bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Energy Storage Systems for Long Charge/Discharge Duration
Authors: Poli Nicola , Bonaldo Cinzia , Trovo Andrea , Guarnieri Massimo
Published: July 2022

The interest for long-term energy storage in electrical grid provided with renewable energy sources is presently growing, because of the wide range of service that such systems can offer [1,2]. Although the choice of optimal duration of the charge / discharge cycles of energy storage systems for stationary applications is still an open question, among the different energy storage technologies available at a high readiness level (TRL), a few fit particularly well this kind of services [3,4]. Depending on the application and the market in which the energy storage systems are applied, the optimal duration can have different values and call for different technologies. Among electrochemical energy storage systems Vanadium Redox Flow Batteries (VRFBs) are emerging as a very promising solution for long-term stationary applications [5]. In order to find an optimal duration value for applications, the development of a physical-economic model becomes essential. Indeed, the optimal duration of energy storage systems not only depends on the technical features of each energy storage device (e.g. life cycle, self-discharge, ecc...), but also on the specific services required by the market. VRFBs devices which may be very expensive for a specific market, could be a competitive solution for a different one. The purpose of this work is to size the optimal duration of VRFB system according to the specific applications and the reference market.

Reference

Wu Y, Liu Z, Liu J, Xiao H, Li, R, Zhang L, Optimal battery capacity of grid-connected PV-battery systems considering battery degradation, Renewable Energy, 2022,181:10-23. DOI: 1016/j.renene.2021.09.036.

Simoglou CK, Biskas PN, Marneris IG, Roumkos CG, Long-term electricity procurement portfolio optimization, Electric Power Systems Research, 2022, 202:107582. DOI: 1016/j.epsr.2021.107582

Alotto P, Guarnieri M, Moro F, Redox Flow Batteries for the storage of renewable energy: a review, Renewable & Sustainable Energy Reviews, 2014,29:325-335. DOI: 1016/j.rser.2013.08.001.

Ibrahim H, Ilinca A, Perron J, Energy storage systems-Characteristics and comparisons, Renewable and Sustainable Energy Reviews, 2008,12,5:1221-1250. DOI:10.1016/j.rser.2007.01.023

Guarnieri M, Mattavelli P, Petrone G, Spagnuolo G, Vanadium Redox Flow Batteries: Potentials and Challenges of an Emerging Storage Technology, IEEE Industrial Electronics Magazine, 2016,10,4:20-31. DOI: 1109/MIE.2016.2611760.

Figure 1
High Accuracy Measurements for Rapid Evaluation of Extremely Low Decomposition Rates of Redox Active Molecules
Authors: Sosa Jordan D. , Aziz Michael J.
Published: July 2022

Aqueous Organic Redox Flow Batteries (AORFBs) have potential to disrupt the energy storage technology market for renewable energy sources. To combat the issue of intermittency[i] for these energy sources, AORFBs use non-volatile, potentially cheap, and abundant materials to deliver decadal time scale energy storage with the advantage of decoupled energy and power density by scaling the former with the size of electrolyte tank volumes and scaling the latter with the area of the electrode surface where the reactions take place. Because many candidates have been discovered and remain to be discovered for applications as redox active molecules with long chemical lifetimes in AORFBs, in this work we developed a setup for quickly and accurately evaluating molecular decomposition.

To make AORFBs more competitive for commercialization, our group has fine-tuned the electrochemical properties of active organic molecules via new synthetic approaches to achieve capacity fade rates lower than 1% per year.[ii] To better understand the decomposition mechanisms of these redox active species in AORFBs, we have also developed volumetrically unbalanced, compositionally symmetric cell cycling methods to evaluate capacity losses solely from decomposition and not from active species crossover through the membrane or changes in internal resistance of the battery.[iii]

While the symmetric cell cycling technique allows isolating molecular decomposition as the source of capacity fade for AORFBs, for evaluating extremely low decomposition rates, flow batteries can require run times from several weeks to months due to noise in capacity measurements from temperature and pressure fluctuations or droplets in the batteries losing contact with solution being pumped to react in the cell. Additionally, since we have experienced slight variations in fade rates across cells with the same experimental conditions, decomposition rates should be determined from several cycling experiments, not one.[iv] In order to more quickly and more accurately evaluate extremely low decomposition rates, we have developed a simple static cell into which electrolyte is injected into porous electrodes and sandwiched together by current collectors without a flow system. By removing the complexities of the flow system, we may determine capacity fade rates in much shorter times and with lower uncertainties.

[i] J. Rugolo and M. J. Aziz, “Electricity storage for intermittent renewable sources.” Energy Environ. Sci., 2012, 5, 7151

[ii] M. Wu et al., “Extremely Stable Anthraquinone Negolytes Synthesized from Common Precursors”. Chem 6,1–11 June 11, 2020

[iii] M.A. Goulet and M. J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods”. Journal of The Electrochemical Society, 165 (7) A1466-A1477 (2018)

[iv] Eric Michael Fell and Michael J. Aziz 2021 Meet. Abstr.
MA2021-01 207
(Invited) Accelerating Material Design for Aqueous Organic Redox Flow Batteries
Authors: Wang Wei
Published: July 2022

Aqueous soluble organic (ASO) redox-active materials have recently shown great promise as alternatives to transition metal ions to be employed as energy-bearing active materials in redox flow batteries for large-scale energy storage because of their structural tunability, cost-effectiveness, availability, and safety features. Development so far however has been limited to a small palette of organics that are aqueous soluble. How to quickly identify and design organic molecules for the targeted properties became a critical challenge in accelerating the aqueous organic flow battery development.

