Proton-conducting Electrolyte Research Articles

Proton ions migration in amorphous Nd-alumina oxide based- electrolyte

This study presents a groundbreaking advancement in the field of ceramic fuel cells, namely, solid oxide fuel cells (SOFCs) and proton ceramic fuel cells (PCFCs). In contrast to the prevalent crystalline fluorite oxygen ion-conducting electrolytes and proton-conducting perovskite electrolytes, our study underscores the transformative potential of amorphous oxide material. The Nd-alumina amorphous oxide demonstrates exceptional proton conductivity, reaching 0.16 Scm−1 and an impressive power density of 713 mWcm−2 at 500 °C, thereby surpassing the capabilities of existing crystalline electrolyte materials. Furthermore, this study provides a comprehensive comparison between amorphous Nd-alumina and its crystalline counterparts, thus elucidating the inherent advantages of the amorphous form over traditional crystalline structures. Several characterizations and experimental methods have been introduced for in-depth analysis of proton and oxide ions migration in developed NdAl-Aos electrolytes. However, amorphous Nd-alumina emerges as an alternative component in ceramic fuel cells, propelling an electrolyte technology towards unparalleled performance and paving the way for a sustainable SOFC/PCFC future.

Features of electrical transport and H/D isotope effects in the proton-conducting electrolyte BaCe0.7Zr0.1Y0.1Yb0.1O3-δ

The electrical properties of the proton-conducting electrolyte BaCe0.7Zr0.1Y0.1Yb0.1O3-δ were studied using the 4-probe direct current (DC) method depending on temperature and oxygen partial pressure in the atmospheres, humidified with H2O and D2O. Ionic and electron hole contributions to the electrical conductivity were determined, and the transport numbers of charge carriers were calculated. It is shown that in air conditions BaCe0.7Zr0.1Y0.1Yb0.1O3-δ is a mixed ion-electron hole conductor. The contribution of electron hole conductivity decreases with the decrease of temperature and oxygen partial pressure. A significant isotope H/D effect in the electrical conductivity is observed for all investigated conditions expressed in the decrease in conductivity in D2O-containing atmospheres with the increase of activation energy values. Replacing H2O with D2O leads to decrease in the ion transport numbers and ionic conductivity values, while the electron hole conductivity remains almost the same.

Hydrogen extraction from 0.1 % H2–He mixture: The interplay phenomena of electrode, temperature, and voltage in BZYN & BZCYYb

Hydrogen pumps, crafted from proton-conductive ceramic electrolyte and paired with either oxide or metallic electrodes, have been designed for the extraction of hydrogen isotopes from helium gas mixtures containing 0.1 % hydrogen isotopes, particularly within the context of TES for nuclear fusion reactors. This study presents the electrochemical hydrogen permeation research conducted on the perovskite proton conductor materials BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) and BaZr0.8Y0.16Ni0.04O3-δ (BZYN) under these operational conditions. It was observed that nickel electrodes provided superior performance over SrFe0.8Mo0.2O3-δ (SFM) electrodes in terms of hydrogen extraction efficiency. Hydrogen pumps that integrated BZCYYb as the electrolyte with nickel electrodes showed enhanced efficiency, while those utilizing BZYN as the electrolyte coupled with nickel electrodes demonstrated greater stability. Furthermore, the study explored the voltammetric nonlinearity at low hydrogen concentrations and the dependency of concentration polarization efficiency on both voltage and temperature, aiming to establish optimal conditions that balance stability and efficiency for both types of hydrogen pumps.

