Preparation and Characterization of Mesoporous Ce0.5Zr0.5O2 Mixed Oxide

Mesoporous （MSU） Ce0.5Zr0.5O2 mixed oxide with a high specific surface area has been synthesized under weak acidic condition in the presence of an anionic surfactant, sodium dodecylbenzenesulfonate. The effect of the pH value on the formation of mesostructure and the thermal stability of the material has been evaluated. The products were characterized by transmission electron microscopy, powder X-ray diffraction and nitrogen adsorption-desorption measurements. The results showed that the as-prepared Ce0.5Zr0.5O2 mixed oxide possessed a specific surface area of 163.3 m^2·g^-1, which had a cubic fluorite-type structure and possessed specific surface areas of 148.4 and 62.4 m^2·g^-1 after calcination at 500 and 800 ℃ for 2 h, respectively. The material showed excellent thermal stability.     

Perovskite Sr_(0.9)Fe_(0.9)Zr_(0.1)O_(3-δ):Redox-stable Structure,Oxygen Vacancy,Electrical Properties and Steam Electrolysis Performance

Many researchers have studied on perovskite oxide for its unique structure.Perovskite oxides,ABO_(3-δ),with different A and B metals have shown wide applications in many fields,in particular solid oxide electrolysers.SrFeO_(3-δ),typical perovskite oxides,in which iron is the mixed-valence cation with the capacity to change the chemical valence,have a wide range of oxygen nonstoichiometry.In this study,Sr_(0.9)Fe_(0.9)Zr_(0.1)O_(3-δ)(SFZO) is synthesized and then treated in 5%H_2/Ar and air at high temperature,exhibiting excellent redox stability.Redox-stable structure,oxygen vacancy and electrical properties of SFZO are investigated.Steam electrolysis is then performed with SFZO cathode under 5%H_2O/5%H_2/Ar and 5%H_2O/Ar atmospheres,respectively.The present results indicate that the SFZO is a novel promising cathode material for solid oxide steam electrolyser.     

High performance and stability of double perovskite-type oxide NdBa_(0.5)Ca_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ) as an oxygen electrode for reversible solid oxide electrochemical cell

In this study,we successfully synthesized double perovskite-type oxide NdBa_(0.5)Ca_(0.5)Co_(1.5)Fe_(0.5)O_(5+δ)(NBCCF) using a conventional wet chemical method as the oxygen electrode for reversible solid oxide electrochemical cells (RSOCs).The polarization resistance (R_p) of the composite electrode NBCCFGd_(0.1)Ce_(0.9)O_2 (GDC) is only 0.079Ωcm~2 at 800℃under air.The single cell based on NBCCF-GDC electrode displays a peak power density of 0.941 W/cm~2 in fuel cell mode and a low R_p value of 0.134Ωcm~2.In electrolysis cell mode,the cell displays an outstanding oxygen evolution reaction (OER) activity and shows current density as high as 0.92 A/cm~2 with 50 vol%AH (Absolute Humidity) at 800℃and applied voltage of 1.3 V.Most importantly,the cell exhibits admirable durability of 60 h both in electrolysis mode and fuel cell mode with distinguished reversibility.All these results suggest that NBCCF is a promising candidate electrode for RSOC.     

Manipulating interfacial stability of LiNi0.5Co0.3Mn0.2O2 cathode with sulfide electrolyte by nanosized LLTO coating to achieve high-performance all-solid-state lithium batteries

All-solid-state lithium batteries(ASSLBs) based on sulfide solid-state electrolytes and high voltage layered oxide cathode are regarded as one of the most promising candidates for energy storage systems with high energy density and high safety.However,they usually suffer poor cathode/electrolyte interfacial stability,severely limiting their practical applications.In this work,a core-shell cathode with uniformly nanosized Li0.5La0.5TiO3(LLTO) electrolyte coating on LiNi0.5Co0.3Mn0.2O2(NCM532) is designed to improve the cathode/electrolyte interface stability.Nanosized LLTO coating layer not only significantly boosts interfacial migration of lithium ions,but also efficiently alleviates space-charge layer and inhibits the electrochemical decomposition of electrolyte.As a result,the assembled ASSLBs with high mass loading(9 mg cm-2)LLTO coated NCM532(LLTO@NCM532) cathode exhibit high initial capacity(135 mAh g^-1) and excellent cycling performance with high capacity retention(80% after 200 cycles) at 0.1 C and 25℃.This nanosized LLTO coating layer design provides a facile and effective strategy for constructing high performance ASSLBs with superior interfacial stability.     

