Poly(2, 2'-Dithiodianiline)(Poly(DTDA)), a conducting polymer having disulfide bond in it, has been proposed as a new class of high energy storage material. DTDA has one S-S bond interconnected between two moieties of anilines. The structure of the poly(DTDA) was similar to that of polyaniline in addition that the S-S bond is preserved after electropolymerization of DTDA. The poly(DTDA) has some advantages because of its high theoretical energy density, faster kinetics and higher electrical conductivity than other organosulfur cathodes

A series of electroactive spinel compounds, LiMn2-xCuxO4 (0.1 ≤ x ≤ 0.5) has been studied by crystallographic, spectroscopie and electrochemical methods and by electron-microscopy. These LiMn2-xCuxO4 spinels are nearly identical in structure to cubic LiMn2O4 and successfully undergo reversible Li intercalation. The electrochemical data show slight shifts to higher voltage for the delithiation reaction that normally occurs at 4.1 V in standard Li1−xMn2O4 electrodes (1 ≥ x ≥ 0) corresponding to the oxidation of Mn3+ to Mn4+. The data also show a remarkable reversible electrochemical process at 4.9 V which is attributed to the oxidation of Cu2+ to Cu3+. The inclusion of Cu in the spinel structure enhances the electrochemical stability of these materials upon cycling. The initial capacity of LiMn2-xCuxO4 spinels decreases with increasing x from 130 mAh/g in LiMn2O4 (x=0) to 70 mAh/g in “LiMn1.5Cu0.5O4”(x=0.5). Although the powder X-ray diffraction pattern of “LiMn1.5Cu0.5 O4” shows a single-phase spinel product, neutron diffraction data show a small, but significant quantity of an impurity phase, the composition and structure of which could not be identified. X-ray absorption spectroscopy was used to gather information about the oxidation states of the manganese and copper ions. The composition of the spinel component in the LiMn1.5Cu0.5O4 was determined from X-ray diffraction and XANES data to be Li1.01Mn1.67Cu0.32O4 suggesting, to a best approximation, that the impurity in the sample was a lithium-copper-oxide phase.

Potentially biodegradable polyamide (poly(imino-3, 3'-dithiodipropionylimmo-2, 2'-dithiodiethyl), -(NHCOCH2CH2-S-S-CH2CH2CO-NHCH2CH2-S-S-CH2CH2)n-, PIDI) and polyester (crosslinked poly(oxy-3, 3'-dithiodipropionyloxymethylene-l,4-phenylenemethylene,-(ICOCH2CH2-S-S-CH2CH2COO-CH2-C6H5-CH2)n- c-PODOM)) were prepared by interfacial polymerization between 3,3'-dithiodipropionic acid and cystamine, or 1, 4-benzenedimethanol. PIDI and c-PODOM showed the electrochemical responses based on reduction of the disulfide bonds in the polymer chains and re-oxidation of the produced thiolate anions. Degradation of PIDI and PODOM was investigated in various pH buffer solution. The apparent rate constant of c-PODOM at 25 °C was 1.3 × 103 % day−1 at pH 7 and that of PIDI at 37 °C was 3.5 × 103 % day−1 at pH 7. Estimated period for 90 % degradation of the polymers at pH 7 is about 1800 days (c-PODOM, 25 °C) and 630 days (PIDI, 37 °C).

We report Raman scattering measurements for uniaxially textured and randomly oriented polycrystalline LiCoO2 min films as well as for LiCoO2 and LiCo0.4Al0.6O2 single crystals. For both the crystalline LiCoO2 thin film samples and the single crystal LiCoO2 samples, well defined phonon modes are observed at Raman shifts of 486 cm−1 and 596 cm−1corresponding to the expected Eg and Alg modes of the layered LiCoO2 crystal structure with R3m symmetry. Upon Al substitution for Co in LiCoO2, the two phonon modes appear to shift to higher energy, but further work is needed to clarify this point.

Using Neutron Radiography (NR), the transfer of lithium ions has been investigated in the high temperature-type lithium ion conductor, Li 1.33Ti1.67O4. After supplying direct current to the oxides with different isotope ratios (6Li/7Li), NR images were obtained, which confirmed lithium ion movement in the oxides as changes of bright parts on negative films. Analysis of the NR images clarified that lithium ions in the spinel-type Li 1.33Ti1.67O4 were transported almost reversibly according to the polarity of electric field applied. The relations between the lithium contents in the samples and the film gray level showed that the cathode region in the charged sample contains about twice more lithium than in the original sample. Furthermore, NR method was applied to check lithium ion insertion into the TiO2 (rutile) sample. As a result, an informative Neutron Radiogram showing the lithium ion insertion was obtained.

