Research

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18 pages, 3354 KiB

Open AccessArticle

Thin Reinforced Anion-Exchange Membranes for Non-Aqueous Redox Flow Battery Employing Fe/Co-Metal Complex Redox Species

by Hyeon-Bee Song, Do-Hyeong Kim, Myung-Jin Lee and Moon-Sung Kang

Batteries 2024, 10(1), 9; https://doi.org/10.3390/batteries10010009 - 27 Dec 2023

Viewed by 1522

Non-aqueous redox flow batteries (NARFBs) have been attracting much attention because they can significantly increase power and energy density compared to conventional RFBs. In this study, novel pore-filled anion-exchange membranes (PFAEMs) for application to a NAPFB employing metal polypyridyl complexes (i.e., Fe(bpy)₃ [...] Read more.

Non-aqueous redox flow batteries (NARFBs) have been attracting much attention because they can significantly increase power and energy density compared to conventional RFBs. In this study, novel pore-filled anion-exchange membranes (PFAEMs) for application to a NAPFB employing metal polypyridyl complexes (i.e., Fe(bpy)₃²⁺/Fe(bpy)₃³⁺ and Co(bpy)₃²⁺/Co(bpy)₃³⁺) as the redox species are successfully developed. A porous polyethylene support with excellent solvent resistance and mechanical strength is used for membrane fabrication. The PFAEMs are prepared by filling an ionic liquid monomer containing an imidazolium group and a crosslinking agent into the pores of the support film and then performing in situ photopolymerization. As a result, the prepared membranes exhibit excellent mechanical strength and stability in a non-aqueous medium as well as high ion conductivity. In addition, a low crossover rate for redox ion species is observed for the prepared membranes because they have relatively low swelling characteristics in non-aqueous electrolyte solutions and low affinity for the metal-complex redox species compared to a commercial membrane. Consequently, the PFAEM is revealed to possess superior battery performance than a commercial membrane in the NARFB tests, showing high energy efficiency of about 85% and stable operation for 100 cycles. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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9 pages, 2345 KiB

Open AccessArticle

Elucidating Spatial Distribution of Electrochemical Reaction in a Porous Electrode by Electrochemical Impedance Spectra for Flow Batteries

by Jie Zhang, Qilong Gan, Xianzhi Yuan, Zhipeng Xiang, Zhiyong Fu and Zhenxing Liang

Batteries 2023, 9(1), 17; https://doi.org/10.3390/batteries9010017 - 26 Dec 2022

Cited by 1 | Viewed by 2699

Abstract

A porous electrode is an essential component in a flow battery, and its structure determines the battery’s performance. The coupling of the multi-temporal-spatial-scale processes (e.g., electrochemical reaction, mass transfer, charge transfer) makes the recognition of each process complicated. Herein, a symmetric flow cell [...] Read more.

A porous electrode is an essential component in a flow battery, and its structure determines the battery’s performance. The coupling of the multi-temporal-spatial-scale processes (e.g., electrochemical reaction, mass transfer, charge transfer) makes the recognition of each process complicated. Herein, a symmetric flow cell device is developed, and the electrochemical impedance measurement (two- or three-electrode configuration) is realized to elucidate the electrochemical processes. First, the effect of flow rate and concentration on the impedance spectra is investigated to identify the electrochemical processes. Second, the distributed resistance is quantified to describe the spatial distribution of the electrochemical reaction. It is found that the electrochemical reaction occurs near the membrane side at a low polarization current, and the reaction zones spatially extend from the membrane side to the current collector with the increase of imposed polarization. Such an evolution of the spatial distribution stems from the trade-off between the mass transfer and the ion conduction in the porous electrode. This work provides an experimental method to nondestructively probe the electrochemical processes, and the result provides guidance for developing innovative electrode structures for flow batteries. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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11 pages, 1845 KiB

Open AccessFeature PaperArticle

Aluminum/Bromate and Aluminum/Iodate Mechanically Rechargeable Batteries

by Alexander Modestov, Vladimir Andreev and Anatoliy Antipov

Batteries 2022, 8(12), 270; https://doi.org/10.3390/batteries8120270 - 04 Dec 2022

Viewed by 1747

Abstract

The ever-increasing characteristics of microcomputers, sensors, actuators, and communication systems require more powerful and more compact autonomous power sources. Al/bromate and Al/iodate flow batteries are proposed as new power supply units for use in oxygen-deficient environments. The batteries employ a mechanically rechargeable aluminum [...] Read more.

