Proton-Conducting Fuel Cells Research Articles

Tailoring BaCe0.7Zr0.1(Dy0.1|Yb0.1)0.2O3−δ electrolyte through strategic Cu doping for low temperature proton conducting fuel cells: Envisioned theoretically and experimentally

This study addresses the challenge of high sintering temperatures in proton-conducting fuel cells (PCFCs) with BaCeO3-doped electrolytes. We demonstrate that 1 mol% copper (Cu) doping at the B-site of BaCe0.7Zr0.1(Dy0.1|Yb0.1)0.2O3−δ (BCZDYb) improves sintering behavior, enabling densification at 1400 °C. However, Cu doping disrupts stoichiometry, creating barium vacancies and reducing proton-accepting cations, affecting overall conductivity. This mechanism is confirmed through density functional theory (DFT) calculations and various experimental techniques, including crystal structure analysis using X-ray diffraction (XRD) and morphology and elemental analysis via field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS). Electrochemical measurements are performed using the electrochemical impedance spectroscopy (EIS). The ionic conductivity of 1 mol% Cu-doped BCZDYb (BCZDYb-1) is 1.49×10−2 S cm−1 at 650 °C, which is 3.8 times higher than that of BCZDYb sintered at 1200 °C. The BCZDYb-1 exhibits ∼3.5 times higher conductivity when sintered at 1200 °C and ∼16 times higher grain boundary conductivity when sintered at 1400 °C, compared to undoped BCZDYb. The single cell employing BCZDYb-1 as the electrolyte achieved a power density of ∼606 mW cm−2 at 550 °C. These results indicate that a controlled amount of Cu doping can enhance densification while maintaining high ionic conductivity, making it suitable for practical applications in PCFCs operating at lower temperatures.

High proton conductivity within the ‘Norby gap’ by stabilizing a perovskite with disordered intrinsic oxygen vacancies

Proton conductors are attractive materials with a wide range of potential applications such as proton-conducting fuel cells (PCFCs). The conventional strategy to enhance the proton conductivity is acceptor doping into oxides without oxygen vacancies. However, the acceptor doping results in proton trapping near dopants, leading to the high apparent activation energy and low proton conductivity at intermediate and low temperatures. The hypothetical cubic perovskite BaScO2.5 may have intrinsic oxygen vacancies without the acceptor doping. Herein, we report that the cubic perovskite-type BaSc0.8Mo0.2O2.8 stabilized by Mo donor-doing into BaScO2.5 exhibits high proton conductivity within the ‘Norby gap’ (e.g., 0.01 S cm−1 at 320 °C) and high chemical stability under oxidizing, reducing and CO2 atmospheres. The high proton conductivity of BaSc0.8Mo0.2O2.8 at intermediate and low temperatures is attributable to high proton concentration, high proton mobility due to reduced proton trapping, and three-dimensional proton diffusion in the cubic perovskite stabilized by the Mo-doping into BaScO2.5. The donor doping into the perovskite with disordered intrinsic oxygen vacancies would be a viable strategy towards high proton conductivity at intermediate and low temperatures.

Defect Engineering inside Electrolyte for Rapid Proton Conduction

Proton conducting fuel cells (PCFCs) are promising energy conversion devices that are expected to perform better at lower temperatures than conventional solid oxide fuel cells (SOFCs) because they have higher ionic conductivity and lower activation energy than SOFCs below 600℃. In particular, the ionic conductivity at 500°C of BaZr0.4Ce0.4Y0.1Yb0.1O3- δ, one of the most promising electrolyte materials among proton conductors, is same to that of Y0.08Zr0.92O2- δ, the most used electrolyte material among oxygen conductors at 700℃. However, below 500℃, which is the target temperature of the PCFCs, the cathode resistance is much larger than the electrolyte resistance, so the expected performance is not achieved. In this work, we propose an electrolyte structure that can significantly lower the interfacial resistance between cathode and electrolyte by accelerating proton supply to cathode. Concentration gradient of defects is generated inside the electrolyte with a perovskite structure due to the difference in the gas environment between the cathode and anode. In conventional PCFCs, this does not have a significant effect on the ion conduction inside the electrolyte. However, the electrolyte structure, which we proposed, could control the defect concentration gradient inside the electrolyte, and this can eventually generate the steeper proton defect concentration gradient into the cathode than conventional PCFCs. As a result, rapid proton supply to cathode is possible. Through the defect engineering, it is possible to achieve a maximum power density of 0.9 W/cm2 and an electrode resistance of 0.8 ohm cm2 at 500℃. Figure 1