The effects of microstructure on the oxygen permeation in SrCo0.8Fe0.2O3-δ(SCFO) and La0.2 Sr0.8 Fe0.8Cr0.2 O3 (LSFCO) was investigated using disc samples fabricated under different processing conditions. The microstructure of LSFCO remained unchanged when the sintering temperature was increased from 1300 to 1450 °C, but the average grain size of SCFO increased considerably when the sintering temperature was increased from 930 to 1200 °C. The change in grain size was found to have a strong effect on the oxygen permeation flux in SCFO, which increased considerably as the grain size was decreased. This indicates that the contribution of the grain boundary diffusion to the steady state oxygen flux in SCFO is substantial and grain boundaries provide faster diffusion paths in oxygen permeation through the samples.

Complex Sol-Gel Process (CSGP) was applied to the preparation of LiNi0.5Co0.5O2. Starting sol-solutions were prepared in two different ways: I, in which aqueous ammonia was added to a starting solution of Li+-Ni2+-Co2+ acetate-ascorbate, and II in which LiOH was added to a solution of Ni2+- Co2+ and NH4+ acetate-ascorbate. It was found that in the absence of ascorbic acid, or at its lower content (≤0.2 M on 1M σ Li+- Ni2+- Co2+) precipitation of Ni hydroxides occurred. Regular sols were concentrated ∼3 times, gelled and dried at 140°C. Intensive foaming was observed for samples during further heating. Consequently for scaling up to 200g in a run a preliminary long drying procedure followed by self-ignition step (∼400°C) was introduced. Thermal transformation of the gel to solid was studied by TG, DTA, XRD and IR. The main feature of this step is carbonate formation. The final structure LiNi0.5Co0.5O2 is observed after heating for Ih at 800°C. For larger scale production the extension of firing time was necessary. Electrochemical properties of the LiNi0.5Co0.5O2 compound, prepared by the CSGP were evaluated and considered satisfactory.

An improved cathodic material has been obtained by doping vanadium oxide hydrogel with silver. Silver-doped vanadium pentoxides with a silver molar fraction ranging from 0.01 to 1 were synthesized. With the successful doping, the electronic conductivity of V2O5 was increased by 2 to 3 orders of magnitude. The electrochemical performance of the silver doped materials is very high, up to 4 moles of lithium per mole of silver-doped V2O5 were found to be reversibly intercalated. In addition, the lithium diffusion coefficient is found to be high in the silver-doped material and with a smaller dependence on the lithium intercalation level. These enhancements resulted in high rates of insertion and delivered capacities.

The objective of this study was to highlight the usefulness of micron-sized Li4Ti5O12 in three distinctive areas: a) cathode of a low-voltage Li battery, b) insertion type auxiliary electrode to investigate the electrochemistry of oxide cathode materials, and c) anode of a Li-ion cell in conjunction with LiMn2O4 cubic spinel cathode. Li cells with Li4Ti5O12 exhibited an open circuit voltage of ∼1.6V, >90% utilization (in terms of the theoretical capacity) at ∼C/10 rate, ∼40% utilization 5C rate, and extended full-depth charge/discharge cycling at ≥ 1C rates with virtually no capacity fade. LiMn2O4 cathodes, evaluated in Li(4+xTi5O12 (x = ∼1.2)/LiMn2O4 cells, exhibited extended full-depth cycling capability with a small capacity fade rate of <0.1% which appeared to slow down with cycling. At a 1C discharge rate, over 190 cycles were demonstrated corresponding to an end utilization of ∼90 mAh/g or ∼0.6 mole Li per LiMn204. Balanced Li4Ti5O12//solid polymer electrolyte//LiMn2O4 full cells of slightly cathode-limited configuration had an open-circuit voltage of ∼3.0V and a mid-discharge voltage of ∼2.5V showing full-depth extended cycling capability at a utilization of ∼90 mAh/g or ∼0.6 mole Li per LiMn204 at the 1C and ∼0.45 mole Li per LiMn2O4 at the 7.5C discharge rate.

