Integration of renewable energy into modern power grids remains limited by intermittency and the need for reliable energy storage. Redox flow batteries (RFBs) are promising for large-scale energy storage, yet their widespread adoption is hindered by the high cost. In this study, we investigate isopropanol as a redox-active species with Pt-Cu alloy electrocatalysts for aqueous-organic RFBs. A series of PtxCu catalysts with varying Pt:Cu ratios were synthesized and studied for isopropanol electro-oxidation reaction (IPAOR) performance. Among them, PtCu demonstrated the best performance, achieving a low activation energy of 14.4 kJ/mol at 0.45 V vs. RHE and excellent stability at 1 M isopropanol (IPA) concentration. Kinetic analysis and in situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy revealed significantly reduced acetone accumulation on PtCu compared to pure Pt, indicating enhanced resistance to catalyst poisoning. Density functional theory (DFT) calculations further identified the first proton-coupled electron transfer (PCET) as the rate-determining step (RDS) with C-H bond scission as the preferred pathway on PtCu. A proof-of-concept PtCu-catalyzed H-cell demonstrated stable cycling over 200 cycles, validating the feasibility of IPA as a low-cost, regenerable redox couple. These findings highlight PtCu-catalyzed IPA/acetone(ACE) chemistry as a promising platform for next-generation aqueous-organic RFBs.

The rapid proliferation of lithium battery applications has underscored the critical role of lithium supply in the transition to industrial electrification. Existing lithium production methods encounter significant challenges in efficiency, scalability, environmental impact, and cost. The integration of redox-mediated electrodialysis with a dense ceramic Li6/16Sr7/16Ta3/4Hf1/4O3 perovskite membrane, distinguished by its unique lattice structure allowing only lithium-ion exchange and transport, enables efficient, highly lithium-selective extraction directly from a diversity of resources including seawater and various brines. This approach offers continuous operation capability, can utilize renewable power, and has notable advantages, including chemical-free operation and little waste generation. Overall, this innovative solution presents a one-step, ecofriendly, highly selective lithium extraction method.

Deep eutectic solvents (DESs) demonstrate potential as non-aqueous electrolytes for next-generation redox flow batteries (RFBs). DESs are considered not only as environmentally sustainable but also economically attractive electrolytes because they can be resourced from biological feedstock (alcohols, urea, choline) and are earth-abundant and of low toxicity. However, their inherent hydrogen bonding leads to high viscosity, hindering ion and reactant transport, thereby limiting power density. This study investigates the influence of controlled water addition on the Fe²⁺/Fe³⁺ redox couple in DES ethaline (a mixture of choline chloride and ethylene glycol in 1:2 molar ratio) to gradually disrupt the hydrogen bond network between its components. Our results show that the stoichiometric introduction of water effectively reduces viscosity and increases ionic conductivity within the DES electrolyte. The reduced viscosity and three-fold improvement in conductivity enhances mass transport and kinetics of Fe²⁺/Fe³⁺ redox couple in DES ethaline, potentially leading to higher power density RFBs. Also, iron chloride salts exhibit increasing solubility (>2 M) in DES electrolyte with the addition of increasing quantities of water. Notably, the electrochemical stability window remains around 1.90 V, mitigating concerns about water-induced instabilities. These findings suggest that strategically incorporating water into DES electrolytes can overcome mass transport limitations, paving the way for high-performance, environmentally friendly RFBs. This approach eliminates the need for harmful solvents and fossil fuel-based processes.

This perspective delves into electrochemically active and regenerable liquid organic hydrogen carriers (LOHCs), exploring their electrochemical properties and applications in hydrogen storage, regenerative fuel cells, batteries, and flow batteries.

