Protonic Ceramic Membrane Fuel Cells Research Articles

Fabrication of integrated BZY electrolyte matrices for protonic ceramic membrane fuel cells by tape-casting and solid-state reactive sintering

Integrated porous/dense/porous tri-layer BaZr0.8Y0.2O3-δ (BZY) electrolyte asymmetrical matrices were designed for protonic ceramic membrane fuel cells (PCMFCs) and fabricated by multilayer tape-casting and solid-state reactive sintering. The effects of pore-former, sintering aid and sintering program on the microstructure of integrated electrolyte matrices (IEMs) were studied. Graphite and NiO were appropriate pore-former and sintering aid, respectively, and an accelerated heating program was more desirable. The conductivities of the IEM with designed microstructure in different atmospheres were measured by AC impedance spectroscopy at 400–600 °C. The highest conductivity of 6.9 × 10−3 S cm−1 at 600 °C was obtained in wet air atmosphere, and the corresponding activation energy was 0.602 eV. Gas-tightness of the IEM was confirmed by a stable open circuit voltage (OCV) of 0.97 V at 600 °C from a button fuel cell with impregnated NiO anode and BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY) cathode. These indicate that the fabricated BZY-based IEM has great potential for PCMFC application.

Novel layered perovskite GdBaCoFeO 5+ δ as a potential cathode for proton-conducting solid oxide fuel cells

While cobalt-containing perovskite-type cathode materials facilitate the activation of oxygen reduction, they also suffer from problems like poor chemical stability in CO 2, high thermal expansion coefficients, etc. Partial B site substitution with Fe element is expected to be able to mitigate these problems while keeping high catalyst performance. In this paper, a layered perovskite GdBaCoFeO 5+ δ (GBCF) was developed as a cathode material for protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolyte of stable BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7). The button cells of Ni-BZCY7|BZCY7|GBCF were fabricated and tested from 600 to 700 °C with humidified H 2 (∼3% H 2O) as a fuel and ambient oxygen as oxidant. An open-circuit potential of 1.002 V, maximum power density of 482 mW cm −2, and a low electrode polarization resistance of 0.11 Ωcm 2 were achieved at 700 °C. The experimental results indicated that the layered perovskite GBCF is a good candidate for cathode material, while the developed Ni-BZCY7|BZCY7|GBCF cell is a promising functional material system for intermediate temperature solid oxide fuel cells.

GdBa 0.5Sr 0.5Co 2O 5+ δ layered perovskite as promising cathode for proton conducting solid oxide fuel cells

BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7) exhibits adequate proton conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered GdBa 0.5Sr 0.5Co 2O 5+ δ (GBSC) perovskite deposited on a doped ceria electrolyte demonstrates advanced electrochemical properties. This research fully takes advantage of these advanced properties and develops novel protonic ceramic membrane fuel cells (PCMFCs) of Ni-BZCY7|BZCY7|GBSC. The results show that the open-circuit potential of 1.003 V, maximum power density of 430 mW cm −2, and a low polarization resistance of the electrodes of 0.08 Ω cm 2 are achieved at 700 °C. With temperature increases, the total cell resistance decreases, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that GBSC perovskite cathode is a good candidate for intermediate temperature PCMFC development, while the developed Ni-BZCY7|BZCY7|GBSC cell is a promising functional material system for next generation SOFCs.

A novel cobalt-free layered GdBaFe 2O 5+ δ cathode for proton conducting solid oxide fuel cells

While cobalt-containing perovskite-type cathode materials facilitate the activation of oxygen reduction, they also suffer from problems like poor chemical stability in CO 2 and high thermal expansion coefficients. In this research, a cobalt-free layered GdBaFe 2O 5+ δ (GBF) perovskite was developed as a cathode material for protonic ceramic membrane fuel cells (PCMFCs) based on proton conducting electrolyte of stable BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7). The button cells of Ni–BZCY7|BZCY7|GBF were fabricated and characterized using complex impedance technique from 600 to 700 °C. An open-circuit potential of 1.007 V, maximum power density of 417 mW cm −2, and a low electrode polarization resistance of 0.18 Ω cm 2 were achieved at 700 °C. The results indicate that layered GBF perovskite is a good candidate for cobalt-free cathode material, while the developed Ni–BZCY7|BZCY7|GBF cell is a promising functional material system for solid oxide fuel cells.

