (3), 212-222.
Oxygen Evolution Reaction Catalyst Development: Benchmarking IrOx Catalyst Activity and Stability
Authors: Murawski James , Yin Shuaihang , Zalitis Christopher , Stevens James , Rigg Katie , Clapp Mark , Smith Graham , Sharman Jonathan , Hinds Gareth , Stephens Ifan Erfyl Lester
Published: July 2022

While PEM electrolyser catalyst cost may not be a significant portion of system costs1 it does represent a bottleneck for the ability to generate TW level of H2. This is primarily because of the reliance on IrOx as a stable oxygen evolution catalyst in order to meet future green H2 needs either replacement or reduction of iridium loading of at least 50 times is needed while maintaining a high level of stability2. IrOx based materials are the only oxygen evolution catalysts combining activity and stability under PEM electrolysis conditions; even so, they are insufficiently stable.

In the current work, we tailored the activity of IrOx catalysts synthesised by a variant of the Adams fusion reaction3 using decomposition of Iridium nitrate and varying temperature of synthesis to generate a series of catalysts with differing crystallinity and surface area. We benchmarked their stability using both accelerated degradation electrochemical measurements (30k cycles 1.2-1.7VRHE @ 500 mV s-1) and inductively coupled plasma-mass spectrometry(ICP-MS), both in rotating disk electrode(RDE) measurements and in a single cell PEM electrolyser.

We have compared several different methods for probing electrochemical surface area, including BET, double layer capacitance from cyclic voltammetry, adsorption capacitance using impedance spectroscopy and CO stripping using ultrasensitive on chip electrochemical mass spectrometry.

The results from the RDE measurements are shown in figure 1; they show that while the high surface area amorphous IrOx catalysts demonstrate higher activity normalised to geometric area, when normalised to specific activity the difference is insignificant. In addition to electrochemical performance losses, the amorphous IrOx shows an order of magnitude increase in iridium dissolution, determined via ICP-MS. Future studies will look at the ability to overcome the limitations of aqueous model studies for stability testing and utilising testing to select OER catalyst candidates that meet both activity and stability required for long term operation in PEM electrolyser systems.

1 L. Bertuccioli, A. Chan, D. Hart, F. Lehner, B. Madden and E. Standen, Study on development of water electrolysis in the EU, Fuel Cells and hydrogen Joint Undertaking, 2014, vol. 1.

2 P. S. Alexis Grimaud, Jan Rossmeisl, Research nees towards sustainable production of fuels and chemicals, Section 1: Water splitting and sustainable H2 Production, 2019.

3 D. F. Abbott, D. Lebedev, K. Waltar, M. Povia, M. Nachtegaal, E. Fabbri, C. Copéret and T. J. Schmidt, Chem. Mater., 2016, 28, 6591–6604.

Figure 1
Active Site Formation in Oxygen Deficient Cobalt Antimonate for Oxygen Evolution Reaction in Alkaline Media
Authors: Ham Kahyun , Hong Sukhwa , Kang Sinwoo , Cho Kangwoo , Lee Jaeyoung
Published: July 2022

Electrochemical water splitting is the one of the promising ways to obtain hydrogen from aqueous media. Oxygen evolution reaction (OER) at the anode is the rate-determining step due to the sluggish kinetics, which leads to reducing energy efficiency. Recently, anion exchange membrane water splitting has been considered as an alternative way because of its capability of producing hydrogen of high purity and the availability of iron-triad element-based catalysts because of their thermodynamically stability in alkaline media. Besides, cobalt oxides such as spinel, layered double hydroxide are being investigated as active OER electrocatalyst. Among them, the spinel-type Co3O4, which contains one Co2+ in the tetrahedral site and two Co3+ ions in the octahedral site, exhibits outstanding OER performance in alkaline media and has been actively investigated.

