Electrodeposition of Polymer Electrolyte Into Porous LiNi0.5Mn1.5O4 for High Performance All-Solid-State Microbatteries

We report the electrodeposition of polymer electrolyte (PMMA-PEG) in porous lithium nickel manganese oxide (LiNi0.5Mn1.5O4) cathode layer by cyclic voltammetry. The cathode-electrolyte interface of the polymer-coated LNMO electrode has been characterized by scanning electron microscopy and electrochemical techniques. Electrochemical measurements consisting of galvanostatic cycling tests and electrochemical impedance spectroscopy revealed a significant improvement of the capacity values and the increase of the operating voltage. These effects are attributed to the total filling of pores by the electrodeposited polymer that contributes to improve the reversible insertion of Li+. A complete all-solid-state microbattery consisting of electropolymerized LNMO as the cathode, a thin polymer layer as the electrolyte, and TiO2 nanotubes as the anode has been successfully fabricated and tested

Films d'épaisseurs nanométriques de Pd sur Pt(111) (élaboration, caractérisations et étude de l'électro-insertion de l'hydrogène)

Des films ultraminces de palladium (nanofilms) ont été déposés sur un monocristal de platine Pt(111) en présence de chlorures. Ces dépôts, caractérisés électrochimiquement par adsorption de l'hydrogène en milieu sUlfurique et par des mesures AFM ex situ et SXRD in situ, sont pseudomorphes et présentent une faible rugosité atomique. L1sotherme électrochimique d1nsertion de l11ydrogène dans ces nanofilms présente un élargissement du domaine de solution solide, un pseudo-plateau pentu indiquant l'existence d'un domaine biphasé et un taux d1nsertion maximum réduit par rapport au Pd massif, dépendant de l'épaisseur du nanofilm. Des mesures par SXRD in situ révèlent un effet du substrat Pt(ll1) sur l'insertion. Des mesures cinétiques par spectroscopie d1mpédance électrochimique ont été réalisées. L1nsertion dans des nanoparticules de Pd a été étudiée en phase gaz pour s'affranchir du dégagement de l'hydrogène. Les spectres d1mpédance pneumatochimique ont été déduits de ces mesures.Ultrathin palladium films (nanofilms) were deposited on Pt(ll1) single crystal in a chloride-containing electrolyte. Morphological and structural characterization of these deposits, carried out electrochemically, through hydrogen UPD in sulphuric acid and with AFM ex situ and SXRD in situ measurements, show pseudomorphy and low atomic roughness of the deposits. The electrochemical hydrogen insertion isotherm in these nanofilms shows enlargement of solid solution sOlubility, a sloppy plateau in the two-phase domain and a decrease of the maximum insertion rate compared to bulk Pd, depending on thickness. An effect of the Pt(1l1) substrate on insertion has been identified by SXRD in situ measurements. Kinetic measurements were carried out by electrochemical Impedance spectroscopy on nanofilms. Insertion in Pd nanoparticles was studied in gas phase, where no hydrogen evolution occurs. Pneumatochemical impedance spectra were deduced from these measurements.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

The electrochemical behaviour of TiO2 nanotubes with Co3O4 or NiO submicron particles: Composite anode materials for Li-ion micro batteries

International audienceThe electrochemical performance of self-organized TiO2 nanotubes (TiO(2)nts) can be improved for lithium-ion microbatteries by depositing submicron Co3O4 and NiO particles. These transition metal oxides were directly grown onto the titania nanotubes by electrodeposition and thermal treatments. The morphology and the chemical composition of the resulting materials were characterized by scanning electron microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDS), and X-Ray Diffraction (XRD). The electrochemical nucleation and growth mechanisms of Co and Ni onto TiO(2)nts are also discussed. Besides the remarkable capacity retention of the nano-architectured titania electrodes in lithium test cells, we show that the addition of submicron Co3O4 or NiO particles leads to a spectacular increase of the capacity values during the first 25 cycles. (C) 2012 Elsevier Ltd. All rights reserved

Mechanism study of Li+ insertion into titania nanotubes

International audienceLi+ insertion into anatase titania nanotubes (TiO(2)nts) employing PEO-based polymer electrolyte has been studied by cyclic voltammetry and chronoamperometry. The study shows that Li+ storage in the anatase is dominated by the bulk diffusion (into the lattice) and the increasing contribution of the pseudo-capacitive effect with faster kinetics. We also report that the chemical diffusion of Li+ in self-organized TiO(2)nts is around 2 x 10(-16) cm(2) s(-1) suggesting that the use of a solid electrolyte does not alter the charge transport in the nanostructured electrode

Evidence of the Substrate Effect in Hydrogen Electroinsertion into Palladium Atomic Layers by Means of in Situ Surface X-ray Diffraction

