O2 Anode Research Articles

Application of laser produced ion beams to nuclear analysis of materials

The ion beam driven nuclear analysis has been developed for many years by using various electrostatic accelerators. A proton micro-beam with the beam diameter of ∼1.5 μm at Takasaki Ion Acceleration for Advanced Radiation Application (TIARA), JAEA was used to analyze the positive electrode of the Li-ion battery with PIGE and PIXE. WThe PIGE and PIXE images of Li and Ni respectively for LixNi0.8Co0.15Al0.05O2(x = 0.75 ∼ 1.0) anodes have been taken. The PIGE images of LixNi0.8Co0.15Al0.05O2 particles and the depth profile of the Li density have been obtained with high spatial resolution (a few μm). The images of the Li density distribution are very useful for the R&D of the Li ion battery. In order to make the in-situ ion beam analysis of the Li battery possible, a compact accelerator for a high quality MeV proton beam is necessary. Form this point of view, the diagnostics of Li ion battery is an appropriate field for the applications of laser produced ion beams.

Research Progress and Optimization of Non-aqueous Electrolyte for Lithium Air Batteries

Lithium air battery is an advanced electrochemical power source that lies between fuel cell and lithium battery, and it is considered to be one of the most promising next generation batteries due to the fact that it may provide extremely high theoretical energy, i.e. 11140 Wh/kg (Li), which is estimated to be 6~9 times higher than that of the lithium ion batter- ies. The reason for such high theoretical energy is the use of Li sheet (with extremely high energy density) as anode electrode and O2 as cathodic reactant from the air. Other advantages of the battery include stable output voltage, cost effectiveness, and pollution free, and have broad application prospects. If it is successfully developed, the battery could be an excellent energy storage device for renewable energy sources such as wind, solar, and tidal energy, which brings a prospect for human to solve the problem of environment pollution and energy crisis. Electrolyte is a crucial component of lithium air battery and the elec- trochemical performance of the battery is determined by electrolyte to a great extent. Due to the react violently between lith- ium and water, it is not practical for lithium air battery to use directly an aqueous electrolyte unless the anode can be pro- tected from degradation. In this paper, the authors presented the latest research progress on three kind of non-aqueous elec- trolyte, i.e. organic electrolyte, ionic liquid and solid electrolyte. We elaborated the influence of various chemical properties (electrochemical stability, conductivity, polarity), physical properties (dielectric constant, viscosity, oxygen solubility, hy- groscopicity and electrolyte filling) and physicochemical properties (infiltration ability to cathode materials) on lithium air battery's performance, i.e. specific capacity, rate capacity and cycling efficiency. In addition, we also provided insights into the prospect of non-aqueous electrolyte for lithium air battery.

Preparation and characterization of Ir Pt1−O2 anode electrocatalysts for the oxygen evolution reaction

Towards competent production of clean and electrolytic hydrogen, proton exchange membrane (PEM) water electrolysis offers several advantages, such as high purity of the produced gases, very high level of operation safety and direct storage of gases under high pressure. The work presented deals with the development of efficient PEM water electrolyzers, employing high specific surface area IrxPt1−xO2 electrocatalysts synthesized by the modified Adams fusion method. A typical three-electrode cell was used to evaluate the performance of the materials for water splitting. The performance of electrodes for oxygen evolution reaction was assessed by steady-state current–potential measurements while their electrochemical characteristics and stability were studied by cyclic voltammetry. It was found that Ir–Pt bimetallic oxide electrodes present a stable performance for oxygen evolution reaction. Their intrinsic electrocatalytic activity in combination with their large surface area and stability are quite promising for the development of economically feasible electrocatalysts for PEM water electrolyzers.

Codoping effect of Li1.1V0.9O2 anodes for lithium-ion batteries with Mo and W (Li1.1V0.9−2xMoxWxO2): Based on electronic structure calculations using full-potential KKR-Green's function method

Pure crystalline doped Li1.1V0.9O2 powder was prepared. The specific charge/discharge capacities of the doped Li1.1V0.9O2 anodes were more than double of those of the bare Li1.1V0.9O2 anodes, especially at high C-rates. The main origin of such capacities was revealed to be the increase in electronic conductivity upon doping due to the extra free electron.

