Professor: Nyt flowbatteri har lovende fremtid

En ny type flowbatteri kan ifølge en dansk professor vise sig meget konkurrencedygtigt. Batteriet skal drives af organiske molekyler i stedet for dyre, specielle metaller.

En gruppe forskere fra Harvard University i USA har fundet frem til, at quinon-molekyler, der optræder som en almindelig del af biologisk betydningsfulde molekyler, som blandt andet indgår i fotosyntesen, gør det muligt.

»Forskningen er en ny vinkel på flowbatterier, som jeg ikke har set tidligere. Her har man lavet et flowbatteri uden brug af metaller og med en ganske udmærket performance,« siger Tejs Vegge, der er professor ved Institut for energikonvertering og -lagring på DTU.

Hurtig og besparende løsning

Man har ikke tidligere anvendt organiske molekyler som quinon i flowbatterier, men forskningen viser, at der kan skabes en proces, hvor man kan reducere og oxidere molekylerne relativt hurtigt.

»Hastigheden af processen er essentiel for effekten – altså hvor meget energi man kan overføre pr. tidsenhed. Og her foregår det altså relativt hurtigt,« forklarer Tejs Vegge.

Læs også: Nyt materiale kan sikre gennembrud for flowbatterier til vindmøllestrøm

Han påpeger, at metaller er dyre i de enorme mængder, man skal bruge til lagring af vedvarende energi på grid-skala. Det taler for flowbatterierne.

»Der er flere ting, der er kritiske for flowbatterier. Hvis man skal have et batteri, der skal kunne opskaleres til at lagre vedvarende elektricitet fra vind eller sol, så skal det også helst være billigt. Og her kan den nye måde, hvor man ikke anvender metaller, vise sig at være en prismæssigt konkurrencedygtig løsning,« siger Tejs Vegge.

Stadig rum for forbedring

Ifølge Tejs Vegge er batteriet fra Harvard ikke en givet succes endnu. Der er stadig plads til en del forbedringer.

»Optimalt skal flowbatteriet kunne holde til at cykle mange gange, gerne op imod 10.000. I dette projekt har man indtil videre kun forsøgt sig med at cykle relativt få gange,« konstaterer han.

Læs også: Nyt batteri dropper følsom membran

Derudover mister batteriet lidt effektivitet i forhold til for eksempel lithium-ion-batterier, fordi elektrolyten skal pumpes mekanisk rundt, og spændingen ser ikke umiddelbart ud til at være helt så god som på andre flowbatterier.

»Men det er første forsøg, og jeg vil vurdere, at projektet virkelig har potentiale. Hvis de kan få det til at fungere stabilt, så er der rigtig mange muligheder for forskellige typer af molekylære flowbatterier. Samtidig konkluderer forskerne selv, at de kan forbedre det ved at ændre molekylet en lille smule. Hvis det sker, så er der virkelig potentiale for denne type flowbatterier,« konstaterer Tejs Vegge.

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..... er der nogen derude, der ved hvordan det går med den teknik man skrev en del om for 3-4 år siden, der ville bruge et vædskebaseret energibæremedie, som så kunne transporteres - f.eks. fra solcelleanlæg i Sahara - og pumpes på bilerne('s "batterier") lidt ligesom kulbrinteprodukter, blot med den forskel at der her dannes et "udtømt" returprodukt, der skal "genoplades".?? Det lød lidt mere anvendeligt end ovenstående teknologi - hvis den første da vel at mærke stadig holder hvad man stillede os i udsigt.

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Som jeg læser dit spørgsmål er det faktisk flow batterier du spørger til.

Problemet er at selvom der er sket store fremskridt med flow batterier er energitætheden stadig alt for lav til køretøjer, og tænkes derfor primært til energilagring i store stationære tanke.

se evt. http://en.wikipedia.org/wiki/Energy_density http://en.wikipedia.org/wiki/Flow_battery et hurtigt overslag giver at flow batterier har en energitæthed på ca 1/3 af Li-ion batterier.

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Ja, man kan godt kalde det for et flowbatteri, i og med at der sker et vædskeflow igennem batteriet, Den teknik jeg tænkte på (jeg HAR fundet den efterfølgende), betegner opfinderne kun delvist som et flowbatteri, helt præcist et "alkylic-carbonate-electrolyte semi-solid lithium-ion flow battery", men efterfølgende har man valgt at fokusere forskningen i retning af andre (billigere) materialer end lithium.