International audienceIn this work, we report an in situ surface X-ray diffraction study of the hydrogen electroinsertion in a two-monolayer equivalent palladium electrodeposit on Pt(111). The role of chloride in the deposition solution in favoring layer-by-layer film growth is evidenced. Three Pd layers are necessary to describe the deposit structure correctly, but the third-layer occupancy is quite low, equal to about 0.22. As a major result, resistance to hydriding of the two atomic Pd layers closest to the Pt interface is observed, which is linked to a strong effect of the Pt(111) substrate. As a consequence, we observe the lowering of the total hydride stoichiometry compared to bulk Pd. Our measurements also reveal good reversibility of the deposit structure, at least toward one hydrogen insertion−desorption cycle

Electrochemically elaborated palladium nanofilms on Pt(1 1 1): Characterization and hydrogen insertion study

International audienceUltrathin palladium films, from 1 to 60 monolayers (ML) thick, have been obtained on Pt(1 1 1) by electrodeposition of PdII from chloride-containing electrolytes. The first ML was obtained by palladium underpotential deposition (UPD). The role of chloride concentration on the growth mode is discussed. Film roughness obtained with 3 × 10−3 M HCl solutions slowly increases by ca. 25% from 5 to 60 ML. Large terraces remain present on deposits up to 20 ML. For larger thicknesses, their width gradually decreases and new hydrogen adsorption sites appear. The behaviour of these Pd nanofilms with regard to hydrogen insertion was studied in H2SO4 0.1 M. Absorption branches of the electrochemical isotherms were measured for 10 ML and 16 ML deposits. Compared to bulk Pd, enlarged solid solution domains and lower hydrogen solubility are observed. The role of the Pt(1 1 1) substrate is evidenced by comparing the shape of the isotherms with those measured using unsupported Pd nanoparticles

Direct electron transfer of bilirubin oxidase at a carbon flow-through electrode

International audienceThe kinetics and isotherms of adsorption of Myrothecium verrucaria bilirubin oxidase (Mv BOD) on nanoporous carbons (CNP) and carbon nanofibers (CNF) were studied by the solution depletion method. The kinetics of adsorption of Mv BOD on both carbons are very fast, reaching equilibrium within 10 min and 30 min for CNP and CNF, respectively. The adsorption isotherms reveal a strong affinity between Mv BOD and both carbons. An original flow-through device based on electrodes filled with CNP and CNF connected to an UV–vis spectrophotometer was used to correlate the dioxygen catalytic current reduction to the amount of Mv BOD adsorbed on the carbons. It was shown that although the amount of BOD adsorbed on CNP is much lower than the amount adsorbed on CNF, the currents are comparable, suggesting that the Mv BOD orientation is more favourable for direct electron transfer in the case of CNP. Chronoamperometry experiments showed that the catalytic current is stable for a few days (70 h). It was emphasized by stop and flow experiments that the current is limited by mass transport inside the column

Porous polymer-in-silica hybrid electrolyte for all-solid-state Li-ion battery applications

International audiencePorous hybrid electrolytes based on Poly(Ethylene Glycol) (PEG) and mesoporous silica (SBA-15) were prepared by a post-synthetic modification of the silica matrix. The complex composed of the lithium salt (LiTFSI) and PEG is embedded in the silica pores, which offers mechanical properties for the hybrid electrolyte. The textural properties and composition of pure SBA-15 and the hybrid materials were characterized by several techniques. It was evidenced that the inner pores of the inorganic matrix (hexagonally packed cylindrical mesochannels) surface were uniformly coated with the complex PEG-LiTFSI and that the hybrid materials remained slightly mesoporous after the post-synthetic modification. To study the ionic conductivity, the hybrid powders were shaped as a pellet having both inter- and intraparticle porosity. The parameters whose influence were addressed are: the filling of the inter- and intraparticle porosity with PEG-LiTFSI complex, the lithium ion concentration and the PEG molecular weight. First, filling the interparticle porosity is necessary to the formation of continuous lithium conducting pathways while the intraparticle conductivity appeared to be mandatory to improve the overall conductivity. The hybrid of SBA-15 with PEG having a molecular weight of 600 gmol-1 gives the highest conductivity (1.6 x 10 6 S.cm-1 at 30 °C) when used with the optimum molar ratio nEO/nLi of 10 found in this study. Preliminary analysis showed that the conductivity is governed by the segmental dynamics of the polymer chains (VTF model) in the whole temperature range. Finally, this material has an electrochemical window compatible with classical Li ion batteries cathode materials

Self-supported sulphurized TiO2 nanotube layers as positive electrodes for lithium microbatteries

International audienceWe report the synthesis and characterization of self-supported sulphurized TiO 2 nanotube layers as a cathode material for Li microbatteries. Sulphurized TiO 2 nanotubes were obtained by annealing of selfsupported TiO 2 nanotubes in sulphur atmosphere. The morphology, structure, composition and thermal stability of the Ti x O y S z nanotube layers were studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis. The electrochemical behaviors of the chemically modified nanotubes were investigated by cyclic voltammetry and chronopotentiometry techniques. This nanostructured electrode used as a cathode material showed high rate capabilities even at very fast kinetics. Remarkably, a high discharge capacity (340 Ah cm −2) has been retrieved after 100 cycles with 100% coulombic efficiency attesting the excellent stability of the electrode

Self-Assembly and Electrochemical Characterization of Ferrocene-based Molecular Diodes for Solar Rectenna Device

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