Electrochemical Properties of Li1.1V0.75W0.075Mo0.075O2/Graphite Composite Anodes for Lithium-ion Batteries

Novel type Li1.1V0.9-2xWxMoxO2 powders were prepared by a solid-state reaction of Li2CO3, V2O3, WO2 and MoO2 precursors in a nitrogen atmosphere containing 10 mol % hydrogen gas, and assessed as anode materials in lithium-ion batteries. The specific charge and discharge capacities of the Li1.1V0.9-2xWxMoxO2 anodes were higher than those of the bare Li1.1V0.9O2 anode. The cyclic efficiency of these anodes was approximately 73.3% at the first cycle, regardless of the presence of W and Mo doping. The composite anode, which was composed of Li1.1V0.75W0.075Mo0.075O2 (20 wt %) and natural graphite (80 wt %), demonstrated reasonable specific capacity, high cyclic efficiency, and good cycling performance, even at high rates without capacity fading. based on this material could be enhanced significantly because of its low working potential of < 0.3 V vs. Li/Li + during the charge and discharge reactions. The potential of this material as a high-density anode electrode has prompted intensive research on its structure and valence state. Li1.1V0.9O2 has an ordered layered crystalline structure with Li + and V +3 ions occupying alternate (111) planes, and exhibits a hexagonal structure. 8,9 After lithium intercalation, Li1.1V0.9O2 is converted to Li2.1V0.9O2, corresponding to the P-3m1 space group, and the oxidation state of vanadium ions is reduced from V(III) to V(II). The layered structure of Li1.1V0.9O2, gives it a relatively low volume change of 25% during the cycling process compared to that of highly capacitive silicon or tin-based anode materials. On the other hand, the electrochemical properties of Li1.1V0.9O2 might be insufficient for high-current applications owing to its low conductivity. Therefore, surface modification or other treat- ment methods should be applied to enhance the rate cap- ability. Metal doping is one of the most effective methods for improving the electrochemical properties of Li1.1V0.9O2. W and Mo-based oxide materials are used as dopants for Li1.1V0.9O2, which is used as an anode material in lithium-ion batteries. 10,11 These metals are suitable for the preparation of high-density anodes because of their high intrinsic density, low cost and non-toxic environment. In this study, a simple solid-state reaction was used to prepare a conducting Li1.1V0.9-2xWxMoxO2 anode material using a metal doping process. The electrochemical proper- ties of the anodes of these lithium-ion batteries were ex- amined using a range of analytical techniques. Experimental

Novel (Ir,Sn,Nb)O2 anode electrocatalysts with reduced noble metal content for PEM based water electrolysis

A solid solution of IrO2, SnO2 and NbO2, denoted as (Ir,Sn,Nb)O2, of compositions (Ir1−2xSnxNbx)O2 with x = 0, 0.125, 0.20, 0.25, 0.30, 0.35, 0.40, 0.425 and 0.50 has been synthesized by thermal decomposition of a homogeneous mixture of IrCl4, SnCl2·2H2O and NbCl5 ethanol solution coated on pretreated Ti foil. The (Ir,Sn,Nb)O2 thin film of different compositions coated on Ti foil has been studied as a promising oxygen reduction anode electrocatalyst for PEM based water electrolysis. It has been identified that (Ir,Sn,Nb)O2 of composition up to x = 0.30 [(Ir0.40Sn0.30Nb0.30)O2] shows similar electrochemical activity compared to pure IrO2 (x = 0) resulting in ∼60 mol.% reduction in noble metal content. On the other hand, (Ir,Sn,Nb)O2 of composition x = 0.20 [(Ir0.20Sn0.40Nb0.40)O2] shows only 20% lower activity compared to pure IrO2 though the noble metal oxide, IrO2 loading is reduced by 80 mol.%. The accelerated life test of the anode electrocatalyst for 48 h followed by elemental analysis of the electrolyte shows that (Ir,Sn,Nb)O2 improves the stability of the electrode in comparison to pure IrO2 electrocatalyst in oxygen reduction processes. The excellent electrochemical activity as well as long term structural stability of (Ir,Sn,Nb)O2 during water electrolysis has been discussed using first-principles calculations of the total energies, electronic structures, and cohesive energies of the model systems.

