Fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are the most frequently used electrolyte additives to enhance the lifetime of anode materials in Li-ion batteries, but for silicon it is still ambiguous when FEC or VC is more beneficial. Herein, a low-cost nanostructured silicon/carbon anode derived from HSiCl3 is tailored by the rational choice of the additive, to obtain an anode material outperforming current complex silicon structures. We demonstrate highly reversible areal capacities of up to 5 mAh/cm2 at 4.4 mg/cm2 mass loading, a specific capacity of 1280 mAh/gAnode, a capacity retention of 81 % after 500 deep-discharge cycles versus lithium metal and successful full-cell tests with high-voltage cathodes meeting the requirements for real application. Electrochemical impedance spectroscopy and post-mortem investigation provide new insights in tailoring the interfacial properties of silicon-based anodes for high performance anode materials based on an alloying mechanism with large volume changes. The role of fluorine in the FEC-derived interfacial layer is discussed in comparison with the VC-derived layer and possible degradation mechanisms are proposed. We believe that this study gives a valuable understanding and provides new strategies on the facile use of additives for highly reversible silicon anodes in Li-ion batteries

In this study, APS and HVOF processes have been used to prepare alumina (Al 2 O 3 ) and magnesium spinel (MgAl 2 O 4 ) coatings designed for insulating applications. The electrical characteristics, i.e., dielectric strength and electrical resistance (electrical resistivity) were investigated using different methods: dielectric breakdown test, direct current (DC) measurements, and electrochemical impedance spectroscopy (EIS). The electrical resistance was measured at room temperature at different relative humidity (RH) levels (from 6% RH to 95% RH) as well as at 200°C. The coating microstructure, phase composition, and water vapor sorption were studied. Differences in the electrical insulating properties due to the different coating system characteristics are discussed. Of the coatings and conditions investigated in this study, the HVOF spinel coatings showed superior dielectric breakdown strength and electrical resistance stability at high humidity levels.

In this work the microstructural characteristics and electrical insulating properties of thermally sprayed alumina coatings produced by suspension-HVOF (S-HVOF) and conventional HVOF spray processes are presented. The electrical resistance at different relative air humidity (RH) levels (from 6 to 97% RH) and values of dielectric strength were investigated by direct current electrical resistance measurements, electrochemical impedance spectroscopy, and dielectric breakdown tests. Relationships between electrical properties and coating characteristics are discussed. At low humidity levels (up to 40% RH) the electrical resistivities of S-HVOF and HVOF coatings were on the same order of magnitude (10 11 XAEm). At a very high humidity level (97% RH) the electrical resistivity values for the S-HVOF coatings were in the range 10 7 -10 11 XAEm, up to five orders of magnitude higher than those recorded for the HVOF coating (orders of magnitude of 10 6 XAEm). The better electrical resistance stability of the suspension-sprayed Al 2 O 3 coatings can be explained by their specific microstructure and retention of a higher content of a-Al 2 O 3 . The dielectric strength E d of suspension-sprayed coatings was found to be 19.5-26.8 kVAEmm 21 for coating thicknesses ranging from 60 to 200 lm. These values were slightly lower than those obtained for conventional HVOF coatings (up to 32 kVAEmm 21 ). However, it seemed that the dielectric strength of conventionally sprayed coatings was more sensitive to the coating thickness (when compared with the values of E d determined for S-HVOF coatings) and varied to a greater extent (up to 10 kVAEmm 21) when the coating thickness varied in the range 100-200 lm.