In this study, we investigated oxygen-deficient cobalt antimonate oxide (CoSb2O6) as OER catalyst in alkaline media, which has unique crystal structure and contains abundant octahedral Co2+ compared to spinel-type cobalt oxide. Through in situ X-ray absorption near-edge structure analysis, we observed most of octahedral Co2+ ions were oxidized to Co4+ at OER potential, which leaded to increase the OER activity by extending the active site. We also carried out anion exchange membrane water splitting to confirm the availability as the anode catalyst to produce H2 gas.
Seacat - Catalysts for Direct Seawater Electrolysis
Authors: Moretti Enzo , Kiebach Ragnar , Kraglund Mikkel Rykær
Published: July 2022

With current technology, the direct electrolysis of seawater struggles with ACSFRs (active chlorine species formation reactions), including the ClER (chlorine evolution reaction), competing with the formation of gaseous oxygen on the anode side. The corrosive and poisonous chlorine compounds produced in the ClER pose a significant issue, essentially destroying the electrolyser in a short period of time. Since the purification of seawater requires both energy and increased investment and maintenance costs, today water electrolysis is often not economically feasible in regions with no fresh water access.

This marks the starting point of this PhD project. The primary goal of this thesis is the development and demonstration of a catalyst suitable for direct electrolysis of seawater to hydrogen and oxygen, without the formation of Cl2.

Nickel based layered double hydroxides (Ni-LDH) and oxyhydroxides (Ni-OOH), particularly when doped with other transition metals, have shown very high catalytic activity with respect to the OER. If sufficient current densities under practical conditions (1A/cm2, < 80 °C, stable for several thousand hours) below the thermodynamic onset potential of the ClER of around 1.7 V could be reached, an active suppression of the ClER is not necessarily needed.

Initially, we investigate potential highly active mixed-metal LDH catalysts for the OER in sea water splitting, which are synthesized by a particularly simple, quick and efficient procedure proposed by Li et al. in 2020. Based on their work, we conduct a screening study of 36 unique compounds derived from abundantly available transition metals (Ni, Fe, Mn, Cr, Co, Cu, Zn, Al). The LDHs are coated onto a Ni foam substrate by a two-step dip coating process from metal nitrate solutions. In a first approach, we only consider compounds consisting of two transition metals with equal molar ratios. We then investigate their catalytic activity as well as the long term stability for up to 1000 hours in industrially relevant (60 – 80°C, 6M KOH) fresh water and sea water conditions, particularly regarding catalyst poisoning effects of the sea water constituents on the catalyst.

We then give an outlook on the next step in the project, which will be to make use of the simple synthesis procedure by implementing it into an autonomous lab robot setup. The robot platform will comprise all steps of the experiment from synthesis over electrochemical testing, data analysis and machine learning based optimization. This way, we will showcase the potential of combining high-throughput screening with AI-assisted materials discovery. As a proof-of-concept, the robot will reproduce the initial screening study that was carried out manually. Subsequently, autonomous data analysis and synthesis optimization functionality will be implemented and the robot will run several iterations of closed-loop catalyst optimization experiments without human interaction.
Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes and Their Performance in HT-PEMFCs
Authors: Arslan Funda , Chuluunbandi Khajidkhand , Freiberg Anna , Kormanyos Attila , Sit Ferit , Cherevko Serhiy , Kerres Jochen Alfred , Thiele Simon , Böhm Thomas
Published: July 2022

Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes and Their Performance in HT-PEMFCs

Keywords: Proton-exchange membrane, ion pair, high-temperature, phosphoric acid, quaternary ammonium, hydrogen crossover

High temperature proton-exchange membrane fuel cells (HT-PEMFCs) are promising electrochemical energy conversion devices for the hydrogen economy. In this fuel cell type, phosphoric acid is immobilized as an electrolyte within a polybenzimidazole (PBI) membrane acting as a matrix. These membrane systems allow operating temperatures up to 200 °C, which is significantly higher than for sulfonated polymers that are used in low temperatures PEMFCs at around 80 °C.

