A tetradentate Ni(II) complex cation as a single redox couple for non-aqueous flow batteries

Kim, Hyun‐seung; Yoon, Taeho; Jang, Jihyun; Mun, Junyoung; Park, Hosang; Ryu, Ji Heon; Oh, Seung M.

doi:10.1016/j.jpowsour.2015.02.083

Cited by 43 publications

(32 citation statements)

References 31 publications

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“…Cost is the ultimate driver for RFB implementation, and to meet those targets many researchers are focusing on the redox carriers that show very high solubilities (>2.5 m ), carry >2 electrons per molecule, and produce a >3 V cell potential. To meet these goals, we were intrigued by the ability of a Ni‐cyclam complex to generate a cell potential of approximately 2.5 V and operate in both half‐reactions of the cell . An examination of the literature pointed to one ligand motif that might be less expensive than cyclam yet embody other desirable characteristics: the pyridinecarboxamido group linked by an alkyl or aryl group.…”

Section: Figurementioning

confidence: 99%

“…To meet these goals, we were intrigued by the ability of aN icyclam complex to generate ac ell potential of approximately 2.5 Va nd operate in both half-reactions of the cell. [16] An examination of the literature pointedt oo ne ligand motif that might be less expensive than cyclam yet embody other desirable characteristics:t he pyridinecarboxamido group linked by an alkyl or aryl group.T hree variants of the ligand motif were examined;t he ÀCH 2 CH 2 À bridged (bpen 2À ), [17] ÀCH 2 CH 2 CH 2 À bridged (bppn 2À ), [18] and the ÀC 6 H 4 À bridged (bpb 2À ) [19] derivatives. Metal complexes of bpen 2À ,b ppn 2À ,a nd bpb 2À have been used previously as catalysts [20] and anticancer metallodrugs, [21] but not examined for RFB applications.T he nickel complexes Ni(bpen)·H 2 O, Ni(bppn)·H 2 O, and Ni(bpb)·H 2 O ( Figure 2) were synthesized in moderate yield by using av ariation of the literature procedure.…”

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Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries

et al. 2019

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The use of nickel complexes utilizing non-innocent ligands based on picolinamide to functiona sr edox carriers in flow batteries was explored. The picolinamidem oiety was linked together with ÀCH 2 CH 2 À (bpen), ÀCH 2 CH 2 CH 2 À (bppn), and ÀC 6 H 4 À (bpb) moieties, resulting in two, three, and four quasireversible waves, respectively,f or the nickel complexes and > 3V differenceb etween the outermost positivea nd negative waves. Ther edox events were theoretically modelled for each complex, showinge xcellent agreement (< 0.3 Vd ifference)b etween the experimental and modelled potentials. Bulk cycling of the most soluble complex, Ni(bppn), indicated only one of the three waves was reversible. Therefore, Ni(bppn) has the ability to act as an egative charge redox carrier in flow cells.Although lithium ion batteries tend to dominate the headlines, grid-scale energy storagew ill be served by av ariety of technologies depending on the time period of service. [1] For several decades, one technology attractive for > 4h of discharge is the redox flow battery (RFB, Figure 1). In contrastt os econdary batteries, in which the energy is stored within stationarye lectrodes, RFBs store and release energy from ar edox reaction between soluble chemical species, called redox carriers. At ypical non-hybrid RFB design has two storage tanks for the redox carriers that can be scaled independently of the cell, thereby imparting greater flexibility than as econdary battery,i nw hich power and energy are coupled( Figure1). Aqueousv anadium RFBs are the most developed technology availabley et suffer from the high cost of precursors (vanadium) and low stored energy density.D emand for improvements in energy storage has seen RFB research explode with significant advances: [2] greatly improved vanadium RFBc apacities, [3] identification of

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Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries

et al. 2019

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“…Several previous RFBs of this type have been reported, including devices based on vanadium acetylacetonate, nickel(II)-1,4,8,11-tetraazacyclotetradecane and various ruthenium complexes. [21][22][23] Very recently, chromium complexes capable of oxidation about the metal center and reduction on the ligands, have been successfully demonstrated in SRFBs. 24 Here we aim to expand on the nascent work on this interesting type of battery system by first discussing in detail, with the help of simple simulations, several key benefits that accrue from operating a redox flow battery using a symmetric electrolyte.…”

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On the Benefits of a Symmetric Redox Flow Battery