We report here the hydrothermal synthesis of a series of novel zinc vanadium oxides, using tetramethyl ammonium ion in order to stabilize the layered structure of vanadium oxide during electrochemical redox reactions with lithium. The compounds were synthesized by the reaction of zinc chloride, vanadium (V) oxide, and tetramethyl ammonium hydroxide at 165°C for 60 hours. Four new zinc vanadium oxide compounds were discovered, only one of which contained the organic cation; another was found to have a layered structure with bridging V-O-V groups analogous to that of beta alumina. These compounds were characterized by X-ray powder diffraction, and IR. Three of the compounds reacted readily with lithium, and their electrochemical behavior in lithium cells were determined.

We report on investigations of V2O5 thin film cathodes prepared by pulsed laser deposition and the phase transformations which occur during electrochemical cycling. Our experimental results on PLD-grown, textured V2O5 crystalline films concur with reports in the literature that there is a voltage threshold above which, cycling appears to be completely reversible and below which, cycling appears to be irreversible. Crystalline films discharged beyond the threshold to 2.0 V vs. Li exhibited an immediate and continuous fade in capacity as well as a ∼90% decrease in XRD peak intensity and a similar decrease in Raman signal intensity in as few as 10 cycles. We have made co-phase material by both electrochemically discharging virgin, crystalline V2O5 and by further discharging previously cycled films which showed irreversible structural changes.

Plasma Enhanced Chemical Vapor Deposition (PECVD) was used to prepare vanadium oxide thin films as cathodes for rechargeable lithium batteries. The reactants consisted of a high vapor pressure liquid source of vanadium (VOCl3) and hydrogen and oxygen gas. Deposition parameters such as the flow rates of H2, O2 and VOCl3, the substrate temperature and the Rf power were optimized, and high deposition rate of 11 Å/s was obtained. Vanadium oxide films with high discharge capacities of up to 408 mAh/g were prepared. The films also showed a superior cycling stability between 4 and 1.5 V at a C/0.2 rate for more than 4400 cycles. The films were amorphous up to a deposition temperature of 300°C, however, deposition on to substrates with textured surfaces facilitated the formation of crystalline films. We demonstrate that both the vanadium oxide material and the PECVD deposition method are very attractive for constructing thin-film rechargeable lithium batteries with high capacity and long-term cyclic stability.

A comparison of Li insertion in manganese oxide phases with a tunnel (todorokite) framework, its two-dimensional layered precursor (birnessite/buserite), and Li-exchanged materials are presented. The results outline the effect of the MnO6 octahedral arrangement and framework composition on the electrochemical response. The interlayer cations in the lamellar materials are exchangeable for Li, giving rise to a lithiated birnessite that displays a sustainable capacity of 125 mAh/g. For todorokite, molten salt exchange using LiNO3 results in displacement of water from the tunnels, and incorporation of additional Li into the structure. Some of this Li is extractable during charge, resulting in a reversible capacity of 172 mAh/g in the voltage window 4.2–2.0V.

Li1+xV3O8 (LT-M form) was obtained by sol-gel method in CH3OH. This form, prepared at 350°C, possessed smaller grain size and better electrochemical performance than the HT form prepared by conventional high temperature synthesis. High discharge capacity (372 mAh·g−1: x = 4.0) and reversible discharge and charge cycle were attained. When heated at 200°C, CH3OH molecules remained in the compound and crystallinity became lower by lithium insertion over x = 2.0. The lithium de-intercalation was irreversible.

Recent advances in mixed metal oxide (LiNi1−xCoxO2) cathode materials for lithium ion (Li-ion) batteries have resulted in a new generation of high capacity cathode materials. High capacity materials are particularly useful for applications where either volume or weight is limited, such as in space applications. These applications also benefit from cell chemistries with high energy efficiency as this permits reduced ancillary energy storage and dissipation apparatus. Mixed metal oxide materials have been evaluated and demonstrated in prismatic Li-ion cells. The capacity of the mixed metal oxide materials is exceptional, reversible capacity of 160mAh/g is demonstrated although the cell voltage is lower than when LiCoO2 materials are used, 3.58V vs. 3.74V, at low (0.5mA/cm2) discharge rates. The high capacity results in a significant improvement in specific energy, further, the sloping discharge curve characteristic of the mixed metal oxide materials facilitates determination of the state of charge based on cell voltage. The design of composite cathode materials using the mixed metal oxide materials has a significant influence on the cell impedance and the rate capability of the material. Results describing the rate capability of these materials is presented.