Fabrication and characterization of Ba Ce0.8Y0.2O2.9-Ce0.85Sm0.15O1.925 composite electrolytes for IT-SOFCs

The Ba Ce0.8Y0.2O2.9-Ce0.85Sm0.15O1.925 composite electrolytes were prepared with Ba Ce0.8Y0.2O2.9(BCY) and Ce0.85Sm0.15O1.925(SDC). The SDC and BCY powders were mixed in the weight ratio of 95:5, 85:15, and 75:25, respectively(named as BS95, BS85, and BS75). Because of the composite effect between the SDC and BCY phases, the BS95 and BS85 exhibit improved conductivity compared with the pure SDC and BCY. The conductivity of BS95 is higher than that of BS85, indicating that the composite effect of BS95 is greater than that of BS85. Nevertheless, the composite effect in BS75 does not exist. Hence, we conclude that the composite effect in the BCY-SDC composites will decrease with the increase of the amount of BCY and even disappear when the amount of BCY exceeds a certain value. In our case, the optimum composition of the composite electrolyte is 95 wt% SDC and 5 wt% BCY. The BS95 has the highest conductivity(σ1t=0.07808 S cm-1, at 800 °C) and the fuel cell based on the BS95 shows the best performance(the maximum power density reaches as high as 526 mw cm-2 at 750 °C). The encouraging results suggest that the BCY-SDC composites are the very promising electrolyte materials for IT-SOFCs.     

A defective iron-based perovskite cathode for high-performance IT-SOFCs: Tailoring the oxygen vacancies using Nb/Ta co-doping

The sluggish kinetics of the electrochemical oxygen reduction reaction(ORR) in intermediatetemperature solid oxide fuel cells(IT-SOFCs) greatly limits the overall cell performance. In this study,an efficient and durable cathode material for IT-SOFCs is designed based on density functional theory(DFT) calculations by co-doping with Nb and Ta the B-site of the SrFeO_3-δ perovskite oxide. The DFT calculations suggest that Nb/Ta co-doping can regulate the energy band of the parent SrFeO     

Effect of dopant valence on the oxygen desorption and oxygen permeability of SrCo0.4Fe0.5M0.1O3-δ （M -Ni,Al and Zr） mixed-conducting oxides

The effect of dopant valence on oxygen desorption and oxygen permeability of SrCo0.4Fe0.5M0.1O3-δ （M = Ni, Al and Zr） mixed-conducting oxides were investigated in detail by O2-TPD and oxygen permeation measurement. The SrCo0.4Fe0.5M0.1O3-δ for M = Fe, Ni, Al and Zr were denoted as SCF, SCFN, SCFA and SCFZ, respectively. O2-TPD analysis revealed that the amount of α oxygen desorption decreased with increasing the valance of doped metal elements （SCFN 〉 SCFA SCF 〉 SCFZ）. The oxygen permeation flux at the temperature ≈igher than 1148 K decreased in the order of SCFN 〉 SCF 〉 SCFZ 〉 SCFA. Single activation for oxygen permeation was observed for SCFZ oxide and the activation energies of SCF and SCFA change at around 1073 K, while the change temoerature of SCFN was about 1173 K.     

中温固体氧化物燃料电池复合阴极La1.6Sr0.4NiO4-Ce0.9Gd0.1O1.9的制备及性能研究

Composite cathodes consisting of -La_1.6Sr_0.4NiO₄(LSN) and -Ce_0.9Gd_0.1O_1.9(CGO) has been prepared for intermediate temperature solid oxide fuel cell (IT-SOFC). The chemical stability, microstructures and electrochemical performance of the cathode have been investigated using XRD, SEM and AC impedance spectroscopy. Results showed that strong bonding was formed between the composite electrodes and CGO electrolytes after the electrodes were fired at 1 050 ℃ for 4 hours. The polarization resistance changed with oxygen partial pressure, suggesting that charge transfer process was the rate limiting step for electrochemical oxygen reduction at the composite cathodes. Area specific resistance (ASR) for a LSN-40CGO composite cathode was 0.76 Ω·cm² at 700 ℃, which was four times lower than that of a pure LSN cathode. 1.7％ decrease of the cathode current density was observed in the stability test of the composite cathode.     

