bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Recent Advances in Thermally Regenerative Batteries: A New Approach for Generating Electrical Power from Low-Grade Heat
Authors: Hall Derek M. , Cross Nicholas R. , Rochin Jose R.
Published: September 2023

Thermally regenerative flow batteries (TRBs) seek to tap into the unused terawatt-hours of low-grade heat that are currently being expelled from industrial plants and stationary power sources each year. Unlike typical flow batteries, TRBs can be recharged using thermal energy, therefore increasing grid efficiency by using an energy stream that is already widely available. This unique feature is accomplished through a thermally recoverable energy carrier that, when added or removed from an electrolyte, dramatically alters the standard electrode potential of an electrode reaction. To date, most TRBs use ammonia as the energy carrier, which lowers the standard electrode potential of their anode reaction by complexing with transition metal ions such as copper, silver, or zinc. Despite the early successes of TRBs relative to other emerging electrochemical technologies trying to harness low-grade thermal energy sources, they still lacked the energy efficiency and power densities needed to be economically viable. The first iterations of TRBs had peak power densities up to 3 mW cm-2 with competitive theoretical energy efficiencies (up to 1 %), but they suffered from extreme coulombic efficiency issues that limited realizable energy production values. Herein, we will discuss recent changes that have greatly improved the performance possible from these systems and discuss persistent challenges that remain to be solved. Coulombic inefficiencies were resolved by replacing unstable deposition-based reactions with all-aqueous alternatives that provided larger cell potentials and coulombic efficiencies for single metal and bimetallic-TRB systems. Electrolyte composition, operating temperature, and membrane transport all strongly influenced energy efficiency and power density limits from these new electrolyte chemistries. Peak power densities up to 100 mW cm-2 and theoretical energy efficiencies up to 12 % were identified through a preliminary survey of possible design choices. However, tradeoffs between attainable power density and energy efficiency limited cell performance values to a fraction of these values. Future work to better control diffusive transport without conductivity losses will be crucial for approaching theoretical battery performance limits.
Zinc-Iron Rechargeable Flow Battery with High Energy Density
Authors: Gibertini Eugenio , Magagnin Luca
Published: September 2023

In current research, electrochemical energy storage systems have gaining interest because they constitute an essential element in the development of sustainable energy technologies [1,2]. Among them, rechargeable flow batteries (RFBs) are one of the most promising technologies for the integration in grid-connected electricity, especially if combined with unpredictable and intermittent renewable energy sources, due to their high efficiency, power/energy independent sizing and room temperature operation [3]. At the moment, among all RFBs systems, the most investigated and advanced technology is the vanadium based RFB, characterized by an energy efficiency equal to 80% and energy density ranging 15-45 Wh/l [4]. However, nowadays the main bulk of research is focused on finding an economically convenient and technically competitive flow battery chemistry, able to ensure long lifetime and high energy efficiency [5,6]. In this study, a zinc-iron RFBs based on sulfate and sulfamate electrolytes will be presented, discussing the achievement of a charge density in the range 30-70 Wh/l. The combination of high energy efficiency of the Zn-Fe RFB with its ability to withstand a large number of charge/discharge cycles and the low cost, makes this battery system suitable for energy storage applications.

Alotto, M. Guarnieri, and F. Moro. Renewable and Sustainable Energy Reviews 29 (2014): 325-335.

Weber, M.M. Mench, J.P. Meyers, P.N. Ross, J.T. Gostick and Q. Liu. Journal of Applied Electrochemistry (2011), 41(10), 1137.

Kear, A.A Shah, and F.C. Walsh. International journal of energy research, (2012), 36(11), 1105-1120.

Ding, H. Zhang, X. Li, T. Liu, and F. Xing. The Journal of Physical Chemistry Letters, (2013), 4(8), 1281-1294.

C- Xie, Y. Duan, W. Xu, H. Zhang, and X Li. Angewandte Chemie International Edition, (2017) 56 (47), 14953-14957.

Selverston, R. F. Savinell, and J. S. Wainright. Journal of The Electrochemical Society 164, (2017): A1069-A1075.
High Areal-Capacity Aqueous Manganese-Based Batteries Enabled by Redox Mediators
Authors: Lei Jiafeng , Lu Yi-Chun
Published: September 2023

Aqueous manganese batteries based on deposition-dissolution of Mn2+/MnO2 reactions have aroused great attention due to their intrinsic low cost, high potential, and high energy.1, 2 However, the incomplete dissolution and exfoliated dead MnO2 would inevitably lead to capacity loss and poor cyclability at high areal capacity application.3, 4 Herein, we apply a redox mediator strategy to dissolve the accumulated MnO2 via a spontaneous chemical reaction between redox mediators iodide and MnO2.5,6 During the discharge process, the iodide (I–) could react with the residual MnO2 and be oxidized to I3
– that could be further reduced back to I– on the electrode, continuing this process until fully dissolved the accumulated MnO2. We will discuss detailed reaction mechanisms verified by ex-situ UV-vis spectroscopy, scanning electron microscopy, and X-ray diffraction. The zinc-manganese (Zn-Mn) battery with iodide mediator showed improved cycling stability at 2.5 mAh cm–2 (400 vs. 100 cycles, static mode) and 15 mAh cm–2 (225 vs. 60 cycles, flow mode). Areal capacity is one of the most important parameters determining system energy for deposition-based batteries.7 The Zn-Mn flow cell could demonstrate a high areal capacity application at 50 mAh cm–2 for 50 cycles. We will discuss how to expand this strategy to other manganese-based batteries and broaden the horizon of aqueous batteries.

Acknowledgment

This work is supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China (project no. C1002-21G).