Bridging the Gap between fundamentals and efficient devices: Advances in proton-conducting oxides for low-temperature solid oxide fuel cells

Low-temperature solid oxide fuel cells (LT-SOFCs) represent a cutting-edge solution in the domain of clean energy, poised to revolutionize electricity generation for both stationary and mobile applications. At the core of LT-SOFCs lies the proton-conducting solid oxide electrolyte, a subject of extensive exploration and advancement. This comprehensive review investigates the evolution of proton-conducting solid oxide electrolytes for LT-SOFCs, exploring the landscape from fundamental materials to diverse device architectures. The review meticulously examines three pivotal dimensions: 1) strategies for fine-tuning the properties and structures of ceramics and proton-conducting oxides, 2) advancements in techniques for protonic-conducting fuel cells (PCFCs), and 3) an exploration of the opportunities and challenges intrinsic to the progression of electrolyte-based PCFCs. By elucidating the advancements made in optimizing conductivity, chemical stability, sinterability, and electron-blocking characteristics of proton-conducting electrolytes, this review offers invaluable insights into the state-of-the-art for LT-SOFC technology. Furthermore, it casts a forward-looking perspective, envisioning the future trajectory of proton-conducting electrolyte research and its potential to reshape the landscape of LT-SOFC technology. By providing a comprehensive overview of past achievements and future prospects, this review serves as a valuable resource for researchers, engineers, and stakeholders, guiding them towards the realization of efficient and sustainable energy solutions.

Electrochemical behaviour of redox-robust electrode in contact with protonic electrolyte: Case of double-layered Sr2Fe1.5Mo0.5O6-δ - Ce0.8Sm0.2O2-δ composite

Electrochemical devices based on proton-conducting oxides offer a significant potential for implementation in a variety of high-temperature electrochemical applications. It is a well-known fact that electrochemical devices require active electrodes to function optimally. Over the last few years, Sr2Fe1.5Mo0.5O6-δ has received much attention as an effective redox-robust electrode for oxygen conducting electrolytes. This study presents, for the first time, the results of investigations on a double-layered composite electrode based on Sr2Fe1.5Mo0.5O6-δ in contact with a barium-free proton-conducting electrolyte La0.9Sr0.1ScO3-δ. It was found that the investigated electrode exhibits low polarization resistance about 0.15 and 0.22 Ohm cm2 in wet air and wet hydrogen at 600 °C, respectively. In addition, the electrode exhibits acceptable redox stability and CO2 tolerance. Also, the results of electrochemical impedance spectra analysis and a discussion on the parallel pathways of hydrogen oxidation and oxygen reduction reactions and the nature of rate-determining steps are presented in the manuscript. The obtained results show the high prospects for a Sr2Fe1.5Mo0.5O6-δ - based composite electrode for protonic ceramic electrochemical cells.

Enriching Nano-Heterointerfaces in Proton Conducting TiO2-SrTiO3@TiO2 Yolk-Shell Electrolyte for Low-Temperature Solid Oxide Fuel Cells.

A challenging task in solid oxide fuel cells (SOFCs) is seeking for an alternative electrolyte, enabling high ionic conduction at relatively low operating temperatures, i.e., 300-600°C. Proton-conducting candidates, in particular, hold a significant promise due to their low transport activation energy to deliver protons. Here, a unique hierarchical TiO2-SrTiO3@TiO2 structure is developed inside an intercalated TiO2-SrTiO3 core as "yolk" decorating densely packed flake TiO2 as shell, creating plentiful nano-heterointerfaces with a continuous TiO2 and SrTiO3 "in-house" interfaces, as well the interfaces between TiO2-SrTiO3 yolk and TiO2 shell. It exhibits a reduced activation energy, down to 0.225eV, and an unexpectedly high proton conductivity at low temperature, e.g., 0.084 S cm-1 at 550°C, confirmed by experimentally H/D isotope method and proton-filtrating membrane measurement. Raman mapping technique identifies the presence of hydrogenated HO─Sr bonds, providing further evidence for proton conduction. And its interfacial conduction is comparatively analyzed with a directly-mixing TiO2-SrTiO3 composite electrolyte. Consequently, a single fuel cell based on the TiO2-SrTiO3@TiO2 heterogeneous electrolyte delivers a good peak power density of 799.7mW cm-2 at 550°C. These findings highlight a dexterous nano-heterointerface design strategy of highly proton-conductive electrolytes at reduced operating temperatures for SOFC technology.

