Influence of cell design and hydrodynamics on performance of redox flow batteries
Author
Giaquinto, Talitha
Term
4. term
Education
Publication year
2019
Submitted on
2019-06-07
Pages
79
Abstract
Redox-flowbatterier er lovende til lagring af svingende vedvarende energi, fordi energi (hvor længe) og effekt (hvor hurtigt) kan skaleres uafhængigt, hvilket kan sænke omkostningerne. Dette projekt fokuserede på alkaliske flowbatterier med redox-aktive organiske molekyler (kinoner) sammen med en opløsning af fødevaretilsætningsstoffet kaliumferricyanid; sådanne systemer kan opnå et cellepotentiale på omkring 1,2 V. Vi undersøgte 2,6-dihydroxyanthraquinon og 2,5-dihydroxy-1,4-benzoquinon og målte deres reduktionskinetik med cyklisk voltammetri, en standardteknik der fejer spændingen for at følge reaktionshastigheder, for at evaluere et nyindkøbt redox-flowbatteri med en kompakt 'zero-gap'-celle. Vi undersøgte også, hvordan strømning og hydrodynamik påvirker elektronoverførsel med en grænsestrøm-tilgang (limiting current), men denne metode gav ikke nyttige indsigter. Selvom resultaterne støttede valget af disse to kinoner som negolyter (elektrolytten på den negative side), opstod der praktiske problemer under test af flowbatteriet.
Redox flow batteries are promising for storing variable renewable energy because energy (how long) and power (how fast) can be scaled independently, which can reduce storage costs. This project focused on alkaline flow batteries that use redox-active organic molecules (quinones) together with a solution of the food additive potassium ferricyanide; such systems can reach a cell potential of about 1.2 V. We studied 2,6-dihydroxyanthraquinone and 2,5-dihydroxy-1,4-benzoquinone and measured their reduction kinetics with cyclic voltammetry, a standard technique that sweeps the voltage to track reaction rates, to evaluate a newly acquired redox flow battery with a compact 'zero-gap' cell design. We also examined how flow and hydrodynamics influence electron transfer using a limiting-current approach, but this method did not provide useful insights. Although the results supported selecting these two quinones as negolytes (the electrolyte on the negative side), practical issues arose during flow-battery testing.
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