Operating PEMFCs above 100 °C harbors advantages such as faster reaction kinetics, higher tolerances against fuel impurities, and easier cooling. Nonetheless, phosphoric acid doped membranes also is the main challenge and drawback of these systems due to leaching of the dopant over time. A high acid-oping level is desired since it ensures high proton conductivity. However, the mechanical properties of PBI-based materials generally deteriorate upon increasing acid doping levels. In this regard, cross-linking PBI with another polymer is a promising route to enhance the mechanical properties of acid-doped membranes. Further, polymers with specific functional groups, such as quaternary ammonium (QA), can be used as cross-linkers to enhance the retention of phosphoric acid by forming strong interactions with biphosphate anions.

Here, we present a new ion-pair-coordinated membrane (IPM) system decorated with QA groups. Poly(vinylbenzyl chloride) is used as a macromolecular cross-linker for PBI, and three different amines (Quinuclidine, Quinuclidinol, DABCO) are used as quaternizing agents. The performance of these membranes is evaluated ex-situ as well as electrochemically within HT-PEMFC operation and compared to a commercial m-PBI membrane (Dapazol). The IPMs show reduced swelling and better mechanical properties upon doping. Further, the commercial reference can be outperformed within HT-PEMFC operation at less acid doping than conventional PBI membranes. The best-performing IPM led to a 25% improved fuel cell performance. The peak power density of an HT-PEMFC incorporating a Dapazol membrane was 430 mW cm–2 at 180 °C under H2/air conditions and at ambient pressure, while the HT-PEMFC with the best-performing IPM yielded 530 cm–2 at equal parameters. Further, the hydrogen gas crossover of the IPMs is similar or less than that of the commercial reference even at lower membrane thicknesses, which renders these membranes as promising candidates for application in HT-PEMFC.
Influence of Three-Dimensional Flow Field Structures Consisting of Expanded Metal Meshes on the Physicochemical Loss Processes in Pemfcs
Authors: Raab Sebastian , Goosmann Tobias , Weber Andre
Published: July 2022

To further increase the performance of polymer electrolyte membrane fuel cells (PEMFCs) at high current densities, a reduction of mass transport losses by an enhanced evacuation of water from the cell and an improved supply of gases to the reactive sites are necessary.

The application of three-dimensional flow field structures in PEMFCs is a promising measure to promote the evacuation of excess liquid water from the cell while boosting the transport of reactants from the gas channel in the direction of the cell. Expanded metal meshes offer a three-dimensional geometry, which predestines them to be used as flow field structures in PEMFCs. In the past, their application as flow fields has primarily been investigated for direct methanol fuel cells (DMFCs) [1, 2, 3] and electrolyzers [4, 5]. To gain a profound understanding of the impact of such three-dimensional flow field structures on the electrochemical properties of PEMFCs, the physicochemical loss processes of the cell have to be analyzed in detail.

In this contribution, the results of an in-depth analysis of the influence of three-dimensional flow field structures consisting of expanded metal meshes on the physicochemical loss processes in PEMFCs and their effect on the cell performance is presented. To assess the impact of expanded metal meshes in comparison to a conventional channel rib flow field design, the physicochemical loss processes were examined for both flow field designs. The operating conditions (j, RH, T, pO2) of the incremental PEM fuel cells (1 cm2 active cell area) [6] were varied systematically and the cells were analyzed by means of polarization curves and electrochemical impedance spectroscopy (EIS). The physicochemical loss processes of the cells were identified by a subsequent impedance data analysis by the distribution of relaxation times (DRT) [7, 8].

This investigation aims to determine the physicochemical loss process in PEMFCs with expanded metal meshes as flow field structures and compare them to the results of a conventional flow field design. Based on the physical interpretation of the results, consequences and conclusions for the further development of the expanded metal flow field geometries are discussed.

References:

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[3] Mallick et al., Electrochimica Acta
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[4] Stiber et al., Adv. Energy Materials
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[5] Lafmejani et al., J. Power Sources
397, pp. 334-342 (2018).

[6] M. Heinzmann et al., J. Power Sources
402, pp. 24-33 (2018).

[7] H. Schichlein et al., J. Appl. Electrochem. 32, pp. 875-882 (2002).

[8] E. Ivers-Tiffée et al., J. Ceram. Soc. Japan 125, pp. 193-201 (2017).