Syngas reactivity over (LaAg)(CoFe)O3 and Ag-added (LaSr)(CoFe)O3 anodes of solid oxide fuel cells

The syngas, H2+CO gas mixture with various H2/CO ratios, is used as the anode fuel of solid oxide fuel cell with La0.7Ag0.3Co0.2Fe0.8O3 (LACF) and 2wt% Ag-added La0.58Sr0.4Co0.2Fe0.8O3 (LSCF) as the anode, respectively, both being in composite with 50wt% Ce0.9Gd0.1O1.95 (GDC). Both the current–voltage and the fixed-voltage measurements are performed at 800°C. The reactivity with H2 as the fuel is larger than that with CO. The syngas reactivity increases with increasing H2 content. The results of the current–voltage and the fixed-voltage measurements are in agreement with each other. Ag-added LSCF–GDC has better reactivity with H2, CO and syngas and better stability in the H2 atmosphere than LACF–GDC as the anode material.

Electrochemical Characteristics of Lithium Vanadium Oxide for Lithium Secondary Battery

The pure crystalline Li1.1V0.9O2 powder has been prepared by a simple solid state reaction of Li2CO3 and V2O3 precursors under nitrogen gas containing 10 mol % hydrogen gas flow. The structure of Li1.1V0.9O2 powder was analyzed using Xray diffraction (XRD) and scanning electron microscope (SEM). The stoichiometric Li1.1V0.9O2 powder was used as anode active material for lithium secondary batteries. Its electrochemical properties were investigated by cyclic voltammetry and constant current methods using lithium foil electrode. The observed specific discharge capacity and charge capacity were 360 mAh/g and 260 mAh/g during the first cycle, respectively. In addition, the cyclic efficiency of this cell was 72.2% in the first cycle. The specific capacity of Li1.1V0.9O2 anode rapidly declines as the current rate increases and retains only 30 % of the capacity of 0.1C rate at 1C rate. The crystallinity of the Li1.1V0.9O2 anode decrease as discharge reaction proceeds. However, the relative intensity of main peaks was almost recovered when the cell was charged up to 1.5 V.

Electrochemical removal of CuII in the presence of humic acid

The removal of CuII (10 mg L-1) complexed by commercial humic acid (100 mg L-1) was studied at different current densities (30-80 mA cm-2) using a filter-press cell, Ti/Ru0.3Ti0.7O2 anode and stainless steel cathode. The electrolyses were performed with and without membrane separating the cell compartments [(homogeneous anionic (Nafion R117), heterogeneous cationic (Ionac MC-3470) and heterogeneous anionic (Ionac MA-3475)]. The influence of the membrane on the rate of CuII removal was bigger for cationic membranes. Current efficiencies up to ca. 55% (Ionac MC-3470) for CuII removal at 30 mA cm-2 were obtained. By combining oxidation and reduction, 100% CuII removal was achieved at current efficiencies of 75%. The main path for the removal is the electrostatic interaction with the anode followed by diffusion through the membrane and deposition at the cathode. Additionally, the oxidative degradation of humic acid contributes to the rate of CuII removal.

Stability and morphology of (Ti0·1Ru0·2Sn0·7)O2 coating on Ti in chloralkali medium

Today's mixed metal oxide anodes are widely used in the chloralkali industry. Stability is one of the main properties of these anodes because of their high cost. Morphology of mixed metal oxide coating is a determining factor in electrochemical stability of mentioned anodes. In this article the effect of temperature and times of heat treatment on the morphology and electrochemical stability of Ti/(Ti0·1Ru0·2Sn0·7)O2 anode has been investigated. The anodes were prepared by brushing and thermal decomposition method. Mud cracked morphology appeared on the sample by this process. Increasing the temperature of calcination causes the density of cracks on the surface and electrochemical stability of coating to decrease. Increasing the time had different effects in the first and final calcination times. The anode which was prepared at 450°C, for 10 min in the first calcination time and 1 h in the final calcination time had the highest stability and optimum morphology.