Effects of oxidation pretreatment temperature on Kovar used as CO_2 reforming catalyst

The effect of oxidation pretreatment temperature(500 ~ 1 000 ℃) on the catalytic activity of Kovar applied on hydrocarbon CO2reforming was examined. Catalytic performance evaluation using tetradecane at 800 ℃ with 70 μmol/s CO2revealed 700 and 1 000 ℃ as the best pre-oxidation temperature in producing CO and H2,respectively. XRD and SEM-EDX analyses showed that a separate metal oxide layer composed of iron oxide(Fe2O3and F3O4),nickel,cobalt,and possibly their respective oxides started to form when oxidation was conducted at 700 ℃ or higher.The presence of iron enhanced the stability of nickel in the structure while the compact structure of Fe3O4resulted into the formation of a thick and rigid metal oxide layer on the surface of the Kovar tube. The strong physical bond between the metal oxide layer and Kovar tube provided the catalyst good mechanical strength and consequently good catalytic activity.     

Enhanced CO_2 Electrolysis with Metal-oxide Interface Structures

The ever-decreasing fossil fuels and the increasing greenhouse effect have caused substantial concern.Solid oxide electrolyser cell(SOEC)with La_0.75Sr_0.25Cr_(0.5 )Mn_0.5O_3-δ(LSCM)as a cathode was used for CO₂ electrolysis to CO.In this work,the metal-oxide interface was constructed on the LSCM framework by in-situ exsolution and impregnation,and the uniform distribution of metal nanoparticles on the LSCM framework was confirmed by spectroscopy techniques and electron microscopy techniques.The existence of three-phase boundary promoted the absorption and electrolysis of CO₂.(La_0.75 Sr_0.25)0.9(Cr_(0.5 )Mn_0.5)_0.9(Ni_0.5 Cu_0.5)_0.1 O_3-δ(LSCMNC)showed the best electrolytic CO₂ performance at 850℃and exhibited excellent electrocatalytic activity after 100 hours of long-term testing and 8 redox cycles.     

甘氨酸-硝酸盐法制备中温SOFC电解质及电极材料

采用一种新的燃烧合成陶瓷粉末的方法--甘氨酸-硝酸盐法合成中温SOFC所有元件的初始粉体,电池的电解质材料是(CeO₂)x(SmO_1.5)_{1-x(x=0.9,0.85,0.8),阳极材料是掺(CeO2)0.8(SmO1.5)0.2(SDC)的NiO,阴极材料是SDC与La0.6Sr0.4Fe0.8Co0.2O3的复合材料.其中以(CeO2)0.9(SmO1.5)0.1为电解质的单电池性能最好,在750℃时短路电流密度为0.5A/cm²,最大功率密度达0.104W/cm².通过SEM结果分析,掺杂摩尔分数20%SmO1.5的电解质晶界非常明显,而掺杂10%的电解质晶界有很强的融合消失的趋势.}     

Influence of NaCl on Cathode Performance of Solid Oxide Fuel Cells

Degradation induced by sodium chloride in air was investigated for (La_0.8Sr_0.2)_0.98MnO₃(LSM) and La_0.6Sr_0.4Co_0.2Fe_0.8O₃(LSCF) cathodes in solid oxide fuel cells(SOFC). Cell performance was measured by volatilizing NaCl to be supplied to the cathode at a constant current density of 200 mA/cm² for up to 100 h. At 800 ℃, an exposure of the cathode to 30 mg/L NaCl caused negligible degradation of LSM at least for 100 h. Slight change in the composition of the cathode materials was observed which may imply the gradual degradation of cell performance for the long-term. In addition, cell performance degradation was compared between 700 ℃ and 900 ℃, being poisoned by 30 mg/L NaCl. Degradation was negligible for LSM cathode, while LSCF cathode showed slightly poor tolerance at 700 ℃ due to the decomposition of the cathode material. Further studies should be done to clarify the long-term influence of NaCl on cathode performance.     