Reference

W. Chen, G. Li, A. Pei, Y. Li, L. Liao, H. Wang, J. Wan, Z. Liang, G. Chen, H. Zhang, J. Wang and Y. Cui, Nat. Energy, 2018, 3, 428-435.

D. Chao, W. Zhou, C. Ye, Q. Zhang, Y. Chen, L. Gu, K. Davey and S.-Z. Qiao, Angew. Chem. Int. Ed. Engl., 2019, 58, 7823-7828.

C. Liu, X. Chi, Q. Han and Y. Liu, Adv. Energy Mater., 2020, 10, 1903589.

G. Liang, F. Mo, H. Li, Z. Tang, Z. Liu, D. Wang, Q. Yang, L. Ma and C. Zhi, Adv. Energy Mater., 2019, 9, 1901838.

J. Lei, Y. Yao, Z. Wang and Y.-C. Lu, Energy Environ. Sci., 2021, 14, 4418-4426.

J. Lei, Y. Yao, Y. Huang and Y.-C. Lu, ACS Energy Letters, 2022, DOI: 10.1021/acsenergylett.2c02524, 429-435.

Y. Yao, J. Lei, Y. Shi, F. Ai and Y.-C. Lu, Nat. Energy, 2021, 6 (6), 582–588.
(Invited) New Membranes for Preventing Crossover in Non-Aqueous Redox Flow Batteries
Authors: Minteer Shelley D.
Published: September 2023

Non-aqueous redox flow batteries have been considered as an alternative battery technology for grid storage due to the ability to operate at higher potentials with organic solvents. However, there are no commercial ion exchange membranes capable to handling these non-aqueous redox flow batteries, because they swell or degrade over time. This paper will discuss strategies for synthesizing stable anion exchange membrane separators for non-aqueous redox flow batteries to prevent crossover and improve long term stability.
Pentablock Copolymer Membranes for Non-Aqueous Redox Flow Batteries
Authors: Lehmann Michelle , Self Ethan , Saito Tomonori , Yang Guang
Published: September 2023

Long duration energy storage devices, such as redox flow batteries, are needed to enable smart grids and widespread adoption of renewable energy sources. Sodium based electrochemical energy storage is of interest for large-scale applications due to sodium’s low cost and high abundance compared to lithium and vanadium. The membrane plays a critical role in flow batteries by providing counterion transport while separating the catholyte and anolyte. Considering that the membrane is a significant source of internal resistance and capacity fade (e.g., due to crossover) in an operating battery, developing membranes with controlled swelling, high ionic conductivity, and low active species crossover is imperative. In this work, we studied electrolyte uptake and ion transport in cation exchange pentablock copolymer membranes with sodium sulfonate and sodium trifluoromethanesulfonimide (TFSI) functionality for nonaqueous flow battery applications. The TFSI Na membranes exhibit an ionic conductivity of 7.2 x 10-5 S/cm at room temperature and a cation transport number of 0.75 in 0.5 M sodium triflate/tetraethylene glycol dimethyl ether (TEGDME) electrolyte. Methods improve the ionic conductivity and limit electrolyte uptake of the membranes, such as crosslinking will be discussed.

Acknowledgements

This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is sponsored by the U.S. Department of Energy through the Energy Storage Program in the Office of Electricity.
Comparative Testing of Li-Ion Battery Chemistries for Stationary Energy Storage
Authors: Choi Daiwon , Kim Namhyeong , Shamim Nimat , Crawford Alasdair , Viswanathan Vilayanur , Modachur Sivakumar Bhuvaneswari , Huang Qian , Thomsen Edwin , Canfield Nathan L , Reed David , Sprenkle Vincent
Published: September 2023

Li-ion batteries are the most widely deployed battery energy storage system (BESS) today but understanding the benefits and cost-effectiveness for a wide range of grid services needs to be fully validated to further expand the market. Hence, various Li-ion battery chemistries currently deployed must be evaluated and compared in terms of performance, lifecycle, economics, and safety under grid services using standardized testing protocols. In this work, commercially available cylindrical cells with four different chemistries from major Li-ion battery manufacturers are subjected to standardized tests developed by the U.S. Department of Energy Office of Electricity (DOE-OE) for frequency regulation, peak shaving, and electric vehicle drive cycles. The results of 15 months of continuous grid service tests on different chemistries are presented, analyzed, and compared in terms of capacity retention, resistance, open-circuit voltage (OCV), cyclic voltammetry (CV), incremental capacity (dQ/dV), differential voltage (dV/dQ), and AC impedance
Bipolar Radicals as Active Material for Symmetrical Redox Flow Batteries
Authors: Steen Jelte S. , Tang Wenlong , Hjelm Johan , Otten Edwin
Published: September 2023

Redox-active organic molecules are increasingly investigated as charge-storage materials for redox-flow batteries (RFBs), but material crossover between posolyte/negolyte and chemical degradation are limiting factors in the performance of all-organic RFBs. Bipolar organic radicals can in principle be used to construct batteries with symmetrical electrolyte composition, which mitigates issues due to crossover. This presentation will describe studies to correlate molecular features with battery cycling stability using representative stable organic radicals (Blatter- and verdazyl-type compounds). We illustrate how an understanding of the reaction pathways that contribute to capacity fade can be used to improve battery longevity.
High-Performance K Metal Batteries Enabled by Regulating an Electrolyte Solvation Structure
Authors: Park Jimin , Hwang Jang-Yeon
Published: September 2023