Electrochemical Behavior of Ni-CZO Cermet Anodes Prepared by Glycine-nitrate-process

The impact of H2O for H2 oxidation on Ni-Ce0.75Zr0.25O2 (Ni-CZO) anode material synthesized by glycine-nitrate-process has been successfully investigated under dry and wet H2 fuel atmospheres over a range of operating conditions using yttria-stabilized zirconia (YSZ) electrolytes. Using electrochemical impedance spectroscopy (EIS), the polarization resistance (comprised of high frequency (HF) and low frequency (LF) features) of Ni-CZO symmetrical cells (Ni-CZO/YSZ/Ni-CZO) has been studied. The LF arc was almost negligible at all the operating temperatures in wet condition, and the HF arc was linearly increased with time at 800oC only in dry condition. The EIS response in dry and wet H2 conditions clearly exhibited that, water vapor enhanced the dissociative adsorption and surface diffusion of hydrogen and achieved the stable electrochemical performance at 3PB on the Ni-CZO cermet.

Study of IrxRu1−xO2 oxides as anodic electrocatalysts for solid polymer electrolyte water electrolysis

Abstract Electrocatalysts of the general formula IrxRu1−xO2 were prepared using Adams’ fusion method. The crystallite characterization was examined via XRD, and the electrochemical properties were examined via cyclic voltammetry (CV) in, linear sweep voltammetry (LSV) and chronopotentiometry measurements in 0.5 M H2SO4. The electrocatalysts were applied to a membrane electrode assembly (MEA) and studied in situ in an electrolysis cell through electrochemical impedance spectroscopy (EIS) and stationary current density–potential relations were investigated. The IrxRu1−xO2 (x = 0.2, 0.4, 0.6) compounds were found to be more active than pure IrO2 and more stable than pure RuO2. The most active electrocatalyst obtained had a composition of Ir0.2Ru0.8O2. With an Ir0.2Ru0.8O2 anode, a 28.4% Pt/C cathode and the total noble metal loading of 1.7 mg cm−2, the potential of water electrolysis was 1.622 V at 1 A cm−2 and 80 °C.

Precious-Metal Impregnated (La,Sr)(Cr,Mn)O3/Gd0.2Ce0.8O2 Anodes for Direct Utilization of Methane in SOFCs

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Direct utilization of ethanol on ceria‐based anodes for solid oxide fuel cells

AbstractThe direct utilization of ethanol was investigated in CuCeO2, CuZr0.35Ce0.65O2 (ZDC) and Cu/RuZr0.35Ce0.65O2 anodes for solid oxide fuel cells (SOFC). The anodes were prepared by impregnation with nitrate precursors on a porous layer of yttria‐stabilized zirconia (YSZ) obtained by tape casting, while (La0.8Sr0.2MnO3−δ) LSM cathodes were screen‐printed. The cells were tested in both hydrogen and ethanol. The outlet gas composition was monitored with a gas chromatograph, which showed that almost all the ethanol was decomposed, mainly to H2, CH4, CO, H2O and C2H4. The maximum power outputs obtained in ethanol were 0.075 and 0.400 W/cm2 on CuCeO2|YSZ|LSM and CuZDC|YSZ|LSM, respectively. All cells were more active in alcohol than in hydrogen with the peak performance occurring after approximately 4 h. That is, the power density initially increased, peaked and then decreased. This behavior was likely a consequence of carbon deposition that initially results in an improvement of the electronic conductivity in the anode but later results in the blocking of the active sites. Zirconia doping (in the ZDC anodes) resulted in better stability and, in addition, the initial activity of the ZDC anodes could be recovered after approximately 1 h of exposure to humidified hydrogen, whereas the initial activity of the ceria anodes could not be recovered. The addition of ruthenium (&lt;0.5 wt%) further improved the stability by delaying the onset of carbon formation. Copyright © 2008 Curtin University of Technology and John Wiley &amp; Sons, Ltd.