Aluminum is of interest as a constituent for Li battery electrodes due to its low cost and low mass, and because ab initio calculations indicate that solid solution of LiAlO2 with LiMO2 (M = transition metal) in the α-NaFeO2 structure can increase intercalation voltage [1]. In this study, we investigated the effect of Al doping on LiCoO2 and LiMnO2. Single phase LiAlyCo1-yO2 has been synthesized up to y = 0.5 by firing homogenous hydroxide precursors. A systematic increase in the open circuit voltage is observed with Al content. In LiAlyMn1-yO2, the addition of LiAlO2 stabilizes LiMnO2 in the α-NaFeO2 structure under conditions where neither endmember is stable in the structure. High reversible capacity was obtained over both a 4 V and 3 V plateau, indicating that the compound transforms to a spinel-related structure during cycling, but that the cooperative Jahn-Teller distortion is suppressed.

This investigation involves the synthesis of MnO2 nanofibrous materials, via an aqueous chemical synthesis route. A critical step in the synthesis is the extended period of the refluxing of the reactive constituents, which enables the gradual transformation of the initial amorphous nanoparticles into a random-weave nanofibrous structure, in the form of a bird's nest superstructure. The bird's nest has a diameter of approximately 10 μm, which is an assemblage of many individual nanofibers with a diameter of about 15 nm, and a length up to 1 μm. Partial transformation of the nanostructured MnO2 realizes a novel bimodal morphology, which combines a high density of chemically active sites with an enhanced percolation rate. Characterization of these nanofibers include SEM, TEM, surface area, and chemical analysis. High resolution TEM observations reveals that the as-synthesized MnO2 nanofibers contain lattice defects, including molecular pores, meso- and micro-pores.

We report the vibrational spectra of numerous 4-volt cathode materials, the transition metal oxides which are potential materials for advanced Li-ion batteries. They provide high specific energy density, high voltage, and remarkable reversibility for lithium intercalation-deintercalation process. Studied were carried out by Raman and FTIR spectroscopies. Oxides such as LiMn2O4, LiNiVO4, LiCoVO4 spinels, LiMeO2 (Me=Co, Ni, Cr) layered compounds and their mixed compounds have been investigated. The local environment of cations against oxygen neighboring atoms has been determined by considering tetrahedral and octahedral units building the lattice. Structural modifications induced by the intercalation-deintercalation process, by the cation substitution, or by the low-temperature preparation route are also examined. The results are compared with those of end members.

Oxo ions (MO4)n- (M = V, Cr, Mn and Mo) have been reduced in aqueous solutions with potassium borohydride to obtain the binary oxides MO2+δ. While the vanadium and manganese oxides are nanocrystalline, the chromium and molybdenum oxides are amorphous. The nanocrystalline VO2 having a metastable structure and the amorphous CrO2 and MoO2.3 transform to the thermodynamically more stable phases upon heating above 300–400 °C. These metastable oxides after heating in vacuum at 200–300 °C to remove water show good electrode performance in lithium cells. VO2, CrO2 and MoO2.3 show a reversible capacity of, respectively, 290 mAh/g in the range 4–1.5 V, 180 mAh/g in the range 3.3–2.3 V, and 220 mAh/g in the range 3–1 V. MnO2 obtained by this process does not show good electrode properties.

We have synthesized lithiated nickel oxide-based cathode materials containing stoichiometric and excess lithium using a new low temperature colloidal paniculate sol-gel process. The process yields a xerogel precursor that transforms to the crystalline oxide at 800 °C in 2h. We studied the Li environment with nuclear magnetic resonance (NMR) and that of the transition metal ions with x-ray absorption spectroscopy. We measured samples of LiNi1−xCoxO2, with x = 0 and 0.25. The effect on each composition of the incorporation of 5 mol % Li was also examined. The precursor material appears to have no Ni3+, as indicated x-ray absorption measurements, and is highly disordered, showing little sign of interatomic correlations beyond the nearest neighbor in extended x-ray absorption fine structure (EXAFS) spectra. The 7Li NMR line widths and spin-lattice relaxation (T1) behavior are dominated by strong interactions with the paramagnetic Ni3+. The presence of 5 % excess Li causes almost no change in NMR line width or T1 in the mixed (Ni/Co) cathode, but does produce an almost 30% reduction in line width for the pure LiNiO2, implying that Co stabilizes the structure. The near-edge x-ray absorption measurements show the local Ni environment is relatively unaffected by Co substitution, a result confirmed by EXAFS analysis. The heat-treated samples are highly ordered, and both the near-edge and extended analysis imply Co substitutes primarily for Ni2+, not Ni3+. The Jahn-Teller distortion is apparent in both the stoichiometric and Li-excess materials.