Ag Composite Cathode Research Articles

Improved electrochemical performance of Ag-modified Bi0.7Sr0.3FeO3 cathodes by electroless plating for intermediate-temperature solid oxide fuel cells

The Bi0.7Sr0.3FeO3-δ (BSFO)-Ag composite cathode is prepared by modifying BSFO with in-situ chemical plating of Ag. The plated Ag effectively reduces the polarization resistance (Rp) of BSFO. At the Ag loading of 20 wt.%, the optimized Rp of BSFO at 650oC in air condition is 0.35 Ω cm2, which is only 18.6% of that of BSFO cathode (1.88 Ω cm2). The electrochemical performance improvement is primarily attributed to the low oxygen adsorption energy (Eads) domain at the interfaces of BSFO-Ag, as indicated by the first-principles calculations (Eads, -0.81eV). Thus, the addition of Ag changes the cathodic reaction rate control step from the molecular oxygen on the cathode surface adsorption and diffusion to charge transfer on the cathode. The maximum power density (Pmax) of the prepared single cell at 650oC is 450.98 mW cm-2 using H2 (∼3 vol.% H2O) as fuels. The open-circuit voltage (OCV) does not decay significantly (around 0.66 V) after 50 h at the current density of 400 mA cm-2, showing good long-term stability.

Composite cathode material LSCF-Ag for solid oxide fuel cells obtained in one step sintering procedure

The lanthanum strontium cobalt ferrite (LSCF)-Ag composite cathode material was prepared in aqueous solution by new one-step method. In this method silver nanoparticles obtained by the reduction of [Ag(NH3)2]+ complex with sucrose were directly deposited onto the surface of LSCF powder. UV–Vis spectra of supernatant solution taken during synthesis showed the presence of a sharp excitation band near 397 nm attributed to the surface plasmon excitation of silver nanoparticles. Obtained composite powder was sintered to samaria doped ceria electrolyte in one step sintering procedure at 1000 °C. The presence of silver in LSCF cathode facilitates the oxygen reduction. The comparison of impedance spectra of LSCF-Ag cathodes with spectra reported in literature for similar LSCF cathodes shows that this effect is important at lower oxygen partial pressures. The analysis of the electrochemical impedance spectra recorded in the range 10−2–1010 Hz reveals that the second high frequency semicircle ascribed to the electrolyte grain boundary impedance is distorted due to process belonging to oxygen reduction reaction.

Morphological and Physical Behaviour of LSCF-SDCC-Ag Composite Cathode with the Incorporation of Ag as an Additive Element

The composite cathode, lanthanum strontium cobalt ferrite-samarium-doped ceria carbonate-argentum (LSCF–SDCC–Ag), was developed and investigated for low-temperature solid oxide fuel cell (LTSOFC) applications. This research studied the effect of Ag on the development and properties of the composite cathode. The composite cathode powders, LSCF– SDCC–Ag with an Ag addition of 1–5 wt% were developed via high energy ball milling technique, and all prepared pellets were sintered at 500, 550, and 600 °C. The morphological properties of the composite cathode powders were observed via FESEM micrograph, and the average particle sizes of the composite powders were measured via SmartTiff Software. The total porosity (%) of the LSCF–SDCC–Ag composite cathode pellets was determined using the Archimedes method. The FESEM micrograph revealed that the obtained composite cathode powder is homogeneous, with particle sizes of 100–200 nm. The particle size of the LSCF– SDCC–Ag cathode increased with the increase of Ag content. Meanwhile, the porosity decreased in value with the increase of the Ag content and the sintering temperature. The porosity percentage range from 26.6% to 33.8%.

Enhanced Performance and Stability of Metal–Supported Solid Oxide Fuel Cells with (Bi2O3)0.7(Er2O3)0.3–Ag Composite Cathode

Metal–supported solid oxide fuel cells with the structure of Ni–Ce0.8Sm0.2O2-δ (SDC) infiltrated porous 430L anode, YSZ electrolyte and in–situ sintered (Bi2O3)0.7(Er2O3)0.3–Ag (ESB–Ag) cathode was fabricated and a high power density of 1.3 W cm−2 was obtained at 750°C. Cell performance was enhanced by the Ni–SDC infiltrated porous 430L anode applied here. Replacing the cell electrolyte by SSZ with higher oxide ionic conductivity than that of the YSZ resulted in an improved power density of 1.55 W cm−2 at 750°C and the improvement was more obvious at the low temperature. Moreover, cell stability was improved by the application of ESB–Ag–La0.74Bi0.10Sr0.16MnO3-δ (LBSM) composite cathode.

