Current Development Trends and Challenges for Redox-Flow Batteries

Current Development Trends and Challenges for Redox-Flow Batteries Jens Noack1,2, Nataliya Roznyatovskaya1,2, Nicholas Gurieff2,3, Chris Menictas2,3, Jens Tübke1,2, Maria Skyllas-Kazacos2,3 1

Fraunhofer-Institute for Chemical Technology, Joseph-von-Fraunhofer-Str. 7, 76327 Pfinztal, Germany German-Australian Alliance for Electrochemical Technologies for Storage of Renewable Energy, Mechanical and Manufacturing Engineering, University of New South Wales (UNSW), UNSW Sydney NSW 2052 Australia 3 University of New South Wales (UNSW), UNSW Sydney NSW 2052 Australia 2

1900

1E+01

1800 1700

Current density (mA/cm²)

Treatment potential (mV) vs. Hg/Hg2SO4

2000

1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500

1E-03

-0,24 -0,12

0

0,12

0,24

0,36

Potential (V) vs. NHE

1

© CENELEST

1E-01

0,48

0,6

CENELEST

 German-Australian Alliance for Electrochemical Technologies for Storage of Renewable Energy  Project to establish a center (CENELEST) at UNSW/Sydney  Project start 08/2017, Collaboration Fraunhofer ICT - UNSW 2

© CENELEST

What is a Flow Battery?

3

© CENELEST

What is a Flow Battery?

4

© CENELEST

Development Trends – Active Material Redox Flow Batteries Aprotic conventional molecular solvents and ILs

One-phase (all-liquid)

Ru(bpy) Ni(bpy)/Fe(bpy) Ru(acac) V(acac) Cr(acac) Mn(acac) U(acac) Co(acacen) V(mnt) TEMPO/NMPI DBBB/TMQ Fe(TEA)/Br

Two-phases (suspension, nanofluids etc.)

LiCoO2/LTO Li/15D3GAQ LiFePO4/LTO Li/Fe Na/EMICl-Fe Cu/Cu(DEA-EHN) Cu/Cu(Cholinchlorid)

Protic Electrolytes

One-phase (all liquid)

V/V V/Fe V/BrCl V/Ce Cr/Fe Cr/Br Cr/Cr S/Br POxM Ti/Fe Ti/BrCl Np/Np I/I Fe(EDTA)/Br Cr(EDTA) Quinones/Br MV/TEMPO Org/Org

5

© CENELEST

Two-phases (hybrid)

Zn/Ni Zn/Br Zn/Cl Zn/BrCl Zn/V Zn/Ce V/O2 Fe/Fe Cd/Br Pb/Pb Cu/Cu Cu/Pb Zn/PANI Cd/Chloranil Pb/Tyron V/Glyoxal(O2) V/Cystine (O2)

Two-phases (liquid/gaseous)

H/Br H/Cl H/Fe H/V

Modelling for Flow Batteries

Electrochem is try Reaction mechanism

S y s tem Pumps Heat management BMS

6

Š CENELEST

Half-Cell Fluid dynamics

Heat

TechnoEconom ics Costs

Cell

S tack

Membrane

Shunt currents

Microgrid LCOE Energy flow

Churrent Challenges Redox Flow Batteries  General

 Electrolyte

 Lifetime!

 Cheap and/or recycling

 Invest Cost (Stack, Aktive Material)

 Recombination/Regeneration ?

 Current density / material cost  Recycling  VRFB

 Stack  Microporous Separators  Thermoplastic Electrodes

 Lifetime !

 Replacement of felt

 Electrode

 Production Technology !

 Membrane

 Active Material Recycling

 Organic Flow Batteries

 Electrolyte Regeneration (O2, H2)

 Stable redox couples in the whole potential range of the battery !

 Electrolyte impurities

 Potential of redox couples

7

© CENELEST

Electrochemistry Electrochemical equilibrium: Nernst Eq. Current-overpotential behavior:

-

C x  z  z e-

Ax

 C x  z  c RT      0  ln zF   Ax  a   

   

     0'

 zF  (1RT) zF  i  i0  e  e RT    Butler-Volmer-Eq.

Cyclic Voltammetry Linear Sweep Voltammetry Rotating Disc Electrode Impedance Spectroscopy Chronopotentiometry & voltammetry Spectroelectrochemistry (UV-VIS, IR, RAMAN, ESR)

Properties of active materials, electrodes, electrolytes 8

© CENELEST

VRFB – Electrochemical Treatment of Electrodes

1

0



1,2

0,001 1E-4

1,0

1E-5

0,8

1E-6

0,6

1E-7

0,4

polished electrode

1E-8 0,2 1E-9

0,8

1,0

1,2

1,4

1,6

1,8

400

2,0

600

800

1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800

1E+00

1E-01

1E-02

700 600 500

1000 1200 1400 1600 1800 2000 2200

1E-03

0,994

Treatment potential (mV) vs. Hg/Hg2SO4

Potential (V) vs. NHE

Current density (mA/cm²)

2

iref

0,01

Symmetry factor 

3

Reference current density (mA/cm²)