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et al. 2015

J. Electrochem. Soc.

151

177

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Redox flow batteries (RFBs) are of interest for large-scale energy storage, but implementation has been challenged by their low energy density, high complexity, high cost, and insufficient lifetime due to several types of irreversible losses in the electrolyte. To address the issue of system complexity and irreversible losses, we have undertaken a detailed analysis of the concept of the symmetric redox flow battery, or SRFB, which relies on a single parent molecule as the charge storage species in both the positive and negative electrode reactions. Herein we elaborate on the operating principles and advantages of a SRFB and report the salient electrochemical properties of a class of organic molecules, diaminoanthraquinones (DAAQs) as promising candidates for use in SRFB redox electrolytes. Modeling of various modes of operation for SRFBs are presented along with an example of an operational, lab-scale SRFB based on a DAAQ system. © The Author Renewable energy sources are rapidly growing in both implementation and research interest due to rising fossil fuel prices and concerns over pollution and climate change.1 However, a major challenge for implementing renewables, such as wind and solar, on a large scale, is their inherent temporal intermittency. For continued growth of renewables, while maintaining the expected level of stability/reliability in the energy grid, significant advances are needed in the area of large-scale energy storage. 2-7Electrochemical energy storage (EES) systems have been broadly identified as promising for short-term grid leveling and long-term energy storage.8 Of the available technologies, redox flow batteries (RFBs) are gaining increasing levels of attention as a viable approach for grid-scale EES.9-13 RFBs differ from conventional batteries in that charge is stored in a pair of liquid-phase redox couples with disparate electrochemical potentials, unlike the solid-phase anodes and cathodes used in conventional batteries (e.g. Li ion, Ni-Cd, and Pb-acid).14 Thus, these liquid species can be stored in tanks of arbitrary size and flowed through separate electrode stacks to store and recover electrical energy. These properties lend well to modular, flexible designs that decouple energy density and power. RFBs also enjoy comparatively high stability due to the lack of phase changes upon cycling.Most of the existing RFB technologies rely on aqueous transition metal redox couples. [9][10][11][12][13] The most common systems use transition metal cations in various oxidation states such as the Fe-Cr system 15 or the extensively studied aqueous vanadium flow battery (VFB). 16Hybrid systems have also been developed that make use of a solidliquid phase change at one electrode, such as the Zn-bromide flow cell.12 Implementations of RFBs are still in their early stages, and several significant research challenges have precluded their scalable implementation. Some of the major challenges include (1) low energy density, (2) high system cost and (3) limited lifetime. 9,13,17 The VFB is the most widely ...

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“…[3][4][5] As energy is stored externally to the electrochemical reactor,t he capacity can be increased independently of the battery power.A tp resent,c ommercial RFBs utilize aqueous electrolyte solutions of inorganic metal salts, however, despite continualp rogress in powero utputs and efficiencies being made, the cell potentiali si nherently limitedb y the narrow (1.23 V) electrochemical window of water.I nstead, the developmento fn onaqueous RFBs, which use organic solvents with wide electrochemical windows,i sa nticipated to improve the voltage outputs. [12][13][14][15] Indeed, several metal coordination complexes have been tested as electrolytes for nonaqueous RFBs with cell potentials in excess of 1.23 V; these contain acetylacetonate, [12,[16][17][18][19][20][21] bipyridine, [13,15,[22][23][24][25] phenanthroline, [26,27] terpyridine-like, [14,15] trimetaphosphate, [28] and macrocyclic [29,30] ligands. [11] Metal-ligandc oordination complexes are good candidates for nonaqueous RFBelectrolytes as they can be stable in multiple oxidation states and have high solubility in organic solvents.F urthermore, careful choice of metal ion as well as modification of the ligand scaffold (e.g.,s olubilizing groups, denticity,d onorg roups) can allow for fine tuning of the desired properties for RFB applications.…”

Section: Introductionmentioning

confidence: 99%

“…[11] Metal-ligandc oordination complexes are good candidates for nonaqueous RFBelectrolytes as they can be stable in multiple oxidation states and have high solubility in organic solvents.F urthermore, careful choice of metal ion as well as modification of the ligand scaffold (e.g.,s olubilizing groups, denticity,d onorg roups) can allow for fine tuning of the desired properties for RFB applications. [12][13][14][15] Indeed, several metal coordination complexes have been tested as electrolytes for nonaqueous RFBs with cell potentials in excess of 1.23 V; these contain acetylacetonate, [12,[16][17][18][19][20][21] bipyridine, [13,15,[22][23][24][25] phenanthroline, [26,27] terpyridine-like, [14,15] trimetaphosphate, [28] and macrocyclic [29,30] ligands.…”

Section: Introductionmentioning

confidence: 99%

Dithiolene Complexes of First‐Row Transition Metals for Symmetric Nonaqueous Redox Flow Batteries

2019

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Five metal complexes of the dithiolene ligand maleonitriledithiolate (mnt2−) with M=V, Fe, Co, Ni, Cu were studied as redox‐active materials for nonaqueous redox flow batteries (RFBs). All five complexes exhibit at least two redox processes, making them applicable to symmetric RFBs as single‐species electrolytes, that is, as both negolyte and posolyte. Charge–discharge cycling in a small‐scale RFB gave modest performances for [(tea)2Vmnt], [(tea)2Comnt], and [(tea)2Cumnt] whereas [(tea)Femnt] and [(tea)2Nimnt] (tea=tetraethylammonium) failed to hold any significant capacity, indicating poor stability. Independent negolyte‐ and posolyte‐only battery cycling of a single redox couple, as well as UV/Vis spectroscopy, showed that for [(tea)2Vmnt] the negolyte is stable whereas the posolyte is unstable over multiple charge–discharge cycles; for [(tea)2Comnt], [(tea)2Nimnt], and [(tea)2Cumnt], the negolyte suffers rapid capacity fading although the posolyte is more robust. Identifying a means to stabilize Vmnt 3−/2− as a negolyte, and Comnt 2−/1−, Nimnt 2−/1−, and Cumnt 2−/1− as posolytes could lead to their use in asymmetric RFBs.

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A tetradentate Ni(II) complex cation as a single redox couple for non-aqueous flow batteries

Cited by 43 publications

References 31 publications

Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries

Linked Picolinamide Nickel Complexes as Redox Carriers for Nonaqueous Flow Batteries

On the Benefits of a Symmetric Redox Flow Battery

Dithiolene Complexes of First‐Row Transition Metals for Symmetric Nonaqueous Redox Flow Batteries

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