In this presentation, a data-driven material design process is discussed. This process incorporates database building, machine learning modeling for properties prediction, and the subsequent material synthesis and testing. Examples including Fluorenone and Phenizane derivative development for the flow battery application will be discussed.

Reference: Feng et al., Science 372, 836–840 (2021)
Suppression of Dendrite Formation with Porous and Conductive Carbon on Anode for Aqueous Zinc-Ion Hybrid Capacitors
Authors: Su Tzu-Chi , Chen Han-Yi
Published: July 2022

Electrochemical energy storage systems with high power and energy density have been drawing attention with the increasing demand for electric vehicles and portable electronics. However, rechargeable nonaqueous lithium-based energy storage system, which is the most widely-used type, is still limited with unsafety, resulting from its toxic organic electrolyte and flammability. Hence, zinc has been considered a strong candidate in rechargeable aqueous energy storage systems. With high theoretical capacity (823 mAh g−1) and low operating potential (−0.76 V vs. standard hydrogen electrode), Zinc-ion batteries show the highest energy density among all aqueous batteries at low cost. Moreover, to improve the low power density and short cycle life for batteries, Zinc-ion hybrid capacitors (ZICs) are introduced by combining the characterizations of both battery and supercapacitor.

Despite the advantages of ZICs mentioned above, the instability during the charging and discharging process are unneglectable. Formation of dendrites due to uneven zinc electrostripping and electroplating process on zinc metal anode can cause internal short-circuit after they penetrate the separators of the batteries. Hydrogen generation also results in low Columbic efficiency. To enhance electrochemically stability for zinc metal anode, a zinc anode modification with porous reduced graphene oxide (rGO) is reported.

Electrostatic Spray Deposition (ESD) is a technique through which liquid droplets of a precursor solution are accelerated by a high DC voltage to form aerosol and deposit on the heated substrate. By coating rGO with ESD on zinc anode, the study of how the morphology of coating affects the electrostripping and electroplating process can be discussed in detail. The modified materials were examined by scanning electron microscopy and electrochemical active surface area. The porous rGO coated zinc anode shows small voltage polarization and long cycle life. With porous rGO coated zinc anode, the charge distribution on the electrode can be optimized, and the porous structure can guide pathways for zinc ions. Furthermore, the zinc deposition is much uniform than bare zinc during cycling, which can be observed in several operando techniques, including transmission X-ray microscopy and optical microscopy.
Cation-Modified Anionic Redox Mechanism for High-Performance Layered Oxide As Sodium-Ion Batteries Cathode Material
Authors: Kang Jin-Wei , Chen Han-Yi
Published: July 2022

Sodium-ion batteries (NIBs) have been selected as a promising candidate for large-scale energy storage systems due to their abundance. Among several NIB cathode materials, P2-type transition metal layered oxides (NaxTMO2, TM = Ti, V, Cr, Mn, Fe, Co, Ni) featuring high theoretical capacity and better rate performance have attracted much attention. However, the practical applications have to endure the low energy density of NIB cathode materials compared to lithium-ion batteries. In tradition, the capacity is constrained by transition metal ions and is closed to their limits. Hence,in order to obtain extraordinarily high capacity in cathode materials, both anionic and cationic redox chemistry are utilized. Nevertheless, their performance is impeded by irreversible structure evolution and lattice oxygen emission. Therefore, it is highly urgent to develop stable anionic redox chemistry for high energy density and long-cycle-life layered oxide cathode materials.

In this study, cation-doped NaxMgyCuzMn(1−y−z)O2 cathode material featuring synergistic effects of cationic and anionic redox was reported. By cations doping, the inhibited structure evolution and lattice oxygen stabilization were achieved. Moreover, the effects of cation-doped NaxMgyCuzMn(1−y−z)O2 were also studied by electrochemical measurements. Also, the mechanism of cation-doped NaxMgyCuzMn(1−y−z)O2 was confirmed by operando synchrotron X-ray absorption spectrum, operando X-ray diffraction, and density functional theory computations. Cation-doped NaxMgyCuzMn(1−y−z)O2 was synthesized through a facile sol-gel method followed by heat treatment. The cation-doped NaxMgyCuzMn(1−y−z)O2 showed high specific capacity (203 mAh g−
1 cycled at 0.1C) as well as better cycling stability, providing sodium layered oxides a new developing stage toward high-performance cathode materials in NIBs for large scale energy storage systems.