Co-Generation of Hydrogen and Propylene Via Proton Conducting Fuel Cell Under Intermediate Temperature

Propylene and hydrogen are the two primary products of the proposed process. Propylene is an important raw material for polymer synthesis and chemical manufacture, while hydrogen is widely used in refining petroleum, treating metals, producing fertilizer, and processing foods. At present, the dominant technology for producing propylene is steam cracking, which is highly energy intensive and low energy efficiency due to side reactions and severe coke formation. This work demonstrates an electrochemical process which is achieved through a deprotonation reaction at the catalyst-assisted anode of an electrochemical membrane reactor (EMR) to co-produce propylene and hydrogen, using a highly active 3D ultra-porous nickel-free deficient layered perovskite anode, BaZrCe (BZC) electrolyte and Ni-cermet cathode. The electrochemical propane dehydrogenation reaction (PDR) performance was evaluated and optimized by varying reaction parameters, including current density, voltage, propane concentration, and temperature. Preliminary thermal catalytic measurements in a fixed bed flow reactor using a dilute (10%) propane gas as the feedstock. The results showed that propane conversion could reach up to 40% at 550°C. By reducing operation temperature to 350-500°C, the technology also improves the durability of the catalyst and the electrochemical system. Therefore, the proposed technology represents an innovative and significant improvement with respect to existing commercial processes.

Interface-reinforcing sintering step for highly stable operation of proton-conducting fuel cell stack

Proton conducting fuel cells (PCFCs) are promising power generation systems due to their low operating temperature by conducting proton activated with low kinetic energy. However, well-known proton conducting materials such as Y-doped BaCeO3−δ (BCY), Y-doped BaZrO3−δ (BZY), and BaCe0.8-xZrxY0.1Yb0.1O3−δ (BCZYYb) have a limitation in that the planar cell is fragile during operation attributed to the low mechanical strength. This study proposes a two-step sintering method to fabricate mechanically superior PCFC large cells based on the BCZYYb electrolyte. The two-step sintering process consists of a heat treatment step at a temperature in which the anode and electrolyte have similar shrinkage values during the sintering process and another step that can improve the bonding strength of each layer by grain growth. The vulnerable anode/electrolyte interface, which acts as a significant mechanical failure factor, is optimized through the two-step sintering process. Two-step sintered cells show high mechanical stability in lab-scale and 6 cm × 6 cm planar cells for stack systems. A two-step sintered large cell exhibits outstanding stability during 350 h at 600 °C with the stack system. Our strategy provides a method to build practical proton-conducting fuel cells.

Repeatable preparation of defect-free electrolyte membranes for proton-conducting fuel cells

Proton-conducting ceramic cells are promising devices for high-efficient energy conversion, while the preparation of defect-free electrolyte membranes is difficult and blocks their quick development. Here, a vacuum-assistant dip-coating method is developed to prepare defect-free BaCe0.4Zr0.4Y0.1Yb0.1O3-δ (BCZYYb4411) proton-conducting electrolyte membranes on porous anode (40 wt%BCZYYb4411 - 60 wt%NiO) substrates. Unlike the conventional dip-coating process, by using the vacuum-assistant dip-coating method, defects (like running through pinholes, cracks) that would cause gas leakage, short-circuit and low open-circuit voltage (OCV) in following electrochemical tests can be eliminated. By tuning the mass concentration of electrolyte powders in the coating slurry, thin electrolyte membranes with different thicknesses can be reproducibly prepared. Proton-conducting fuel cells (PCFCs) with BaCo0.4Fe0.4Zr0.1Y0.1O3-δ (BCFZY0.1) cathode show high OCV values closing to the theoretical value of 1.13 V at 600 °C, demonstrating that dense and defect-free electrolyte membranes are fabricated. The as-prepared PCFC with a 10-μm-thickness defect-free electrolyte membrane shows a high peak power density reaching up to 761 mW cm−2 at 650 °C and stability of more than 250 h at the current density of 200 mA cm−2 at 600 °C. All these results illustrate that the developed method is feasible to prepare dense and thin electrolyte membranes without defects for proton-conducting ceramic cells.

