The synthesis of vanadates from aqueous solutions leads to a large variety of crystalline materials. The nature of molecular precursors mainly depends on pH and three different pH ranges can be distinguished. Cationic precursors are formed at low pH. Precipitation is obtained via the addition of anions leading to materials in which [VO6] octahedra are linked through anions. V2O5,nH2O gels are formed around the Point of Zero Charge (pH=2). They are made of ribbon-like particles and exhibit interesting properties as cathodic materials. Electrochemical properties depend on the drying procedure. Moreover, intercalation reactions lead to a whole range of new inorganic and organic bronzes. Chain metavanadates are precipitated from anionic precursors in basic aqueous solutions. Vanadium coordination decreases and they are made of corner sharing [VO4] tetrahedra. Layered structures are formed in the pH range where negatively charged species such as [VO(OH)4(OH2)]− should behave as precursors. Condensation occurs via V-OH groups in the equatorial plane leading to layered structures in which cations are inserted between the vanadate planes. Some reduction occurs when organic cations such as tetramethyl ammonium [N(CH3)4]+ are used leading to mixed valence vanadates. Electron delocalization is observed in these compounds but Li insertion is hindered by large organic cations. Better electrochemical properties are observed with smaller inorganic cations. Fibrous crystals of NaV3O8,H2O are formed in the presence of NaOH whereas the mixed valence bronze α'-NaxV2O5 is obtained when both NaOH and TMAOH react with V2O5. This fibrous morphology appears to improve diffusion processes at the electrode-electrolyte interface.

Clays have been synthesized and several types of molecules have been intercalated into them to enhance their ionic conductivity. The clay has the molecular formula of Litaeniolite, Li(Mg2Li)Si4O10F2, and the inserted molecules include PEO and two varieties of sulfone, tetramethylene sulfone and ethylmethyl sulfone. These have been made in the interest of electrolytes in lithium secondary batteries in order to produce a truly solid state cell. The products have been thoroughly characterized by x-ray diffraction to verify the uptake of the molecules into the layers, thermal analysis to observe the stabilization of the intercalated molecules, along with impedance measurements to test their conductivity.

We have studied the modifications of structural and physical properties which occur during delithiation of lithium-nickel-cobalt oxide cathode materials. Long-range and short-range orders have been investigated using XRD, Raman and FTIR spectroscopies. Different samples LixNi0.7Co0.3O2 (0.5≤x_≤1) were prepared by electrochemical lithium deintercalation from LixNi0.7Co0.3O2. Electrochemical extraction of lithium was carried out using Li/LiCIO4 in PC/LixNi0.7Co0.3O2 cells in the potentiometric method with potential step of 10 mV. During the first charge of the Li//LixNi0.7Co0.3O2 cell, the change in the cathode structure was followed by x-ray powder diffraction and vibrational spectroscopies at room temperature. A good correlation is found between XRD data and the local environment of the host lattice. Detailled analysis of vibrational spectra shows that the octahedral oxygen environment of Li+ ions remains stable in the investigated domain of concentration.

We report electrical properties of the lithium manganospinel LiMn2 O 4 and its delithiated/lithiated forms, Li1−x−∂Mn2−∂O4 with 0.0≤x≤0.4 and 0.00≤∂0.18. The electrical conductivity has been determined from d.c. measurements as a function of temperature and lithium content in the host lattice. LiMn2O4 exhibits a phase transition in the vicinity of 280 K, which disappears in the lithium-rich samples. Electrical data are analysed using the model of small-polaron transport. ESR spectroscopy has been applied to identify the singular structural features. Investigations as a function of temperature show a reliable determination of the modifications in the cationic sublattice and of the lithium overstoichiometry. The hopping conductivity mechanism between the Mn3+ and Mn4+ sites gives a coherent explanation for the observed ESR signal of cyclotron resonance.

6Li MAS NMR spectra of lithium manganese oxides with differing manganese oxidation states (LiMn2O4, Li4Mn5O12, Li2Mn4O9, and Li2Mn2O4) are presented. Improved understanding of the lithium NMR spectra of these model compounds is used to interpret the local structure of the LixMn2O4 cathode materials following electrochemical Li+ deintercalation to various charging levels. In situ x-ray diffraction patterns of the same material during charging are also reported for comparison. Evidence for two-phase behavior for x < 0.4 (LixMn2O4) is seen by both NMR and diffraction.