Keywords: Na-ion batteries, layered oxides, anionic redox, cathode
Development of High-Performance Electrode Materials for Supercapacitor Application through Combinatorial Electrodeposition
Authors: Singh Harish , Nath Manashi , Hines McKenzie Marley
Published: July 2022

Electrochemical capacitors (ECs) are promising energy storage devices that have received great attention because of their excellent electrochemical performance with high output power, short discharging time, and long-term cycle stability. Metal chalcogenides (especially selenides and tellurides) are considered to be a new class of battery-like electrode materials and have contributed to ameliorate the electrochemical performance with better electronic conductivity and chemical stability. In the current investigation, a series of mixed transition metal-based chalcogenides have been grown directly on nickel foam by electrodeposition without the addition of a binder to the electrode composite. It was observed that the supercapacitor activity was dependent on the quantity of Cu and Co in the Cu-Co-Se ternary selenide electrocatalysts. Surprisingly, Cu–Co ternary selenides exhibit superior specific capacitance in comparison to their pure parent compounds, CoSe and Cu3Se2. Among the series of Cu–Co ternary selenides, the specific capacitance achieved for Cu0.6Co0.4Se2 showed the best specific capacitance value of 2063 F/g at a current density of 1 A/g and also maintained a cyclic stability of more than 90 % at a higher current density of 10 A/g after 1000 charge-discharge cycles. Moreover, doping effects at the transition metal site are also illustrated in this work and had a positive influence on the supercapacitor activity because, it led to lattice distortion, electronic structure modification, as well as helping to tune the surface redox behavior. The observed results clearly demonstrate that the binder free metal chalcogenide-based catalysts may be used as a potential electrode material for future energy storage devices.

Figure 1
In Situ Stress Generation during Oxygen Evolution and Reduction Reactions on Au Positive Electrode in Li-O2 Batteries
Authors: Dykes Hannah , Ozdogru Bertan , Capraz Omer Ozgur Özgür
Published: July 2022

Li-O2 batteries have received enormous interest from the scientific community due to its extremely high theoretical specific energy density, which is originated from the oxygen reduction reactions during discharge at the surface of the cathode electrode. Unfortunately, the commercial implementation of this technology is hindered by the poor cycling performance, mostly due to the sluggish oxygen evolution/reduction kinetics and the nature of the discharge reaction product. The lithium peroxide (Li2O2) is the discharge reaction product and its insulating nature limits to harvest the theoretical capacity of the Li-O2 batteries practically. The impact of the salt and solvent species on the formation mechanisms of the discharge product has been reported widely. However, underlying mechanisms dictating the reaction pathway is still under debate.

In this study, we employed in situ stress measurement to investigate the impact of the electrolyte salt on nanoscale dynamic changes on the surface of the thin Au film cathode (1-D) during charge / discharge of Li-O2 batteries. Stress measurements have been applied to various electrochemical and electrocatalytic application areas in order to probe the dynamic changes on the surface of the materials. The electrolyte was prepared by mixing 1 M LiTFSI or LiNO3 salts in DMSO or Diglyme solvents. Electrolytes were saturated either with oxygen or argon prior to performing electrochemical measurements. In situ stress measurements were conducted using a multiple beam optical sensor (MOS). A custom cell was designed to monitor the physical response of the cathode during cycling while enabling optical access to the back of the substrate for stress measurements1. In situ curvature evolution on Au thin film cathode was monitored during discharge and charge via galvanostatic cycling and cycling voltammetry.

In this talk, we will present the impact of the electrolyte salt on the potential-dependent surface stress generation during the formation and oxidation of electrochemical redox reaction products at nanoscale on the Au thin film cathode. Shortly, in situ stress measurements pointed out the contribution of charge-induced stress, electrostriction stress, and intrinsic stress associated with the formation of discharge reaction products. Revealing the mechanical response of the discharge products on cathode electrode will shed light into the formation mechanisms of these products, which is crucial to design new electrolyte and cathodes for Li-O2 batteries.

Acknowledgement:

This work was supported by the Binational Science Foundation (#2018327), and we are thankful to both Dr. Malachi Noked and Rosy for fruitful discussions.

References:

Dykes, H., . R., Sharon, D., Noked, M. & Capraz, O. O. In Situ Stress Measurements on Thin Film Au Positive Electrode during the First Discharge of Li-O2 Batteries. J. Electrochem. Soc. (2021). doi:10.1149/1945-7111/AC3937
Thin Nasicon Sodium-Ions Solid State Electrolyte By Tape Casting Method
Authors: Oh Jin An Sam , Zeng Zhihan , Lu Li
Published: July 2022

In recent years, sodium ion batteries have shown its potential to compliment lithium ion batteries, especially in stationary energy storage system. Additionally, all-solid-state battery is perceived as the holy-grail battery. While numerous research efforts have been devoted to the search of solid-state materials with high ionic conductivity, it is paramount to reduce the thickness of the electrolyte to achieve a high energy density. In this study, the NASICON electrolyte is prepared by tape casting method and its thickness is controlled by the scrapper height during casting. It is realised that the areal specific resistance of the electrolyte is proportional to the thickness of the electrolyte and the 60 μm thick electrolyte shows an extremely low resistance of 42.7 Ω cm2. More importantly, such process is highly repeatable for large-scale production of thin freestanding solid-state electrolyte, which can be used in conventional bulk battery, redox-flow batteries, or metal-air batteries.
(Digital Presentation) Higher Surface Area Lithium Anode for Mediated Lithium-Sulfur Flow Batteries
Authors: Meyerson Melissa L , Small Leo J.
Published: July 2022

There is a need for safe, reliable, high capacity storage for long duration energy storage. The low cost and high capacity of sulfur make Li-S batteries ideal for this purpose. However, sulfur has poor electrical conductivity and Li-S batteries are prone to polysulfide shuttling that decreases the battery life. Additionally, lithium metal cannot be cycled at high rates or dendritic growth is produced. We have previously addressed the issues with the S by combining aspects of a static Li-S battery with aspects of a redox targeting system and flow battery. With this system we demonstrated that fundamental Li-S chemistry and novel SEI engineering strategies can be adapted to the hybrid redox flow battery architecture, obviating the need for ion-selective membranes or flowing carbon additives, and offering a potential pathway for inexpensive, scalable, safe MWh scale Li-S energy storage.

