Assessment methods and performance metrics for redox flow batteries

Yao, Yanxin; Lei, Jiafeng; Shi, Yang; Ai, Fei; Lu, Yi‐Chun

doi:10.1038/s41560-020-00772-8

Cited by 272 publications

(216 citation statements)

References 51 publications

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“…3a. We considered triplet (t 2g 4 ) and quintet (t 2g 3 e g 1 ) states for each Cr II -based compound in order to nd the energetic stable spin states (Table S4). 1a and Supplementary Fig.…”

Section: Theoretical Consideration By Dft Simulation Of Chromium-based Compoundsmentioning

confidence: 99%

“…The high solubility also bene ts to increase the available energy densities and the output current would be controlled by the size of the electrode stacks in RFBs. Of course, aqueous systems are advantageous in many aspects of: they are inexpensive, environmentally benign, and highly soluble rather than the use of organic liquid systems 4 . As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…These Fe II/III redox couples are expected to be more stable as a posolyte with a combination of cyanide ligands that have extensively used to a posolyte material in RFB reference [11][12][13][14] . However, the redox chemistry of Cr II/III in chromium-based negolytes generally involves strong Jahn-Teller effects due to the unequal occupation of electrons in e g orbitals of high-spin Cr II (d 4 ) as shown in Fig. 1b.…”

Section: Introductionmentioning

confidence: 99%

“…[CrCl 6 ] 4-, [Cr(H 2 O) 6 ] 2+ , and [Cr(NH 3 ) 6 ] 2+ are stable in their quintet states (high-spin state), whereas [Cr(CN) 6 ]4is stable in its triplet states (low-spin state); these nding are consistent with conventional understanding that strong-eld ligands such as CNresult in low-spin states due to their large d orbital splitting.Since the Cr II -based compounds with high-spin state have single electron at e g states, thereby leading to strong Jahn-Teller distortions, bonds with two ligands along z direction are more elongated than the bonds with other fours, as shown in Fig.3b. In contrast, [Cr(CN) 6 ] 4has weak Jahn-Teller distortions due to unevenly occupied t 2g orbitals in the low-spin state, allowing for negligible elongation of bonds along the z direction.3a.…”

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confidence: 99%

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Hexacyanometallate aqueous flow battery

Jang¹,

Kim²,

Lee³

et al. 2021

Preprint

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Aqueous redox flow batteries (RFBs) have attracted significant attention as energy storage systems by virtue of their inexpensive nature and long-lasting features. Although all-vanadium RFBs exhibit long lifetimes, the cost of vanadium resources fluctuates considerably, and is generally expensive. Iron–chromium RFBs take advantage of utilizing a low-cost and large abundance of iron and chromite ore; however, the redox chemistry of CrII/III generally involves strong Jahn–Teller effects. Herein, we introduce a new Cr-based negolyte coordinated with strong-field ligands capable of mitigating strong Jahn–Teller effects, thereby facilitating low redox potential, high stability, and rapid kinetics. Density functional theory (DFT) calculations reveal that the complex of [Cr(CN)6]4− prefers low-spin states, facilitating a stable and fast redox reaction. The prototype full-cell configuration features a high-energy density of 11.4 Wh L− 1 and a stable lifetime of 250 cycles. Consequently, our proposed system opens new avenues for the development of high-performance RFBs.

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“…3a. We considered triplet (t 2g 4 ) and quintet (t 2g 3 e g 1 ) states for each Cr II -based compound in order to nd the energetic stable spin states (Table S4). 1a and Supplementary Fig.…”

Section: Theoretical Consideration By Dft Simulation Of Chromium-based Compoundsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Hexacyanometallate aqueous flow battery

Jang¹,

Kim²,

Lee³

et al. 2021

Preprint

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“…Electrochemical energy storage techniques which can balance the intermittent production and smooth consumption are effective routes to fulfill the highly penetration of renewable energy sources [1–3] . Among them, redox flow batteries (RFBs) are one of the most promising large‐scale energy storage technology ascribed to the decoupled energy capacity and power output, long lifetime, full charge and discharge capability, high safety and environmental‐friendly [4–9] . As depicted in Figure 1, RFBs comprise three main components: electrolyte, electrode, and ion exchange membrane.…”

Section: Introductionmentioning

confidence: 99%

Application of Nanomaterials in Aqueous Redox Flow Batteries

2021

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It is challenging to directly integrate renewable energies into the grid due to the inherent random and intermittent nature. Electrochemical energy storage techniques which can balance the intermittent production and smooth consumption are effective routes to fulfill the highly penetration of renewable energy sources. Among them, redox flow batteries (RFBs) are regarded as promising large‐scale energy storage and conversion devices attributed to the flexible design, long lifetime and high safety. Electrode and ion exchange membrane materials have crucial influences on cell performance of RFBs in terms of efficiency, rate performance, output power density and cyclability. Application of nanomaterials to obtain advanced electrode and membrane materials has prompt improvements of aqueous RFBs. This minireview includes the design, synthesis, and application of nanomaterials in preparation of both electrodes and ion exchange membranes for aqueous RFBs. Furthermore, current challenges and future prospects of application of nanomaterials in aqueous RFBs are outlined. We expect to provide a guide for the fabrication of advanced electrodes and membranes incorporation of nanomaterials towards high performance and low cost RFBs in future.

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