Electrophoretic deposition of ceramic coatings from modified suspensions of microsized powders of doped BaCeO3 and BaCeO3–BaZrO3 proton-conducting electrolytes

This work investigates the influence of molecular iodine introduced as a charging agent into the suspensions based on the BaCe0.8Sm0.19Cu0·01O3 (BCSCuO), BaCe0·5Zr0·3Y0.1Yb0.1O3-δ (BCZYYbO) and BaCe0.89Gd0.1Cu0·01O3-δ (BCGCuO) proton-conducting electrolytes at concentrations up to 1.0 g/L on their electrokinetic properties. The peculiarities of changes in zeta potential, pH, conductivity of the suspensions, the thickness and morphology of the coatings depending on the amount of iodine added are determined. It has been established that when the iodine concentration increases to 1 g/L, the electrical charge of the particles and the sign of the zeta potential undergo a reversal. Additionally, there is a natural decrease in the pH value towards the acidic side and a corresponding increase in the suspension conductivity. The research has demonstrated that in the suspension with a high iodine content (1 g/L), cathodic and anodic deposition can occur simultaneously under electrophoretic deposition (EPD) conditions at low voltage values (below 8 V). However, as the voltage increases, only cathodic deposition occurs. Therefore, the impact of altering the type of the EPD is threshold in nature relative to the magnitude of the EPD voltage. It has been shown that in order to practically implement EPD of ceramic coatings from modified suspensions of microsized powders of doped BaCeO3 and BaCeO3–BaZrO3 proton-conducting electrolytes, it is necessary to select a small amount of added iodine (0.1–0.2 g/L) to initiate a stable deposition process and to ensure continuity and uniformity of the coatings. This article discusses possible mechanisms of zeta potential inversion, electrophoretic mobility, and the EPD nature under conditions of high concentrations of iodide ions in the suspension bulk. The experiments have demonstrated the viability of the EPD process for the formation of a uniform BCSCuO coating (∼10 μm) on a supporting NiO–BCSCuO anode substrate using an iodine-modified suspension. This coating was subsequently sintered into a dense ceramic film at 1450 °C. In addition to the fundamental significance, the study results have implications for the practical use to improve and simplify the thin-film SOFC technology.

Sulfonated poly(ether ether ketone)-Protic ionic Liquid-Based anhydrous Proton-Conducting composite polymer electrolyte membranes for High-Temperature fuel cell applications

A high-temperature polymer electrolyte membrane fuel cell (PEMFC) has enormous potential to produce clean energy with minimal environmental pollution along with high energy density and conversion efficiency. In the present work, anhydrous proton-conducting polymer electrolyte membranes for prospective high-temperature fuel cell application were successfully prepared using different protic ionic liquids (PILs) and sulfonated poly(ether ether ketone) (SPEEK). The protic ionic liquids (PILs), 2-hydroxyethylammonium formate, diethylmethyl ammonium triflate, 1-ethylimidazolium bis(trifluoromethylsulfonyl)imide, 1,2-dimethyl imidazolium bis(trifluoro methylsulfonyl)imide, and diethylmethylammonium methanesulfonate were selected based on their favorable physicochemical properties. The effect of the incorporation of the PIL on the structural, thermal, and electrical transport properties of the composite SPEEK polymer electrolyte membranes was studied. The prepared polymer electrolyte membranes (PEMs) were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffractometry (XRD), and electrochemical impedance spectroscopy (EIS) techniques. FTIR results indicated an interaction between the PIL and the SPEEK, which resulted in homogeneous and flexible membranes. The DSC results confirmed good miscibility and elucidated plasticizing effect of the incorporated PIL on the SPEEK polymer matrix. All the PEMs showed good thermal stability and high-temperature anhydrous proton conductivity, achieving best proton conductivity, ≈8 × 10–3 S cm−1 at 120 °C and low activation energy ≈0.26 eV, making it suitable for prospective high-temperature PEMFC applications.

"All in One" Strategy for Achieving Superprotonic Conductivity by Incorporating Strong Acids into a Robust Imidazole-Linked Covalent Organic Framework.

