Review of composite cathodes for intermediate-temperature solid oxide fuel cell applications

A composite cathode exhibits low activation polarisation by spreading its electrochemically active area within its volume. Composite cathodes enable the development of high-performance electrodes for solid oxide fuel cells (SOFCs) at intermediate temperatures (600 °C – 800 °C) because of their significant role in determining the kinetics of oxygen reduction reaction (ORR). Few anions O²⁻ are transferred through the electrolyte component when the ORR is low, thereby lowering the reaction with cation H⁺ from an anode side to transfer electrons along the outer circuit to the cathode side to participate in ORR. The resistance to the ORR at the cathode is minimised, thereby contributing to performance degradation and efficiency loss in existing SOFCs, especially at intermediate temperatures. The suitability and compatibility of the cathode and electrolyte are crucial in the development of cathodes and electrochemical reactions. The intercomponent compatibility is important to ensure the robustness and durability of SOFCs, especially at an operating temperature around 800 °C, at which the components experience extreme thermal and mechanical stresses. Composite cathodes are used to improve cathode performance. These composite cathodes help enhance the properties of mixed electronic–ionic conductors and the intercomponent compatibility. Herein, we reviewed historical data of composite-cathode development for SOFCs, including its basic principle and criteria. The overall performance of as-synthesised composite cathodes in terms of microstructure, electrochemical reaction and intercomponent compatibility is briefly discussed.     

快离子导体材料特性的正确测定

快离子导体的导电离子种类、导电率、离子输率、分解电压值的正确测定,是综合判定快离子导体性质及其应用前景的重要前提条件。本文在扼要叙述快离子导体特性的测定原理及测定方法的同时,提出实际测定中应注意的若干关键问题。     

Novel processing,testing and characterization of copper/carbon nanotube (Cu/CNT) yarn composite conductor

Sustainable electrified aircraft propulsion (EAP) is likely to lead to an increase in the electrical wiring contained within a single aircraft. Since the electrical resistance and mass of copper (Cu) conductors are associated with power losses, it is desirable to design high-conductivity lightweight conductor materials, thus reducing the mass of components like motor windings, low-voltage signal cables, and transmission cables for data and power to improve the overall energy efficiency. This paper describes a unique framework for manufacturing metalized carbon nanotube (CNT) composite conductors, measuring their electrical conductivity and strength, and modeling the overall conductivity and current sharing within such composites. Tensile testing was conducted on the processed composite conductor cables with the use of acoustic emission and electrical resistivity to determine stress-dependent-failure mechanisms while monitoring the electrical conductivity. The average of measured electrical conductivities of annealed Cu/CNT samples from batch 5 was greater than theoretical predictions by 9.8 percent and was also greater than the conductivity of pure annealed Cu by 4.8 percent and had comparable ultimate tensile strengths. Additionally, those Cu/CNT samples provide a 13.5% weight saving over current state of the art copper wires. Theories explaining improved intrinsic conductivity are discussed.     

Influence of Mg-substitution on structural and electrical properties of ion-conducting Ca-doped tri-yttrium gallate

The signature of oxide ion conductivity was perceived in acceptor-doped (alkaline-earth metals) Y₃GaO₆. An acceptor doping of 2%Ca in Y₃GaO₆ (i.e., Y_2.94Ca_0.06GaO₆) has been found to exhibit a remarkable conductivity. The present work examines the conductivity behavior of 2% Ca-doped tri-yttrium gallate (Y_2.94Ca_0.06GaO₆) and also the effect of Mg-substitution on the phase formation and electrical conductivity of Y_2.94Ca_0.06GaO₆ for its possible application as a solid electrolyte. Polycrystalline dense ceramic samples of Y_2.94Ca_0.06Ga_1−xMg_xO_6−δ (with x = .00–.04) were fabricated using the conventional solid-state reaction route. The X-ray diffraction patterns were recorded to confirm the phase formation. The solid solubility limit of Mg²⁺ at Ga³⁺ site was found for x < .03. All the samples were observed to exhibit orthorhombic structure with Cmc21 symmetry (ICSD no.: 155086). Scanning electron microscopy (SEM) morphology reveals dense polygonal grains with vibrant grain boundaries. A significant increase in the conductivity is observed by substituting 1 mol% of Mg²⁺ at the Ga³⁺ site of Y_2.94Ca_0.06Ga_1−xMg_xO_6−δ. However, a further addition of higher dopant concentration of Mg²⁺ leads to a decline in the electrical conductivity. A relationship between the dopant concentration, phase formation, and structural characterizations has been established to analyze the conductivity behavior.     