Repeatable Preparation of Defect-Free Electrolyte Membranes for Proton-Conducting Fuel Cells

Repeatable Preparation of Defect-Free Electrolyte Membranes for Proton-Conducting Fuel Cells

BaCo0·4Fe0·4Zr0·1Y0·1O3–δ triple conductor for boosting electrode efficiency for proton conducting fuel cells

Proton conducting fuel cells (PCFCs) are considered as promising energy generation system due to their possibility for lowering the operation temperature. PCFCs operated at low temperature by conducting small and light protons, which enables stable operation without undesirable side reactions by thermal corrosion. However, kinetic energy for redox reaction at electrodes is insufficient due to the decreased operating temperature, resulting in degraded electrochemical performance. In this study, by forming BaCo0·4Fe0·4Zr0·1Y0·1O3-δ (BCFZY), a triple conducting material which could conduct proton, oxygen ions, and electrons at the electrodes, the power generation performance of PCFCs has been improved dramatically. BCFZY nanoparticles provide a charge passage, and effectively expand the reaction site. A proton conducting fuel cells with electrodes containing BCFZY exhibit an enhanced power density of 1.06 W cm−2 at 650 °C, which is almost 3 times higher value than the cell without formation of BCFZY on the electrodes. Our study proposes an effective strategy for enhancing the performance PCFCs by facilitating the conduction of charge carriers within the electrodes through applying BCFZY triple conductor.

Structural and Conductivity of NiO-BCZY Anode Functional Layer for Proton Conducting Fuel Cell

The main objective of this study is to perform a structural analysis of NiO-BCZY anode functional layer (AFL) with different weight ratio (NiO:BCZY = 20:80 and 40:60). NiO commercial powder and in-house developed BCZY synthesized by a sol-gel method are mixed and ground and then sintered at 1450° C for 5 hours to produce AFL powder. The single-cell (anode | CG-AFL| electrolyte | cathode) is fabricated with the anode substrates firstly die-pressed, then compositionally gradient anode functional layer (CG-AFL) and spin-coated with electrolyte thin film, accordingly. Structural characterization of AFL powder and conductivity of the single cell is performed using room temperature X-ray diffraction (XRD) and in-house developed electrochemical impedance spectroscopy (EIS) test station, respectively. Rietveld refinement analysis of the XRD data confirms the high purity single phase of NiO and BCZY. Both NiO and BCZY show a cubic crystal structure and each belongs to space group Fm-3m and Pm-3m, respectively. The lattice parameter (a = b = c) of NiO and BCZY are about 4.1818 Å3 and 4.3433 Å3 for 20NiO-80BCZY and 4.1825 Å3 and 4.3439 Å3 for 40NiO-60BCZY. EIS results show ohmic resistance (RS) and polarization resistance (RP) of the single cell are 14.8 and 16.23 Ωcm2 at 800 °C, respectively.

Analysis of La4Ni3O10±δ-BaCe0.9Y0.1O3-δ Composite Cathodes for Proton Ceramic Fuel Cells

Layered Ruddlesden-Popper (RP) lanthanide nickelates, Lnn+1NinO3n+1 (Ln = La, Pr, and Nd; n = 1, 2, and 3) have generated great interest as potential cathodes for proton conducting fuel cells (PCFCs). The high-order phase (n = 3) is especially intriguing, as it possesses the property of a high and metallic-type electronic conductivity that persists to low temperatures. To provide the additional requirement of high ionic conductivity, a composite electrode is here suggested, formed by a combination of La4Ni3O10±δ with the proton conducting phase BaCe0.9Y0.1O3-δ (40 vol%). Electrochemical impedance spectroscopy (EIS) is used to analyse this composite electrode in both wet (pH2O ~ 10−2 atm) and low humidity (pH2O ~ 10−5 atm) conditions in an O2 atmosphere (400–550 °C). An extended analysis that first tests the stability of the impedance data through Kramers-Kronig and Bayesian Hilbert transform relations is outlined, that is subsequently complemented with the distribution function of relaxation times (DFRTs) methodology. In a final step, correction of the impedance data against the short-circuiting contribution from the electrolyte substrate is also performed. This work offers a detailed assessment of the La4Ni3O10±δ-BaCe0.9Y0.1O3-δ composite cathode, while providing a robust analysis methodology for other researchers working on the development of electrodes for PCFCs.