The fabrication of solid-state proton-conducting electrolytes possessing both high performance and long-life reusability is significant but challenging. An "all-in-one" composite, H3PO4@PyTFB-1-SO3H, including imidazole, sulfonic acid, and phosphoric acid, which are essential for proton conduction, was successfully prepared by chemical post-modification and physical loading in the rationally pre-synthesized imidazole-based nanoporous covalent organic framework (COF), PyTFB-1. The resultant H3PO4@PyTFB-1-SO3H exhibits superhigh proton conductivity with its value even highly up to 1.15 × 10-1 S cm-1 at 353 K and 98% relative humidity (RH), making it one of the highest COF-based composites reported so far under the same conditions. Experimental studies and theoretical calculations further confirmed that the imidazole and sulfonic acid groups have strong interactions with the H3PO4 molecules and the synergistic effect of these three groups dramatically improves the proton conductivity properties of H3PO4@PyTFB-1-SO3H. This work demonstrated that by aggregating multiple proton carriers into one composite, effective proton-conducting electrolyte can be feasibly achieved.

Unraveling the conundrum of electronic leakage in protonic ceramic cells: Operation-specific insights and rational design strategies

Electronic conduction through proton-conducting electrolytes significantly impairs the efficiency of protonic ceramic cells (PCCs). In this study, we explore the electron and ion mixed transport properties of four common protonic ceramics, BaZr0.8Y0.2O3-δ (BZY82), BaZr0.7Ce0.2Y0.1O3-δ (BZCY721), BaZr04Ce0.4Y0.1Yb0.1O3-δ (BZCYYb4411), and BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb1711). It marks the first instance of investigating these properties under operation-specific scenarios: fuel side of electrolysis cell, air side of electrolysis cell, fuel side of fuel cell, and air side of the fuel cell. BZCYYb1711 exhibits the highest ionic conductivity, but two to three times higher electronic leakage when exposed to oxygen-containing environments than the others. BZY82 exhibits approximately two times higher electronic leakage in a hydrogen-containing environment. BZCY721 demonstrates excellent ion transport numbers (∼0.95) across these four operating conditions. BZCYYb4411 behaves quite similarly to BZCY721. The most challenging operating environment for all candidates is the air side of fuel cell mode. This mode leads to a high initial electronic leakage, followed by a significant increase with polarization. The probable cause for this behavior is a H2-free, polarization-induced reduction that leads to the formation of VO•. The electron small polaron associated with VO• is released by the electrical field due to the Poole-Frenkel effect. ZnO and NiO sintering aids are found to be detrimental to the ionic conductivity of the electrolytes. In particular, NiO substantially lowers the ion transport number. The correlation of the operation-specific electronic leakage to full cells is discussed. It is suggested that a rational PCC design should synergistically couple BZCYYb1711 at fuel side with BZCY4411 at air side to deliver a well-balanced performance and faradaic efficiency simultaneously, and the high temperature sintering process with a NiO fuel electrode should be shortened or replaced by ultra-fast sintering techniques or using a fuel electrode scaffold-infiltration fabrication strategy.

Single composite electrolyte prepared by infiltration and characterization

Oxygen-ion and proton-conducting electrolytes should be combined into a composite to improve fuel cell capacity and electrocatalytic efficiency. To realize a single membrane of a composite electrolyte with dual charge carriers, we use only a single process. A BaZr0.8Ni0.01Y0.19O3 (BZNY) proton-conducting electrolyte solution and suspension are infiltrated into a porous oxygen-ion-conducting electrolyte (La0.75Sr0.2Ba0.05)0.175Ce0.825O1.891 (LSBC) substrate using a simple pumping process. The infiltration of BZNY into the porous LSBC results in a gradient composition of BZNY. The obtained single-composite electrolyte, BZNY-LSBC, possesses individual perovskite and fluorite crystal structures after sintering. The BZNY solution infiltrates the porous LSBC substrate to a smaller depth than the phase-preformed nano-BZNY slurry. The effective infiltration depth is approximately 50 μm for the BZNY solution, and 300 μm for the nano-BZNY into a 400 μm thickness of LSBC. The infiltrated composite electrolyte exhibites lower conductivity compared to the solid-state-prepared single-phase LSBC electrolyte at 600 °C, but almost the same conductivity at 800 °C from the AC impedance analyses. When the Sr2Fe1.5Mo0.5O6 (SFM) are applied as symmetric electrodes, the SFM|BZNY-LSBC|SFM fuel cells maintain the higher open circuit voltage of 0.8 V than 0.5 V for SFM|LSBC|SFM fuel cells at 600 °C. The fuel cell with nano-BZNY infiltrated composite electrolyte achieves over double power density than cells with single LSBC and solution BZNY infiltration electrolytes at 600 °C that may be due to the proton conduction enhancement at lower temperature and further promotes the triple power density at 800 °C contributed from the oxygen ions conduction of LSBC and BZNY at high temperature. Those results provide evidence that dual ions pass through individual conduction paths in a two-phase composite electrolyte.

