Redox Flow Batteries for stationary storage applications

Transcription

1 Redox Flow Batteries for stationary storage applications Dr. P. Fischer, Prof. Dr. J. Tuebke New Dehli, Fraunhofer

2 Redox Flow Application Center Dep. of Applied Electrochemistry Germany Germany Folie 2

3 Redox Flow Battery - principle Membrane Electrode Electrode Electrolyt e + - Electrolyt e Pump Pump Pow er source/load Folie 3

4 Redox Flow Battery - principle Folie 4

5 Redox Flow Battery - principle flow frame terminal bipolar plate electrode membrane redox flow battery stack each electrochemical cell consists of bipolar plate/ current collector embedded in flow frame, electrode felt and separator/ membrane Folie 5

6 Redox Flow Battery - principle Small-size RFB (Adiro/ Fraunhofer ICT for Festo Didaktik) Folie 6

7 Redox Flow Battery - principle Large-scale RFB (Fraunhofer ICT ) Folie 7

8 Redox Flow Battery - Chemistry Requirements for the perfect flow battery: High solubility of active species: solubility has the biggest impact on energy density. Due to the solubility single ion/ molecule flow batteries are preferred over mixed electrolytes. High potential difference: a high potential difference also increases energy density. A OCP of more than 1V is preferential Highly conductive electrolyte: a highly conductive electrolyte can be achieved with aqueous electrolytes only. The best conductive electrolytes are mid-concentrated strong acids or alkalines. Folie 8

9 Redox Flow Battery - Chemistry Requirements for the perfect flow battery: stable material: side reactions can decrease capacity and may cause problems no side reactions on electrode material: especially hydrogen evolution can decrese efficiency fast kinetic of electrode reaction: prefferred is a highly reversible reaction Folie 9

10 Redox Flow Battery - Chemistry Requirements for the perfect flow battery: hihgly abundant active material: decreasing material costs, the active material has to be abundant and always available low toxic material: Hazardous materials makes it more difficult to fullfill legal requirements of bigger installations ethical issues: it should be also taken care, that the materials are mined/ produced under justifiable conditions. Folie 10

11 Redox Flow Battery - Chemistry There are not many real flow battery chemistries with two inert electrodes with aqueous electrolyte. These fewcanbesubcathegorized: Image: Carretero-Gonzalez et al, Energy Environ. Sci., 2016, 9, Image: K. Gong et al, ACS Energy Le/. 2016, 1, singleion: all-vanadium, all-chromium, all-iodine, all-uranium, all-neptunium, indigocarmine, polyoxymetallates anion-/ cathion couple: vanadium bromide, chromium bromide mixedelectrolyte: ironchromium, vanadiumcerium, polysulfide bromide, titanium iron, quinones bromine, quinone ferricyanide, iron TEOA Folie 11

12 Redox Flow Battery - Chemistry There are three other cathegories, which are calles hybride flow batteries. These are combinationsofan inert electrodewith a metal deposition/ intercalation electrode like zincbromine, zinccerium, zincferricyanide, all-copper a gas diffusionelectrodelike Vanadium air, hydrogen vanadium, hydrogen bromine, hydrogen iron Folie 12

13 Redox Flow Battery - Chemistry Therearestill flowbatteries, whichdoesnot fit into these cathegories, because they don t exhibit inert electrodes Extended secondary batteries like alllead flow battery, nickel-zinc flow battery Image: University South Hampton Slurrysystemslike zincslurryair, organic slurry with aqueous electrolytes Image: Wattech Power Folie 13

14 Redox Flow Battery historic systems Some commercialized systems were unfortunately not successfull ironchromium nocompanyat themoment, but some in the past(enervault) Regenesys project polysulfidebromide-nocompanyat the moment, but some in the past(regenesys) zinccerium -nocompanyat themoment, but some in the past(plurion) Enervault iron chromium battery Folie 14

15 Redox Flow Battery state of the art cabinet system single-/ multi container system Therearetwocommercialsystemsestablishedin themarket. all-vanadium - companieslike Sumitomo electrics, RongkePower, UniEnergy, ThyssenKruppC. andmanymanymore zincbromine companieslike redflow, EnSync, Primus Power, Meineng Energy, Lotte Chemical, Jofemar They usually come in different sizes, but mostly as container systems. platform system Folie 15