Batteries using a potassium metal (K-metal) anode are attention to a new type of low-cost and high-energy storage devices. However, the thermodynamic instability of the K-metal anode in organic electrolyte solutions causes uncontrolled growth of dendrites and parasitic reactions, which leads rapid capacity loss and low Coulombic efficiency.[1-4] In this presentation, I will introduce the advanced electrolyte using dual-salt for regulated solvation chemistry showing an improved the K-metal anode stability. Experimental and theoretical studies supported the details of solvation chemistry and results. Incorporating dual-salt into the electrolyte solution decreased the number of free solvent molecules surrounding the K+ leading to facile K+ desolvation as well as lowering the exchange current density improving the uniform K electrodeposition. Moreover, the modified electrolyte mitigates decomposition of the solvent molecules and leads to form enhanced mechanical rigidity of the SEI layer on the surface of the K–metal electrode with larger fraction of KF compound. Compared to previous studies, the K-metal anode using modified electrolyte shows long cycling stability at fast charge-discharge capability in symmetrical K | K cells. Even under high current density, the modified electrolyte ensures high areal capacity and an unprecedented lifespan with stable Coulombic efficiency for the K-metal full battery employing a sulfurized polyacrylonitrile cathode.

M. Park, Y. Jeong, M. H. Alfaruqi, Y. Liu, X. Xu, S. Xiong, M.–G. Jung, H.–G. Jung, J. Kim, J.–Y. Hwang, Y.–K. Sun. Stable Solid Electrolyte Interphase for Long–Life Potassium Metal Batteries, ACS Energy Lett. 7 (2022) 401–409.

Kim, W. Song, D.–Y. Son, L. K. One, Y. Qi. Lithium–Ion Batteries: Outlook on Present, Future, and Hybridized Technologies. J. Mater. Chem. A 7 (2019) 2942–2964.

–H. Kim, G.–T. Park, B.–K. Son, G. W. Nam, J. Liu, L.–Y. Kuo, P. Kaghazchi, C. S. Yoon, Y.–K. Sun. Heuristic Solution for Achieving Long–Term Cycle Stability for Ni–Rich Layered Cathodes at Full Depth of Discharge, Nat. Energy 5 (2020) 860.

–Y. Hwang, S.–T. Myung, Y.–K. Sun. Recent Progress in Rechargeable Potassim Batteries, Adv. Funct. Mater. 28 (2018) 1802938.
Self-Standing Porous Carbon Electrodes with Lean Electrolyte and High Areal Capacity Conditions for Rechargeable Lithium–Oxygen Batteries
Authors: Saengkaew Jittraporn , Kameda Takashi , Ono Manai , Matsuda Shoichi
Published: September 2023

Rechargeable lithium–oxygen batteries (LOBs) have the highest theoretical energy densities of all the lithium-based batteries; however, the key challenges facing them are excessing electrolyte amounts and operating at low areal capacity conditions. Thus far, few studies have investigated the performance of the LOBs under practical conditions using appropriate technological parameters. In this study, we prepared a series of carbon-black based self-standing membranes with different pore structures. The self-standing carbon membranes, which were prepared by applying a non-solvent-induced phase separation (NIPS) technique have investigated the relationship between the physicochemical properties and battery performance at low electrolyte/areal capacity ratio (E/C < 10 g/Ah) condition. As a result, the discharge capacity exhibits a clear correlation with the physicochemical property. On the other hand, the cycle number of the LOBs did not simply correlate with the total discharge capacity of the self-standing carbon electrodes. Interestingly, it is observed that the self-standing electrode mainly composed of a unique mesoporous structure exhibits superior cycle performance under small E/C conditions (E/C < 5 g/Ah). Therefore, a turbostratic morphology with a three-dimensional hexagonal array of the unique mesoporous structure is beneficial for exhibiting superior LOB performance under lean electrolyte condition (Figure 1). We believe that the results obtained in the present study give an insight into the development of a new direction for the material design of porous carbon electrodes for achieving a high LOB performance and long cycle life of practical significance.

Figure 1
Cyclic Voltammetry on Carbon in Sulphuric Acid and Its Relationship to Electrode Kinetics in Vanadium Flow Batteries
Authors: Al Hajji Safi Maria , Bourke Andrea , Buckley D. Noel , Lynch Robert P.
Published: September 2023

Demand for energy stability and balancing of electricity is growing rapidly, driven by the increased use of energy from renewable sources such as the sun, wind and ocean. Due to the intermittency and/or unpredictability of such sources, there is a growing need for energy storage solutions that allow such energy to be harvested when available and stored until needed. Redox flow batteries offer a promising solution for large-scale energy storage and several advantages over other electrical energy storage technologies. For example, their power output and energy capability can be scaled independently of one another to suit the desired application.

Among the numerous flow battery systems, vanadium flow batteries (VFBs) are the most common commercial system in operation or development worldwide.The main advantage of VFBs is that they use the same element on both sides which reduces cross-contamination problems due to mass transfer, in turn resulting in long operational lifetimes without the need for expensive system reconditioning.

In the literature, there is considerable variation in the data regarding the kinetics of vanadium reactions at carbon electrodes.1,2 We have previously1-4 reported that cathodic treatment enhances the kinetics of the positive (VIV-VV) electrode in VFBs but inhibits the kinetics of the negative (VII-VIII) electrode, while anodic treatment inhibits the kinetics of the positive electrode but enhances the kinetics of the negative electrode. Recently, we have shown evidence that cathodic treatment can also inhibit activity of the positive electrode and that anodic treatment can also inhibit activity of the negative electrode, confirming the existence of three states of carbon.1,4 In addition, we showed evidence that the activity of carbon-based electrodes depends strongly on the electrode history and in particular on the most positive and most negative potential used to treat an electrode.4

In this presentation, we will show how cyclic voltammetry of carbon electrodes in sulphuric acid (in the absence of a vanadium redox couple) varies as the electrochemical treatment of the electrode and the cyclic voltammetry window are changed. Furthermore, we will relate these cyclic voltammetry results to the enhancement and inhibition of both VII-VIII and VIV-VV kinetics at carbon electrodes that have undergone the same electrochemical treatments.

