Framework Convention on Climate Change

Magnetic fluid hyperthermia: focus on superparamagnetic iron oxide nanoparticles.

Progress in material selection for solid oxide fuel cell technology: A review

Tandem devices combining perovskite and silicon solar cells are promising candidates to achieve power conversion efficiencies above 30% at reasonable costs. State-of-the-art monolithic two-terminal perovskite/silicon tandem devices have so far featured silicon bottom cells that are polished on their front side to be compatible with the perovskite fabrication process. This concession leads to higher potential production costs, higher reflection losses and non-ideal light trapping. To tackle this issue, we developed a top cell deposition process that achieves the conformal growth of multiple compounds with controlled optoelectronic properties directly on the micrometre-sized pyramids of textured monocrystalline silicon. Tandem devices featuring a silicon heterojunction cell and a nanocrystalline silicon recombination junction demonstrate a certified steady-state efficiency of 25.2%. Our optical design yields a current density of 19.5 mA cm−2 thanks to the silicon pyramidal texture and suggests a path for the realization of 30% monolithic perovskite/silicon tandem devices.

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Fully textured monolithic perovskite/silicon tandem solar cells with 25.2% power conversion efficiency.

With a global market share of about 90%, crystalline silicon is by far the most important photovoltaic technology today. This article reviews the dynamic field of crystalline silicon photovoltaics from a device-engineering perspective. First, it discusses key factors responsible for the success of the classic dopant-diffused silicon homojunction solar cell. Next it analyzes two archetypal high-efficiency device architectures – the interdigitated back-contact silicon cell and the silicon heterojunction cell – both of which have demonstrated power conversion efficiencies greater than 25%. Last, it gives an up-to-date summary of promising recent pathways for further efficiency improvements and cost reduction employing novel carrier-selective passivating contact schemes, as well as tandem multi-junction architectures, in particular those that combine silicon absorbers with organic–inorganic perovskite materials.

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High-efficiency crystalline silicon solar cells: status and perspectives

Solid oxide fuel cells are able to convert fuels, including hydrocarbons, to electricity with an unbeatable efficiency even for small systems. One of the main limitations for long-term utilization is the reduction-oxidation cycling (RedOx cycles) of the nickel-based anodes. This paper will review the effects and parameters influencing RedOx cycles of the Ni-ceramic anode. Second, solutions for RedOx instability are reviewed in the patent and open scientific literature. The solutions are described from the point of view of the system, stack design, cell design, new materials and microstructure optimization. Finally, a brief synthesis on RedOx cycling of Ni-based anode supports for standard and optimized microstructures is depicted.

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A Review of RedOx Cycling of Solid Oxide Fuel Cells Anode

Microstructural evolution of anode supported solid oxide fuel cells (SOFC) during medium-term stack testing has been characterized by scanning electron microscopy (SEM). Low acceleration voltage SEM imaging is used to separate the three anode phases (nickel, yttria-stabilized zirconia and porosity). Microstructural quantification is obtained using a software code that yields phase proportion, particle size, particle size distribution and a direct measure of triple phase boundary (TPB) density. In addition, an anode degradation model is proposed. The model describes the gradual degradation of the anode due to nickel particle sintering and the concomitant loss of TPB. Fundamental operational and structural parameters of the anode can be used to estimate the TPB length change with time from the degradation rate. The combination of experimental results and modeling allows separating the degradation due to sintering of nickel particles from total stack degradation. Anode degradation occurs principally during the first 500 operating hours. For stack tests carried out over more than 1000 h, anode degradation was responsible for 18 % to 41 % of the total degradation depending on initial microstructure.

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Nickel–Zirconia Anode Degradation and Triple Phase Boundary Quantification from Microstructural Analysis

Performance degradation data obtained on single solid oxide fuel cells tested at 850°C with air and humidified H2 and using Ni-YSZ anode supported cells are presented. Microscopic investigation is carried out on both anode and cathode to quantify variations in morphology at different operation times. The comparison between the measurements on the cells and the SEM image analysis allows concluding that there is no relationship between the initial cell activation and micro-structural modifications of the electrodes. On the other hand, it was found that cell degradation is strictly related to the coarsening of Ni particles occurring in the anode. A theoretical analysis based on an electrode micro-model has been performed in order to compare the variation in performance, expected from particle size change, with the observed data. The model confirmed the conclusions taken from the experimental results.

Experimental and Theoretical Investigation of Degradation Mechanisms by Particle Coarsening in SOFC Electrodes

Reference EPFL-ARTICLE-172690View record in Web of Science Record created on 2011-12-16, modified on 2016-08-09

Antonin Faes

Papers

A Review of RedOx Cycling of Solid Oxide Fuel Cells Anode

Nickel–Zirconia Anode Degradation and Triple Phase Boundary Quantification from Microstructural Analysis

Experimental and Theoretical Investigation of Degradation Mechanisms by Particle Coarsening in SOFC Electrodes

Nickel-Zirconia Anode Degradation and Triple Phase Boundary Quantification from Microstructural Analysis (vol 9, pg 841, 2010)

The in vivo performance of magnetic particle-loaded injectable, in situ gelling, carriers for the delivery of local hyperthermia