Search

Doping engineering is an effective modification strategy to enhance the electrochemical performance of electrode materials. In this paper, the impacts of heteroatom doping in monolayer titanium disulfide (TiS2) by substituting the S atom with the heteroatoms (B, C, N, O, F, and P) on the adsorption and diffusion capabilities of alkali metals (Li, Na, and K) have been systematically investigated using first-principles calculations to evaluate the material performance for application in alkali metal-ion batteries. The doping of most heteroatoms can promote the adsorption capability of alkali metal atoms on monolayer TiS2 as their adsorption energies decrease compared with the pristine system, particularly for p-type doping with C, N, and P. The diffusion energy barriers decrease when alkali metals approach the doping site of most heteroatom-doped TiS2, and the barriers near the doping site are extremely small (0.00-0.08 eV), whereas they slightly increase as alkali metals move away from the doping site. P doping has the lowest overall diffusion energy barrier for each metal. Thus, monolayer TiS2 with heteroatom doping, especially P doping, can be used as a potential anode material for alkali metal-ion batteries. This study can help comprehend the impacts of heteroatom doping and design high-performance electrode materials for rechargeable batteries.

The selective removal of ions by an electrochemical process is a promising approach to enable various water-treatment applications such as water softening or heavy-metal removal. Ion intercalation materials have been investigated for their intrinsic ability to prefer one specific ion over others, showing a preference for (small) monovalent ions over multivalent species. In this work, we present a fundamentally different approach: tunable ion selectivity not by modifying the electrode material, but by changing the operational voltage. We used titanium disulfide, which shows distinctly different potentials for the intercalation of different cations and formed binder-free composite electrodes with carbon nanotubes. Capitalizing on this potential difference, we demonstrated controllable cation selectivity by online monitoring the effluent stream during electrochemical operation by inductively coupled plasma optical emission spectrometry of aqueous 50 mm CsCl and MgCl2 . We obtained a molar selectivity of Mg2+ over Cs+ of 31 (strong Mg preference) in the potential range between -396 mV and -220 mV versus Ag/AgCl. By adjusting the operational potential window from -219 mV to +26 mV versus Ag/AgCl, Cs+ was preferred over Mg2+ by 1.7 times (Cs preference).

This work introduces for the first time titanium disulfide (TiS2)/carbon nanotube (CNT) electrodes for desalination of high molarity saline water. Capitalizing on the two-dimensional layered structure of TiS2, cations can be effectively removed from a feedwater stream by intercalation. The TiS2–CNT hybrid electrode is paired in an asymmetric cell with microporous activated carbon cloth without an ion exchange membrane. By electrochemical analysis, the correlation between the state of charge and the stability of TiS2 was investigated. By using post-mortem X-ray diffraction, the sodium-ion intercalation mechanism gives an insight into how the state of charge affects the structure and cyclic stability. Our system showed stable desalination performance over 70 cycles at high molar concentration (600 mM), with a cell salt removal capacity of 14 mg/g (equivalent to a sodium removal capacity of 35.8 mg/g normalized to the mass of TiS2–CNT). This novel approach of membrane-free hybrid Faradaic capacitive deioniza...

Magnesium rechargeable batteries potentially offer high-energy density, safety, and low cost due to the ability to employ divalent, dendrite-free, and earth-abundant magnesium metal anode. Despite recent progress, further development remains stagnated mainly due to the sluggish scission of magnesium-chloride bond and slow diffusion of divalent magnesium cations in cathodes. Here we report a battery chemistry that utilizes magnesium monochloride cations in expanded titanium disulfide. Combined theoretical modeling, spectroscopic analysis, and electrochemical study reveal fast diffusion kinetics of magnesium monochloride cations without scission of magnesium-chloride bond. The battery demonstrates the reversible intercalation of 1 and 1.7 magnesium monochloride cations per titanium at 25 and 60 °C, respectively, corresponding to up to 400 mAh g−1 capacity based on the mass of titanium disulfide. The large capacity accompanies with excellent rate and cycling performances even at room temperature, opening up possibilities for a variety of effective intercalation hosts for multivalent-ion batteries., Magnesium rechargeable batteries potentially offer high-energy density, safety, and low cost. Here the authors show a battery that reversibly intercalates magnesium monochloride cations with excellent rate and cycle performances in addition to the large capacity.

Lithium–sulfur (Li–S) batteries show significant advantages for next-generation energy storage systems owing to their high energy density and cost effectiveness. The main challenge in the development of long-life and high-performance Li–S batteries is to simultaneously facilitate the redox kinetics of sulfur species and suppress the shuttle effect of polysulfides. In this contribution, we present a general and green water-steam-etched approach for the fabrication of H- and O-incorporated porous TiS2 (HOPT). The conductivity, porosity, chemisorptive capability, and electrocatalytic activity of HOPT are enhanced significantly when compared with those of raw TiS2. The synthetic method can be expanded to the fabrication of other highly conductive transition metal dichalcogenides such as porous NbS2 and CoS2. The as-obtained HOPT can serve as both a substitute of conductive agents and an additive of interlayer materials. The optimal electrode delivers discharge capacities of 950 mA h g–1 after 300 cycles at 0....

