Limited Accessibility to Surface Area Generated by Thermal Pretreatment of Electrodes Reduces Its Impact on Redox Flow Battery Performance

2021 ◽  
Author(s):  
Katharine V. Greco ◽  
Jude K. Bonesteel ◽  
Nicolas Chanut ◽  
Charles Tai-Chieh Wan ◽  
Yet-Ming Chiang ◽  
...  
Keyword(s):  
Surface Area ◽  
Redox Flow Battery ◽  
Thermal Pretreatment ◽  
Flow Battery

Limited Accessibility to Surface Area Generated by Thermal Pretreatment of Electrodes Reduces Its Impact on Redox Flow Battery Performance

2021 ◽  
Author(s):  
Katharine Greco ◽  
Jude Bonesteel ◽  
Nicolas Chanut ◽  
Charles Wan ◽  
Yet- Ming Chiang ◽  
...  
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Gas Adsorption ◽  
Active Species ◽  
Model Material ◽  
Carbon Paper ◽  
Thermal Pretreatment ◽  
Flow Battery ◽  
Redox Species ◽  
Physical Surface

Thermal oxidation of carbon electrodes is a common approach to improving flow battery performance. Here, we investigate how thermal pretreatment increases electrode surface area and the effect this added surface area has on electrode performance. Specifically, we rigorously analyze the surface area of Freudenberg H23 carbon paper electrodes, a binder-free model material, by systematically varying pretreatment temperature (400, 450, and 500 °C) and time (0 to 24 h) and evaluating changes in the physical, chemical, and electrochemical properties of the electrodes. We compare physical surface area, measured by a combination of gas adsorption techniques, to surface area measured via electrochemical double layer capacitance. We find good agreement between the two at shorter treatment times (0-3 h); however, at longer treatment times (6-24 h), the surface area measured electrochemically is an underestimate of the physical surface area. Further, we use gas adsorption to measure a pore size distribution and find that the majority of pores are in the micropore range (< 2 nm), and ca. 60% of the added surface area are in the sub-nanometer (< 1 nm) pore size range. We postulate that the solvated radii and imperfect wetting of electrochemical species may hinder active species transport into these recessed regions, explaining the discrepancy between electrochemical and physical surface area. These results are supported with in situ flow cell testing, where single-electrolyte polarization measurements show little improvement with increasing surface area. Further, using a simple convection-reaction model to simulate electrode overpotential as a function of surface area, we find that increasing surface area improves the performance to a point, but the mass transport to and the catalytic activity of the reaction sites offer greater comparative impact. Ultimately, this work aims to inform the design of electrodes that offer maximal accessible surface area to redox species.

Limited Accessibility to Surface Area Generated by Thermal Pretreatment of Electrodes Reduces Its Impact on Redox Flow Battery Performance

2021 ◽  
Author(s):  
Katharine Greco ◽  
Jude Bonesteel ◽  
Nicolas Chanut ◽  
Charles Wan ◽  
Yet- Ming Chiang ◽  
...  
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Gas Adsorption ◽  
Active Species ◽  
Model Material ◽  
Carbon Paper ◽  
Thermal Pretreatment ◽  
Flow Battery ◽  
Redox Species ◽  
Physical Surface

Thermal oxidation of carbon electrodes is a common approach to improving flow battery performance. Here, we investigate how thermal pretreatment increases electrode surface area and the effect this added surface area has on electrode performance. Specifically, we rigorously analyze the surface area of Freudenberg H23 carbon paper electrodes, a binder-free model material, by systematically varying pretreatment temperature (400, 450, and 500 °C) and time (0 to 24 h) and evaluating changes in the physical, chemical, and electrochemical properties of the electrodes. We compare physical surface area, measured by a combination of gas adsorption techniques, to surface area measured via electrochemical double layer capacitance. We find good agreement between the two at shorter treatment times (0-3 h); however, at longer treatment times (6-24 h), the surface area measured electrochemically is an underestimate of the physical surface area. Further, we use gas adsorption to measure a pore size distribution and find that the majority of pores are in the micropore range (< 2 nm), and ca. 60% of the added surface area are in the sub-nanometer (< 1 nm) pore size range. We postulate that the solvated radii and imperfect wetting of electrochemical species may hinder active species transport into these recessed regions, explaining the discrepancy between electrochemical and physical surface area. These results are supported with in situ flow cell testing, where single-electrolyte polarization measurements show little improvement with increasing surface area. Further, using a simple convection-reaction model to simulate electrode overpotential as a function of surface area, we find that increasing surface area improves the performance to a point, but the mass transport to and the catalytic activity of the reaction sites offer greater comparative impact. Ultimately, this work aims to inform the design of electrodes that offer maximal accessible surface area to redox species.