However, with a planar Li anode the current density was limited to 0.5 mA cm-2, severely limiting the flow battery power output. In this study we present recent progress developing higher surface area anodes to enhance the rate performance of Li metal anodes in flow batteries. The high effective surface area of these structures decreases the local current density while maintaining a high device-level current and thus charge rate. The low local current density and seeded nucleation points on the scaffold promote uniform Li deposition during charging. Candidate electrode materials are evaluated in a mediated Li-S flow battery and cycling rate and capacity retention are compared against a traditional planar Li anode.

Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
OH- Conductivity and Water Uptake of Anion Exchange Thin Films Under Humidity Control
Authors: Nagao Yuki , Wang Fangfang , Wang Dongjin
Published: July 2022

Anion exchange membrane fuel cells (AEMFCs) have attracted widespread attention because of the lower cost of using non-precious metal catalysts and high oxygen reduction reaction (ORR) kinetics in alkaline conditions.[1] The previous research focused on the water uptake and OH- conduction properties of anion exchange membranes (AEMs) as thick forms.[2–5] The fuel cell reaction occurs at the triple-phase interface where the junction of ion-conductive ionomer, catalyst, and fuel/oxidant. The ionomer plays an important role to deliver OH- ion between the thick membrane andto electrochemical catalysts in fuel cells. However, the investigation of OH- ion conduction and hydration properties of thin ionomers is important but not sufficient.

This work demonstrated the relations between OH- conductivity and water uptake of anion exchange thin films for the first time.[6] The reported poly[(9,9-bis(6′-(N,N,N-trimethylammonium)-hexyl)-9H-fluorene)-alt-(1,4-benzene)] (PFB+)[6] was synthesized as a model ionomer. We established in situ methods for measuring OH- conductivity and water uptake of anion exchange thin films[7] because OH- ion easily exchanges for carbon dioxide in the air. The OH- conductivity of 273 nm-thick PFB+ thin film form at 25 °C under 95 % relative humidity (RH) is comparable to the reported OH- conductivity value of PFB+ bulk membrane. Reduced OH- conductivity and water uptake were observed in 30 nm-thick PFB+ film compared to thicker 273 nm-thick PFB+ film. This reduced OH- conductivity was caused by the decreased number of water molecules contained in thinner PFB+ films. Under the same number of water molecules contained, similar OH- conductivity results can be obtained for both 273 and 30 nm-thick films as shown in Figure. Results show a different trend compared to the case of the proton conductive thin films.[8]

References

[1] G. Merle, M. Wessling, K. Nijmeijer, J. Memb. Sci.
2011, 377, 1–35.

[2] J. Y. Jeon, S. Park, J. Han, S. Maurya, A. D. Mohanty, D. Tian, N. Saikia, M. A. Hickner, C. Y. Ryu, M. E. Tuckerman, S. J. Paddison, Y. S. Kim, C. Bae, Macromolecules
2019, 52, 2139–2147.

[3] J. Chen, M. Guan, K. Li, S. Tang, ACS Appl. Mater. Interfaces
2020, 12, 15138–15144.

[4] U. Salma, Y. Nagao, Polym. Degrad. Stab.
2020, 179, 109299.

[5] C. G. Arges, L. Zhang, ACS Appl. Energy Mater.
2018, 1, 2991–3012.

[6] W. H. Lee, A. D. Mohanty, C. Bae, ACS Macro Lett.
2015, 4, 453–457.

[7] F. Wang, D. Wang, Y. Nagao, ChemSusChem
2021, 14, 2694–2697.

[8] Y. Nagao, Sci. Tech. Adv. Mater. 2020, 21, 79–91.

Figure 1
Novel Anion-Exchange Blend Membranes Comprised of a Commercially Available & Water-Soluble Ionomer for All-Vanadium Redox Flow Batteries
Authors: Stonawski Julian , Thiele Simon , Kerres Jochen Alfred
Published: July 2022

The All-Vanadium Redox Flow Battery is a promising technology for solving the problem of cost-efficient and safe large-scale storage of renewable energies [1]. One key component of the batteries, which alters the performance and long-term stability of those systems, is the membrane. For this purpose, Nafion based membranes are often used. However, these membranes are high in cost and show a significant capacity fading and reduction of coulombic efficiency mainly due to crossover of vanadium species [2]. One way around this is to use commercially available, low-cost materials with positively charged ammonium groups, which can effectively repel positively charged vanadium species due to the Donnan exclusion effect [3, 4].

In this work we present novel anion-exchange blend membranes comprised of a commercially available and water-soluble ionomer and a PBI blend matrix, which can be used in All-Vanadium Redox Flow batteries. For this approach the water-soluble ionomer was modified to achieve solubility in organic solvents and miscibility with the matrix polymer. The resulting membranes show good mechanical properties even at high IECs and can be modified in a wide range of properties by adjusting the amounts of ionomer and matrix polymer and/or by the addition of crosslinking agents.