Research Progress in the Electrolyte Materials for Protonic Ceramic Membrane Fuel Cells

Protonic ceramic membrane fuel cells have received great attentions because they provide an effective way to reduce the operating temperatures of solid oxide fuel cells.A brief overview of current development in protonic ceramic membrane fuel cells with high temperature proton-conducting electrolytes is given,which points out that the poor chemical stability of traditional electrolyte materials for the protonic ceramic membrane fuel cell is the main obstacle for their applications.The present development of high temperature proton conductors with high chemical stability as electrolyte materials for protonic ceramic membrane fuel cells is reviewed,as well as the influence of novel element doping strategies on the chemical stability,ionic conductivity and sinterability for BaCeO3-based materials.It also indicates the problems of high temperature proton conductors for protonic ceramic membrane fuel cells as well as their prospects.

A novel layered perovskite cathode for proton conducting solid oxide fuel cells

BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7) exhibits adequate proton conductivity as well as sufficient chemical and thermal stability over a wide range of SOFC operating conditions, while layered SmBa 0.5Sr 0.5Co 2O 5+ δ (SBSC) perovskite demonstrates advanced electrochemical properties based on doped ceria electrolyte. This research fully takes advantage of these advanced properties and develops novel protonic ceramic membrane fuel cells (PCMFCs) of Ni-BZCY7|BZCY7|SBSC. The results show that the open-circuit potential of 1.015 V and maximum power density of 533 mW cm −2 are achieved at 700 °C. With temperature increase, the total cell resistance decreases, among which electrolyte resistance becomes increasingly dominant over polarization resistance. The results also indicate that SBSC perovskite cathode is a good candidate for intermediate temperature PCMFC development, while the developed Ni-BZCY7|BZCY7|SBSC cell is a promising functional material system for next generation SOFCs.

Stable, easily sintered BaCe 0.5Zr 0.3Y 0.16Zn 0.04O 3− δ electrolyte-based proton-conducting solid oxide fuel cells by gel-casting and suspension spray

Protonic ceramic membrane fuel cells (PCMFCs) based on oxide proton conductors exhibit more advantages than traditional solid oxide fuel cells (SOFCs) based on oxygen-ion conducting electrolytes, such as low activation energy and high energy efficiency. In order to develop a simple and cost-effective route to fabricate PCMFCs with SrCo 0.9Sb 0.1O 3− δ (SCS) cubic perovskite cathode, a dense BaCe 0.5Zr 0.3Y 0.16Zn 0.04O 3− δ (BCZYZn) electrolyte was fabricated in situ metal oxide on a porous anode support by gel-casting and suspension spray, which is cost-effective, easy to realize, and suitable for mass-production. The key part of this process is to directly spray well-mixed suspension of BaCO 3, CeO 2, ZrO 2, Y 2O 3 and ZnO instead of pre-synthesized BCZYZn ceramic powder on the anode substrate. With SCS cubic perovskite cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H 2 as fuel and the static air as oxidant. An open-circuit potential of 0.987 V, a maximum power density of 364 mW cm −2, and a low polarization resistance of the electrodes of 0.07 Ω cm 2 was achieved at 700 °C.

Stable proton-conducting Ca-doped LaNbO 4 thin electrolyte-based protonic ceramic membrane fuel cells by in situ screen printing

In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs), a stable proton-conducting La 0.99Ca 0.01NbO 4 (LCN) thin electrolyte was fabricated on a porous NiO–La 0.5Ce 0.5O 1.75 (NiO–LDC) anode by in situ screen printing. The key part of this process is to directly print well-mixed ink of La 2O 3, CaCO 3 and Nb 2O 5 instead of pre-synthesized LCN ceramic powder on the anode substrate. After sintering at 1400 °C for 5 h, the full dense electrolyte membrane in the thickness of 20 μm was obtained. A single cell was assembled with (La 0.8Sr 0.2) 0.9MnO 3− δ –La 0.5Ce 0.5O 1.75 (LSM–LDC) as cathode and tested with humidified hydrogen as fuel and static air as oxidant. The open circuit voltage (OCV) and maximum power density respectively reached 0.98 V and 65 mW cm −2 at 800 °C. Interface resistance of cell under open circuit condition was also investigated.

In situ screen-printed BaZr 0.1Ce 0.7Y 0.2O 3− δ electrolyte-based protonic ceramic membrane fuel cells with layered SmBaCo 2O 5+ x cathode

In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs) with layered SmBaCo 2O 5+ x (SBCO) cathode, a dense BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY) electrolyte was fabricated on a porous anode by in situ screen printing. The porous NiO–BaZr 0.1Ce 0.7Y 0.2O 3− δ (NiO–BZCY) anode was directly prepared from metal oxide (NiO, BaCO 3, ZrO 2, CeO 2 and Y 2O 3) by a simple gel-casting process. An ink of metal oxide (BaCO 3, ZrO 2, CeO 2 and Y 2O 3) powders was then employed to deposit BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY) thin layer by an in situ reaction-sintering screen printing process on NiO–BZCY anode. The bi-layer with 25 μm dense BZCY electrolyte was obtained by co-sintering at 1400 °C for 5 h. With layered SBCO cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H 2 as fuel and the static air as oxidant. A high open-circuit potential of 1.01 V, a maximum power density of 382 mW cm −2, and a low polarization resistance of the electrodes of 0.15 Ω cm 2 was achieved at 700 °C.

