Proton Conducting Electrolysers with Tubular Segmented-in-series Cells for Hydrogen Production Marie-Laure Fontaine1, Einar Vøllestad2, Jonathan M. Polfus1, Wen Xing1, ZuoanLi1, Ragnar Strandbakke2, Christelle Denonville1, Truls Norby2, Rune Bredesen1

1 SINTEF Materials and Chemistry, Norway2 University of Oslo, Norway

2

PCE SOE

2H2OΔH

2H2 + O2

Ceramic Electrolysers: utilizing waste heat

Solid Oxide Electrolyzers (SOE)• Well proven technology• Long term stability challenges

• Delamination of O2-electrode• Higher temperature

Proton Ceramic Electrolysers (PCE)• Less mature technology

• Fabrication and processing challenges• Produces dry H2 directly• Potentially intermediate temperatures

• Slow O2-electrode kinetics

Operating Principles of Proton Ceramic Electrolysers (PCEs)

3 Anode CathodeElectrolyte

2H2O

O2

4H+

Ue-

2H2O O2 + 4H+ +4e-

0 e- + h+ h+e- + h+ 0

RionZel,a Zel,c

Re-

4H+ +4e- 2H2

O2-

4

Development of tubular cathode supported

electrolyte cell

Development and optimization of anodes and current collection

Single tube module development and

testing

Multi-tube module testingAim: 1kW demo

H+

H+

H+

O2H2O

e-

e-

BZY

O2e-

O2

H+

H+

H+

H2O

e-

e-

BZY

O2

e-

H+

H+

H+

O2H2O

e-

e-

BZY

O2e-

O2-

Protonic conductor e- Conductor nanoparticlesMixed Oxygen ion-electronic conductor

a b c

Process integration and evaluation

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

Scaling up tubular proton ceramic electrolysers

• Why tubular design?• Simpler sealing technology, lower sealing area• Better stress distribution during transient

conditions• Module design enables to close off a tube /

replace it

• Segmented-in-series cells• Retain high voltage

6

Dip-coatingsuspensions

BZCY-NiO paste

Wet milling of precursors

Solid State Reactive Sintering

Extrusion of BZCY-NiO support

Spray- or dip-coating

Scaling up tubular proton ceramic electrolysers

BaZr0.7Ce0.2Y0.1O3-δ (BZCY72)

7

Dense electrolyte @ 1550°C – 24h1610°C – 6h

Scaling up tubular proton ceramic electrolysers

40 μm

8

Development of new steam electrode 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 (Ω

cm2 )

1000/T (K-1)

750 700 650 600 550 500 450 400 350T (°C)

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

0.8 1.0 1.2 1.4 1.6 1.8

-2

-1

0

1

2

X = 0.1 X = 0.5 X = 0* X = 0.3

Log(

Rp,

app(Ω

cm2 ))

1000 / T (K-1)

800 600 400

0.01

0.1

1

10

100

Rp,

app(Ω

cm2 )

T (°C)

0.04 Ωcm2

9

Steam electrode processing

1. Cap and seal using glass-ceramic from CoorsTek

2. Deposit Ba0.7Gd0.8La0.5Co2O6-δ as steam electrode by paint brush

3. Firing in dual atmosphere: 1000 °C

2% O2 outside, 5% H2 inside

Ecell = 1.4 V during firing

4. Gold paste applied as currentcollector

10

Electrolysis with BGLC electrode

0

1

2

3

4

5

550°C600°C650°C

700°C

Current (A)

700°C 650°C 600°C 550°C

H2 p

rodu

ctio

n (N

mL

min

-1)

Farada

ic H 2

prod

uctio

n

0.00 0.25 0.50 0.75 1.00

0 50 100 150 200

1.0

1.5

2.0

700°C600°C550°C 650°C

Pot

entia

l (V

)

Current density (mA cm-2)

Anode:

pO2 = 30 mbarpH2 = 0.3 barptot = 3 bar

ptot = 3 bar

pO2 = 80 mbarpH2O = 1.5 bar

Cathode:1.0 1.5 2.0

40

60

80

100 550°C 600°C 650°C 700°C

Fara

daic

effi

cien

cy (%

)