Redox flow batteries (RFBs) are membrane-separated rechargeable flow cells with redox electrolytes, offering the potential for large-scale energy storage and supporting renewable energy grids. Yet, creating a cost-effective, high-performance RFB system is challenging. In this work, we investigate an Fe/Mn RFB alkaline system based on the [(TEA)Fe-O-Fe(TEA)](3-/4-) and MnO4-/2- redox couples with a theoretical cell voltage of similar to 1.43 V. This combination has not been systematically studied previously, but it can lead to a very low-cost and sustainable materials for high energy storage. Constant current cycling tests were performed at +/- 41 mA cm(-2)(2) between 20% and 80% SOC over 800 h (400 cycles) with an apparent Coulombic efficiency (CE) approaching 100%, while the voltage efficiency (VE) gradually decreased from similar to 75.3% to similar to 61.4% due to increasing internal resistances. The voltage efficiency loss can be mitigated through a periodic acid treatment to remove MnO2 deposits from the separator.

Magnonic crystals with artificial micro/nanomagnetic pattern act as low‐loss information carriers in many microwave devices. The excitation and control of spin waves inside is essential and fundamental in magnonic crystal applications. Herein, permalloy micro‐disk patterns are constructed on a continuous permalloy film, and they succeed in exciting spin waves in this bilayer‐structured magnonic crystal. The spin‐wave modes can be effectively tuned by varying the periodic parameter (P) of upper‐layer disk pattern, which is confirmed by the transition from single‐peak to multi‐peak in ferromagnetic resonance (FMR) spectra with P decreased from 4 to 0.5 μm. The split in FMR spectra is reconstructed by micromagnetic simulation, revealing that three spin‐wave modes are respectively excited by the domain walls of below‐layer continuous film, geometrical restriction of permalloy micro‐disk, and magnetic coupling between neighboring permalloy micro‐disks. The tunable spin‐wave behavior in this bilayer‐structured magnonic crystal presents broad application prospect in programmable spintronic devices at micro/nanoscale.

Vortex-antivortex pairs have shown great potential in spintronics, where they can be used for information storage and logical devices. However, the physical mechanism for the nucleation of vortex-antivortex pairs is still unclear due to its metastability. We report on spontaneous nucleation of vortex-antivortex pairs in patterned Fe20Ni80 films (circular, square, hexagonal islands). By using a complex approach involving micromagnetic simulations, more in-depth understanding of vortex pair nucleation was achieved. A large amount of vortex-antivortex pairs appear in the as-grown magnetic film, which is the unstable high-energy state. Then, vortex and antivortex moves towards each other and annihilate, transforming magnetic structures and lowering the total energy of the system. With the decrease of sizes of microstructures, isolated vortex becomes stabilized due to confinement effect. These results provide a physical view for the nucleation of vortex-antivortex pairs and may be useful for design and optimization of magnetic microstructures for future spintronic applications.

Developing highly active and durable platinum-based catalysts is crucial for electrochemical renewable energy conversion technologies but the limited supply and high cost of platinum have hindered their widespread implementation. The incorporation of non-noble metals, particularly copper, into Pt catalysts has been demonstrated as an effective solution to reduce Pt consumption while further promoting their performance, making them promising for various electrocatalytic reactions. This review summarizes the latest advances in PtCu-based alloy catalysts over the past several years from both synthetic and applied perspectives. In the synthesis section, the selection of support and reagents, synthesis routes, as well as post-treatment methods at high temperatures are reviewed. The application section focuses not only on newly proposed electrochemical reactions such as nitrogen-related reactions and O2 reduction but also extends to device-level applications. The discussion in this review aims to provide further insights and guidance for the development of PtCu electrocatalysts for practical applications.

Dzyaloshinskii-Moriya interaction (DMI), one of antisymmetric exchanges, originates from the combination of low structural symmetry and large spin-orbit coupling and favors magnetization rotations with fixed chirality. Herein, this work reports a DMI-like behavior in permalloy via coupled vortices in confined structures. Under the in-plane magnetic fields, continuous reversals of different coupled vortices are directly observed by in situ Lorentz transmission electron microscopy, and reproduced by complementary micromagnetic simulations. The statistical results show that coupled vortices with opposite chirality appear more frequently with the frequency up to about 60%. Such an asymmetric phenomenon mainly arises from a DMI-like behavior, associated with the increased total energy difference between different ground-state coupled vortices. Moreover, in the reversal process, the junction between disks accelerates the annihilation of vortices moving toward it and is also the starting point of vortex nucleation. These results provide an effective method to generate a DMI-like behavior in magnetic systems with symmetry breaking surface and benefit the future development of vortex-based spintronic devices.

