Preparation of Ni–YSZ thin and thick films on metallic interconnects as cell supports. Applications as anode for SOFC

In this work, we propose the preparation of a duplex anodic layer composed of both a thin (100 nm) and a thick film (10 lm) with Ni–YSZ material. The support of this anode is a metallic substrate, which is the interconnect of the SOFC unit cell. The metallic support limits the temperature of thermal treatment at 800 C to keep a good interconnect mechanical behaviour and to reduce corrosion. We have chosen to elaborate anodic coatings by sol–gel route coupled with dip-coating process, which are low cost techniques and allow working with moderate temperatures. Thin films are obtained by dipping interconnect substrate into a sol, and thick films into an optimized slurry. After thermal treatment at only 800 C, anodic coatings are adherent and homogeneous. Thin films have compact microstructures that confer ceramic protective barrier on metal surface. Further coatings of 10 lm thick are porous and constitute the active anodic material

Comparison between ultrathin films of YSZ deposited at the solid oxide fuel cell cathode/electrolyte interface by atomic layer deposition, dip-coating or sputtering

The effect of an 80 nm YSZ interfacial layer, deposited onto a YSZ pellet by different techniques (dip-coating, sputtering and atomic layer deposition) at the SOFC cathode/electrolyte interface to allow a maximum adhesion of the thick cathode layer, was thoroughly analysed. The LSM cathode was deposited on the solid electrolyte by painting and sintered in air at 1200°C for 2 h. The morphological and structural analyses of the samples were performed by scanning electron microscopy and X-ray diffraction; their electrical properties were examined between 390 and 700°C by electrochemical impedance spectroscopy. The impedance responses showed three different contributions. The highfrequency arc is attributed to the YSZ electrolyte. The electrode processes associated with the medium- and low frequency arcs were discussed. The electrochemical performance was influenced by the microstructure at the electrode/electrolyte interface

Eco-friendly synthesis of SiO2 nanoparticles confined in hard carbon: A promising material with unexpected mechanism for Li-ion batteries

Times Cited: 3Nita, Cristina Fullenwarth, Julien Monconduit, Laure Le Meins, Jean-Marc Fioux, Philippe Parmentier, Julien Ghimbeu, Camelia MateiGhimbeu, Camelia/N-7855-2015Ghimbeu, Camelia/0000-0003-3600-587731873-3891A fast, simple and environmentally friendly one-pot route to obtain carbon/SiO2 hybrid materials is reported in this work. This consists in simple mixture of carbon and silica precursors, followed by thermal annealing at different temperatures. An interpenetrating hybrid network composed of hard carbon and amorphous SiO2 nanoparticles (2–5 nm) homogeneously distributed was achieved. Increasing the annealing temperature from 600 °C up to 1200 °C, the material porosity and oxygen functional groups are gradually removed, while the amorphous nature of SiO2 is conserved. This allows to diminish the irreversible capacity during the first charge-discharge cycle and to increase the reversible capacity. An excellent cycling capability, with a reversible capacity up to 535 mA h/g at C/5 constant current rate was obtained for C/SiO2 materials used as anodes for Li-ion batteries. An atypical increase of the capacity during the first 50 cycles followed by a stable plateau up to 250 cycles was observed and related to electrolyte wettability limitation through the materials, particularly for those annealed at high temperatures which are more hydrophobic, less porous and the SiO2 nanoparticles less accessible. The SiO2 lithiation mechanism was evaluated by XRD, TEM and XPS post-mortem analyses and revealed the formation of reversible lithium silicate phases

On the use of metal cation-exchanged zeolites in sorption thermochemical storage: Some practical aspects in reference to the mechanism of water vapor adsorption

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Diagnostic of the failure mechanism in NiSb2 electrode for Li battery through analysis of its polarization on galvanostatic cycling

International audienceA simple analysis of the polarization resistance of the electrodes as function of the loading mass for various cycling rates allows identifying the fading mechanism on cycling of NiSb2, a typical conversion material: pulverization of active mass and further degradation of the electronic wiring at high rate and agglomeration of the active mass at low rate. Such rate-control of the degradation mechanism might reflect a thermodynamic instability of interfaces in the lithiated compound, which would however be in kinetic competition with the Lithium de-insertion. The analysis of the electrode polarization resistance fingerprint to rapidly identify the failure mechanism in a composite electrode can be generalized to other active materials

The evaluation of Sb and SnSb negative electrode materials in full Na-ion cells

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MnP4 electrode for Na-ion batteries: a complex and effective electrochemical mechanism

International audienceMnP 4 has recently been identified as a possible negative electrode for Li-ion batteries. This study shows that this material can also perform as a negative electrode for Na-ion batteries (SIBs), demonstrating that a suitable electrode formulation allows an exceptional performance, i.e., a stable specific capacity of 1000 mA h g −1 after 50 cycles, much higher than that of hard-carbon-based anodes currently used in SIBs. The combination of operando X-ray diffraction, ex situ Mn K-edge X-ray absorption spectroscopy (XAS) and NMR spectroscopy reveals a complex conversion mechanism with the formation of numerous amorphous sodiated phosphide species. 31 P and 13 Na NMR were particularly effective in identifying these species, demonstrating that their formation is dependent on the preparation of the electrode, especially the amount of carbon additive. XAS analysis, on the other hand, proved the complete reversibility of the mechanism, including the reformation of MnP 4 during the desodiation process

NiP3: a promising negative electrode for Li- andNa-ion batteries

International audienceDue to the abundance and low cost of sodium-containing precursors ambient temperature sodium ionbatteries are promising for large scale grid storage. The low melting point of Na (97.7 °C) compared to180.6 C for Li represents a significant safety hazard for the use of Na metal anodes at ambienttemperatures, which emphasizes the need for scientists and engineers to identify, design and developnew negative electrodes for Na-ion batteries. The identification of a suitable negative electrode is acrucial challenge for any further successful development of new cells, and to date efficient andcompetitive negative electrodes for NaB are still very rare. In this work we demonstrate that NiP3 couldbe a good challenger for this purpose. NiP3 based electrodes are evaluated as negative electrodematerials for Li-ion batteries (LiB) and Na-ion batteries (NaB). The study of the reaction mechanismreveals the formation of a phase of composition close to Li3P and Na3P embedding Ni nanoparticles asthe final reaction product after a full discharge. While the direct conversion of NiP3 into Na3P is identifiedfor the reaction versus Na, it is still unclear whether an amorphous phase exists during the first dischargefor the reaction versus Li before the conversion. Furthermore, thanks to the carboxymethyl cellulose/carbon black (CMC/CB) electrode formulation, the NiP3 electrode possesses a very promising capacitywith a reversible storage capacity higher than 1000 mA h g-1 after 50 cycles for LiB and 900 mA h g-1after 15 cycles for NaB, which represents one of the highest capacities ever sustained in Na-ion batteries