No abstract

SOFC modules with a power of 5 to 50 kW are a serious competitor to commercially available combined heat and power plants for decentralized electricity and heat supply with high electrical efficiency. Electrical efficiency and electrical power of a SOFC stack are essential for its profitable operation. The highest power density and electrical efficiency can only be achieved with planar SOFC stacks. Electrolyte supported cells with 10ScSZ electrolytes allow power densities of more than 500 mW/cm². On account of the thermomechanical properties of electrolyte, this potential can only be used in stacks with chromium based interconnects (CFY from Plansee SE). High power, robustness and long-term stability are essential for stationary SOFC systems. In order to fulfill these requirements, Fraunhofer IKTS in close collaboration with Plansee SE develops a new stack design with larger active area, simple cathode contacting, external cathode manifold and optimized interconnect layer. This paper will give an overview of the current SOFC stack development focused on power output, long-term stability, temperature cycling and reliability of SOFC stack assembling. Material Combination for SOFC Stacks with High EfficiencyPlanar Solid Oxide Fuel Cells (SOFC) are considered to be highly efficient power generators with low emission levels even for small power units (1-200 kW el ). The recently developed and up-scaled net-shape technology for powder metallurgical production of bipolar plates allows new options for application of electrolyte supported cells with area specific resistances (ASR) <0.3 Ωcm² and are a match to stacks with anode supported cells (1-4). The electrolyte supported cells have benefits in long-term stability and thermal cyclability which were previously tested and are important parameter for a robust SOFC-system.The development of SOFC stacks with interconnects made from powder metallurgical processed chromium-iron-yttria based alloy (CFY) and scandia stabilized zirconia electrolytes (10ScSZ) have a long history and have surpassed the line to mass production in recent years.The bipolar plates of the new stack design (MK35x) have dimensions of 130x150x3.2 mm³. Currently, it is the biggest CFY interconnect and has a good ratio of active area to ECS Transactions, 35 (1) 269-277 (2011) 10.1149/1.3570002 © The Electrochemical Society 269 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 160.39.73.191 Downloaded on 2015-03-24 to IP

Fraunhofer IKTS and Plansee SE continuously develop SOFC stacks with Chromium based interconnects (CFY) and electrolyte supported cells based on Scandia doped Zirconia. This technology has a great potential for cost-effective manufacturing and rapid up-scaling due to availability of major stack components and essential improvements in manufacturing made last year. The stacks are already available on the market and are in test at several potential customers. The paper gives an overview of the current status of CFY-stack development focused on performance map and system cycling. The results of operation of CFY-stacks in modules with stacks working on different fuels with and without internal steam reforming in partial and full load are presented.

Chromium-based interconnects (CFY) in combination with electrolyte supported cells are perfectly matching the requirements of different SOFC applications. Furthermore, this type of stacks and the related manufacturing of cells and interconnects is already proven in very high volumes today. Plansee SE and Fraunhofer IKTS, together with partners in the SOFC20 project and lead customers, have developed the advanced MK351 stack-platform, which is now available for interested new customers. A suitable, well-adjusted combination of materials, especially regarding the cathode protection and contacting, has been developed. Sample test results have been verified in long term stack testing for more than 8,000 h. The stack has proven very low power degradation of less than 0.7 %/ 1,000 h.

After long and successful development history of Solid Oxide Cells (SOC) continuous improvement in performance, longevity, manufacturing, and system integration it is necessary to bring this highly efficient technology to the market. The activities on material development and optimization at IKTS are focused mainly on enhancement of durability for SOFC, SOEC, and rSOC operation and on boosting the power density. During recent years considerable efforts on simplification and automation of cell and stack manufacturing processes have been addressed. The processes for electrode manufacturing have been adjusted for high yield automated printing on thin electrolytes with integrated quality control measures. Efficient ways for reduction of time and energy consumption for sealing process of SOC stacks have been found and demonstrated in pilot production as well as automated assembling of components to stacks was shown. The increasing interest in “green hydrogen” created multiple opportunities for SOEC technology to be considered as inherent part of industrial and chemical processes. IKTS pioneering work on coupled operation of SOEC module with Fischer-Tropsch reactor provided first demonstration of feasibility of this approach for wax production. However, high power electrolysis applications (>10 MW) will need new approaches for stack design and put higher requirements on durability.