The ever-increasing characteristics of microcomputers, sensors, actuators, and communication systems require more powerful and more compact autonomous power sources. Al/bromate and Al/iodate flow batteries are proposed as new power supply units for use in oxygen-deficient environments. The batteries employ a mechanically rechargeable aluminum anode flooded with aqueous salt electrolytes or seawater, a cation-exchange membrane, and a carbonaceous porous cathode, where acidified alkali metal bromate, or iodate, is reduced in a six-electron process. The theoretical energy density of an Al/bromate flow cell per reactants is 0.65 kWh kg⁻¹. Seawater is assumed as an electrolyte for the anode compartment. Using a H₂/iodate flow cell, it is shown that iodate–iodine–iodide electrochemical transformations can be realized in both directions in acidic media at carbonaceous electrodes. At 30 °C, the area-specific power of the single cells of the Al/bromate and Al/iodate flow batteries reaches 0.26 W cm⁻² and 0.075 W cm⁻², respectively. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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12 pages, 4669 KiB

Open AccessFeature PaperArticle

Ways to Ensure Parallel Operation of Vanadium Flow Batteries to Create High Power Energy Storage Systems

by Alexey Loskutov, Andrey Kurkin, Ivan Kuzmin and Ivan Lipuzhin

Batteries 2022, 8(9), 120; https://doi.org/10.3390/batteries8090120 - 07 Sep 2022

Cited by 4 | Viewed by 2788

Abstract

Vanadium redox flow batteries are a highly efficient solution for long-term energy storage. They have a long service life, low self-discharge, are fire safe and can be used to create a large-scale storage system. The characteristics of the flow battery are determined by [...] Read more.

Vanadium redox flow batteries are a highly efficient solution for long-term energy storage. They have a long service life, low self-discharge, are fire safe and can be used to create a large-scale storage system. The characteristics of the flow battery are determined by the parameters of its main components: a stack determines the battery power and its efficiency, and an electrolyte determines the battery’s capacity and service life. Several stacks must be combined into one system to create a powerful energy storage system; however, the discharge characteristics differ even for two identical stacks connected in parallel. This article proposes hydrodynamic and electrotechnical methods for ensuring the parallel operation of several flow stacks under the same conditions. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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17 pages, 35648 KiB

Open AccessArticle

Numerical Parametric Investigation of Nonaqueous Vanadium Redox Flow Batteries

by Shaopei Huang and Yujuan Lu

Batteries 2022, 8(8), 75; https://doi.org/10.3390/batteries8080075 - 23 Jul 2022

Cited by 2 | Viewed by 2090

Abstract

Nonaqueous redox flow batteries are promising candidates for large-scale energy storage technologies. However, the effect of structural design and key factors limiting the performance are still not thoroughly understood. In this work, we constructed a physical model to study the effect of various [...] Read more.

Nonaqueous redox flow batteries are promising candidates for large-scale energy storage technologies. However, the effect of structural design and key factors limiting the performance are still not thoroughly understood. In this work, we constructed a physical model to study the effect of various design parameters on the performance of such a battery. It was found that the kinetics of redox reaction was improved with active material concentration and electrode surface area. The modeling results also showed that the local current density was much higher in the vicinity of membrane than near the current collector due to relatively low ionic conductivity of electrolytes. Furthermore, decreasing the electrode thickness and increasing the membrane conductivity both reduced the voltage loss associated with ohmic resistance, thereby resulting in improved battery performance. The obtained numerical simulation results would be helpful not only for understanding the physicochemical process in nonaqueous vanadium flow batteries but also for future structural optimization of these batteries. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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Review

Jump to: Research

27 pages, 3551 KiB

Open AccessFeature PaperReview

High-Throughput Virtual Screening of Quinones for Aqueous Redox Flow Batteries: Status and Perspectives

by Abhishek Khetan

Batteries 2023, 9(1), 24; https://doi.org/10.3390/batteries9010024 - 28 Dec 2022

Cited by 6 | Viewed by 2390

Abstract

Quinones are one of the most promising and widely investigated classes of redox active materials for organic aqueous redox flow batteries. However, quinone-based flow batteries still lack the necessary performance in terms of metrics, such as specific capacity, power density, and long-term stability, [...] Read more.

Quinones are one of the most promising and widely investigated classes of redox active materials for organic aqueous redox flow batteries. However, quinone-based flow batteries still lack the necessary performance in terms of metrics, such as specific capacity, power density, and long-term stability, to achieve mass market adoption. These performance metrics are directly related to the physicochemical properties of the quinone molecules, including their equilibrium redox potential, aqueous solubility, and chemical stability. Given the enormous chemical and configurational space of possible quinones and the high tunability of their properties, there has been a recent surge in the use of high-throughput virtual screening (HTVS) for the rational design and discovery of new high-performing molecules. In this review article, HTVS efforts for the computational design and discovery of quinones are reviewed with a special focus on the enumerated space of core quinone motif, the methods and approximations used for the estimation of performance descriptors, and the emergent structure-property relationships. The knowledge and methodological gaps in conventional HTVS efforts are discussed, and strategies for improvement are suggested. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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37 pages, 7168 KiB