Potential (V)4 5 6 7 8

3

2

1

0

-1

OCV 50 100 300

Z// (Ωcm

2 )

Z/ (Ωcm2)

bends off

Post-characterization: poor electrode adhesion

11

Steam electrode processing

1. BZCY72-Ba0.5Gd0.8La0.7Co2O6-δ

applied as steam electrode Fired in air at 1200°C for 5h

Infiltrated with nanocrystallineBa0.5Gd0.8La0.7Co2O6-δ

Thin Pt layer current collection

2. Capped and sealed at 1000°C Semi-dual atmosphere to keep BGLC

layer intact

3. NiO reduction at 800°C in 10% H2

for 24h Kept in electrolytic bias during

reduction to avoid re-oxidation

12

Electrolysis with BZCY-BGLC composite electrode

0

5

10

15

20

400°C

500°C

600°C

H2 p

rodu

ctio

n (N

mL

min

-1)

Farada

ic H 2

prod

uctio

n

700°C

0 100 200Current Density (mA cm-2)

0 1 2 3

1.0

1.5

2.0

Anode:

pO2 = 30 mbarpH2 = 0.5 barptot = 3 bar

ptot = 3 bar

pO2 = 30 mbar

400°C

500°C600°C

Vol

tage

(V)

Current (A)

700°C

pH2O = 1.5 barCathode:

4 5 6 7 8 9

-2

0

2

4

Zreal (Ωcm2)

400°C

500°C

600°C

-Zim

700°C

0.3 0.4 0.5 0.6 0.7 0.8 0.9Zreal (Ω)

Improved faradaic efficiency primarily due to enhanced electrode kinetics

13

4 5 6 7 8 9-2

0

2

4

Cell 1

Z// (Ωcm

2 )Z/ (Ωcm2)

Cell 2

600C30 mA cm-2

0 50 100 150 200

1.0

1.5

2.0

Cell 1 Cell 2

Vol

tage

(V)

Current density (mA cm-2)

0

20

40

60

80

100

Fara

daic

effi

cien

cy (%

)

Porous support

H2 electrode

H2O+O2 electrodeNovel interconnects

Electrolyte

14

Segment-in-series: print masking

15

Segment-in-series: print masking

Segment-in-series: print masking

16

Temperature:• 1500 °C• 1525 °C• 1530 °C• 1540 °C• 1550 °C• 1600 °C

• Addition of pore formers (A) in the electrode + reduction of temperature

Support

Various thermal profiles

Dwell:• 2h• 5h• 10h

Pore formers and sintering aid

• Addition of sintering aid + pore formers (B) in the support

RT RT

100°C

350°C

xx°C – xxh

1450°C – xxh

1.6°C/min

1.6°C/min

0.5°C/min

0.5°C/min

RT RT

xx°C – 10h

1.6°C/min 1.6°C/min

Electrolyte

Electrode

NiO-BZCY BZCY

NiO-BZCY BZCY

NiO-BZCYSupport Support

Collar for hang-firing

Segment-in-series: print masking

18

30 µm

300 µm

NiO-BZCY72

BZCY72

BZCY72

BZCY72

NiO-BZCY72

BZCY72

30 µm

30 µm

Segment-in-series: print masking

Conclusions

• Tubular PCEs fabricated• BZCY-NiO tubular cathode support• Spray coated BZCY72 electrolyte• BGLC-BZCY72 steam electrode

• Enhanced faradaic efficiencies observed with improved anode performance• Current densities of 220 mA cm-2 at 600°C obtained with > 80% faradaic efficiency• PCEs may suffer from electronic leakage due to p-type conductivity in oxidizing conditions

0 50 100 150 200

1.0

1.5

2.0

Cell 1 Cell 2

Vol

tage

(V)

Current density (mA cm-2)

0

20

40

60

80

100

Fara

daic

effi

cien

cy (%

)

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.

Marie-Laure Fontaine1, Einar Vøllestad2, Jonathan M. Polfus1, Wen Xing1, Zuoan Li1, Ragnar Strandbakke2, Christelle Denonville1, Truls Norby2, Rune Bredesen1

1 SINTEF Materials and Chemistry, Norway2 University of Oslo, Norway