中温复合固体电解质SDC-LSGM的制备和性能

采用甘氨酸-硝酸盐法分别制备了Ce0.85Sm0.15O2-δ(SDC)与La0.9Sr0.1Ga0.8Mg0.2O3-δ(LSGM)两种电解质材料, 并用固相混合法将两种材料按不同质量比(SDC与LSGM的质量比分别为9∶1, 8∶2, 5∶5)混合制备复合电解质材料. 采用交流阻抗技术对样品的电学性能进行研究. 实验结果表明, SDC与LSGM的质量比为9∶1(SL91)时, 样品具有较高的电导率, 在350—800 ℃温度范围内其电导率均比SDC的高. 以复合电解质为支撑体, 以Sm0.5Sr0.5CoO3 为阴极、NiO/SDC 为阳极制成单电池, 测试结果显示, 在800 ℃时以SL91为电解质的单电池的最大输出功率密度为0.25 W/cm2, 最大电流密度为1.06 A/cm2. 在电池的工作温度区间(600—800 ℃)内以复合材料为电解质的单电池的开路电压比以SDC为电解质的高.     

Effect of SO2 on Performance of Solid Oxide Fuel Cell Cathodes

Effects of SO₂ in ambient air on the performance and durability of solid oxide fuel cell(SOFC) cathode were evaluated by galvanostatic measurement. Comparison between two cathode materials was made to consider the cathode degradation mechanisms. The degradation performance is associated with a slow decomposition of the La_0.6Sr_0.4Co_0.2Fe_0.8O₃(LSCF) due to the segregation of strontium oxide. Negligible deterioration for (La_0.7Sr_0.3)MnO₃ (LSM) cathode was caused by SO₂ poisoning under a current density of 200 mA/cm². Metal sulphate formation may explain a slight deterioration under increasing high the concentration of SO₂. It was verified that the poisoning mechanism for the two cathode materials resulted from the gradual decomposition of the cathode materials.     

Cobalt-free cathode material SrFe0.9Nb0.1O3−δ for intermediate-temperature solid oxide fuel cells

A cobalt-free cubic perovskite oxide, SrFe_0.9Nb_0.1O_3?δ (SFN) was investigated as a cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). XRD results showed that SFN cathode was chemically compatible with the electrolyte Sm_0.2Ce_0.8O_1.9 (SDC) for temperatures up to 1050 °C. The electrical conductivity of SFN sample reached 34–70 S cm^?1 in the commonly operated temperatures of IT-SOFCs (600–800 °C). The area specific resistance was 0.138 Ω cm² for SFN cathode on SDC electrolyte at 750 °C. A maximum power density of 407 mW cm^?2 was obtained at 800 °C for single-cell with 300 μm thick SDC electrolyte and SFN cathode.     

阴极支撑型固体氧化物燃料电池的制备与测试

采用固相反应法合成A缺位的(La_0.8Sr_0.2)_0.95MnO₃(LSM95)作为阴极材料,Zr_0.9Sc_0.1SO_1.95(SSZ)商业粉体作为电解质材料,溶胶-凝胶法合成的La_0.8Sr_0.2Cr_0.5Mn_0.5O₃-(LSCrM)作为阳极电催化材料,利用流延、共烧结及浸渍法得到结构为LSCrM-CeO₂|SSZ|3YSZ-LSM95的阴极支撑型固体氧化物燃料电池,分别在氢气气氛和甲烷气氛中进行电化学性能测试. 结果表明,浸渍0.11 g·cm ^-2 CeO₂的LSCrM-CeO₂|SSZ|3YSZ-LSM95单电池在以CH₄为燃料时,600、650、700、750和800 ^oC下的功率密度分别为1.68、4.70、12.40、28.08和54.78 mW·cm ^-2,表现出一定的电化学性能和较好的稳定性.     

