Beyond energy density: flow battery design driven by safety and location

Reber, David; Jarvis, Sam; Marshak, Michael P.

doi:10.1039/d3ya00208j

Cited by 7 publications

(6 citation statements)

References 39 publications

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“…Highthroughput systems are needed that can electrochemically cycle commercially relevant high-concentration electrolytes with full capacity accessed, but the economic role of electrolyte energy density in AORFBs for stationary grid storage should also still be considered. 94,95…”

Section: Constant Current Constant Voltage (Cccv)mentioning

confidence: 99%

High-Throughput Electrochemical Characterization of Aqueous Organic Redox Flow Battery Active Material

Fell,

Aziz

2023

J. Electrochem. Soc.

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The development of redox-active organics for flow batteries providing long-discharge-duration energy storage requires an accurate understanding of molecular lifetimes. Herein we report the development of a high-throughput setup for the cycling of redox flow batteries. Using common negolyte redox-active aqueous organics, we benchmark capacity fade rates and compare variations in measured cycling behavior of nominally identical volumetrically unbalanced compositionally symmetric cells. We propose figures of merit for consideration when cycling sets of identical cells, and compare three common electrochemical cycling protocols typically used in battery cycling: constant current, constant current followed by constant voltage, and constant voltage. Redox-active organics exhibiting either high or low capacity fade rates are employed in the cell cycling protocol comparison, with results analyzed from over 50 flow cells.

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Section: Constant Current Constant Voltage (Cccv)mentioning

confidence: 99%

High-Throughput Electrochemical Characterization of Aqueous Organic Redox Flow Battery Active Material

Fell,

Aziz

2023

J. Electrochem. Soc.

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“…Although the 2 M cell had a CE comparable to the 1 M cells, the maximum discharge power density for the RFB was only 232 mW cm −2 , as would be expected with the more viscous electrolyte. Our results highlight the tradeoff between higher energy density (high concentration) and reduced energy efficiency (high viscosity) [29,30]. To demonstrate cell cycling with the highest concentration of active species that can be achieved in the mixed electrolyte system, a cell was assembled using a negolyte containing 1 M each of the Cr(1,2-and 1,3-PDTA) species with 0.1 M borate buffer for a total 2 M Cr concentration at pH 7.4 (10 mL).…”

Section: Resultsmentioning

confidence: 79%

Disparate Redox Potentials in Mixed Isomer Electrolytes Reduce Voltage Efficiency of Energy Dense Flow Batteries

Davis,

Waters,

Robb

et al. 2023

Batteries

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Electrolytes containing multiple redox couples are promising for improving the energy density of flow batteries. Here, two chelated chromium complexes that are structural isomers are characterized and combined to generate electrolytes containing up to 2 M of active species, corresponding to 53.6 Ah L−1. The mixed isomer approach enables a significantly higher active material content than the individual materials would allow, affording energy dense cells with Coulombic efficiencies of ≥99.6% at 100 mA cm−2 and an open circuit voltage of 1.65 V at 50% state-of-charge. This high concentration, however, comes with a caveat; at a given concentration, an equimolar mixed electrolyte leads to lower voltage efficiency compared to using the individual isomers, while Coulombic efficiency remains constant. Our work demonstrates that exploiting structural isomerism is an efficient approach to improve capacity, but active materials must be selected carefully in mixed systems as differences in operating potentials negatively affect energy efficiency.

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“…Much of the concern regarding the lower volumetric energy density of RFBs, in comparison to Li-ion batteries, is somewhat unfounded for stationary energy storage systems i.e., concern for areal footprint of RFB systems may be overstated. 19 One expected trade-off is increased solubility contributing to increased electrolyte viscosity, thus leading to increased pumping requirements and mass-transport limitations. 20,21 Additionally, significant reductions in RAOM costs are still required before the cost of larger tanks (due to lower active species concentrations) becomes a considerable contribution to the total system cost.…”

mentioning

confidence: 99%

Leveraging Temperature-Dependent (Electro)Chemical Kinetics for High-Throughput Flow Battery Characterization

Fell,

George,

Jing

et al. 2024

J. Electrochem. Soc.

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The library of redox-active organics that are potential candidates for electrochemical energy storage in flow batteries is exceedingly vast, necessitating high-throughput characterization of molecular lifetimes. Demonstrated extremely stable chemistries require accurate yet rapid cell cycling tests, a demand often frustrated by time-denominated capacity fade mechanisms. We have developed a high-throughput setup for elevated temperature cycling of redox flow batteries, providing a new dimension in characterization parameter space to explore. We utilize it to evaluate capacity fade rates of aqueous redox-active organic molecules, as functions of temperature. We demonstrate Arrhenius-like behaviour in the temporal capacity fade rates of multiple flow battery electrolytes, permitting extrapolation to lower operating temperatures. Collectively, these results highlight the importance of accelerated decomposition protocols to expedite the screening process of candidate molecules for long lifetime flow batteries.

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Beyond energy density: flow battery design driven by safety and location

Abstract: As renewable energy penetration increases, energy storage is becoming urgently needed for several purposes, including frequency control, peak shifting, and relieving grid congestion. While battery research often focuses on cell...

Cited by 7 publications

References 39 publications

High-Throughput Electrochemical Characterization of Aqueous Organic Redox Flow Battery Active Material

High-Throughput Electrochemical Characterization of Aqueous Organic Redox Flow Battery Active Material

Disparate Redox Potentials in Mixed Isomer Electrolytes Reduce Voltage Efficiency of Energy Dense Flow Batteries

Leveraging Temperature-Dependent (Electro)Chemical Kinetics for High-Throughput Flow Battery Characterization

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