A. Bourke, M. A. Miller, R. P. Lynch, X. Gao, J. Landon, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc.
163, A5097 (2016).

A. Bourke, M. A. Miller, R. P. Lynch, J. S. Wainright, R. F. Savinell and D. N. Buckley, J. Electrochem. Soc., 162, A1547 (2015).

M. A. Miller, A. Bourke, N. Quill, J. S. Wainright, R. P. Lynch, D. N. Buckley and R. F. Savinell, J. Electrochem.
Soc., 163, A2095 (2016).

M. Al Hajji Safi, A. Bourke, D. N. Buckley, R. P. Lynch, ECS Trans., 109, 67-84 (2022).
All-Vanadium Redox Flow Battery Electrodes of Carbon Cloth Modified with Tungsten-Bismuth-Based Oxide Nanostructures for an Enhanced V(II)/(VIII) Reaction Kinetics and Inhibited H2 Evolution
Authors: Al Najjar Taher , K. Allam Nageh , El Sawy Ehab
Published: September 2023

All-vanadium redox flow batteries (VRFBs) are the most promising and highly efficient storage systems for renewable energy power plants. VRFBs can store high amounts of energy and are designed to work for long periods and their solutions can be used indefinitely.1 VRFBs are mainly carbon-based electrodes as they have high conductivity, high surface area, and high chemical stability, are relatively cheap and available,2 and can be tailored as desired for specific properties. However, these electrodes' performance is limited in their pristine form due to their resistance, hydrophobicity, and surface structure among other factors, resulting in VRFBs with a low power density. The VRFBs' low power density is usually related to the electrodes’ poor performance. Modifying the carbon electrodes using nanomaterials was proven to increase the power density of the battery. Metal oxides like tungsten oxide3 are known to enhance vanadium reactions when used as composites with carbon nanomaterials, while bismuth is known to inhabit the parasitic hydrogen evolution reaction.4 The material of the electrode and the metal molar ratio and the types of metal oxide modifiers highly affect the final performance of the carbon-based electrodes in VRFBs.

In this work, different tungsten-bismuth-based oxide nanostructures were synthesized using the hydrothermal method. It is suggested that using different metal molar ratios, pH, and metal precursors significantly affects the electrode's physical and chemical structure and hence its electrochemical performance. The synthesized BiWOx nanostructures are evaluated using XRD, SEM, FT-IR, EDS, XPS, and water contact angle measurements. The effect of using BiWOx nanostructures as a modifier for carbon cloth electrodes on the kinetics of the VRFBs negative half-cell reaction (V2+/V3+) was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy. Results showed that using BiWOx as an electrode modifier led to an increase in electrode activity and stability, with BiWOx showing the best stability and BiW2Ox showing the best activity. The enhancement effect of BiWOx nanostructures is related to the interaction between the two metal oxides and the electrode surface, the enhanced hydrophilicity of the modified electrode, and the increase of the catalytic active sites.

References:

S. Aberoumand, P. Woodfield, B. Shabani, and D. V. Dao, Phys. Rep., 881, 1–49 (2020).

J. Sun, M. Wu, H. Jiang, X. Fan, and T. Zhao, Adv. Appl. Energy, 2, 100016 (2021).

F. A. El Diwany, T. Al Najjar, N. K. Allam, and E. N. El Sawy, Sci. Rep., 12, 14348 (2022).

Z. Yang, Y. Wei, Y. Zeng, and Y. Yuan, J. Power Sources, 506, 230238 (2021).
High Performance Metal Oxide–Reduced Graphene Oxide Electrocatalyst for All Vanadium Redox Flow Batteries
Authors: Kabtamu Daniel Manaye , Bayeh Anteneh W , Ou Ying Yi , Wang Chen-Hao
Published: September 2023

Vanadium redox flow battery (VRFB) is one of the most favorable technologies for large-scale energy storage applications owing to its numerous gorgeous features, such as flexible design, high safety, and long cycle life. In this study, metal oxide (MOx)–reduced graphene oxide (rGO) nanohybrid was successfully synthesized via a facile hydrothermal route followed by annealing and employed as an electrocatalyst to modify the graphite felt (GF) electrode material for all-vanadium redox flow batteries (VRFBs) application. The as-synthesized MOx–rGO nanohybrid reveals good electrocatalytic reversibility and higher anodic and cathodic peak current density for V3+/V2+ and VO2
+/VO2+ redox couples compared with those of rGO and MOx samples. The voltage efficiency of the VRFB using MOx–rGO nanohybrid reaches 84% at 80 mA cm−2, which is 4% and 13% higher than the VRFBs using the rGO-loaded GF electrode and the pristine GF electrode, respectively. It still shows the voltage efficiencies of 76% and 70% at relatively high current densities of 120 mA cm−2 and 140 mA cm−2, respectively, but other samples have no effective discharge. This improvement is accredited to the uniform distribution of MOx nanoparticles on the rGO surfaces, avoiding the restacking of the rGO sheets and conquering nanoparticles aggregation, which might boost the effective active surface area and improve mass transport at the electrode-electrolyte interfaces. Besides, the existence of oxygen vacancies on MOx, the high electrical conductivity of rGO, and the high content of oxygen functional groups play the prodigious roles to facilitate the reversibility of vanadium ions redox reactions.
Advanced ORR Catalysts Based on Intermetallic Nanoparticles and Metal Organic Frameworks
Authors: Spendelow Jacob S. , Chen Kate , Li Kui , Wang Xiaojing , Wu Gang
Published: September 2023

