Proton Conducting Electrolysers with Tubular Segmented-in-series - PowerPoint PPT Presentation

Proton Conducting Electrolysers with Tubular Segmented-in-series Cells for Hydrogen Production Marie-Laure Fontaine 1 , Einar Vøllestad 2 , Jonathan M. Polfus 1 , Wen Xing 1 , Zuoan Li 1 , Ragnar Strandbakke 2 , Christelle Denonville 1 , Truls Norby 2 , Rune Bredesen 1 1 SINTEF Materials and Chemistry, Norway 2 University of Oslo, Norway

Ceramic Electrolysers: utilizing waste heat ΔH 2H 2 + O 2 2H 2 O Solid Oxide Electrolyzers (SOE) PCE SOE • Well proven technology • Long term stability challenges • Delamination of O 2 -electrode • Higher temperature Proton Ceramic Electrolysers (PCE) • Less mature technology • Fabrication and processing challenges • Produces dry H 2 directly • Potentially intermediate temperatures • Slow O 2 -electrode kinetics 2

Operating Principles of Proton Ceramic Electrolysers (PCEs) e - U 2H 2 O O 2- 4H + 2H 2 O  O 2 + 4H + +4e - 4H + +4e -  2H 2 Z el,a Z el,c R ion O 2 R e- h + 0  e - + h + e - + h +  0 Anode Electrolyte Cathode 3

High temperature electrolyser with novel proton ceramic tubular modules (2014-2017) Development of tubular O 2 a b c O 2 O 2 O 2 O 2 H 2 O H 2 O e - H 2 O e - e - e - e - e - cathode supported H + H + H + e - e - e - O 2 electrolyte cell O 2- H + H + H + BZY H + BZY H + BZY H + e - Conductor Protonic conductor nanoparticles Mixed Oxygen ion-electronic conductor Development and Single tube module optimization of anodes development and and current collection testing Multi-tube module testing Aim: 1kW demo Process integration and evaluation 4

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

Scaling up tubular proton ceramic electrolysers Wet milling of precursors Extrusion of BZCY-NiO support Spray- or dip-coating Solid State Reactive Sintering Dip-coating suspensions BZCY-NiO paste BaZr 0.7 Ce 0.2 Y 0.1 O 3- δ (BZCY72) 6

Scaling up tubular proton ceramic electrolysers Dense electrolyte @ 1550 ° C – 24h 1610 ° C – 6h 40 μ m 7

Development of new steam electrode materials T ( ° C) T ( ° C) 750 700 650 600 550 500 450 400 350 800 600 400 2 100 1.5 1.0 1 10 2 ) 0.5 2 )) log (( R p ( Ω cm Log( R p,app ( Ω cm 2 ) R p,app ( Ω cm 0 1 0.0 GBCF / BZCY X = 0.1 BSCF / BCY X = 0.5 -0.5 Pr 2 NiO 4 / BCY X = 0* -1 0.1 LSCF / BCY X = 0.3 BGCF / BCY -1.0 BGLC (x=0) / BZCY 0.04 Ω cm 2 BCZF -2 0.01 -1.5 1.0 1.1 1.2 1.3 1.4 1.5 1.6 0.8 1.0 1.2 1.4 1.6 1.8 -1 ) 1000/T (K -1 ) 1000 / T (K Ba 1-x Gd 0.8 La 0.2+x Co 2 O 6- δ displays best PCE steam electrode performance (symmetrical disk samples) 8

Steam electrode processing 1. Cap and seal using glass-ceramic from CoorsTek 2. Deposit Ba 0.7 Gd 0.8 La 0.5 Co 2 O 6- δ as steam electrode by paint brush 3. Firing in dual atmosphere:  1000 °C  2% O 2 outside, 5% H 2 inside  E cell = 1.4 V during firing 4. Gold paste applied as current collector 9