Metal-supported solid oxide fuel cells with in-situ sintered (Bi2O3)0.7(Er2O3)0.3–Ag composite cathode

Metal-supported solid oxide fuel cells (SOFCs) containing porous 430L stainless steel support, Ni-YSZ anode and YSZ electrolyte were fabricated by tape casting, laminating and co-firing in a reduced atmosphere. (Bi2O3)0.7(Er2O3)0.3–Ag composite cathode was applied by screen printing and in-situ sintering. The polarization resistances of the composite cathode were 1.18, 0.48, 0.18, 0.09 Ω cm2 at 600, 650, 700 and 750 °C, respectively. A promissing maximum power density of 568 mW cm−2 at 750 °C was obtained of the single cell. Short-term stability was measured as well.

Pr2NiO4–Ag composite cathode for low temperature solid oxide fuel cells with ceria-carbonate composite electrolyte

Pr 2 NiO 4 –Ag composite was synthesized and evaluated as cathode component for low temperature solid oxide fuel cells based on ceria-carbonate composite electrolyte. X-ray diffraction analysis reveals that the formation of a single phase K 2 NiF 4 –type structure occurs at 1000 °C and Pr 2 NiO 4 –Ag composite shows chemically compatible with the composite electrolyte. Symmetrical cells impedance measurements prove that Ag displays acceptable electrocatalytic activity toward oxygen reduction reaction at the temperature range of 500–600 °C. Single cells with Ag active component electrodes present better electrochemical performances than those of Ag-free cells. An improved maximum power density of 695 mW cm −2 was achieved at 600 °C using Pr 2 NiO 4 –Ag composite cathode, with humidified hydrogen as fuel and air as the oxidant. Preliminary results suggest that Pr 2 NiO 4 –Ag composite could be adopted as an alternative cathode for low temperature solid oxide fuel cells. ► Pr 2 NiO 4 (PNO) is used as low temperature SOFCs cathode with composite electrolyte. ► The K 2 NiF 4 type structure of PNO is formed at 1000 °C. ► PNO, Ag and electrolyte show chemical compatibility with one another at 650 °C. ► Infiltration of nano-Ag to PNO improves the ORR activity and fuel cell performance. ► A peak power output of 695 mW cm −2 is obtained at 600 °C with PNO–Ag composite cathode

LaNi 0.6Fe 0.4O 3–Ce 0.8Sm 0.2O 1.9–Ag composite cathode for intermediate temperature solid oxide fuel cells

LaNi 0.6Fe 0.4O 3 (LNF), LNF–Sm 0.2Ce 0.8O 1.9 (SDC), and LNF–SDC–Ag cathodes on SDC electrolytes were investigated at intermediate temperatures using AC impedance spectroscopy. Results show that adding 50 wt.% SDC into LNF yields a significant low area specific resistance (ASR) which was found to be 0.92 Ω cm 2 at 700 °C. Infiltrating 0.3 mg/cm 2 Ag into LNF-50 wt.% SDC can improve the electronic conductivity and oxygen exchange reaction activity, and thereby remarkably decrease the ASRs. The ASR value of the LNF–SDC–Ag cathode is as low as 0.18 Ω cm 2 at 700 °C, and 0.46 Ω cm 2 at 650 °C. The long-term test shows that the LNF–SDC–Ag cathode may be a promising candidate for solid oxide fuel cells operating at temperatures lower than 650 °C.