Over the past decade, substantial resources have been devoted to developing proton exchange membrane fuel cells (PEMFCs). The high cost and insufficient durability of oxygen reduction reaction (ORR) catalysts are the main factors delaying the commercialization of high-efficiency fuel cells. Development of new catalysts with enhanced activity and durability would have a transformative effect on fuel cells and related energy devices. Catalyst design for ORR requires creation of catalytic sites with high ORR activity, but these sites must also have good accessibility for transport of reactants (oxygen, protons, electrons) and products (water). They must also have high durability, with lifetimes of up to 30,000 hours required for heavy duty vehicle applications. The most successful ORR catalysts for PEMFCs are PtM/C, i.e., nanoparticles of Pt alloys with a base metal (e.g., Co, Ni) dispersed on a nanostructured carbon catalyst support. Tuning properties of both the PtM nanoparticles and the C support is necessary to achieve high performance and durability. In recent years, intermetallic PtM nanoparticles in which Pt and M occupy distinct sites in a highly ordered structure have emerged as a leading candidate for PEMFC applications. However, development of nanostructured carbon supports with improved control of morphology and pore properties is needed to fully reap the benefits of advanced intermetallic nanoparticle catalysts. Herein, we report recent advances in development of both intermetallic PtM nanoparticles and nanostructured carbon supports with controlled morphology and pore seize distribution. By combining novel nanostructured materials synthesis with advanced characterization and fuel cell testing, we demonstrate a path to produce highly active catalysts with sufficient durability to meet the challenging requirements of heavy duty trucking applications.
Insights into the Structure - Composition - Activity Relationship of PtCo Alloy Nanoparticles towards Oxygen Reduction Reaction (ORR)
Authors: Janssen Marek , Klein Jochen , Dworzak Alexandra , Blaseio Sonja , Oezaslan Mehtap
Published: September 2023

PtCo alloy nanoparticles (NPs) are widely used as highly active oxygen reduction reaction (ORR) catalysts for polymer electrolyte membrane fuel cells (PEMFCs). Despite large efforts, the critical relationships between structure, composition and ORR performance of catalyst materials are not fully understood to date. In this study, we prepared two PtCo alloy NP catalysts with an atomic ratio of 1:1 using wet-impregnation route by varying the annealing parameters under reductive conditions. The as-prepared PtCo alloy catalysts were structurally characterized using ex-situ HR-TEM, EDX, XRD, and EXAFS. We show that the annealing temperature and holding time affect the particle size, composition and homogeneity of the PtCo NPs. With higher annealing temperature and longer holding time, the particle size grows from 3.1 ± 0.7 nm (400 °C, 4 h) to 4.4 ± 0.6 nm (800 °C, 6 h) and simultaneously, the alloy formation within the NPs improves. After electrochemical activation in 0.1 M HClO4, the electrochemically active Pt surface area (ECSA) for activated PtCo T400 (65 ± 8 m2 gPt
-1) is slightly lower than that for pure Pt/C (70 ± 11 m2 gPt
-1), but significantly higher than that for the activated PtCo T800 (50 ± 4 m2 gPt
-1). However, the activated PtCo T800 shows the highest ORR mass activity (0.56 ± 0.14 A mgPt
-1 at 0.9 VRHE, iR-free) than the activated PtCo T400 (0.43 ± 0.03 A mgPt
-1) and Pt/C (0.24 ± 0.04 A mgPt
-1). Altogether, we provide deeper understanding of the structure - composition - ORR activity relationships for two differently annealed PtCo alloy catalyst materials.
High-Performance Bimetallic Mo/Ni-N-C Electrocatalyst for Efficient Oxygen Evolution Reaction
Authors: Yusibova Gulnara , Kongi Nadezda
Published: September 2023

The oxygen evolution reaction (OER) is a crucial process in a variety of energy-related technologies, including water splitting and electrochemical conversion. Despite significant progress in the development of OER catalysts, there is still a need for more efficient and cost-effective materials. M-N-C (metal-nitrogen-carbon) materials appear as efficient, low-cost, and sustainable alternatives for the oxygen evolution reaction (OER).

In this work, we have synthesized bimetallic Mo/Ni-C catalysts using shungite carbon codoped with nitrogen, molybdenum, and nickel precursors and characterized their physical and chemical properties using a variety of techniques, including X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Due to their highly porous structure along with the high concentration of active sites these catalysts exhibit excellent activity and stability for the OER, with low overpotentials.

Overall, our work highlights the potential of bimetallic Mo/Ni-N-C catalysts as efficient and cost-effective alternatives to noble-metal-based catalysts for the OER with significant implications in renewable energy technologies.
(Invited) Textile Composite Electrodes for Wearable Batteries and Beyond
Authors: Zheng Zijian
Published: September 2023

Wearable energy storage devices are indispensable corner stones for future wearable electronics. Current energy storage technologies are based on materials and devices that are rigid, bulky, and heavy, making them difficult to wear. On the other hand, fibers are flexible and lightweight materials that can be assembled into different textiles and have been worn by human beings thousands of years. Different from conventional two-dimensional thin films and foils, the three-dimensional fibre and textile structures not only provide superior wearing ability, but also much larger surface areas. This talk will introduce how our research group makes use of the attributes of fibres for high-performance wearable energy storage devices. We will demonstrate the strategies and discuss the perspectives to modify fibers and textiles for making wearable capacitators and batteries with excellent mechanical durability, electrochemical stability, and high energy/power density. We will also show that the fibrous materials can significantly enhance the stability and energy density of battery for wearable applications and others such as Na battery.

References

[1] Q. Huang, D. Wang, Z. J. Zheng*, Adv. Energy Mater. 2016, 6, 1600783.