Deep eutectic solvents (DESs) have recently attracted much attention as potential green electrolyte solvents for redox flow batteries. DESs are considered not only as environmentally sustainable but also economically attractive electrolytes because they can be resourced from biological feedstock (alcohols, urea, choline) and are earth-abundant and of low toxicity. Despite these advantages, DESs still have limitations in important aspects such as reactant and ion transport, which is inhibited due to hydrogen-bonding-induced viscosity. Thus, improving the transport properties of redox species in DESs is essential. In addition, we explore the quantitative addition of water to ethaline (a 1:2 choline chloride: ethylene glycol mixture) in order to understand its influence on the kinetics and mass transport properties of DESs. In this work, we show that DESs can be made more fluid and less dense, while avoiding most of the electrochemical instabilities of water. Herein, we investigate the effects of gradually increasing amounts of water to the redox system of Fe2+/3+in ethaline. Our study shows that systematic addition of water leads to a three-fold increase in ionic conductivity and decrease in viscosity that enhances the mass transport and kinetics of DES-based electrolytes while still maintaining an electrochemical window of approximately 1.90 V. The use of environmentally benign electrolyte components together with the observed increase in conductivity will result in a more efficient redox flow battery (RFB) that operates at higher power density without relying on harmful solvents and fossil fuel-based processes.

Eutectic solvents (ESs) have been widely studied due to their tunable solvation and physical properties. The properties of eutectic solvents that are formed from mixtures of hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs) are governed by a complex hydrogen (H) bonded network among their constituents. However, an understanding of the key factors effecting the H-bonding structure and dynamics, and the resulting physical and electrochemical properties at interfaces is still in its infancy. In this study, the influence of the cation's alkyl chain length and the anion chemical identity on the characteristics of the H-bonding network in eutectic solvents were examined. In particular, ESs formed from mixtures of tetraalkylammonium salts as HBAs and ethylene glycol as the HBD were studied. Complementary spectroscopic studies revealed the changes in the solvation environment as a function of the ammonium chain length (C1, C2, C3, and C4) and the anion type (Cl-, Br-, I-). With an increase in the alkyl chain length or a decrease in the electronegativity of halide anions (X-), it was found that the O-H bond length shortens and the H center dot center dot center dot X- bond elongates in the H-bond (O-H center dot center dot center dot X- ) structure, thus resulting in an increase of the solvated ion size and a decrease in the bulk ionic conductivity. Further, double layer capacitance measurements showed that increased capacitance was correlated with shorter H-bonds in anion solvates.

The catalyst intrinsic area-specific activity for the oxygen reduction reaction (ORR) was constrained by the scaling relations governing the adsorption of reaction intermediates. In this study, we strategically modified the electronic band structures of Pt(CuNi)x alloy nanoparticles by varying their composition, resulting in a specific activity trend resembling a volcano shape. The introduction of MoOy shattered the existing scaling relations, leading to a significant enhancement in ORR activity of Pt alloys, surpassing the activity of Pt(CuNi)x catalysts. These findings proved the effectiveness of MoOy deposition on Pt(CuNi)x in disrupting the scaling relations, ultimately improving ORR activity.