Accurate XRD, often in combination with ND, has long been used to study electron density features in crystalline compounds. The method is particularly successful for light-atom systems in which the valence-to-core electron ratio is high. The same method is clearly applicable to the study of (typically) lithium insertion/extraction processes in TMO compounds; the greatest hinder has been the availability of sufficiently large single crystals, which do not then disintegrate into micron-size particles during the reaction. The case of V6O13 is especially advantageous in this context, however: millimeter-size crystals can be grown by CVT methods, which do not then exhibit severe cracking on lithium insertion, probably as a result of the layer-like nature of the structure. A sequence of single-crystal phases have now been studied in this way (LixV6O13 for x= 0, 1.0, 2.0 and 3.0) following in situ electrochemical synthesis in the composite cathode of a <Li| PE |V6O13> half-cell. The resulting structures have been solved, and their associated electron-density distributions carefully analysed by so-called Hirshfeld deformation electron density refinement. The method would appear to provide meaningful information relating to oxidation state changes occurring on lithium-ion insertion.

Films of insertion compounds and solid state electrolytes have been synthesized in order to study their applications in the domain of electrochemical ion and gas sensors. Laser ablation was used to deposit lithium metal oxides (LiMO2 where M is a transition metal Co or Mn).

The chemical composition in the films has been studied by Rutherford Backscattering spectrometry and nuclear reactions analysis in the case of the light elements (O, Li). For lithium transition metal oxides (LiMO2), the oxygen and lithium contents are determined by a thermodynamical equilibrium between the films and the partial pressures in the chamber. In these cases, laser ablation allows the synthesis of crystalline structures with a large range of oxygen non stoichiometry as compared to solid state reactions. They lead to interesting electrical properties. Using the appropriate temperatures and oxygen pressures, films with the correct stoichiometry could be obtained as polycrystalline onto Si or Si/Pt substrates whereas they exhibit high texturing and epitaxial growth onto MgO or MgO/Pt.

The films of LiMn2O4 and LiCoO2 have been used as electrochemical sensors for the measurement of the lithium concentration in solutions. They show a very rapid and selective response.

We have studied the growth and the physical properties of LiCoO2 films as a function of formation conditions, i.e., substrate temperature and partial oxygen pressure. These films were grown on various substrates by the laser ablation technique using a Nd:YAG laser at 100 MW/cm2 power density. LiCoO2 films were characterized by XRD, SEM, and vibrational spectroscopy. The synthesized compounds show high homogeneity in composition and in particle dimension. The main advantage of this method is the less time needed for the reaction to occur completely. Raman scattering spectroscopy provides information on the local environment of cations.

Oxide-hydrates of molybdenum [OHM] are investigated as 3-volt cathode materials for rechargeable lithium batteries. The oxides and oxide-hydrates of molybdenum have been prepared at various degrees of heat treatment. The oxide-hydrates of molybdenum with different water content showed a much better performance as cathode of the rechargeable lithium battery than that of MoO3. From these results, it was found that the crystalline-bonded water molecules play an important role for the high discharge capacity and high cyclability. We report the electrochemical characteristics of Li/OHM batteries using the oxides and oxide-hydrates of molybdenum which have been prepared with various degrees of heat treatment of molybdic acid. The oxide has a corrugated layer structure consisting of corner-shared MoO6 octahedra. This structure provide electronic conductivity within a layer and high lithium ion mobility between layers. The mechanism of dehydration and structural rearrangement of molybdic acid during heat treatment were studies by thermal analysis, X-ray diffraction, Raman and infrared spectroscopy. Thermal analysis indicates a two-step dehydration and formation of orthorhombic α-MoO3 and monoclinic β-MoO3. Discharge profiles and kinetics of the materials are dependent on the amount of “structural water” into the host lattice. The electro-insertion of Li ions occurs mainly in two steps in the potential range between 3.0 and 1.5 V (compositional range 0<xLi<l.5). Kinetic measurement show that Li ions are highly mobile in the OHM framework. The partial molar quantities δGx, δSx, and δHx, estimated from EMF-temperature measurements and coulometric titration.