Perovskite Oxides La0.8Sr0.2Co1-xFexO3 for CO Oxidation and CO+NO Reduction: Effect of Redox Property and Surface Morphology

This work aims to study the effect of redox property and surface morphology of perovskite oxides on the catalytic activity of CO oxidation and CO+NO reduction, with the redox property being tuned by doping Fe at the Co site of La_0.8Sr_0.2Co_1-xFe_xO₃ and the surface morphology being modified by supporting La_0.8Sr_0.2CoO₃ on various mesoporous silicas(i.e., SBA-16, SBA-15, MCF). Characteristic results show that the Fe doping improves the match of redox potentials, and SBA-16 is the best support of La_0.8Sr_0.2CoO₃ when referring to the oxidation ability(e.g., the Co³⁺/Co²⁺ molar ratio). A mechanism for oxygen desorption from perovskite oxides is proposed based on O₂-TPD experiments, showing the evolution process of oxygen released from oxygen vacancy and lattice framework. Catalytic tests indicate that La_0.8Sr_0.2CoO₃ is the best for CO oxidation, and La_0.8Sr_0.2FeO₃ is the best for CO+NO reduction. The mechanism of CO+NO reduction changes as the reaction temperature increases, with X_NO/X_CO value decreases from 2.4 at 250 ℃ to 1.0 at 400 ℃. As for the surface morphology, La_0.8Sr_0.2CoO₃ supported on SBA-16 possesses the highest surface Co³⁺/Co²⁺ molar ratio as compared to the other two, and shows the best activity for CO oxidation.     

硬模板法制备固体氧化物燃料电池Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x包覆管状SDC立体阳极

为在固体氧化物燃料电池中有效利用干甲烷为燃料,需制作多孔立体阳极。采用硬模板法和浸渍法制备Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x包覆管状SDC阳极材料(Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x/SDC),为作对比,用溶胶凝胶法制备粉末状Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x,机械混合SDC粉末制备Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x-SDC。将这两种阳极材料分别制作电解质支撑的单电池Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x/SDC|YSZ|LSMYSZ与Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x-SDC|YSZ|LSM-YSZ,并进行发电性能测试以及长期稳定性实验。结果表明,800℃下,干甲烷环境中,Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x-SDC为阳极的单电池最大功率密度为324.99 m W/cm2,运行10 h后,电压下降5.60%;而以Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x/SDC为阳极的单电池最大功率密度达到384.54 m W/cm2,运行100 h后,电压未严重衰减。实验后阳极的SEM照片表明,Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x-SDC阳极内孔隙狭小,易被积炭堵塞;而Ni_(0.5)Cu_(0.5)Ba_(0.05)O_x/SDC阳极呈立体多孔结构,有利于燃料气体与反应后气体的扩散。催化剂颗粒均匀地包覆在SDC纤维管表面,有利于增加三相界面,提高电池的稳定性。     

制备条件对Ru/Ce_(0.8)Zr_(0.2)O_2催化剂上CO_2甲烷化反应性能的影响

采用均相法制得Ce0.8Zr0.2O2载体,并以其为载体等体积浸渍制得一系列负载型Ru催化剂。在0.1 MPa、GHSV为10000 h-1、H2/CO2为3.5(物质的量比)的条件下,对催化剂进行评价。借助TG-DSC、BET、H2-TPR等技术对所制备的载体和催化剂进行表征,结果表明,500℃焙烧的载体具有适中的比表面积和孔径并形成了Ce-Zr固溶体,与载体形成弱相互作用的Ru能够显著提高催化剂的活性,适宜的还原方式能促进活性组分的均匀分布。采用500℃焙烧的载体浸渍Ru Cl3溶液,干燥后在400℃焙烧,并使用水合肼和H2两次还原后的催化剂活性最高,在290℃时,H2转化率可达到93.57%。     

以甲醇为燃料的中温固体氧化物燃料电池性能研究

制备了阳极负载型LDC-LSGM双层电解质薄膜电池.考察了单电池在分别使用甲醇和氢气两种燃料时,不同温度下的I～V性能.以甲醇为燃料,以空气为氧化剂时,800℃下的最大输出功率密度为1.07W/cm²,而使用氢气为燃料时,最大输出功率密度为1.54W/cm².通过交流阻抗研究了造成甲醇性能降低的可能原因.结果表明,以甲醇作为燃料时,单电池性能较氢气作为燃料时低.