The above-mentioned membranes were characterised ex-situ by using EIS, NMR spectroscopy, IR spectroscopy, DMA, TGA, tensile tests and permeability tests. In addition, first promising in-situ characterisations were performed in a VRFB single-cell test station.

Literature

[1] Fan, X; Liu, B; Liu, J; Ding, J; Han, X; Deng, Y; Lv, X; Xie, Y; Chen, B; Hu, W; Zhong, C.: Battery Technologies for Grid-Level Large-Scale Electrical Energy Storage. Trans. Tianjin Univ.
2020, 92 – 103.

[2] Düerkop, D; Widdecke, H; Schilde, C; Kunz, U; Schmiemann, A.: Polymer Membranes for All-Vanadium Redox Flow Batteries: A Review. Membranes
2021.

[3] Xi, J; Wu, Z; Teng, X; Zhao, Y; Chen, L; Qiu, X.: Self-assembled polyelectrolyte multilayer modified Nafion membrane with suppressed vanadium ion crossover for vanadium redox flow batteries. J. Mater. Chem.
2008, 1232.

[4] Mohammadi, T; Kazacos, M.: Modification of anion-exchange membranes for vanadium redox flow battery applications. Journal of Power Sources
1996, 179 – 186.
Novel Sulfonated and Phosphonated Ionomers and Ionomer (blend) Membranes for Electrochemical Applications
Authors: Martschin Philipp , Thiele Simon , Kerres Jochen Alfred
Published: July 2022

The heart of a HT-PEM fuel cell is represented by the proton conductive membrane. Nowadays PFSA-based materials e.g. Nafion are state of the art in large scale energy applications. However, the PFSAs are relatively expensive, and give rise to concerns regarding toxic intermediates in the production process, and the questionability of their recyclability. This leads to a strong need for development of cost effective alternatives. Such alternatives have to exihibit customized properties, like reduced gas crossover, high ionic conductivity, mechanical strength, thermal stability and durability.

In this work, we present novel cation-exchange ionomers, which are suitable as proton exchange membranes in electrochemical applications such as fuel cells, electrolysers, and redox-flow batteries. For our approach we developed novel fully and partially aromatic polymers with customized mechanical behavior, using two different synthetic pathways, the first being modification of the aromatic building blocks to more flexible ones and/or introduction of flexible side chains into the monomers or polymers.

With these two approaches it was possible to synthesize ionomer materials which are less brittle than our earlier developed sulfonated[1] or phosphonated[2] poly(pentafluorostyrene) ionomers. Our development lead to ionomers which are suitable in pure form or as blend in proton exchange membranes with promising proton conductivity, mechanical and thermal stability.

The novel ionomers and ionomer membranes were characterized in terms of ex-situ characterization including impedance spectroscopy, IR spectroscopy, NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Moreover, preliminary in-situ tests of the ionomer membranes in low and high-temperature fuel cells have been performed, yielding promising results. Furthermore the synthesized membranes were characterized in-situ in redox-flow batteries, yielding promising results.

[1] Highly phosphonated polypentafluorostyrene. V. Atanasov, J. Kerres, Macromolecules 2011, 44, 6416–6423; DOI: 10.1021/ma2011574

[2] Sulfonated poly(pentafluorostyrene): synthesis & characterization. V. Atanasov, M. Bürger, S. Lyonnard, G. Gebel, J. Kerres, Solid State Ionics, 2013, 252, 75-83; DOI: 10.1016/j.ssi.2013.06.010
Tuning Electrode-Membrane Interface for Highly Efficient Polymer Electrolyte Membrane Fuel Cells
Authors: Yang Gaoqiang , Lee ChungHyuk , Komini Babu Siddharth , Martinez Ulises , Wang Xiaojing , Spendelow Jacob S.
Published: July 2022

Polymer electrolyte membrane fuel cells (PEMFCs) are typically comprised of porous electrodes with randomly distributed mixtures of Pt/C catalyst and ionomer formed during the ink deposition process. The randomness of catalyst particles, ionomer films, and voids, create a non-ideal disordered electrode structure with high tortuosity. These intrinsic characteristics of conventional electrodes create significant challenges during PEMFC operation. These challenges include: 1) low catalyst utilization; 2) high O2 transport resistance to catalyst through the ionomer and pores of carbon support; and 3) limited electronic/protonic conductivities. To improve the performance of the PEMFC electrode, we have previously shown that structured electrodes based on a patterned membrane surface can increase the interfacial area between the electrode and the membrane, enhancing mass transport at high current densities, and augmenting its ionic conductivity.[1][2] In this work, we will present further optimization of these type of structured electrodes using free-standing architectures, reduced ionomer content, and new catalyst deposition processes. More importantly, these newly tuned electrode structures can improve the performance of PEMFCs by maximizing three-phase boundaries and optimizing the electron, proton, gas, and water transport paths.

Acknowledgement:

We gratefully acknowledge support from the Laboratory Directed Research & Development Program at Los Alamos National Laboratory.

Reference:

[1] S. K. Babu, R. Mukundan, D. A. Cullen, and J. S. Spendelow, “Co-Axial Nafion Nanowire Electrode.” ECS, Oct. 15, 2019.