ZnO sintering aid effect on proton conductivity of BaCe0.6Zr0.3Y0.1O3-δ electrolyte for hydrogen sensors

Proton-conducting solid-state electrolytes, including perovskite-type materials, hold promise for hydrogen sensor development. These sensors leverage the proton conductivity of such materials to detect hydrogen gas presence. However, achieving both high density for gas tightness and good protonic conductivity in these refractory materials can be challenging.In this study, we propose the preparation of dense pellets of BaCe0.6Zr0.3Y0.1O3-δ using ZnO as a sintering aid (BCZY-Zn). These pellets were extensively characterized using X-ray diffraction and electrochemical impedance spectroscopy and compared with pellets sintered without sintering aid (BCZY). Subsequently, BCZY-Zn electrolyte was utilized to fabricate amperometric sensors for hydrogen monitoring. Finally, amperometric measurements were conducted at 500 °C while maintaining a voltage of 150 mV between electrodes. The sensors' performance was evaluated for hydrogen partial pressures ranging from 12 to 100 Pa within an argon atmosphere. Additionally, response and recovery times were calculated.

Towards highly dense electrolytes at lower sintering temperature (∼1200 °C): Optimization strategies for BaCe0.7Zr0.1CuxY0.2-xO3-δ in SOFCs

High-conducting and long-term stable proton-conducting electrolytes are of utmost importance. This study investigates the synthesis and characterization of BaCe0.7Zr0.1CuxY0.2-xO3-δ (BCZCuxY; x = 0, 0.005, 0.01, 0.02, 0.05, and 0.1) electrolytes tailored for proton-conducting solid oxide fuel cells (SOFCs). Through Cu2+ doping at the B-site of BaCe0.7Zr0.1Y0.2O3-δ (BCZY), a successful reduction of the sintering temperature to 1200 °C was achieved. BCZCu0.02Y exhibited a high relative density of approx. 98.1% at this temperature, but beyond 2 mol% Cu doping, the appearance of a BaCuO2 secondary phase adversely impacted conductivity. The electronic properties of BCZY and BCZCuxY are elucidated via partial density of states (PDOS) analysis, revealing optimized crystal structures and band gap reductions (from approx. 1.9 eV–1.1 eV) upon Cu doping. Notably, BCZCu0.02Y demonstrated a commendable conductivity, with values of 3.5 × 10−2 S. cm−1 in air and 4.8 × 10−2 S. cm−1 in a moist atmosphere at 750 °C. Remarkably, excellent electrochemical stability was observed in a moist hydrogen atmosphere for up to 450 h at 600 °C. Single cells incorporating BCZCu0.02Y electrolytes exhibited peak power densities of 380 mW/cm2 at 750 °C. The incorporation of 2 mol% Cu2+ in the BCZY lattice holds promise for achieving low-temperature sintering and high-performance proton-conducting SOFCs.