A New Pd Doped Proton Conducting Perovskite Oxide with Multiple Functionalities for Efficient and Stable Power Generation from Ammonia at Reduced Temperatures

AbstractThe combination of ammonia fuel and proton‐conducting fuel cells (PCFCs) technology may provide an ideal clean energy system for the future, considering matured NH3 synthesis technology and transportation and storage infrastructure, the high energy density of NH3, and the high efficiency of fuel cells. However, poor catalytic activity of the anode for NH3 decomposition, quick performance degradation due to the ammonia induced nickel coarsening, difficult sintering, and insufficient proton conductivity of electrolytes are the main challenges for stable and high‐power generation from ammonia‐fueled PCFCs. Herein, a new Ba(Zr0.1Ce0.7Y0.1Yb0.1)0.95Pd0.05O3−δ perovskite is reported as a key anode component and electrolyte, which demonstrates multifunctionalities and tackles most challenges of conventional PCFCs. The incorporation of a small amount of Pd boosts catalytic activity of the nickel‐perovskite cermet anode for NH3 decomposition and increases proton conductivity from the creation of B‐site cation deficiency and electrolyte sintering. The corresponding thin‐film electrolyte PCFC delivers a maximum power density of 724 mW cm–2 at 650 °C operated on NH3, much higher than the similar cell without Pd incorporation (450 mW cm–2). Furthermore, no apparent performance decay is observed for the cell operated at 550 °C in H2 and NH3 for 350 h, making it highly promising for practical applications.

Short Review on the Suitability of CFD Modeling for Proton Conducting Fuel Cell Performance

Electrochemical performance optimization of a conventional solid oxide fuel cell (SOFC) has been massively performed with computational fluid dynamic (CFD) modelling but it’s usage in a proton conducting fuel cell (PCFC) is still minimal. PCFC is a category of SOFC but with proton conductor as electrolyte instead of oxygen-ion conductor in a conventional SOFC. The fabrication of high electrochemical performance of PCFC is desirable because of its ability to operate at lower temperature. The objective of this short review study is to explore the possibilities of CFD modelling application to improve electrochemical performance of a PCFC system. Some CFD study that have been done to SOFC and PCFC were reviewed. One main finding from this short review is that the application of CFD modelling in PCFC design optimization is still minimal. There is a lack of studies that focus on the impact of PCFC anode microstructure on transport phenomena of the PCFC; for example on gas diffusion. It was also found that CFD modelling software Ansys Fluent with add-on Fluent SOFC module that is widely applied to conventional oxygen-ion SOFC need to be modify using User Defined Function (UDF) in order to be used in PCFC system.

Electrochemical Performance of La<sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3-δ</sub> Cathode Material Prepared by a Sol-gel Method Assisted with Functionalized Carbon Nanotubes

A promising perovskite-type oxide ceramics of La<sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3-δ</sub> (LSCF) cathode co-join with BaCe<sub>0.56</sub>Zr<sub>0.3</sub>4Y<sub>0.1</sub>O<sub>3-δ</sub> (BCZY) as supported electrolyte for proton conducting fuel cell (PCFC) was investigated. The ultrafine LSCF was synthesized via a sol-gel process assisted with functionalized carbon nanotubes (f-CNTs) which served as a dispersing agent (denoted as modified-LSCF). The cathode ink of modified-LSCF was prepared by mixing cathode powder with binder that made up of ethyl cellulose and terpeniol. The cathode slurry was then deposited on both surface of the BCZY electrolyte via a spin coating technique to become a symmetrical half-cell. The half-cell of modified-LSCF│BCZY│modified-LSCF was subjected to Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscope/Energy Dispersive X-ray (SEM/EDX). The EIS data revealed the electrochemical reaction of the cell was a thermally activated process that follow the Arrhenius Law. LSCF incorporated with f-CNTs was effectively decreased the ASR value to 0.22 Ωcm<sup>2</sup> at 700<sup>o</sup>C, compared to 0.31 Ωcm<sup>2</sup> using pristine-LSCF. The pellet after EIS measurement showed no sign of crack and delamination at cathode/electrolyte interfaces, with optimum porosity obtained using ImageJ software and its elemental composition still preserved as observed by SEM/EDX analyses. Thus, the LSCF assisted with f-CNTs has a good potential to improve the quality of the cathode for high performance PCFC that operated at intermediate temperature.