[2] S. K. Babu, J. S. Spendelow, and R. L. Borup, “Meso-Structured Array Electrode for Polymer Electrolyte Fuel Cells.” ECS, Oct. 03, 2017.
Fabrication and Scale-up of Highly Durable Heavy Duty Fuel Cell MEAs
Authors: Macauley Natalia , Zhong Sichen , Zeng Yachao , Zhang Bingzhang , Wu Gang , Xu Hui
Published: July 2022

Medium and heavy-duty PEM fuel cells operate under much harsher conditions than light duty fuel cells and are expected to last 25,000 hours in the field. These systems must therefore operate successfully in the presence of impurities, starting and stopping, freezing and thawing, humidity and load cycling. Therefore, materials, components, and interfaces used in such systems need to be highly resistant to severe mechanical and chemical stress.

Novel, highly active stable Pt and ordered PtCo intermetallic nanoparticles with well-controlled particle size and composition have been synthesized on a highly efficient PGM-free single metal active site rich carbon, to maximize their synergistic effects for enhanced performance and durability. These catalysts were integrated with a variety of ionomers (Aquivion, Nafion, HOPI and high O2 permeability ionomer (HOPI)) to further improve fuel cell performance and to achieve >600 mA/mgPt at 0.9 VIR-free with a mass activity loss less than 30% after 150k square wave accelerated durability cycles; and > 600 mA/cm2 (~65% efficiency) at 0.8 V, with a performance loss < 40 mV after 150K cycles (0.6 to 0.95 V).

In a PEM fuel cell, the catalyst ink formulation and mixing processes control catalyst layer coating quality, electrode morphology, and the resulting fuel cell performance and durability. Catalyst ink properties are a result of complex solvent-catalyst-ionomer interactions that depend on the mixing method employed. Here, we will compare the performance and durability of electrodes made from bath sonicated inks for ultrasonic spray coating vs. ball milled inks for Meyer rod coating. Ink rheology and catalyst particle size will be used to correlate ink properties to electrode morphology and structure and ensure consistency from batch to batch, and from small lab scale to subsequent scale-up. We will evaluate and discuss the challenges that arise when transitioning from spray coating catalyst ink on a small scale, directly on a membrane, to coating more viscous inks on gas diffusion layers (GDLs), and finally developing a roll-to-roll (R2R) fabrication process. The MEA performance and durability of the novel catalyst will be evaluated under heavy duty operating conditions. Finally, the electrode performance and durability of R2R fabricated GDEs will be tested, and compared to small scale GDEs made at Giner.

This work provides a comprehensive understanding of interactions between Pt, PtCo, carbon, ionomer, membrane, and GDLs and their impact on electrode structure, fuel cell performance and durability, as well as considerations for scale up to a R2R fabrication process. The attained information will be used to improve fuel cell electrode design, fabrication and scale-up.

Acknowledgement: The project is financially supported by the Department of Energy’s Fuel Cell Technology Office under the Grant DE-FOA-0002360.
(Energy Technology Division Graduate Student Award sponsored by BioLogic) Design Principles for High-performance and Durable Anion Exchange Membrane water Electrolyzers
Authors: Lindquist Grace , Krivina Raina A , Beaudoin Sarah , Stovall Nathan , Boettcher Shannon W.
Published: July 2022

Water electrolysis powered by renewable sources such as wind or solar produces clean hydrogen gas, which is used for many industrial processes and will be essential in a future clean energy economy. Alkaline water electrolysis (AWE) and proton exchange membrane (PEM) electrolysis are mature technologies at megawatt to gigawatt scale. AWE uses earth abundant electrode and catalyst materials submerged in caustic liquid electrolyte (usually KOH or NaOH) separated by a porous diaphragm. This configuration can suffer from gas crossover and shunt current limitations. PEM electrolyzers circumvent these barriers by using an ionically-conductive solid electrolyte membrane that reduces gas crossover and allows for pure water operation that eliminates shunt currents. However, these membranes create a locally acidic environment that necessitates the use of expensive platinum-group-metal (PGM) catalyst materials and hardware coatings. Anion exchange membrane (AEM) electrolysis is an emerging technology that has the potential to combine the benefits of liquid alkaline and PEM. AEM electrolyzers use an anion-selective membrane, maintaining the pure water operation of PEM but creating a locally-alkaline environment allowing for the use of non-PGM materials. However, AEM electrolysis is still immature. In particular, the hydroxide-conducting membrane and ionomer have not yet achieved sufficient stability in pure water to compete with PEM systems. The specific dominant degradation mechanism and location has also not been conclusively identified. Further, while non-PGM catalysts such as Ni- and Fe-based oxyhydroxide catalysts out-compete PGM catalysts in three-electrode KOH studies, this performance does not carry to the pure water electrolyzer configuration. In my talk I report AEM electrolyzer performance below 2 V at 1 A·cm-2 in pure water for both PGM and non-PGM anode catalysts. I will also discuss the specific degradation mechanism of the ionomer and membrane during electrolyzer operation with both catalysts. Understanding the differences in performance and durability with precious metal and earth abundant materials is key for AEMs to compete with current electrolyzer technologies. I compare the performance and stability of five Ni-, Co-, and Fe-based catalysts and compare to IrOx. XPS and cross-sectional SEM data show oxidation of the ionomer binder at the anode for all catalysts, which results in significant degradation and performance loss. I also show additional degradation is induced by introducing soluble Fe species, indicating separate mechanisms beyond ionomer degradation are present in the non-PGM systems. In addition to the fundamental insights into the dynamic behavior of non-PGM catalysts and oxidative durability of ionomeric polymer materials, these findings contribute to bringing low-cost AEM electrolyzer technology to scale.