The studies of the Li | 1M LiClO4 in propylene carbonate | LixV2O4 cell were carried out. The results of the electrochemical and X-ray investigations indicated that the cathode reaction in this cell proceeds as an intercalation process. Cycling test shows the reversibility of this cell along 35 charge/discharge cycles. However X-ray diffraction of the electrode material shows partial oxidizing of the LixV2O4 phase yielding γ-LiV2O5. The kinetic parameters of this process such as the chemical diffusion coefficient and mobility of lithium in the LixV2O4 were calculated.

Sol gel chemistry has been a useful technique to achieve hard-to-prepare metastable materials. Niobium oxide, for instance has a thermodynamic preference to crystallize on monocyclic lattice. Here, we were able to achieve synthesis of orthorhombic motif with a careful sol-gel preparation and tailored thermal treatment. Furthermore, formation of lithium inserted Nb205 phases were studied by electrochemical methods. When lithium is inserted, several single phases LixNb205 were observed in the range of 0 ≤ x ≤ 3.3 between 3.0 and 0.75 V. Even though the reaction is only reversible for x ≤ 1.8. Also, T-Nb205 polymorph showed improved intercalation characteristics.

A large variety of EMD and HTMD samples with various oxygen and water contents and various structural parameters Pr and Mt has been prepared. We show that the physico-chemical and structural parameters of the λ-MnO2 compounds are related to the synthesis conditions. New compounds were obtained with unusual amounts of intergrowth and twinning defects.

The Li insertion study focuses on a comprehensive investigation of the relationships between the material characteristics of the samples and their Li insertion behavior, and on the structural characterization of selected compounds after cycling. The oxygen content drastically affects the shape of the discharge curve after the first cycle and the total reversible capacity. The amount of structural water has an influence on the transformation kinetics of the starting phase. For optimized oxygen content (y= 2 in MnOY), the intrinsic reversible Li insertion capacity is maximum when the amount of microtwinning defects is minimum and when the structure is either mostly Ramsdellite or faulted Pyrolusite. Results show that, upon cycling, the λ-MnO2 structure seems to evoluate towards less Pyrolusite defects together with the apparition of new kinds of defects.

This work shows that λ-MnO2, compounds could be good candidates for the cathode application of Li-metal rechargeable batteries, provided that the physico-chemical and structural parameters of the starting compound are well chosen.

Several synthetic and natural manganese dioxides (MD) are characterized in terms of chemical composition, structural disorder and electrochemical activity; semi conducting properties are examined on pressed powdered samples. The reactivity scale established between structural disorder and electrochemical reactivity is paralleled by semi conducting properties and proton diffusivity. Conductivity values of 0.15 S.cm−1for stoechiometric β-MnO2, 1.3 10−2, 2.5 10−2 and 3.7 10−2 S.cm−1 for the defect dioxides, respectively Synthetic-Ramsdellite, CMD and EMD are measured. Proton diffusivity study by EIS provides, for low reduction rate, diffusion coefficient D values varying from 10–15 cm2/s value to 10−16 for the best reactive forms EMD and CMD; for NMD and β-MD, D is respectively 10−16 and 10−21 cm2/s. Redox reversibility is obtained around 1.3V (vs Hg.HgO) for EMD for a one electron reduction in [KOH] <IM; at -0.4V for a 2 electrons reduction in 9M KOH for Bi modified NMD.

Beta-iron oxy-hydroxide, which exhibits a (2×2) tunnel-type structure similar to that of (α-MnO2, was found to intercalate reversibly lithium in the tunnels. This material exhibits three voltage plateaus at 2.3, 1.5 and 0.7 V and has an over all discharge capacity of 1100 mAh/g. When cycling in the 2–V region, the material exhibits high capacity of 275 mAh/g and very good cyclic reversibility. X-ray photoelectron spectroscopy (XPS) of the discharged material showed that iron is reduced to the divalent state, and the lithium incorporated in the tunnels is purely ionic. This result explains the good reversibility of this electrode material. When discharged to 0.5 V, however, the structure of the material collapsed, and metallic iron was detected in the X-ray diffraction pattern.

Regioregular, alkyl-substituted poly(heteroaromatics) tend to crystallize in π-stacked structures as opposed to the herringbone pattern characteristic of non-substituted, planar aromatic molecules, e.g. sexithiophene. π-Stacking, favored by the crystallization of the sidechains, induces planarity in the conjugated backbone. The increased planarity causes a large (50-100 nm) shift in λmax (abs.) compared to the solution phase in which the backbone is twisted out of coplanarity, π-Stacking is a form of ground state aggregation that causes “fine structure” on the absorption peak. Excitation into the aggregate states rapidly leads to the formation of excimers as shown by the excitation spectra. In -stacked polymers, photoluminescence is almost entirely from the excimer states.