Studying Proton Conducting Ceramic Electrolyte Stability with in Situ Raman Spectroscopy

Ceramic-based proton conducting fuel cells (PCFCs) are attractive devices for directly converting chemical energy to electrical energy. Like conventional solid oxide fuel cells (SOFCs), PCFCs are fuel flexible and efficient. Because PCFC electrolytes conduct protons rather than oxides, these devices can function between 400˚C and 600˚C, temperatures that are much lower than the ≥700˚C required for SOFC operation. PCFC technology remains relatively new, however, meaning that fundamental questions about electrochemical redox mechanisms, material compatibility and device resilience must be answered before PCFCs become a viable technology for commercial development.In this work, we use in situ vibrational Raman spectroscopy and ex situ XPS to examine the chemical stability of yttria-stabilized barium zirconate (BZY) and ceria doped BZY (BZCY) – both common PCFC electrolytes – as a function of temperature and chemical stress. In particular, in situ Raman data show that electrolyte surface and near surface composition is sensitive to steam in reducing environments with new features appearing in vibrational spectra. (The reducing environment consisted of 25% H2 in Ar; all humidified conditions included 3% H2O from running the incident gas(es) through a room temperature bubbler.) Spectral changes indicate that that the electrolyte structure and/or composition is changing on the electrolyte surface and in the near surface region (as defined by the penetration depth of the incident Raman excitation light). These changes are reversible and vibrational spectra return to their original appearance when steam is removed from the reducing atmosphere. Two important points to note are 1) new spectral features only appear within a limited temperature window between 300˚C and 450˚C and 2) new spectral features do not appear when the ambient atmosphere is inert (Ar), inert with steam (Ar with 3% H2O), or simply a reducing atmosphere (H2 in Ar). While spectral changes are reversible, the steam-altered electrolytes can be isolated by quickly cooling materials showing extraneous vibrational features back to room temperature under a humidified environment. This ability allows for additional ex situ analysis using conventional surface science methods. XPS data suggest that humidified H2 leads to enhanced Ba content on the electrolyte surface raising interesting questions about the role(s) played by surface segregation and secondary phase formation on the catalytic activity and charge transport properties of PCFC electrolytes.

Characterization of nio-bczy as composite anode prepared by a one-step sol-gel method

A high polarization resistance (Rp) at intermediate temperature (500–800°C) operation has become one of the major challenges in the development of proton-conducting fuel cells (PCFCs). Rp is the resistance of the cell that contributes by the electrodes parts which are anode and cathode as well as their interfacial components. The present study focused on the NiO-Ba(Ce0.6Zr0.4)0.9Y0.1O3-δ (NiO-BCZY) composite anode and its interfacial parts where the oxidation process takes place. The NiO-BCZY with a ratio of 50:50 was prepared by a sol-gel method and characterized by X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray (FESEM/EDX), and Electrochemical Impedance Spectroscopy (EIS). At calcination temperature of 1100°C, NiO and BCZY oxides can preserve their phases to form composite anode as proven by XRD analysis. Morphology of the composite anode as observed by FESEM was spherical with particle size in the range of 30-70 nm. XRD analysis showed the formation of Ni-BCZY after undergoing reduction process under wet H2:N2 (10%:90%). As confirmed by the EIS data, the increased conductivity of the composite anode in wet H2:N2 (10%:90%) indicates that the NiO in the composite anode was reduced to Ni metal. The fabricated NiO-BCZY composite anode has shown a good potential to be a promising anode in PCFC application.

High-Performance Proton-Conducting Fuel Cell with B-Site-Deficient Perovskites for All Cell Components

Proton-conducting fuel cells (PCFCs) with a perovskite-type proton-conducting electrolyte show many advantages over conventional oxygen-ion-conducting ceramic fuel cells. Both electrode catalytic a...

Characterization of LSCF Cathode Material Modified with f-CNTs

Cathode is one of the important parts in performing the high efficiency of proton conducting fuel cell (PCFC). Selection of appropriate cathode material may resolve the major drawbacks at the cathode part associated with the high Rp. Accordingly, tremendous effort have been done to reduce the Rp and one of the alternatives is the modification of cathode microstructure that can be achieved by introducing dispersing agent in the synthesis route. Thus, in this present work, a functionalized carbon nanotubes (f-CNTs) obtained from acidification process was used as a dispersing agent in the synthesis of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode material. The amount of 4 mg, 8 mg and 12 mg of f-CNTs were respectively added to LSCF cathode during the synthesizing process by a sol-gel method. Semi-solid gel obtained was calcined at 900 °C to form high purity of LSCF powder and respectively denoted as LSCF4, LSCF8 and LSCF12. The powder was characterized by Fourier Transform Infrared (FTIR) Spectroscopy, Pycnometer, Particle Size Analyzer and Scanning Electron Microscopy with Energy Dispersive X-ray (SEM/EDX). The FTIR analysis depicted the peak of respective metal complexes, metal oxide, symmetrical and asymmetrical stretching of carboxylate. The pycnometer showed the lowest density of LSCF4 was 2.8777 g/cm3. The Particles Size Analyzer confirmed the particle size of 38 nm ultrafine powder for LSCF4. The SEM image depicted the highly disperse spherical particles found in LSCF4 with particle size about 30 nm. The elemental composition of the samples is comparable with the nominal stoichiometric of LSCF4 as corroborated by the EDX analysis. Therefore, the LSCF with optimum 4 mg f-CNTs as dispersing agent has potential as nanoporous cathode material for proton conductivity fuel cell.