scholarly journals High surface area bio-waste based carbon as a superior electrode for vanadium redox flow battery

2017 ◽  
Vol 362 ◽  
pp. 50-56 ◽  
Author(s):  
Makhan Maharjan ◽  
Arjun Bhattarai ◽  
Mani Ulaganathan ◽  
Nyunt Wai ◽  
Moe Ohnmar Oo ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Vanadium Redox

scholarly journals 3D-printed conductive static mixers enable all-vanadium redox ow battery using slurry electrodes

2019 ◽  
Author(s):  
Matthias Wessling
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
State Of The Art ◽  
Graphite Powder ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Static Mixers ◽  
3D Printed ◽  
Vanadium Redox

State-of-the-art all-vanadium redox flow batteries employ porous carbonaceous materials as electrodes. The battery cells possess non-scalable fixed electrodes inserted into a cell stack. In contrast, a conductive particle network dispersed in the electrolyte, known as slurry electrode, may be beneficial for a scalable redox flow battery. In this work, slurry electrodes are successfully introduced to an all-vanadium redox flow battery. Activated carbon and graphite powder particles are dispersed up to 20 wt% in the vanadium electrolyte and charge-discharge behavior is inspected via polarization studies. Graphite powder slurry is superior over activated carbon with a polarization behavior closer to the standard graphite felt electrodes. 3D-printed conductive static mixers introduced to the slurry channel improve the charge transfer via intensified slurry mixing and increased surface area. Consequently, a significant increase in the coulombic efficiency up to 95% and energy efficiency up to 65% is obtained. Our results show that slurry electrodes supported by conductive static mixers can be competitive to state-of-the-art electrodes yielding an additional degree of freedom in battery design. Research into carbon properties (particle size, internal surface area, pore size distribution) tailored to the electrolyte system and optimization of the mixer geometry may yield even better battery properties.

A cobalt sulfide cluster-based catholyte for aqueous flow battery applications

2018 ◽  
Vol 6 (44) ◽  
pp. 21927-21932 ◽  
Author(s):  
Matthew B. Freeman ◽  
Le Wang ◽  
Daniel S. Jones ◽  
Christopher M. Bejger
Keyword(s):  
Active Material ◽  
Water Soluble ◽  
Molecular Cluster ◽  
Cobalt Sulfide ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Aqueous Flow ◽  
Sulfide Cluster

A water-soluble Co6S8 molecular cluster was prepared and electrochemically analyzed as a potential active material for redox flow battery applications.

Zirconium boride as a novel negative catalyst for vanadium redox flow battery

2021 ◽  
Author(s):  
Tongxue Zhang ◽  
Yingqiao Jiang ◽  
Zixuan Zhang ◽  
Jing Xue ◽  
Yuehua Li ◽  
...  
Keyword(s):  
Vanadium Redox Flow Battery ◽  
Zirconium Boride ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Vanadium Redox

scholarly journals Graphene-Based Electrodes in a Vanadium Redox Flow Battery Produced by Rapid Low-Pressure Combined Gas Plasma Treatments

2021 ◽  
Author(s):  
Sebastiano Bellani ◽  
Leyla Najafi ◽  
Mirko Prato ◽  
Reinier Oropesa-Nuñez ◽  
Beatriz Martín-García ◽  
...  
Keyword(s):  
Low Pressure ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Plasma Treatments ◽  
Gas Plasma ◽  
Vanadium Redox

Promoting vanadium redox flow battery performance by ultra-uniform ZrO2@C from metal-organic framework

2021 ◽  
Vol 415 ◽  
pp. 129014
Author(s):  
Yingqiao Jiang ◽  
Gang Cheng ◽  
Yuehua Li ◽  
Zhangxing He ◽  
Jing Zhu ◽  
...  
Keyword(s):  
Metal Organic Framework ◽  
Vanadium Redox Flow Battery ◽  
Redox Flow Battery ◽  
Flow Battery ◽  
Metal Organic ◽  
Vanadium Redox ◽  
Organic Framework
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