16 Redox Flow Battery - principle Type Vanadium / Vanadium Vanadium / Bromine Iron / Chromium Polysulfide / Bromine Energy Density of Electrolyte [Wh/L] Current Density [ma/cm²] Power Density [W/m² electrode] Cell Voltage [V] (25 C, 1 mol/l electrolyte conc.) ~ 800 1,40-1, % , % ~ 200 1,18 75 % ~ 800 1, % Zinc / Bromine 28 >100 ~ , % Cerium / Zinc ,00-2,40 Lead 75 ~ ,00 EE Folie 16

17 Redox Flow Battery state of the art V 2 O 5 percipitation above 40 C 1. day 2. day 3. day 4. day Drawbacks: There are some drawbacks of the commercial system. There is a limited temperatur window of VRFB due to percipation of electrolyte above 40 C. Regular operation temperatur window: 5 C 38 C Some electrolyte formulations are temperatur stable for higher temperatures (e.g. mixed acid electrolyte by UET) Folie 17

18 Redox Flow Battery state of the art Drawbacks: The vanadium price is quite constant during the last 5 years at around 6 8 $/lb. Nevertheless tis price limits capacity costs of electrolyte to ~60-80 $/kwh. New financial models like leasing are evaluated at the moment to deacrtease costs. Image: TTP Sqaures Inc. / Vanitec Folie 18

19 Redox Flow Battery state of the art Drawbacks: Bromine storage on the other hand needs some safety requirements. Complexing agents are used to bind free bromine to prevent bromine evaporation. Image: University of Sydney Also zinc deposition has to be depleated completely in certain time frames to avoid irregular deposition and dendride formation. These so called stripping cycles can increase cycle live. Nevertheless bromine batteries exhibit limited cycle life. Bromine complexing agents for zinc bromine batteries Folie 19

20 Redox Flow Battery emerging systems Therenewsystems, whichareverycloseto commercialization. Image: ViZn/ green Energy Times alkaline zinc ferricyanide/ iron ferricyanide companieslike Vizn, ESS Inc., WhEST, Arrotech, Epsilor aqueousorganic companieslike Jena Batteries, Kemwatt, Green Energy Storage hydrogen bromine companieslike Elestor, Enstorage aqueousmetalcomplex companieslike Lockheed Martin Image: Elestor Folie 20

21 Project - RedoxWind Fundedbythecountyof Baden Württemberg Lighthouseprojekt RedoxWind: storageoffluctuatingrenewablesin themegawattrange. Development anderectionofa 2 MW / 20 MWh redox flow battery Couplingofbatteryat directcurrentintermittentcircuitofthe2 MW wind at ICT Campus Development of cost efficient production technology for the production of stacks. Synnergies of shared power electronics in wind turbine and battery Folie 21

22 RedoxWind Energy Infrastruktur at Fraunhofer ICT 2MW wind turbine 2MW/20MWh VRFB 200 kw/200kwh LiFePo Battery Folie 22

23 Project RedoxWind Erection of the 2MW wind turbine For the battery a building was build with laboratories, workshops and testing facilities for flow batteries and the battery hall (20 x 30 m). The Building was finished end of In 2017 the company Qreon erected the 2MW wind turbine based on the Repower E82. The Qreon wind can connect the wind turbine with the VRFB as well as the 200kW/200kWh LIB battery (iron phosphate). Folie 23

24 Project RedoxWind- Images of the plant Planning the plant Folie 24

25 Project RedoxWind- Images of the plant Installation tanks/ filling with electrolyte Folie 25

26 Project RedoxWind- Images of the plant Installation of the piping The first module has been put in operation end of December Folie 26

27 Project RedoxWind- Images of the plant Current status Foto with courtesy of J. Schmalz GmbH & Co KG Current status: At the moment 42 Stacks are connected in the first half module and brought into operation. The first testing cycles confirms data of measured on individual stacks Nearly 360 t of the vanadium electrolyte has been filled in the tanks already. Wind turbineisin operation, but DC connection to battery will be established in 2018 Trumpf-Hüttinger DC-Power Electrinics für VRFB Folie 27

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