Electrolysis with BGLC electrode Current (A) 0.00 0.25 0.50 0.75 1.00 5 700°C 650°C n -1 ) bends off o 4 600°C i t H 2 production (NmL min c u d 550°C o r p 700°C 100 H 2 3 c i a 650°C 550°C d a r -1 a 600°C F 600°C 2 550°C Faradaic efficiency (%) 650°C 700°C 80 0 1 2 ) // ( Ω cm 0 1 OCV Z 60 50 2.0 100 2 300 Potential (V) 1.5 3 700°C 650°C 550°C 600°C 40 Anode: 1.0 1.5 2.0 4 5 6 7 8 Cathode: p tot = 3 bar Potential (V) 1.0 / ( Ω cm 2 ) Z p H 2 O = 1.5 bar p tot = 3 bar p O 2 = 30 mbar p O 2 = 80 mbar p H 2 = 0.3 bar Post-characterization: poor electrode adhesion 0 50 100 150 200 -2 ) Current density (mA cm 10

Steam electrode processing 1. BZCY72-Ba 0.5 Gd 0.8 La 0.7 Co 2 O 6- δ applied as steam electrode  Fired in air at 1200°C for 5h  Infiltrated with nanocrystalline Ba 0.5 Gd 0.8 La 0.7 Co 2 O 6- 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% H 2 for 24h  Kept in electrolytic bias during reduction to avoid re-oxidation 11

Electrolysis with BZCY-BGLC composite electrode -2 ) Current Density (mA cm 0 100 200 20 Faradaic H 2 production -1 ) Z real ( Ω ) H 2 production (NmL min 600°C 15 0.3 0.4 0.5 0.6 0.7 0.8 0.9 4 500°C 10 700°C 600°C 2 400°C 5 -Z im 500°C 700°C 0 0 400°C 2.0 400°C 500°C Voltage (V) -2 600°C 700°C 1.5 4 5 6 7 8 9 Anode: Z real ( Ω cm 2 ) Cathode: p tot = 3 bar p H 2 O = 1.5 bar p tot = 3 bar 1.0 p O 2 = 30 mbar p O 2 = 30 mbar p H 2 = 0.5 bar 0 1 2 3 12 Current (A)

Improved faradaic efficiency primarily due to enhanced electrode kinetics 2.0 100 600C 4 -2 30 mA cm 80 Faradaic efficiency (%) Voltage (V) 2 ) 60 1.5 // ( Ω cm 2 Cell 1 40 Z 0 20 Cell 1 1.0 Cell 2 Cell 2 0 -2 0 50 100 150 200 4 5 6 7 8 9 -2 ) Current density (mA cm / ( Ω cm 2 ) Z 13

Segment-in-series: print masking Novel interconnects H 2 O+O 2 electrode Electrolyte H 2 electrode Porous support 14

Segment-in-series: print masking 15

Segment-in-series: print masking Various thermal profiles Pore formers and sintering aid • Addition of pore formers • Addition of sintering aid (A) in the electrode + + pore formers (B) in the Temperature: xx°C – xxh 0.5°C/min reduction of temperature support • 1500 °C 1450°C – xxh 1.6°C/min 350°C • 1525 °C 100°C 0.5°C/min 1530 °C • 1.6°C/min • 1540 °C RT RT • 1550 °C • 1600 °C xx°C – 10h Dwell: 1.6°C/min 1.6°C/min • 2h • 5h RT RT Electrolyte 10h • Electrode Support 16

Segment-in-series: print masking NiO- NiO- NiO- BZCY Support BZCY BZCY Support BZCY BZCY Collar for hang-firing

Segment-in-series: print masking 300 µ m BZCY72 NiO-BZCY72 BZCY72 BZCY72 NiO-BZCY72 BZCY72 30 µ m 30 µ m 30 µ m 18

Conclusions 2.0 100 80 Faradaic efficiency (%) Voltage (V) 60 1.5 • Tubular PCEs fabricated 40 • BZCY-NiO tubular cathode support 20 Cell 1 1.0 Cell 2 • Spray coated BZCY72 electrolyte 0 0 50 100 150 200 • BGLC-BZCY72 steam electrode -2 ) Current density (mA cm • 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

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 Fontaine 1 , Einar Vøllestad 2 , Jonathan M. Polfus 1 , Wen Xing 1 , Zuoan Li 1 , Ragnar Strandbakke 2 , Christelle Denonville 1 , Truls Norby 2 , Rune Bredesen 1 1 SINTEF Materials and Chemistry, Norway 2 University of Oslo, Norway