Development ofTubular Proton Conducting Electrolysers Einar - - PowerPoint PPT Presentation

Development ofTubular Proton Conducting Electrolysers

Einar Vøllestad2, M.L. Fontaine1, C. Denonville1, R. Strandbakke2, J.M. Serra3, D.R. Beeaff4, C. Vigen4 and T. Norby2

1 SINTEF Materials and Chemistry, 2 University of Oslo, 3 CSIC, 4 CoorsTek Membrane Sciences AS

Development ofTubular Proton Conducting Electrolysers

Einar Vøllestad2, M.L. Fontaine1, C. Denonville1, R. Strandbakke2, J.M. Serra3, D.R. Beeaff4, C. Vigen4 and T. Norby2

1 SINTEF Materials and Chemistry, 2 University of Oslo, 3 CSIC, 4 CoorsTek Membrane Sciences AS

• Why high temperature proton ceramic

electrolysers?

• Processing and performance of early-stage

single cells

• Up-scaling strategies for tubular proton

ceramic electrolysers

High temperature electrolysis enables utilization of waste heat resources

PCE SOE

2H2O

ΔH 2H2 + O2

Key differences between SOE and PCE

• advantages and challenges

 Solid Oxide Electrolysers

 Well proven technology

 Scalable production  High current densities at thermo-neutral voltage

 Long term stability challenges

 Delamination of O2-electrode  Oxidation and degradation of Ni-electrode with high

steam contents

 High temperatures

 Proton Ceramic Electrolysers

 Less mature technology

 Fabrication and processing challenges

 Produces dry H2 directly  Potentially intermediate temperatures

 Slow O2-electrode kinetics

U 2O2- 2H2O 2H2 O2 SOEC

600-800°C

4e-

U 4H+ 2H2 O2 2H2O PCEC

400-700°C

4e-

Development of tubular cathode supported electrolyte cell Development and

• ptimization of anodes

and current collection Single tube module development and testing Multi-tube module testing Aim: 1kW demo

H+

BZY

O2 e- O2 H+

BZY

O2 e- H+ H+ H+ O2 H2O e- e-

BZY

O2 e- O2-

Protonic conductor e- Conductor nanoparticles Mixed Oxygen ion-electronic conductor

a b c

Process integration and evaluation

High temperature electrolyser with novel proton ceramic tubular modules (2014-2017)

Tubular half-cell production

Dip-coating suspensions NiO based paste

Wet milling of precursors Solid State Reactive Sintering Extrusion of BZCY-NiO support Spray- or dip-coating

BZCY72 // BZCY72-NiO BZY10 // BZY10-NiO BZY10 // BZCY72-NiO Dense electrolyte @ 1550°C – 24h 1610°C – 6h Porous electrolyte @ 1550°C – 24h 1610°C – 6h 1650°C – 6h 1670°C – 6h Dense electrolyte @ 1550°C – 24 h 1610°C – 6 h

100 microns 100 microns 100 microns 40 microns 40 microns 40 microns

Development of new anode materials

1.0 1.1 1.2 1.3 1.4 1.5 1.6

• 1.5
• 1.0
• 0.5

0.0 0.5 1.0 1.5

GBCF / BZCY BSCF / BCY Pr2NiO4 / BCY LSCF / BCY BGCF / BCY BGLC (x=0) / BZCY BCZF

log ((Rp (Ωcm

2)

1000/T (K

• 1)

750 700 650 600 550 500 450 400 350

T (°C)

Ba1-xGd0.8La0.2+xCo2O6-δ displays best PCE O2-H2O-electrode performance (symmetrical disk samples)

0.8 1.0 1.2 1.4 1.6 1.8

• 2
• 1

1 2

X = 0.1 X = 0.5 X = 0* X = 0.3 Log(Rp,app(Ωcm

2))

1000 / T (K

• 1)

800 600 400 0.01 0.1 1 10 100

Rp,app(Ωcm

2)

T (°C) 0.04 Ωcm

2

Anode processing on tubular cells

Electrolysis tests using gold as the current collector Fired in dual atmosphere with applied bias:

• 2% O2 outside, 5% H2 inside
• Ecell = 1.4

V during firing (above 500°C) Steam electrode (BGLC785) drip-coated and brush-painted Capped and sealed using custom-made glass ceramic (CoorsTek Membrane Sciencies) Single segment, reduced at 1000°C for 24h in 5% H2