Chapter 35 Fe / Fe Flow Battery Robert F. Savinell, Robert F. Savinell Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this authorNicholas Sinclair, Nicholas Sinclair Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this authorXiaochen Shen, Xiaochen Shen Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this authorJulia Song, Julia Song ESS Inc., 26440 SW Parkway, Wilsonville, OR, 97070 USASearch for more papers by this authorJesse S. Wainright, Jesse S. Wainright Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this author Robert F. Savinell, Robert F. Savinell Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this authorNicholas Sinclair, Nicholas Sinclair Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this authorXiaochen Shen, Xiaochen Shen Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this authorJulia Song, Julia Song ESS Inc., 26440 SW Parkway, Wilsonville, OR, 97070 USASearch for more papers by this authorJesse S. Wainright, Jesse S. Wainright Case Western Reserve University, Department of Chemical and Biomolecular Engineering, 10700 Euclid Avenue, Cleveland, Ohio, 44106 USASearch for more papers by this author Book Editor(s):Christina Roth, Christina RothSearch for more papers by this authorJens Noack, Jens NoackSearch for more papers by this authorMaria Skyllas-Kazacos, Maria Skyllas-KazacosSearch for more papers by this author First published: 06 January 2023 https://doi.org/10.1002/9783527832767.ch35 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Summary This chapter describes the operating principles and key features of the all-iron flow battery (IFB). This energy storage approach uses low-cost iron metal (Fe) ions for both the positive and negative electrode reactions thereby requiring less stringent membrane properties. The chemistry of the positive and negative electrode reactions is discussed along with electrolyte factors affecting performance and membrane separators. Methods of rebalancing the electrolytes following proton loss via the negative electrode parasitic reaction on charge are described. A rudimentary comparison of the estimated costs of the IFB and the vanadium flow battery (FB) is summarized and a discussion of recent commercialization activities is given. A slurry electrode approach is described to overcome cell capacity limit caused by the iron plating reaction at the negative electrode. The IFB is a promising approach for low-cost large-scale energy storage. References Aguilo-Aguayo , N. and Bechtold , T. ( 2018 ). Monitoring the state-of-charge in all-iron aqueous redox flow batteries . Journal of the Electrochemical Society 165 ( 13 ): A3164 – A3168 . Zito , R. , inventor ( 1978 ). REDOXX Energy Corp, Gel Inc, assignee . Energy conversion patent US4069371A. 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High Energy Storage Capacity Low Cost Iron Flow Battery . Report No.: AR-0000352 United States 10.2172/1506426 HQPR English. Cleveland, OH (United States): Case Western Reserve University. Tucker , M.C. , Phillips , A. , and Weber , A.Z. ( 2015 ). All-iron redox flow battery tailored for off-grid portable applications . ChemSusChem 8 ( 23 ): 3996 – 4004 . Tucker , M.C. , Lambelet , D. , Oueslati , M. et al. ( 2016 ). Improved low-cost, non-hazardous, all-iron cell for the developing world . Journal of Power Sources 332 : 111 – 117 . Flow Batteries: From Fundamentals to Applications, Volume 2 ReferencesRelatedInformation

Exchange bias is a common phenomenon that appears at the interfaces between ferromagnetic and ferrimagnetic materials due to the presence of frozen spins. However, systematic quantification of their intrinsic correlation remains to be a challenge. Herein, the exchange bias induced by frozen spins is assumed as the synergy of an effective static magnetic field and an effective anisotropy, and thus the effect of intrinsic frozen spins at core@shell interfaces of iron@iron‐oxide nanoparticles is estimated. It is confirmed that the shift of the hysteresis loop is 2322 Oe and the coercivity increases from 360 to 1590 Oe. Using micromagnetic simulations, such a hysteresis loop is reconstructed by introducing an effective static magnetic field of 7360 Oe and an effective anisotropy of 45 × 10 3 J m −3 . Therefore, a connection between the intrinsic interfacial frozen spins and the exchange bias effect is established from a mesoscale perspective, mediated by the effective magnetic field and effective anisotropy. The results can provide an understanding of exchange bias effect and promote applications of ferromagnetic/ferrimagnetic heterostructures.