[2] Y. Gao, C. Xie, Z. J. Zheng*, Adv. Energy Mater. 2020, 2002838

[3] L. Liu, Y. Yu, C. Yan, K. Li, Z. J. Zheng*, Nat. Commun. 2015, 6, 7260.

[4] Y. Yu, C. Yan, Z. J. Zheng*, Adv. Mater. 2014, 26, 55085516.

[5] Y. Yang, Q. Huang, L. Niu, D. Wang, C. Yan, Y. She, Z. J. Zheng*, Adv. Mater. 2017, 160667.

[6] J. Chang, Z.J.Zheng* et al., Nat. Commun. 2018, 2018, 9, 4480.

[7] J. Chang, Q. Huang, and Z. J. Zheng*, Joule 2020, 4, 7, 1346

[8] J. Chang, Q. Huang, Y. Gao, Z. J. Zheng*, Adv. Mater. 2021, 202004419.

[9] Y. Gao, H. Hu, J. Chang, Q. Huang, Q. Zhuang, P. Li, Z. J. Zheng*, Adv. Energy Mater. 2021, 2101809.

[10] L. Wang, J. Shang, Q. Huang, H. Hu, Y. Zhang, C. Xie, Y. Luo, Y. Gao, H. Wang, Z. J. Zheng*, Adv. Mater. 2021, 2102802.
Linking Multicomponent Interactions of Catalyst Ink and Catalyst Layer Fabrication with Electrochemical CO2 Reduction Performance
Authors: Liu Guangxin , McLaughlin David , Thiele Simon , Pham Chuyen
Published: September 2023

The controllable fabrication of catalyst layers (CL) by tuning the multiscale structure formation is complex but vital to achieving optimum CO2 reduction (CO2R) performance. The CL formation is deeply influenced by catalyst ink. An in-depth understanding on the role of each catalyst ink component and how multicomponent interactions affect ink status, catalyst layer structure, and CO2R performance is crucial.

In this work, the roles of various ingredients of catalyst ink were systematically investigated from simple binary inks to complete catalyst inks. Our results showed Ag agglomerates can be broken down more efficiently in water than in alcohols due to stronger inter-particle repulsive forces induced by water disassociation. Ag particles-Nafion networks were found to play a decisive role in stabilizing catalyst ink, mitigating agglomeration and particle sintering. The catalyst ink was comprehensively characterized and reported by static multiple light scattering (SMLS) for the first time in this study. The evolution of catalyst ink was identified in three stages: stable, flocculation and sedimentation. Isopropanol (IPA)-rich solvents were demonstrated to be more effective in stabilizing catalyst ink due to better dispersed Nafion aggregates and further enhanced Ag particle-Nafion interactions.

Subsequently, catalyst layer structure and CO2R performance were correlated with multi-component interactions in catalyst ink. Strong Ag particle-Nafion interactions were proven to promote not only ink stability, but also catalyst layer homogeneity and reaction site distribution. Water-rich inks helped improve the porosity and durability of GDEs. The cathodic potential of GDEs made by 70%-water inks (-0.75 V vs. NHE) was 30% lower than zero-water inks (-1.1 V vs. NHE), and the highest CO selectivity was boosted to 97% at an industrial meaningful current density of 200 mA/cm2 by enhancing Ag particle-Nafion interactions through rational design of ink formulation, dispersing and fabrication processes.

Simultaneously, a scalable manufacturing methodology of robust GDE was developed and validated to achieve optimal CO2R performance. It will not only provide a meaningful reference for lab applications (fast and reproducible GDE fabrication aiming at new catalysts, ionomers, membranes or operation conditions development), but also provide a steppingstone to industrial applications (GDE fabrication aiming at large scale, good durability and quality of conformance).

Figure 1
Effect of Supporting Pd Nanoparticles on WOx Nanorods on Their Stability and Catalytic Activity Towards the Electrochemical Oxidation of Concentrated Formic Acid
Authors: Al Najjar Taher , Soliman Alaa , El Sawy Ehab
Published: September 2023

Direct formic acid fuel cells (DFAFC) are considered one of the most promising fuel cells to penetrate the market due to their desired and unique properties. Formic acid (FA) could be easily produced from different sources (especially biomass) and is non-toxic. The FA-based fuel cell has a high open circuit potential in comparison to methanol and Ethanol1, high energy conversion efficiency, and fast kinetics. However, the major drawback that affects using DFAFCs is the catalysts' stability and reaction intermediates' poisoning effect, especially at high concentrations of FA.

FA has a dual pathway mechanism: either the simple and desired pathway of direct oxidation to CO2
2 or the unfavorable indirect oxidation to poisonous CO-like species that strongly adsorb on the catalyst surface, deactivating it,3 before it is hardly oxidized in a second step to give CO2. Therefore, the catalyst should be designed to direct the reaction towards the direct pathway and facilitate the poisoning species removal. The most active catalyst for FA oxidation in acidic media is palladium4 but it is highly susceptible to CO poisoning, especially as the FA concentration increases due to the high contribution of the indirect pathway. In addition, palladium nanoparticles supported on carbon material are known to suffer from dissolution in the acidic media making the electrode unstable for long-term application.5

In this presentation, the synthesis of nonstoichiometric WOx nanorods using hydrothermal methods will be reported. The Pd nanoparticles are synthesized and loaded on the WOx nanorods using ethanol as both a solvent and a reducing agent to produce a surfactant-free Pd surface. The synthesized materials are evaluated using XRD, TEM, FT-IR, EDS, and XPS. The effect of WOx nanorods as catalyst support on Pd nanoparticles activity and stability towards the oxidation of different concentrations (1-4 M) of FA in acidic media are evaluated using cyclic voltammetry (CV) and chronopotentiometry (CP), and compared with that of carbon-supported Pd catalyst. The Pd behavior in both cases will be correlated to its chemical and physical properties and thoroughly discussed.