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»Optimalt skal flowbatteriet kunne holde til at cykle mange gange, gerne op imod 10.000. I dette projekt har man indtil videre kun forsøgt sig med at cykle relativt få gange,« konstaterer han.

Her står ellers at det kan holde til 5.000 ladecykler:

University of Southern California. (2014, June 25). Scientists create new battery that's cheap, clean, rechargeable ... and organic. ScienceDaily http://www.sciencedaily.com/releases/2014/... Citat: "... "The batteries last for about 5,000 recharge cycles, giving them an estimated 15-year lifespan," said Sri Narayan, professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences ... "Such organic flow batteries will be game-changers for grid electrical energy storage in terms of simplicity, cost, reliability and sustainability," said Prakash. ..."

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Harvard University. (2015, September 24). Green storage for green energy: Rechargeable battery to power a home from rooftop solar panels. ScienceDaily: http://www.sciencedaily.com/releases/2015/... Citat: "... In the operation of the battery, electrons are picked up and released by compounds composed of inexpensive, earth-abundant elements (carbon, oxygen, nitrogen, hydrogen, iron and potassium) dissolved in water. The compounds are non-toxic, non-flammable, and widely available, making them safer and cheaper than other battery systems. ... "We combined a common organic dye with an inexpensive food additive to increase our battery voltage by about 50 percent over our previous materials," says Gordon. The findings "deliver the first high-performance, non-flammable, non-toxic, non-corrosive, and low-cost chemicals for flow batteries." ... Their new battery, described in a paper published today in the journal Science, replaces bromine with a non-toxic and non-corrosive ion called ferrocyanide. ..."

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Friedrich-Schiller-Universitaet Jena. (2015, October 21). Synthetic batteries for the energy revolution: Chemists present an innovative redox-flow battery based on organic polymers and water. ScienceDaily: http://www.sciencedaily.com/releases/2015/... Citat: "... In the redox-flow battery of the Jena scientists, on the other hand, novel synthetic materials are used: In their core structure they resemble Plexiglas and Styrofoam (polystyrene), but functional groups have been added enabling the material to accept or donate electrons. No aggressive acids are necessary anymore; the polymers rather 'swim' in an aqueous solution. "Thus we are able to use a simple and low-cost cellulose membrane and avoid poisonous and expensive materials," Tobias Janoschka, first author of the new study, explains. ... In first tests the redox-flow battery from Jena could withstand up to 10,000 charging cycles without losing a crucial amount of capacity. The energy density of the system presented in the study is ten watt-hours per liter. Yet, the scientists are already working on larger, more efficient systems. In addition to the fundamental research at the University, the chemists develop their system, within the framework of the start-up company JenaBatteries GmbH, towards marketable products. ..."

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DOE/Pacific Northwest National Laboratory. (2015, December 21). New flow battery offers lower-cost energy storage: Organic battery will be cheaper than standard vanadium flow battery. ScienceDaily http://www.sciencedaily.com/releases/2015/... Citat: "... The organic aqueous flow battery, described in a paper published in the journal Advanced Energy Materials, is expected to cost $180 per kilowatt-hour once the technology is fully developed. The lower cost is due to the battery's active materials being inexpensive organic molecules, compared to the commodity metals used in today's flow batteries. ... PNNL's new flow battery features two main electrolytes: a methyl viologen anolyte (negative electrolyte) and a 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl, or 4-HO-TEMPO catholyte (positive electrolyte). A third, supporting electrolyte carries sodium chloride, whose chloride ions enable the battery to discharge electricity by shuffling electrons in the central stack. ... To test the new battery design, Wang and his colleagues created a small, 600-milliwatt battery on a lab countertop. They repeatedly charged and then discharged the battery at various electric current densities, ranging from 20 to 100 milliAmperes per square centimeter. The test battery's optimal performance was between 40 and 50 milliAmperes per square centimeter, where about 70 percent of the battery's original voltage was retained. They also found the battery continued to operate well beyond 100 cycles. ..."

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Nov 27, 2015, physicsworld.com: New high-capacity battery goes with the flow: Citat: "... Wang and colleagues have developed a new type of redox-flow battery in which the cathodic tank contains lithium–iron-phosphate granules and the anodic tank contains granules of titanium dioxide. ... When the battery is discharged, the reaction runs in reverse, returning the lithium to the cathode. Because the lithium is stored in solid form in both of the charged and discharged states of the battery, the energy density of the new lithium-flow battery is about 500 Wh/l. This is around 10 times that of a vanadium redox battery. ..." High–energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane: http://advances.sciencemag.org/content/1/1...

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