Nonflammable eutectic solvents show great potential to enhance the concentrations of the redox-active materials and the cell voltages for redox flow batteries (RFBs). Herein, we report a promising redox-active eutectic electrolyte (1.5 M total redox species) with viologen and ferrocene derivatives where both of the redox reactions are reversible with a maximum open-circuit voltage of 1.35 V and an energy density of 15.1 Wh L-1, which is relevant to large-scale energy storage. The charge-discharge (from 75 to 25% state of charge) characteristics in a flow cell (0.15 M negolyte and 0.3 M posolyte) showed that it can be cycled with consistent discharge capacity for 12 h (19 cycles), beyond which pressure-driven crossover between the posolyte and negolyte reservoirs leads to capacity decay. This study points to promising new directions toward eutectic electrolyte development for RFBs where we demonstrate increasing the polarity, functionalizing the redox molecules, and separating redox intermediates to prevent undesired side reactions can make improvements in operating cell voltage, energy density, and cyclability.

Target skyrmions have been attracting intensive attention as the building block of spintronic devices. However, due to the topological protection of these magnetic textures, an extra driving force is needed to realize the transition between different magnetic textures. Herein, we achieve the transition of these magnetic textures with the breaking of topological protection by applying perpendicular microwave magnetic field, which is assisted by the excitation of breathing modes and hybridized modes (combination of breathing modes and radial spin wave modes). Another distinct resonance mode originating from the interaction of hybridized mode and breathing mode is also found, which is excited by isolated annular domain in different positions of nanodisks. Our results provide an insight for the understanding of complex dynamic behaviors in magnetic textures and the designing of spintronics devices.

Electromagnetic losses in composites could be synergistically controlled by permeability and permittivity, associated with multiple ferromagnetic resonances and dielectric polarization. However, it is still challenging for simultaneous tunability for both the terms in a magnetic/dielectric composite system. Here, we demonstrate the tunable ferromagnetic resonances and the enhanced dielectric losses at gigahertz frequencies in permalloy/carbonized cotton fiber composites with different annealing temperatures. It is theoretically confirmed that the stress field acting on the magnetic permalloy layer increases with increasing temperature because of the shrinkage of the dielectric carbonized cotton fibers, resulting in multiple ferromagnetic resonances, in which there is a linear relationship (f(r) = 1.52 x sigma + 9.38) between the resonance frequency (f(r)) and the stress (sigma). The present work provides a fundamental insight into understanding the micromagnetic dynamics of the magnetic/dielectric composite system. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

(i) The three-dimensional conductive network of CNFs improves intrinsic activity. (ii) Fe–Phen complex encapsulated in ZIF-8 provides atomically dispersed FeN x sites. (iii) Hierarchical Fe–N x –CNFs presents excellent ORR performance.

Deep eutectic solvent (DES), formed by the intermolecular hydrogen bonding between its components of an H–bond acceptor (HBA) and an H–bond donor (HBD), has been extensively studied in the area of material synthesis, catalysis, electrochemistry, etc. The properties of DES including melting point, color, density, viscosity, conductivity, etc. are closely related to the H-bond network. Establishing an understanding of the H-bond structure offers an opportunity to fine-tune these properties. Hence, in this study, we systematically investigated the effects of halide anion type and alkyl chain length on the hydrogen bond network of a series of eutectic solvent systems and attempted to establish an unambiguous H-bond correlation with the conductivity. We varied the halide anion from Cl − to I − (Cl − , Br − , I − ) and the alkyl chain length from methyl to butyl ( n c = 1, 2, 4), and performed FTIR and conductivity measurements. Results show that the OH stretching peak exhibits a blue shift with the halide anion varies in the order of Cl − , Br − , I − when compared with the neat ethylene glycol (Figure 1a), indicating an increase in H-bond strength. A similar trend can be found with the increasing alkyl chain length as well. A stronger H-bond network inhibits the mobility of these halide anions in the eutectic system, as a result, the conductivity will decrease as shown in Figure 1b. Further probing the H-bond network with ultrafast spectroscopy is currently underway. Figure 1. (a) FTIR spectrum of neat EG and TBAX:EG(1:10) sample, X= Cl − , Br − ,I − . (b) Trend between the OH stretching peak shift (vs. neat EG) and conductivity of these investigated samples. Acknowledgememts This work was supported as part of the Breakthrough Electrolytes for Energy Storage (BEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0019409 Figure 1