A composite of two conducting polymers, polyaniline and polypyrrole, could result in much improved physical properties with respect to their applications in pH electrodes and conducting paints/coatings. However, the composite has time dependant properties that made the use of dynamic computational algorithms necessary to control its behaviour. We used a sandwich-modified electrode as a pH-sensing electrode, which was integrated with a pre-trained computer for data processing and knowledge discovery. Conducting polypyrrole/polyaniline colloidal composites have been also prepared by deposition of the mixture solution of polypyrrole and polyaniline at negative potentials. Different substrates were dipped in the solution containing the mixture together with an acrylic latex and after drying the adhesive strength and electroactivity of the paint were studied. Several colloidal composite based coatings were investigated. At last a computer facilitated with powerful artificial ncural network based algorithms classified the paints.

A filled ionomeric membrane was achieved by dispersing phosphatoantimonic acid H3Sb3P2014, ×H20 (H3) in a Sulfonated PolySulfone (SPS) solution [1]. Water up-take is higher for filled than unfilled membrane as well as Protonic conductivity which is larger than that expected from the overall calculated concentration in charge carriers : a conductivity value of 0.135 S.cm−1 was gained at 50°C under 1003% Relative Humidity (HR) for a 1.6 meq.g−1 cationic exchange capacity (cec) SPS filled with 8% in H3 against 0.06S.cm−1 for an unfilled one. Mechanical measurements on the wet membrane shows the plasticizing effect of sulfonation, water and of the filler content which simultanously reinforced the cohesion of the membrane.

Poly (2,2'-(m-phenylene) 5,5'-bibenzimidazole), PBI and poly (2,5-benzimidazole), ABPBI, were cast into films and doped with phosphoric acid. Their mechanical properties were studied as a function of inherent viscosity and phosphoric acid content. The commercial PBI with an I. V. of 0.8 to 0.9 had relatively low elongation at break. It was fractionated; the higher the inherent viscosity the higher the modulus and elongation. At low phosphoric acid doping the modulus rose because a crystalline phase developed, and then dropped as more phosphoric acid was added. A second doping method produced films with high crystallinity and higher conductivity (0.02-.03 vs. 0.06-.08 S/cm) but poorer elongation than those made by doping a cast film in phosphoric acid. In order to get higher molecular weight films that could have better mechanical properties, we decided to polymerize 3,4-diaminobenzoic acid to ABPBI, an AB polymer for which I. V.'s of∼16 have been reported. After learning how to purify and polymerize the monomer, I. V.'s of 6–8 were easily obtained. Conductivities of the doped ABPBI films were as high as those of the best PBI films. With their high viscosities, the ABPBI films were much tougher and had better elongation than the doped PBI films.

The swelling behavior of poly(vinylidene fluoride-hexafluoropropylene), noted as P(VdF- HFP), was under various conditions. Increasing the HFP unit content in P(VdF-HFP) and temperature increased the swelling degree of the polymers considerably. The amount of the electrolyte solution absorbed by P(VdF-HFP) at room temperature showed the following trend: DMC>EC/DMC>DEC≈EC/DEC. The presence of LiPF6 in carbonate solvents did not affect on the swelling degree of PVdF and P(VdF-8%IIFP) in all solutions studied but lowered the swelling degree of P(VdF-15%HFP) in DMC, EC/DEC and EC/DMC/DEC solution at room temperature or prevented it from dissolution in the them at 55°C. A variable search experiment indicated that changing the pre-conditioning temperature from 21 to 55°C is more effective than other changes considered in the experiment for increasing high rate discharge capability. Some coins cells using the composite GPE separators had higher discharge capability than those using microporous polyethylene separators.

A comparative infrared spectroscopic study of the local vibrational potential energy environment of the CF3SO3 (triflate) anion in the poly(ethylene oxide)-lithium triflate and poly(ethylene oxide)-sodium triflate systems is presented. Analysis of the crystalline stoichiometric compounds in the two systems identifies significant differences in the ionic association. Comparison of the relative percentages of the anionic species in the PEO-NaTf system at various concentrations suggests that crystalline compound formation may proceed through intermediate structures. A symmetry-based vibrational analysis is applied to the crystalline compounds.