Figure 1
A Systematic Investigation of Carbon Pretreatment for the Synthesis of Platinum Nano-Catalysts for Oxygen Reduction Reaction
Authors: Buchauer Fabian Luca , Cleemann Lars , Jensen Jens Oluf , Li Qingfeng , Brandes Benedikt Axel
Published: July 2022

The synthesis of electrocatalysts for low- and high temperature fuel cells is dependent on many different factors that determine the activity of the produced catalysts. One important and highly underrepresented factor in literature are carbon pretreatments, which have a strong impact on the electrochemical activity of the produced catalyst. A web of science search showed that less than 1% of the articles working with the synthesis of Pt-based catalysts for the Oxygen reduction reaction (ORR) contain information on carbon pretreatments. In recent years no articles on the topic of carbon pretreatment for the synthesis of Pt-based ORR catalyst have been published.

However, different forms (as powder, nano tubes, etc.) of carbon are commonly used as support material for Pt-based catalysts. Previous work has shown the importance of pretreatment of carbon supports to change the surface-active groups, enhancing the dispersion and reducing agglomeration of Pt-nanoparticles [1]. Oxidizing treatments are known to change the surface groups and decreasing the BET surface area [2]. Furthermore, carbon pretreatments can effectively reduce impurities present in as-purchased carbon [3].

A systematic study of pretreatments of Vulcan XC72-R and Ketjen 300 have been carried out followed by the synthesis of supported Pt-nanoparticles using XPS, XRD, TEM, BET and RDE techniques. We found that the presence of sulfur in the surface strongly correlates with the ECSA of the supported Pt catalyst. This talk will elaborate on the effect of pretreatments on the carbon support, the synthesis of Pt nanoparticles and its impact on the resulting electrochemical performance: Compared to as received carbon, the Pt mass activity could be increased by a factor 4, exceeding the mass activity of comparable commercial Pt/C electrocatalysts.

[1] Bimetallic Pt–Sn catalysts supported on activated carbon I. The effects of support modification and impregnation strategy - A. Erhan Aksoylu; M. Madalena A. Freitas; Jose L. Figueiredo

[2] The effect of pretreatment of Vulcan XC-72R carbon on morphology and electrochemical oxygen reduction kinetics of supported Pd nano-particle in acidic electrolyte - Senthil Kumar, S. M.; Soler Herrero, Jaime; Irusta, Silvia; Scott, Keith

[3] Effect of the carbon pre-treatment on the properties and performance for nitrobenzene hydrogenation of Pt/C catalysts - Torres, G. C.; Jablonski, E. L.; Baronetti, G. T.; Castro, A. A.; De Miguel, S. R.; Scelza, O. A.; Blanco, M. D.; Peña Jiménez, M. A.; Fierro, J. L.G.

Figure 1
Highly Active TAL2 and TAL4 Metal-Organic Framework Derived Bifunctional Oxygen Electrocatalyst
Authors: Yusibova Gulnara , Assafrei Jurgen-Martin , Aruväli Jaan , Käärik Maike , Paiste Päärn , Leis Jaan , Starkov Pavel , Kongi Nadezda
Published: July 2022

The development of green energy conversion technologies and sophisticated energy storage devices are crucial for a sustainable future. Currently, metal-air batteries and fuel cells promise cost-effective, efficient and clean operation. However, highly active bifunctional noble-metal-free catalyst materials are needed to boost sluggish kinetics of oxygen electrode reactions for replacing conventional benchmark catalysts (Pt/C; RuO2/IrO2). Herein, we report highly active manganese and cobalt containing metal-organic framework (MOF)-derived bifunctional electrocatalyst with rich porous and well-dispersed structure. Mn/Co-containing material displayed excellent electrocatalytic performance toward both oxygen evolution and reduction reactions (Ej=10 =1.66 V; E1/2 = 0.85 V vs RHE, 0.1 M KOH) due to the desired active sites and architecture. Proposed bifunctional electrocatalyst was also tested in Zn-air battery setup and demonstrated outstanding durability within 10 h cycling without any noticeable degradation and great efficiency with high power density.
Cobalt Nanoparticles Supported Graphitic Carbon Nitride Electrocatalyst for Oxygen Reduction
Authors: Zabielaite Ausrine , Balciunaite Aldona , Upskuviene Daina , Vaiciuniene Jurate , Jasulaitiene Vitalija , Tamasauskaite-Tamasiunaite Loreta , Norkus Eugenijus
Published: July 2022

This study is focused on the fabrication of cobalt nanoparticles supported graphitic carbon nitride (CoNPs-g-C3N4) by microwave synthesis and their application for oxygen reduction reaction (ORR). X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) were employed to characterize the prepared catalysts. The electrocatalytic activity of CoNPs-g-C3N4 for ORR was investigated using the rotating disk electrode technique in 0.1 M KOH solution.

It has been determined that the g-C3N4, prepared by annealing melamine at a temperature of 520 oC for two h, had a high nitrogen content of 67.92 at.%. The data of the oxygen reduction on the CoNPs-g-C3N4 catalysts with different Co loadings and under various conditions are presented. Compared to the metal-free g-C3N4, the doping of g-C3N4 with CoNPs enhances the electrocatalytic activity and the selectivity towards the 4e- reduction reaction of O2 to H2O.