端面粘贴包覆火药界面粘结强度研究

包覆火药装药控制燃气生成速率，降低弹性温度系数，提高弹丸初速的效果部分来自于包覆层的作用，对预制包覆层端粘包覆火药，其包覆层的厚度，密度，强度等性能已根据弹道和装药表确控制，包覆层与基药的界面粘结度就决定了包覆层控制燃气生成速率的有效性和可靠性，它是检验端面粘贴包覆火药工艺质量的关键指标，本文采用落锤实实验检包覆火药的界面结强度，研究了粘结工艺条件对端面粘贴包覆火药界面粘结强度的影响，通过实验选择出了合适的粘结剂及粘结工艺条件，制备了界面粘结强度良好的端面粘贴包覆火药。     

包膜型缓释/控释肥料的研究现状和发展前景

对包膜型缓释／控释肥料的一些概念、包膜材料、制备工艺及性能的影响因素等方面进行了论述，并简单分析了缓释／控释肥料发展进程和发展前景。     

热压制备低温固体氧化物燃料电池的初步研究

引言固体氧化物燃料电池(Solid Oxide Fuel Cells,SOFC)由于具有能量转化效率高,不采用贵金属(如铂等)作催化剂,可直接使用碳氢燃料,易实现热-电联供或与燃气轮机组成联合循环系统,对环境友好,可实现长寿命运行等优点受到     

Development of a novel proton conducting fuel cell based on a Ni‐YSZ support

A new proton conducting fuel cell design based on the BZCYYb electrolyte is studied in this research. In high‐performance YSZ‐based SOFCs, the Ni‐YSZ support plays a key role in providing required electrical properties and robust mechanical behavior. In this study, this well‐established Ni‐YSZ support is used to maintain the proton conducting fuel cell integrity. The cell is in a Ni‐YSZ (375 μm support)/Ni‐BZCYYb (20 μm anode functional layer)/BZCYYb (10 μm electrolyte)/LSCF‐BZCYYb (25 μm cathode) configuration. Maximum power density values of 166, 218, and 285 mW/cm² have been obtained at 600°C, 650°C, and 700°C, respectively. AC impedance spectroscopy results show values of 2.17, 1.23, and 0.76 Ω·cm² at these temperatures where the main resistance contributor above 600°C is ohmic resistance. Very fine NiO and YSZ powders were used to achieve a suitable sintering shrinkage which can enhance the electrolyte sintering. During cosintering of the support and BZCYYb electrolyte layers, the higher shrinkage of the support layer led to compressive stress in the electrolyte, thereby enhancing its densification. The promising results of the current study show that a new generation of proton conducting fuel cells based on the chemically and mechanically robust Ni‐YSZ support can be developed which can improve long‐term performance and reduce fabrication costs of proton conducting fuel cells.     

High lithium ionic conductivity in the garnet‐type oxide Li7−2xLa3Zr2−xMoxO12 (x=0‐0.3) ceramics by sol‐gel method

Lithium garnet‐type oxides Li_7?2xLa₃Zr_2?xMo_xO₁₂ (x=0, 0.1, 0.2, 0.3) ceramics were prepared by a sol‐gel method. The influence of molybdenum on the structure, microstructure and conductivity of Li₇La₃Zr₂O₁₂ were investigated by X‐ray diffraction, scanning electron microscopy, and impedance spectroscopy. The cubic phase Li₇La₃Zr₂O₁₂ has been stabilized by partial substitution of Mo for Zr at low temperature. The introduction of Mo (x≥0.1) can accelerate densification. Li_6.6La₃Zr_1.8Mo_0.2O₁₂ sintered at lower temperature 1100°C for 3 hours exhibits highest total ionic conductivity of 5.09 × 10^?4 S/cm. Results indicate that the Mo doping LLZO synthesized by sol‐gel method effectively lowers its sintering temperature and improves the ionic conductivity.     

耐高温陶瓷绝缘电磁线

本文回顾了陶瓷绝缘电磁线的发展状况,探讨了陶瓷绝缘电磁线选择导体材料的要点,论述了陶瓷绝缘电磁线的分类及主要制备方法,通过对比陶瓷绝缘电磁线与同规格的有机绝缘电磁线的性能,指出陶瓷绝缘电磁线的在耐温,线芯的机械强度都明显优于有机绝缘电磁线,室温下的击穿电压为12.33 V/μm.