Preparation of Porous Ni-BaZr(Y)O3 Anode Cermet for High Temperature Proton-conducting Oxide Fuel Cell

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High-performance cathode-supported SOFC with perovskite anode operating in weakly humidified hydrogen and methane

A high-performance, cathode-supported solid oxide fuel cell (SOFC), suitable for operating in weakly humidified hydrogen and methane, has been developed. The SOFC is essentially made up of a YSZ–LSM composite supporting cathode, a thin YSZ film electrolyte, and a GDC-impregnated La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) anode. A gas-tight thin YSZ film (27 μm) was formed during the co-sintering of the cathode/electrolyte bilayer at 1200°C. The cathode-supported SOFC developed in this study showed encouraging performance with maximum power density of 0.182, 0.419, 0.628 and 0.818 W/cm2 in air/3% H2O–97% H2 (and 0.06, 0.158, 0.221 and 0.352 W/cm2 in air/3% H2O–97% CH4) at 750, 800, 850 and 900°C, respectively. Such performance is close to that of the cathode-supported cell (0.42 W/cm2 versus 0.455 W/cm2 in humidified H2 at 800°C) developed by Yamahara et al.[1] [DOI: 10.1016/j.ssi.2004.09.023] with a Co-infiltrated supporting LSM-YSZ cathode, an (Sc2O3)0.1(Y2O3)0.01(ZrO2)0.89 (SYSZ) electrolyte of 15 μm thickness and an SYSZ/Ni anode, indicating that the performance of the GDC-impregnated LSCM anode is comparable to that made of Ni cermet while stable in weakly humidified methane fuel.

Electrochemical oxidation of 4-chlorophenol and its by-products using Ti/Ru0.3M0.7O2 (M = Ti or Sn) anodes: preparation route versus degradation efficiency

The electrochemical degradation of 4-chlorophenol and its main by-products was investigated in acid medium using binary oxides electrodes of nominal composition Ti/Ru0.3Ti0.7O2 and Ti/Ru0.3Sn0.7O2 prepared by thermal decomposition through two different routes: inorganic precursors dissolved in isopropanol and polymeric precursors (PPM). The aim of this study was to investigate the influence of both the composition and preparation methodology of these electrodes in the electrooxidation of the organic pollutants 4-chlorophenol and its by-products. Electrolyses were carried out using a filter press-type flow cell and monitored by high performance liquid chromatography (HPLC), total organic carbon (TOC), and chloride analyses. Besides CO2, the by-products formed in the reactions were 1,4-benzoquinone, 4-chlorocatechol, and hydroquinone, as well as oxalic, maleic, malic, malonic, and succinic acids. The electrocatalytic efficiency with respect to the degradation of by-products was evaluated through the electrooxidation of 1,4-benzoquinone and oxalic acid (OA).

Electrochemical oxidation of an acid dye by active chlorine generated using Ti/Sn(1−x)Ir x O2 electrodes

The generation of active chlorine on Ti/Sn(1−x)Ir x O2 anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of chloride ions (0.05 mol L−1) and a low current density (5 mA cm−2) it was possible to produce up to 60 mg L−1 of active chlorine on a Ti/Sn0.99Ir0.01O2 anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated with in situ electrogenerated active chlorine on Ti/Sn(1−x)Ir x O2 anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4, 25 mA cm−2 and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus time reveal a zero order reaction at dye concentrations up to 1.0 × 10−4 mol L−1. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed.

GDC-Impregnated ( La0.75Sr0.25 ) ( Cr0.5Mn0.5 ) O3 Anodes for Direct Utilization of Methane in Solid Oxide Fuel Cells

Gd-doped ceria (GDC)-impregnated (LSCM) is investigated as an alternative Ni-free anode for the direct utilization of methane in solid oxide fuel cells. Impregnation of submicrometer and ionic conducting GDC greatly improves the electrocatalytic activity of the LSCM anodes for the oxidation reaction in weakly humidified (3% ) methane. At , electrode polarization resistance for the reaction in wet is on a GDC-impregnated LSCM anode. In comparison, the electrode polarization resistance is 11.4 and on a pure LSCM and a LSCM /yttria-stabilized zirconia (YSZ) composite anode, respectively, under the same testing conditions. The polarization performance of GDC-impregnated LSCM is also substantially higher than that of the pure LSCM and LSCM/YSZ composite anodes. Based on the results, a mechanism involving the dry reforming of methane, followed by the electrochemical oxidation of the dry reforming products is proposed for the methane oxidation on Ni-free mixed ionic and electronic conductors such as LSCM. Impregnation of nanosized GDC greatly enhances the catalytic as well as electrochemical activities for the dry reforming of methane and for the electrochemical oxidation reactions of the dry reforming products.

Performance of (La, Sr)(Cr, Mn)O3 Anode for Direct Oxidation of Methane in Solid Oxide Fuel Cell

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