References:

J. Sun et al., RSC Adv., 8, 18619–18625 (2018).

K. Jiang, H.-X. Zhang, S. Zou, and W.-B. Cai, Phys Chem Chem Phys, 16, 20360–20376 (2014).

T. Gunji and F. Matsumoto, Inorganics, 7, 36 (2019).

A. Gharib and A. Arab, Int. J. Hydrog. Energy, 46, 3865–3875 (2021).

T. Al Najjar, N. Ahmed, and E. N. El Sawy, RSC Adv., 11, 22842–22848 (2021).
Electrochemical Hydrogen Peroxide Production on Single Atoms and Atomic Clusters
Authors: Choi Jisik , Yoo Suhwan , Koh Ezra Shanli , Aymerich-Armengol Raquel , Meyer Gregor Maurice , Scheu Christina , Fortunato Guilherme Vilalba , Hwang Yun Jeong , Ledendecker Marc
Published: September 2023

The electrochemical oxygen reduction reaction (ORR) involving the transfer of two electrons (2-electron ORR) offers a sustainable alternative for the production of hydrogen peroxide (H2O2) on-site. Minimizing the use of expensive noble metal catalysts and maximizing their atomic utilization can be achieved by reducing the size of the catalysts. While previous studies have primarily focused on the relationship between particle size and oxygen reduction activity in the 4-electron ORR using Pt-based catalysts, less attention has been paid to the 2-electron ORR for H2O2 production. In this study, we prepared a series of size-controlled Pd clusters and investigated the oxygen reduction in acidic conditions to understand the relationship between cluster size and catalytic performance. Our results showed that larger Pd clusters favored the 4-electron ORR and the production of H2O, while smaller clusters favored the 2-electron ORR and the production of H2O2. To estimate the contribution of single atoms in the catalysts to their performance, we introduced CO. Using in-situ attenuated total reflection-surface enhanced infrared reflection absorption spectroscopy (ATR-SEIRAS), we observed a range of CO vibrational signatures that correlated with specific ORR behaviors depending on the particle/cluster size.
Reactive Force-Field Molecular Dynamics and Experimental FTIR Analyses of the Impact of State-of-Hydration on Nafion Morphology
Authors: Donnelly Dan J , Yang Moon Young , Rava Celia , Renon Alexandre , Cruse Ryan N. , Jang Seung Soon , Goddard William A , Smotkin Eugene S.
Published: September 2023

For any average value of H2O/exchange-site (λave) for a hydrated Nafion membrane, we show that there exists a wide distribution of local (λlocal) values at any instant. These distributions can be quantified by site-by-site analyses of exchange site environments characterized by molecular dynamics. Reactive force field molecular dynamics (ReaxFF MD) enables consideration of bond breaking events (sulfonic acid dissociation) that occur at λlocal values of 4 or greater. We use ReaxFF MD to predict the distribution λlocal values at any λave, and show how the dynamics elucidate water-rich, hydrophobic and interphasial regions of hydrated membranes. Each λlocal contributes to the vibrational spectrum of the polymer. The overall spectrum of the polymer electrolyte is correlated to the distribution of λlocal.

Figure 1
Strain Relaxation and Activity in PtCo Fuel Cell Catalyst Nanoparticles
Authors: Padgett Elliot , Holtz Megan E , Kongkanand Anusorn , Muller David A
Published: September 2023

Interest is growing in applying fuel cells to heavy duty transportation applications, which requires the fuel cell design to prioritize efficiency and durability to provide a low lifetime cost of ownership. This motivates further development of catalysts for the oxygen reduction reaction (ORR), as ORR kinetics are a key factor in fuel cell efficiency and catalyst degradation is a major factor limiting lifetime. Pt-alloy catalysts have seen success in light-duty fuel cell applications, where they provide enhanced activity believed to originate (at least in part) from strain of the active Pt surface by the underlying Pt-alloy core. Concerns remain regarding the viability of PtCo catalysts for heavy duty applications, as they may not sustain their activity advantage over extended lifetimes and leaching of the base metal can lead to additional performance degradation. These concerns motivate investigation into the fundamental mechanisms of strain-induced activity enhancements to guide further catalyst development and understand the ultimate limits for the performance and stability of PtCo catalysts. However, practical Pt-alloy fuel cell catalysts are complex, and understanding of real strain effects in these systems remains elusive.

Here we will present an investigation into strain effects in Pt-Co ORR catalysts for fuel cells, combining scanning nanobeam electron diffraction (NBED), continuum elastic strain modelling, and full-cell electrochemistry measurements. We leverage recent developments in NBED to make high-throughput strain maps in heterogeneous, carbon-supported PtCo catalysts and identify different mechanisms of strain relaxation, including dislocations and geometric effects. Supported by continuum elastic modelling, we correlate shell thickness, strain state, and activity of PtCo catalysts. Finally, we will comment on how these results provide rational guidance to optimize stable, efficient Pt-alloy catalysts.
Atomically Dispersed Pt and Fe Sites and Pt-Fe Nanoparticles for Durable Proton Exchange Membrane Fuel Cells
Authors: Xiao Fei , Shao Minhua
Published: September 2023

Proton exchange membrane fuel cells (PEMFCs) as a promising clean energy conversion technology have gained considerable attention. However, the high cost and low durability of Pt-based nanocatalysts for the cathodic oxygen reduction reaction (ORR) hinder the wide adoption of this technology.1 Despite great efforts on the development of advanced Pt-based catalysts to improve the Pt utilization and mass activity toward ORR, 2-3 their high activities/durability measured in liquid cells have rarely been realized in fuel cells. On the other hand, carbon-based Pt group metal (PGM)-free ORR electrocatalysts consisting of highly dispersed transition-metal single atoms in nitrogen-coordinated carbon surfaces (Me-N-C) are promising candidates to replace Pt.4 Unfortunately, the poor durability of Me-N-C has limited their practical applications.5 Some early studies6-7 shown that Me-N-C as a support for Pt-based electrocatalyst could improve the stability of the latter.