Energy storage application of plasticized biopolymer blend electrolyte doped with ammonium nitrate as H+ provider

Recently, proton-conducting electrolytes for energy storage purposes attracted the focus of many research groups as possible alternatives for Li-based energy storage applications. Natural polymers offer a promising solution to counter the environmental impact of synthetic polymers. In this work proton conducting CS:POZ based natural polymer electrolytes were plasticized with glycerol (GL) to improve the ion conductivity and increase the free ion percentage. The films of CS:POZ:NH4NO3 electrolyte were prepared using the casting technique. The plasticizers were changed from 9 to 36 wt%. The FTIR method revealed ion interaction among polymer, salt, and plasticizer. The deconvolution of FTIR band associated with NO3 anion was used to calculate the ion transport parameters (ITPs). It was found that the free ion contour area was enhanced by increasing plasticizer concentration. The EIS plot fitted with equivalent circuit elements was used to determine the DC conductivity and ITPs. The dominancy of ion species was examined using TNM measurement. The safety region for energy storage device (ESD) application was found from the LSV examination. The activated carbon was used to manufacture the electrodes for ESD application. The cyclic voltammetry (CV) investigation found that the capacitances of the ESD influenced by scan rates.

Multicomponent doping realized superior triple-conducting within cobalt-free Ruddlesden-Popper-type perovskite for Proton-conducting fuel cells cathode

Proton-conducting solid oxide fuel cells (H-SOFCs) are appealing for low-to-intermediate temperature operation due to their intrinsic lower activation energy and better ionic conductivity. Unfortunately, there are currently few acceptable and high-performing cathode materials available for H-SOFCs. Herein, we present a novel high performance multicomponent Ruddlesden-Popper (RP) type cathode Pr3Ni1.5Cu0.3Nb0.05Ta0.05Zr0.05Y0.05O7-δ (PNCNTZY) with superior triple conducting property. The multicomponent co-doping of Nb, Ta, Zr, and Y brings about the enhancement of configurational entropy and cocktail effect for improving H+/O2-/e- triple conductivity and oxygen vacancy concentration. Naturally, the ORR activity is improved by facilitated charge transfer and oxygen surface exchange, exhibiting reduced polarization resistance to just 0.24 Ω cm2 at 550 °C. When used as the cathode in H-SOFC single cells, excellent power production is demonstrated at 550 °C, with a peak power density of up to 0.84 W cm-2. Furthermore, the PNCNTZY sample shows adequate thermal compatibility with proton conductor electrolytes BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) and then appropriate endurance durability (0.8 A cm-2 at 550 °C for about 250 h) due to their match of thermal expansion coefficient (TEC) brought about by the Co-free and partial replacement of larger-size elements. This extremely promising Co-free RP perovskite cathode for H-SOFCs produced by this work might provide a new type candidate and novel strategy for the commercialization of H-SOFCs.

An innovative perovskite oxide enabling improved efficiency for low-temperature ceramic electrochemical cells

In recent years, energy carriers for renewable sources and devices that convert chemical energy into electrical energy, such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), have made hydrogen production economically viable and have numerous industrial uses. We have designed SrFe0.3TiO3 (SFT) materials to function as SOFC and H-SOEC electrolytes at low operational temperatures of 520–420 °C. The SFT (600 °C) shows a higher fuel cell power density of 650 mW/cm2 and a reasonable current density of 1.14 A/cm2 in fuel cell and electrolysis cell mode at 520 °C. The formation of the surface layer enables high ionic and Proton conduction due to a high number of oxygen vacancies, and the core–shell type interface enables easy and quick proton transportation restricted to the surface. Energy band alignment and distribution relaxation time (DRT) were also evaluated to study ion transport in SFT materials. These results open up advanced avenues for the design of high-performance, sophisticated proton-conducting electrolytes for ceramic electrochemical cells.