Electrolysis tests of single cell

50 100 150 200 250 1.0 1.5 2.0 600°C 550°C 650°C 700°C

Potential (V) Current (mA cm

• 2)

pO2: 80 mbar pH2O: 1.5 bar pH2: 300 mbar

Improved performance with increasing steam content and current load

4 5 6 7 8 3 2 1

• 1

OCV 11 mA cm

• 2

21 mA cm

• 2

64 mA cm

• 2

Z

// (Ωcm 2)

Z

/ (Ωcm 2)

Both electrolyte and electrode performance improved with increased steam content

0.00 0.05 0.10 0.15 0.20 0.25 0.8 1.0 1.2 1.4 1.6 1.8

pH2O: 1.5 bar pH2O: 0.5 bar Voltage (V) Current density (mA cm

• 2)

High ohmic resistance indicates current collection limitations

Electrode resistance an order of magnitude higher than expected values from button cell testing

50 100

• 0.4
• 0.2

0.0 0.2 0.4 0.6 0.8

Rp (Ωcm

2)

Log(Rp (Ωcm

2))

I (mA cm

• 2)

550 600 600 (x =0.5) 650 700 700 (x = 0.5)

1

Target: 0.2Ωcm2

1.0 1.2 1.4 1.6

• 2
• 1

1 2

1000/T (K

• 1)

log(Rp(Ωcm

2))

RP (x = 0) RP modelled RP modelled (x = 0) RP (x = 0.3) RP (x = 0.5)

700 600 500 400 0.01 0.1 1 10 100

Rp(Ωcm

2)

T (°C)

Tube segment 1.5 bar steam Button cell wet air

Scaling up – segmented tubes to drive up the voltage

Scaling up – stacking individual segments

Scaling up – “Printing in series”

Segmented-in-series tubular cells

Porous support H2 electrode (PCEC cathode) H2O+O2 electrode (PCEC anode) with integrated and patterned external current collection Novel interconnects

H2O + O2 flow H2 flow

Electrolyte Novel external current collectors at closed/open ends of tube

1 1

BZCY (SSRS) + sintering aid + pore formers

2

BZY10 (SSRS or oxide)

• r BZCY72 (SSRS or
• xide)

+ NiO

3

BZCY72 or BZY10 (SSRS or

• xide)

Manufacturing process

Powder conditioning Pastes preparation Production of tubes by extrusion and collars Dip-coating

• f tubes

Slurries preparation Annealing of tubes (hang- firing)

• Milling of SSRS

precursors and

• xide powders
• Drying
• Sieving
• Batching
• Water based slurry

for SSRS mixtures

• Organic based

slurries for oxide mixtures

• Drying
• Cutting
• Masking and coating
• Drying in air (organic

based coating) or at 60°C for water based suspensions

Green supports with electrodes Green support coated with cathode (green) and electrolyte (white) layers Hang-firing of cells

Clean room activities

3 cm 20 cm

Parameters investigated

Supports Support + fuel electrode Support + fuel electrode + electrolyte Shrinkage; porosity

• Annealing
• PF content
• Sintering aid

Shrinkage, porosity

• Coated part
• Uncoated part

Thickness of electrode

• Viscosity
• Powder loading

Shrinkage, porosity

• Coated part
• Uncoated part

Thickness of electrode

• Viscosity
• Powder loading

Thickness and densification

• f electrolyte
• Oxide vs SSRS
• Powder loading

NiO- BZC Y BZCY electrolyte NiO- BZC Y BZCY electrolyte NiO- BZC Y Support Support 100 µm 100 µm 50 µm 50 µm 50 µm

 Broken section: several segments; non-optimized sintering

Optimized processing parameters for multi-layer sintering

23

30 µm 300 µm

 Dense electrolyte  Dense NiO-BZCY (porosity will be generated by NiO reduction to Ni)  Porous BZCY support

Conclusions

 High temperature proton ceramic electrolysers can produce dry,

pressurized hydrogen

 Processing and manufacturing of tubular half cells is now well established  State-of-the-art electrolyser anodes are developed on button cell scale



Deposition and firing protocols for tubular cells currently being developed

 Segmented-in-series tubular cells are needed to reduce total current of

tubes in real operational conditions

Acknowledgements

The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n° 621244.

Thank you for your attention!