Open AccessReview

Building Bridges: Unifying Design and Development Aspects for Advancing Non-Aqueous Redox-Flow Batteries

by Luuk Kortekaas, Sebastian Fricke, Aleksandr Korshunov, Isidora Cekic-Laskovic, Martin Winter and Mariano Grünebaum

Batteries 2023, 9(1), 4; https://doi.org/10.3390/batteries9010004 - 22 Dec 2022

Cited by 6 | Viewed by 2452

Abstract

Renewable energy sources have been a topic of ever-increasing interest, not least due to escalating environmental changes. The significant rise of research into energy harvesting and storage over the years has yielded a plethora of approaches and methodologies, and associated reviews of individual [...] Read more.

Renewable energy sources have been a topic of ever-increasing interest, not least due to escalating environmental changes. The significant rise of research into energy harvesting and storage over the years has yielded a plethora of approaches and methodologies, and associated reviews of individual aspects thereof. Here, we aim at highlighting a rather new avenue within the field of batteries, the (noaqueous) all-organic redox-flow battery, albeit seeking to provide a comprehensive and wide-ranging overview of the subject matter that covers all associated aspects. This way, subject matter on a historical perspective, general types of redox-flow cells, electrolyte design and function, flow kinetics, and cell design are housed within one work, providing perspective on the all-organic redox-flow battery in a broader sense. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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33 pages, 7304 KiB

Open AccessEditor’s ChoiceReview

Review of the Research Status of Cost-Effective Zinc–Iron Redox Flow Batteries

by Huan Zhang, Chuanyu Sun and Mingming Ge

Batteries 2022, 8(11), 202; https://doi.org/10.3390/batteries8110202 - 31 Oct 2022

Cited by 33 | Viewed by 5417

Abstract

Zinc–iron redox flow batteries (ZIRFBs) possess intrinsic safety and stability and have been the research focus of electrochemical energy storage technology due to their low electrolyte cost. This review introduces the characteristics of ZIRFBs which can be operated within a wide pH range, [...] Read more.

Zinc–iron redox flow batteries (ZIRFBs) possess intrinsic safety and stability and have been the research focus of electrochemical energy storage technology due to their low electrolyte cost. This review introduces the characteristics of ZIRFBs which can be operated within a wide pH range, including the acidic ZIRFB taking advantage of Fen+ with high solubility, the alkaline ZIRFB operating at a relatively high open-circuit potential and current densities, and the neutral ZIRFB providing a non-toxic, harmless, and mild environment. No matter what kind of ZIRFB, there are always zinc dendrites limiting areal capacity on the anode, which has become an obstacle that must be considered in zinc-based RFBs. Therefore, we focus on the current research progress, especially the summarizing and analysis of zinc dendrites, Fe(III) hydrolysis, and electrolytes. Given these challenges, this review reports the optimization of the electrolyte, electrode, membrane/separator, battery structure, and numerical simulations, aiming to promote the performance and development of ZIRFBs as a practical application technology. Based on these investigations, we also provide the prospects and development direction of ZIRFBs. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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23 pages, 32545 KiB

Open AccessEditor’s ChoiceReview

Toward Dendrite-Free Deposition in Zinc-Based Flow Batteries: Status and Prospects

by Zeyu Xu and Maochun Wu

Batteries 2022, 8(9), 117; https://doi.org/10.3390/batteries8090117 - 06 Sep 2022

Cited by 9 | Viewed by 5962

Abstract

Safe and low-cost zinc-based flow batteries offer great promise for grid-scale energy storage, which is the key to the widespread adoption of renewable energies. However, advancement in this technology is considerably hindered by the notorious zinc dendrite formation that results in low Coulombic [...] Read more.

Safe and low-cost zinc-based flow batteries offer great promise for grid-scale energy storage, which is the key to the widespread adoption of renewable energies. However, advancement in this technology is considerably hindered by the notorious zinc dendrite formation that results in low Coulombic efficiencies, fast capacity decay, and even short circuits. In this review, we first discuss the fundamental mechanisms of zinc dendrite formation and identify the key factors affecting zinc deposition. Then, strategies to regulate zinc deposition are clarified and discussed based on electrode, electrolyte, and membrane. The underlying mechanisms, advantages, and shortcomings of each strategy are elaborated. Finally, the remaining challenges and perspectives of zinc-based flow batteries are presented. The review may provide promising directions for the development of dendrite-free zinc-based flow batteries. Full article

(This article belongs to the Special Issue Redox Flow Batteries: Recent Advances and Perspectives)

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