Acknowledgment

This project has received funding from European Social Fund (project No. 09.3.3-LMT-K-712-23-0188) under a grant agreement with the Research Council of Lithuania (LMTLT).
Designing Highly Active Nanoporous Carbon Electrocatalysts for H2O2 Production Via Active Site Elucidation
Authors: Lim June Sung , Kim Jae Hyung , Woo Jinwoo , Baek Du San , Sa Young Jin , Joo Sang Hoon
Published: July 2022

Fossil fuel-based hydrocarbon economy has invoked a serious climate change due to ever-increasing emission of CO2. In this regard, electrosynthesis has emerged as a promising route that enables the clean and continuous production of chemicals and fuels.[1] Electrochemical production of hydrogen peroxide (H2O2) via the two-electron (2e−) oxygen reduction reaction (ORR) can serve as a promising alternative for the currently prevailing anthraquinone process [1,2]. However, improving H2O2 selectivity remains one of important challenges in electrochemical H2O2 production because 2e− ORR competes with 4e− ORR, further reduction of H2O2 (2e−+2e− ORR), and H2O2 chemical disproportionation. Carbon nanomaterials have demonstrated promising performance for H2O2 production as low-cost electrocatalysts [3–5], however understanding of key structural factors and active sites is still lacking. In this work, we have prepared nanoporous carbon-based model catalysts and conducted a systematic study to identify the active oxygen functionality and carbon structure factor [6]. We have found that the carboxyl (O−C=O) groups located at the graphitic edge carbons are the major active sites for the electrosynthesis of H2O2 (Figure (a)). The best-performing carbon catalyst (O-GOMC-5.5) with abundant active oxygenated graphitic edge carbons exhibited the highest H2O2 production activity among the reported carbon-based catalysts (Figure (b)) and excellent long-term stability (168 h) with almost 100% of H2O2 faradaic efficiency.

Figure 1
CO2 Turned into a Nitrogen Doped Carbon Catalyst for the Fuel Cell and Metal-Air Battery Applications
Authors: Ratso Sander , Walke Peter Robert , Mikli Valdek , Ločs Jānis , Šmits Krišjānis , Vītola Virgīnija , Sutka Andris , Kruusenberg Ivar
Published: July 2022

Metal-free catalysts based on nitrogen-doped carbon are among the most promising replacements for Pt-based materials on polymer electrolyte membrane fuel cell (PEMFC) cathodes due to their inherent stability (lack of metal atoms bypasses most of the degradation mechanisms encountered in metal-based non-precious metal catalysts). However, the production of carbon nanostructures that have suitable oxygen reduction reaction (ORR) activities for fuel cell cathode use can create massive amounts of CO2 as a by-product, which counteracts the environmental friendliness of fuel cells. Here, we demonstrate a new method for creating ORR catalysts directly from CO2, which can produce a catalyst with a negative carbon footprint instead of a positive one. Via a fused Li-K carbonate eutectic mixture or pure Li2CO3, CO2 was split into gaseous oxygen and solid carbon, which was then doped with nitrogen using a pyrolysis process with the presence of dicyandiamide and polyvinylpyrrolidone. A thorough physico-chemical characterization of the catalyst materials is presented alongside their electrocatalytic properties for the ORR. The reasons for the properties of the resulting carbon depending on the electrolyte mixture for CO2 electrolysis and deposition temperature are explored. The best performing material had ORR activity nearing that of Pt/C, showing the potential that this method has for creating competitive catalysts while remaining environmentally benign [1].

References

Ratso, S.; Walke, P. R.; Mikli, V.; Ločs, J.; Šmits, K.; Vītola, V.; Šutka, A.; Kruusenberg, I. CO2 Turned into a Nitrogen Doped Carbon Catalyst for Fuel Cells and Metal–Air Battery Applications. Green Chem.
2021, 23 (12), 4435–4445. https://doi.org/10.1039/D1GC00659B.

Figure 1
Transformation of the Active Moiety in Fe-N-C Electrocatalyst through Invasive P-Doping for Highly Efficient Oxygen Reduction Reaction
Authors: Roh JeongHan , Cho Ara , Kim Sungjun , Lee Kug-Seung , Shin Jaewook , Bak Junu , Lee SangJae , Song DongHoon , Kim Eom-Ji , Cho Yong-Hun , Han Jeong Woo , Cho EunAe
Published: July 2022

Iron- and nitrogen-doped carbon (Fe-N-C) materials have been suggested as the most promising replacement for Pt-based catalysts in oxygen reduction reaction (ORR) owing to the FeN4 active moiety. Based on the relationship between the oxygen binding energy and the catalytic activity, Fe-N-C has very strong oxygen binding energy so that hard to desorb the final reaction intermediate of *OH. Herein, we provide for the first time an effective method of tuning the active moiety using a phosphine gas-phase treatment for Fe-N-C. Combined analyses of experimental and computational results reveal that the conventional FeN4 moiety is transformed into FeN3PO through the P-doping post-treatment. Furthermore, we propose an ORR mechanism on the unique FeN3PO moiety based on a microkinetic model, in which *OH intermediates are considered. The invasive P-doping effects on the ORR performance are also validated in both anion exchange membrane fuel cell (AEMFC) and proton exchange membrane fuel cell (PEMFC).

Figure 1