Current Density / mA/cm²

4

1,4

Treatment potential (mV) vs. Hg/Hg2SO4

2000

0,1 red 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000

5

1,194

1,394

1,594

1,794

Potential (V) vs. NHE

3

2

1

0

1,00 0,95

1 0,90 0,1

0,85 0,80

0,01

0,75 0,001

0,70

1E-4

0,60

iref

1E-5

 1E-6

-0,3

-0,2

-0,1

0,0

0,1

0,2

0,3

0,4

600

J. Noack et al., Journal of Energy Chemistry, 2018 in Press

© CENELEST

800

1000

1200

1400

1600

Treatment potential (mV) vs. Hg/Hg2SO4

Potential (V) vs. NHE

9

0,55 0,50

400

-0,4

0,65

polished electrode

1800

Symmetry factor 

Current Density / mA/cm²

4

Reference current density (mA/cm²)

red 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000

1900

1E+01

1800 1700

Current density (mA/cm²)

10

5

Treatment potential (mV) vs. Hg/Hg2SO4

2000

1600 1500 1400 1300 1200 1100 1000 900 800

1E-01

700 600 500

1E-03

-0,24 -0,12

0

0,12

0,24

0,36

Potential (V) vs. NHE

0,48

0,6

VRFB – Influence of Counter Ion theor. Ucell

1.38 V 1.46 V 1.40 V

Complexation: V(III) HCl>MSA>H2SO4 V(IV) H3PO4 >HCl~MSA~H2SO4

Chemical stability of V(V): HCl: unstable at SOC 100% at RT, reacts with chloride H2SO4 : stable (RT and till 2 days at 50°C)

iR post-corrected CV curves

10

© CENELEST

Energy efficiency (cell performance) 0.8V to 1.65 V HCl: 73% H2SO4 : 75%

Organic Flow Batteries

Source: Fraunhofer ICT.

• • •

rough estimate of UOCV electrochem. reversibility/irreversibility, kinetics no information about products, i.e. their stability

11

© CENELEST

•

Example: in case of crossover complete inhibition of anodic and cathodic half-cell reactions

Microporous Separators for Flow and Non-Flow Batteries 100

1,8

12 1,0

10

0,9

6

40

2 0 1,2

-2

0,8

EE, CE, VE

60

4

1,4

Capacity /Ah

Voltage /V

0,7 0,6 0,5

-4

FAP-450 Porous Mb-1 Porous Mb-2 Nafion 117

20

0 20

30

40

50

60

70

1,0

0,4

-6

Voltage Capacity

0,8 22

23

Current Density (mA/cm²)

24

25

-10 26

27

28

29

EE CE VE

0,3

-8

0,2

-12 30

0

50

100

150

200

250

300

Cycle Nr

Time /h

25

-

-

Porous MB-2 is an ASAHI for ZnBr RFB (not produced anymore) ~50 $/m² V(V) stability test can result in false negative results (O2)

20 15

Ah-Step [Ah]

Eenergy Efficiency (%)

8

1,6

80

10 5 0

-

Bjorn Hage Consulting MPM still running for 7 months now with negative V(V) stability test (2 weeks stability) ~30 $/m²

-5 -10 -15 0

-

Passive blancing possible with MPM

12

© CENELEST

50

100

Time [d]

150

200

Technoeconomics - VRFB

-> 1078 €/kWh @ 50 mA/cm²; Cpower = 7923 €/kW, Cenergy = 417 €/kWh 13

© CENELEST

Technoeconomics - VRFB

 Iso-cost line at 30 S/m and 5000 S/m - Advantages from mechanical properties, but contact resistance  Cell voltage is important for expensive power! (Cu/Cu)  The same for current density (Li-RFB) 14

© CENELEST

Velocity (m/s)

Frame Simulation – Novel Geometries

0,025

0,025

0,1

0,020

0,020

0,08

0,015

0,015

0,06

0,010

0,010

0,04

0,005

0,005

0,02

0

0,000

0,000

0

50

100

Depth (mm)

15

© CENELEST

0

50

100

Depth (mm)

0

50

100

150

Depth (mm)

200

250

Computer Tomography of Stacks (1 kW class stack)

- 2D & 3D Measurements - Construction Details - Any size !

- Possibility for time resolved measurements - Flow distribution in cells 16

Š CENELEST

VRFB – Upscaling to 2 MW/20 MWh

2MW wind turbine

2MW/20MWh VRFB 200 kW/200kWh LiFePo Battery

17

© CENELEST

VRFB – Upscaling to 2 MW/20 MWh

18

© CENELEST

VRFB – Upscaling to 2 MW/20 MWh

The first module has been put in operation end of December 2017.

19

© CENELEST

VRFB – Upscaling to 2 MW/20 MWh 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 turbine is in operation, but DC connection to battery will be established in 2018

Trumpf-Hüttinger DC-Power Electrinics für VRFB 20

© CENELEST

Thank you for your attention!

Jens Noack Fraunhofer ICT Joseph-von-Fraunhofer-Str. 7 76327 Pfinztal/Germany

Jens Noack CENELEST University of New South Wales UNSW Sydney NSW 2052 Australia

Jens.Noack@ict.fraunhofer.de

info@cenelest.org

21

© CENELEST