Fabrication of Compositionally Gradient Anode Functional Layer for Proton Conducting Fuel Cell at Intermediate Temperatures: A Preliminary Study

In this work, an anode-supported button cell was fabricated with compositionally gradient (CG) NiO-BaCe0.54Zr0.36Y0.1O2.95 (NiO-BCZY) anode functional layer (AFL). The button cell has a configuration of NiO-BCZY (50:50) | NiO-BCZY (30:70) | NiO-BCZY (10:90) | BCZY | LSCF. All powder materials were synthesized using a sol-gel method. Firstly, NiO-BCZY anode substrate was fabricated using dry-pressing method. Next, NiO-BCZY CG-AFL and BCZY electrolyte thin film were spin-coated on the anode substrate and lastly the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode was spin-coated on the electrolyte thin film. The microstructure of the fabricated button cell with good adhesion between all the layers, thin and dense electrolyte layer, and gradient increase in density of materials from anode substrate to electrolyte were observed using Scanning Electron Microscopy (SEM). Cell’s performance in terms of resistivity was evaluated using Electrochemical Impedance Spectroscopy (EIS) and conductivity meter using four-point probe method. Values of ohmic (Ro) and polarization resistance (Rp) of the cell are 7.3 and 2.4 Ωcm2 at 700 °C, respectively. The lower resistance values obtained compared to our previous work on a conventional 3-layers BCZY-based single button cell (Ro = 9.6 and Rp = 7.8 Ωcm2 at 700 °C) confirmed the functionality of GC-AFL in enhancing the cell’s performance. This preliminary result shows that simple deposition technique of CG-AFL plays a significant role in the optimization of PCFC button cell designs and electrochemical performance.

Manipulating cation nonstoichiometry towards developing better electrolyte for self-humidified dual-ion solid oxide fuel cells

Dual-ion (oxygen ion and proton) conducting electrolyte BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) is one of the most commonly used electrolyte materials for proton conducting fuel cells (PCFCs). Here, we improve conducting property and performance of BZCYYb electrolyte through simply introducing B-site cation deficiency. Dual-ion conductivities for Ba(Zr0.1Ce0.7Y0.1Yb0.1)0.95O3-δ (BZCYYb-0.95) electrolyte are improved to a large extent as 2.5 times protonic conductivity (4.6 × 10−2 S cm−1 at 700 °C) and 6.3 times oxygen ionic conductivity (1.2 × 10−2 S cm−1 at 900 °C) compared to BZCYYb electrolyte. Low-temperature (1350 °C) sinterability of BZCYYb-0.95 is achieved for the higher concentration of defect compared to the original material (BZCYYb, 1500 °C). Meanwhile, a cell with the BZCYYb-0.95 electrolyte illustrates prominent power density of 794 mW cm−2 at 650 °C, superior to the cell with BZCYYb (643 mW cm−2) at the same condition. The collaborative diffusions of dual-ion via two different conducting mechanisms enhance the cell performance with BZCYYb-0.95 electrolyte. The cell voltage and power density actually have no observable performance degradation during the course of the 300-h test. Therefore, it indicates the dual-ion diffusions of BZCYYb-0.95 electrolyte as the promising future for practical application.

Ni-YSZ a New Support for Proton Conducting Fuel Cells

In this research, the possibility of reducing the YSZ content inside the Ni-YSZ support of tubular solid oxide fuel cells (SOFCs) based on proton conducting electrolyte material BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) is studied. The cell consists of a Ni-yttria stabilized zirconia (YSZ) support (with different Ni:YSZ ratios), Ni-BZCYYb anode functional layer (AFL), BZCYYb electrolyte and LSCF-BZCYYb cathode. The results indicate that the addition of only 10 wt% YSZ to the support improves the microstructure by preventing severe Ni grain growth, thereby providing higher density of active sites at the support/AFL interface and more uniform distribution of fuel gas to the active sites. The polarization resistance of the optimized cell with 10 wt% YSZ in the support is lower than the fully Ni supported cell. The promising results of this study reveal that Ni-YSZ can be a suitable support for proton conducting fuel cells.