Low-temperature protonic ceramic membrane fuel cells (PCMFCs) with SrCo 0.9Sb 0.1O 3− δ cubic perovskite cathode

The SrCo 0.9Sb 0.1O 3− δ (SCS) composite oxide with cubic perovskite structure was synthesized by a modified Pechini method and examined as a novel cathode for protonic ceramic membrane fuel cells (PCMFCs). At 700 °C and under open-circuit condition, symmetrical SCS cathode on BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7) electrolyte showed low polarization resistances ( R p) of 0.22 Ωcm 2 in air. A laboratory-sized tri-layer cell of NiO–BZCY7/BZCY7/SCS was operated from 500 to 700 °C with humidified hydrogen (∼3% H 2O) as fuel and the static air as oxidant. A high open-circuit potential of 1.004 V, a maximum power density of 259 mW cm −2, and a low polarization resistance of the electrodes of 0.14 Ωcm 2 was achieved at 700 °C.

High performance protonic ceramic membrane fuel cells (PCMFCs) with Ba 0.5Sr 0.5Zn 0.2Fe 0.8O 3−δ perovskite cathode

Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7) electrolyte based PCMFCs with stable Ba 0.5Sr 0.5Zn 0.2Fe 0.8O 3− δ (BSZF) perovskite cathode were investigated. Using thin membrane BZCY7 electrolyte (about 15 μm in thickness) synthesized by a modified Pechini method on NiO-BZCY7 anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.015 V, a maximum power density of 486 mW cm −2, and a low polarization resistance of the electrodes of 0.08 Ω cm 2 was achieved at 700 °C. The results have indicated that BZCY7 proton-conducting electrolyte with BSZF cathode is a promising material system for the next generation solid oxide fuel cells.

Stable, easily sintered BaCe 0.5Zr 0.3Y 0.16Zn 0.04O 3− δ electrolyte-based protonic ceramic membrane fuel cells with Ba 0.5Sr 0.5Zn 0.2Fe 0.8O 3− δ perovskite cathode

A stable, easily sintered perovskite oxide BaCe 0.5Zr 0.3Y 0.16Zn 0.04O 3− δ (BCZYZn) as an electrolyte for protonic ceramic membrane fuel cells (PCMFCs) with Ba 0.5Sr 0.5Zn 0.2Fe 0.8O 3− δ (BSZF) perovskite cathode was investigated. The BCZYZn perovskite electrolyte synthesized by a modified Pechini method exhibited higher sinterability and reached 97.4% relative density at 1200 °C for 5 h in air, which is about 200 °C lower than that without Zn dopant. By fabricating thin membrane BCZYZn electrolyte (about 30 μm in thickness) on NiO–BCZYZn anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.00 V, a maximum power density of 236 mW cm −2, and a low polarization resistance of the electrodes of 0.17 Ω cm 2 were achieved at 700 °C. This investigation indicated that proton conducting electrolyte BCZYZn with BSZF perovskite cathode is a promising material system for the next generation solid oxide fuel cells.

Prontonic ceramic membrane fuel cells with layered GdBaCo 2O 5+ x cathode prepared by gel-casting and suspension spray

In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs) with layered GdBaCo 2O 5+ x (GBCO) cathode, a dense BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7) electrolyte was fabricated on a porous anode by gel-casting and suspension spray. The porous NiO–BaZr 0.1Ce 0.7Y 0.2O 3− δ (NiO–BZCY7) anode was directly prepared from metal oxide (NiO, BaCO 3, ZrO 2, CeO 2 and Y 2O 3) by a simple gel-casting process. A suspension of BaZr 0.1Ce 0.7Y 0.2O 3− δ powders synthesized by gel-casting was then employed to deposit BaZr 0.1Ce 0.7Y 0.2O 3− δ (BZCY7) thin layer by pressurized spray process on NiO–BZCY7 anode. The bi-layer with 10 μm dense BZCY7 electrolyte was obtained by co-sintering at 1400 °C for 5 h. With layered GBCO cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H 2 as fuel and the static air as oxidant. An open-circuit potential of 0.98 V, a maximum power density of 266 mW cm −2, and a low polarization resistance of the electrodes of 0.16 Ω cm 2 was achieved at 700 °C.