Comparative Analysis of LiCo0.6Sr0.4O2 Cathode Electrochemical Performance in Oxide- and Proton-Conducting Intermediate-Temperature Solid Fuel Oxide Cells

Solid fuel oxide cells (SOFCs) are made up of three main parts: anode, electrolyte, and cathode. The main challenge in SOFCs is their high operating temperature, which can reach 1000 °C and lead to cell degradation issues. To address this, the utilization of lithium-based materials is suggested for the cathode component, facilitating intermediate-temperature SOFC operation within the temperature range of 500 to 800 °C. Previous studies have demonstrated the potential of producing high-quality lithium-based cathode ink using a triple-roll mill (TRM). By employing the fabrication parameters recommended in these studies, the lithium-based cathode (LCSO) was tested in different working environments, specifically the oxide-conducting SOFC and proton-conducting SOFC. The LCSO inks were screen-printed on SDC for oxide-conducting SOFC and BCZY for proton-conducting SOFC electrolyte before the analysis. Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) are used to characterize the electrochemical performance and morphology of the LCSO cathode. Based on the results, the LCSO cathode is found to respond well in oxide-conducting SOFC environment with an area-specific resistance (ASR) value of 0.75 ohms-cm2 compared to proton-conducting SOFC which shows an ASR value higher by 11.45 ohms-cm2.

Effect of NiO Addition on the Sintering and Electrochemical Properties of BaCe0.55Zr0.35Y0.1O3-δ Proton-Conducting Ceramic Electrolyte.

Proton ceramic fuel cells offer numerous advantages compared with conventional fuel cells. However, the practical implementation of these cells is hindered by the poor sintering activity of the electrolyte. Despite extensive research efforts to improve the sintering activity of BCZY, the systematic exploration of the utilization of NiO as a sintering additive remains insufficient. In this study, we developed a novel BaCe0.55Zr0.35Y0.1O3-δ (BCZY) electrolyte and systematically investigated the impact of adding different amounts of NiO on the sintering activity and electrochemical performance of BCZY. XRD results demonstrate that pure-phase BCZY can be obtained by sintering the material synthesized via solid-state reaction at 1400 °C for 10 h. SEM analysis revealed that the addition of NiO has positive effects on the densification and grain growth of BCZY, while significantly reducing the sintering temperature required for densification. Nearly fully densified BCZY ceramics can be obtained by adding 0.5 wt.% NiO and annealing at 1350 °C for 5 h. The addition of NiO exhibits positive effects on the densification and grain growth of BCZY, significantly reducing the sintering temperature required for densification. An anode-supported full cell using BCZY with 0.5 wt.% NiO as the electrolyte reveals a maximum power density of 690 mW cm-2 and an ohmic resistance of 0.189 Ω cm2 at 650 °C. Within 100 h of long-term testing, the recorded current density remained relatively stable, demonstrating excellent electrochemical performance.

Ba-doped Pr2NiO4+δ electrodes for proton-conducting electrochemical cells. Part 3: Electrochemical applications

Layered nickelates, Ln2NiO4+δ, are promising electrode materials for many electrochemical applications, including solid oxide fuel cells and electrolysis cells. Although Ln2NiO4+δ has been extensively modified by various doping strategies to tune its functional properties, the partial substitution of Ln3+ with Ba2+ remains among the least studied routes. At the same time, such substitution is found to be favorable when Ln2NiO4+δ materials are used for protonic ceramic electrochemical cells based on Ba-containing proton-conducting electrolytes (i.e., BaCeO3, BaZrO3, Ba(Ce,Zr)O3). In this work, which is the third part of a systematic study, Pr2–xBaxNiO4+δ materials are used as electrodes for a proton ceramic fuel cell and as oxygen permeable membranes. The oxygen permeation experiments confirm that the compositions with x = 0.2 and 0.3 prevail over x = 0 and 0.1 in terms of their oxygen-ionic conductivity, while the electrochemical cell characterizations confirm the high electrochemical activity of the Pr1.8Ba0.2NiO4+δ electrode in both fuel-cell- and electrolysis-cell modes. Our research thus confirms that a Ba-doping strategy is highly promising for designing new Ln2NiO4+δ-based phases, simultaneously offering good chemical and thermal compatibility with state-of-the-art proton-conducting electrolytes and high electrochemical performance.

Nanoarchitectonics of yttrium-doped barium cerate-based proton conductor electrolyte for solid oxide fuel cells

Nanoarchitectonics of yttrium-doped barium cerate-based proton conductor electrolyte for solid oxide fuel cells