Herein, we report a hybrid electrocatalyst (denoted as Pt-Fe-N-C) consisting of Pt-Fe alloy nanoparticles on highly dispersed Pt and Fe single atoms in a nitrogen-doped carbon support (Figure 1a). The multiple types of active sites result in not only a 3.7 times higher Pt mass activity, but also excellent durability. The performance loss is negligible even after 100,000 potential cycles (Figure 1b), and no current drop is observed at 0.6 V in a fuel cell test with an ultra-low Pt loading (0.015 mgPt cm−2) in the cathode. The morphology and structure of Pt-Fe-N-C catalyst after 100,000 cycles in a fuel cell were further analyzed. Abundant single atoms were still uniformly distributed on the carbon support. No noticeable aggregation of Pt-Fe nanoparticles was observed. Most of particle size was smaller than 4 nm, a solid PtFe@Pt core-shell structure was formed. Around 7% large size particles formed a percolated structure.

This work highlights the importance of the synergistic effects among different active sites in hybrid electrocatalysts and provide an alternative way to design more active and durable low-PGM electrocatalysts for fuel cells and other electrochemical devices.

This work was supported by the Research Grant Council (HKUST C6011-20G) and Shenzhen Science and Technology Innovation Committee (SGDX2019081623340748).

Figure 1. (a) Scanning transmission electron microscope image (the spots in the blue and red dashed circles are ascribed to the Fe and Pt single atoms, respectively). (b) H2/O2 fuel cell polarization (solid symbols and left axis) and power density (hollow symbols and right axis) plots of the Pt-Fe-N-C cathode before cycling (blue) and after 100,000 potential cycles (red) between 0.6 and 0.95 V.

Figure 1
Scalable Synthesis of Highly Efficient Nife-Layered Double Hydroxides as Electrocatalyst for Water Oxidation
Authors: Seijas Da Silva Alvaro , Hartert Adrian , Oestreicher Victor , Romero Jorge , Coronado Eugenio , Lloret Segura Vicent , Abellán Gonzalo
Published: September 2023

Oxygen evolution reaction (OER) is reckoned as the limiting step for water splitting, suffering slow kinetics (>10 000 lower than the hydrogen evolution reaction), and therefore requiring high overpotentials. Nowadays, there is a huge effort in the development of low-cost, earth-abundant, efficient, and stable electrocatalysts. Layered double hydroxides (LDHs) based on NiFe fulfil these requirements, and in addition, it possesses one of the best performances for oxygen evolution reaction (OER) in basic media reported to date.[1] LDHs exhibit a hydrotalcite-like structure composed of M(II) and M(III) cations and depict wide tunability regarding the metallic composition. However, despite their great performance, the implementation of Fe-based LDHs as electrocatalysts in real devices remains unexplored, mainly due to the current challenging synthetic approaches, incompatible with their scaling.[2] Herein we present a high clustering nanometric NiFe-LDHs obtained by a scalable synthesis. The synthetic protocol gets the opportunity to obtain ca. 100 g/L of our materials, almost two orders of magnitude bigger than the state-of-the-art synthetic approaches. Moreover, the intrinsical characteristics of this scale-up NiFe-LDH confer a better electrochemical performance than traditional synthesized NiFe-LDH in all current density ranges and different electrochemical setups from rotatory disk electrode (RDE) to Anion Exchange Membrane Water Electrolyzer (AEMWE), being tested up to a current density of 3 A·cm-2. For example the overpotential at 2.5 A·cm-2 for the scale up NiFe-LDH and Traditional synthesized NiFe-LDH samples are 1.96 V and 2.18 V, respectively (Figure 1). Interestingly, this behavior is in contrast to the recent result warning about the possibility of cell environments matching the cell performance of design catalysts.[3]

References:

[1] Yi H.; et al. Advanced Energy Materials, 2021, 11, 2002863.

[2] Zheng, Z.; Lin, L.; Mo, S.; Ou, D.; Tao, J.; Qin, R.; Fang, X.; Zheng, N. Small 2018, 14 (24), 1800759.

[3] Abellán G.; Et al. Manuscript in progress.

Figure 1
Catalytic Proton-Hydroxide Recombination for Forward-Bias Bipolar Membranes
Authors: Mitchell James , Chen Lihaokun , Langworthy Kurt , Fabrizio Kevin , Boettcher Shannon W.
Published: September 2023

Bipolar membranes (BPMs) uniquely generate steady state pH gradients in electrochemical cells, enabling half reactions to occur efficiently in different pH environments, and are thus of broad interest. Forward-bias BPMs further enable new fuel-cell, redox-flow batteries, and CO2-electrolyzer concepts. In forward bias, the gradient in electrochemical potential drives ionic charge carriers toward the bipolar junction where they can recombine. We use a H2-pump electrochemical cell to study H+ / OH− recombination at the bipolar junction. We discover that metal oxide nanoparticles substantially catalyze the recombination reaction in the bipolar junction under forward bias and find evidence that H+ / OH− recombination occurs via a surface mechanism on the oxide catalyst. We propose a rate equation to describe the catalytic H+ / OH− recombination mechanism, supported by numerical simulations. Membrane sensing experiments further reveal the nature of the oxide catalyst layers and provide insight into the potential and temperature dependence of H+ / OH− recombination at the bipolar junction. This work thus elucidates materials-design strategies for recombination catalysts to advance forward-bias BPM technologies.