Development of Ceria Based SOFCs With a High Performance La0.6Sr0.4Co0.2Fe0.8O3−δ–Ce0.9Gd0.1O1.95–Ag Composite Cathode

In this work, a microtubular cell consisting of a thin Ce0.9Gd0.1O1.95 (GDC) electrolyte (thickness: below 10 μm) on a support NiO/GDC anode (1.8 mm outer diameter, 200 μm wall thickness) with a La0.6Sr0.4Co0.2Fe0.8O3−δ/GDC functional cathode has been developed for intermediate/low temperature operation. The functional cathode was prepared by in situ infiltrating the electrochemically catalytic nano-Ag particles into the as-established 20 μm thick cathode. The as-proposed Ag-impregnation route ensures a very homogeneous particle dispersion and a good adhesion of Ag to the ceramic matrices. The cells were successfully operated to produce the maximum power densities of 0.41 W cm−2 (1.27 A cm−2, 0.32 V), 0.83 W cm−2 (2.23 A cm−2, 0.37 V), and 1.05 W cm−2 (2.39 A cm−2, 0.44 V) at 450°C, 500°C, and 550°C, respectively.

YBaCo 2O 5+ δ as a new cathode material for zirconia-based solid oxide fuel cells

Microstructure, thermal expansion and electrical conductivity of YBaCo 2O 5+ δ cathode material was studied for solid oxide fuel cell (SOFC) based on yttria-stabilized zirconia (YSZ) electrolytes. YBaCo 2O 5+ δ exhibits metallic conduction behavior and the conductivity of σ = 153–35 S/cm from 100 to 800 °C was observed. Thermal expansion of sample shows a linear characteristics and the average thermal expansion coefficient (TEC) is about 1.45 × 10 −5/K in the temperature range of 200–800 °C. YBaCo 2O 5+ δ -Ag composite cathode was prepared and applied onto YSZ electrolyte. The microstructural and electrochemical characterizations of obtained electrode-electrolyte sample were examined.

High-brightness top-emissive polymer light-emitting diodes utilizing organic oxide/Al∕Ag composite cathode

This work presents the fabrication of high-brightness (over 30000cd∕m2) top-emissive polymer light-emitting diodes (PLEDs) using a hybrid semitransparent cathode capable of efficient injection of electrons. The composite cathode is comprised of the organic oxide/Al complex as the injection buffer layer covered by a thin Ag overlayer. The anode is made of Ag:Ag2O coated on the glass substrate. The electroluminescence (EL) efficiency of 8.9cd∕A for phenyl-substituted poly(para-phenylene vinylene) copolymer based top-emissive PLED markedly exceeds that of 4.3cd∕A for the control device with the bottom-emissive configuration. The high performance is attributed to the balanced injection of charge carriers and the effective extraction of EL emission from the top cathode. The optical microcavity effect significantly promotes the EL emission in the direction along the surface normal.

Synthesis and the Improved High-Rate Performance of LiMn[sub 2]O[sub 4]∕Ag Composite Cathode for Lithium-Ion Batteries

The composite has been prepared by a chemical deposition of silver particles. Well dispersed and nanosized silver particles in the composites were realized by careful control of the preparation conditions. The experimental results showed that the Ag in the composite obviously reduced the impedance of the precursor and the polarization of the cathode/electrolyte interface in the cell and effectively improved the high rate cycling performance of . The reversible capacity after remained at with capacity loss of 10.57% compared to the first cycle even at the charge-discharge rate as high as 10C.

Composite cathode based on yttria stabilized bismuth oxide for low-temperature solid oxide fuel cells

Composites consisting of silver and yttria stabilized bismuth oxide (YSB) have been investigated as cathodes for low-temperature honeycomb solid oxide fuel cells with stabilized zirconia as electrolytes. At 600 °C, the interfacial polarization resistances of a porous YSB–Ag cathode is about 0.3 Ω cm2, more than one order of magnitude smaller than those of other reported cathodes on stabilized zirconia. For example, the interfacial resistances of a traditional YSZ–lanthanum maganites composite cathode is about 11.4 Ω cm2 at 600 °C. Impedance analysis indicated that the performance of an YSB–Ag composite cathode fired at 850 °C for 2 h is severely limited by gas transport due to insufficient porosity. The high performance of the YSB–Ag cathodes is very encouraging for developing honeycomb fuel cells to be operated at temperatures below 600 °C.