Sulfur-doped anatase TiO 2 nanoparticles with sulfur atoms occupying oxygen sites were realized by low-temperature hydrothermal oxidation of titanium disulfide (TiS 2 ) with deionized water as the solvent. S doping can effectively narrow the bandgap of TiO 2 due to the fact that S 3 p level is higher than O 2p orbital. The large surface area caused by this doping method induces higher photocatalytic activity in the visible regime compared with S-TiO 2 oxidized at high temperature. The low-temperature hydrothermal oxidation of TiS 2 in pH neutral solvent is an environmental-friendly method to obtain S-TiO 2 with high photocatalytic activity, which can be extended to other nonmetal doping of TiO 2 or other semiconductors for bandgap engineering.

Although the LiMn1.5Ni0.5O4 spinel operating at 4.7 V presents some beneficial characteristics over more traditional positive electrode materials, instability issues at elevated temperature have limited its practical use so far. While we previously proposed Li1+yMn1.5Ni0.5O4−xFx (LMNOF) spinel that is intrinsically stable at elevated temperatures in Li-excess half-cell configuration, we investigate herein fixed, non-excess Li-content window-shifted Li-ion systems. By utilizing Li4Ti5O12 (LTO) or TiS2 negative electrodes stable in broad electrolyte compositions instead of carbonaceous electrodes, we aim at limiting the Li-consuming side reactions such as the formation of solid-electrolyte interphase and enable a focus on the exploration of electrolyte compositions including additives. Utilizing such an approach, excellent fundamental stability of LMNOF in a fixed Li-content Li-ion environment is demonstrated at 55 °C with the use of relatively common electrolyte components.

The crystal structure of 3R-LiTiS2 was studied with com- bined experimental and theoretical approaches. The 3R polymorph of lithium titanium disulfide crystallizes rhombohedrally in the well- known NaCrS2 type with lattice parameters a = 352.98(1) pm, c = 1807.51(3) pm. The relative stability of 3R-LiTiS2 with respect to

Amorphous titanium trisulfide (TiS3) active materials were prepared by ball milling of an equimolar mixture of crystalline titanium disulfide (TiS2) and sulfur. A high-resolution transmission electron microscope image revealed no periodic lattice fringes on the amorphous TiS3. The all-solid-state lithium secondary batteries using a sulfide solid electrolyte and the amorphous TiS3 electrode showed high capacity of greater than 300 mAh g−1 for 10 cycles. The amorphous TiS3 had a higher capacity than the mixture of crystalline TiS2 and S, which was used as the starting material of amorphous TiS3. The X-ray diffraction patterns and the Raman spectra of the amorphous TiS3 electrode after the first and tenth charge–discharge measurements were similar to those before the measurement. The amorphous structure of TiS3 did not change greatly during the first few cycles. The all-solid-state cells with the amorphous TiS3 electrode showed higher initial coulombic efficiency because the amorphous TiS3 active material retained its structure during the initial electrochemical test.

Single crystals of titanium disulfide TiS2 were synthesized by chemical vapor synthesis and subsequently intercalated with n-butyl lithium (BuLi) in n-hexane. Experiments were carried out using a butyl lithium concentration between 0.8 and 10 mol L-1 and the temperature range was from 248 K to 328 K. The duration of the intercalation was varied from 2 h to 30 d. After the intercalation experiments concentration profiles of lithium, titanium and sulfur were measured parallel to the ab-plane of the crystal by LA-ICP-OES (LASER Ablation — Inductively Coupled Plasma - Optical Emission Spectroscopy). Chemical diffusion coefficients (D) were determined by fitting of the profiles to the specific solution of Fick's 2 nd law for the given boundary conditions. The measured diffusivity in the ab-plane (D|| a/b ) varies between 10-13 and 10-15 m2 s-1 at room temperature. These variations of D cannot be correlated to the reaction time. On the other hand a systematic increase of D|| a/b with the concentration of butyl lithium (cBuLi ) was observed, with a corresponding decrease in activation energy from 59.6 ± 7.6 kJ mol-1 (cBuLi=1.6 mol L-1 ) to 42.6 ± 11.7 kJ mol-1 (cBuLi=10 mol L-1 ). Furthermore, profiles measured on the same crystals reveal D|| a/b values differing by up to a factor of 3. ToF-SIMS (Time-of-Flight Secondary Ion Mass Spectromety) images gave evidence of inhomogenous insertion of lithium along crystal edges. These findings indicate that stress induced by widening of the crystal layers plays a crucial role in the intercalation kinetics. SIMS profiling perpendicular to the ab-plane gives evidence that D⊥ a/b is at least four orders of magnitude lower than D|| a/b .

Bi-doped manganese dioxide (MnO2) has been prepared from γ-MnO2 by physical admixture of bismuthoxide (Bi2O3). The doping improved the cycling ability of the aqueous cell. These results are discussed and compared with the electrochemical behavior of bismuth-free MnO2. Batteries using the traditional potassium hydroxide (KOH) electrolyte are non-rechargeable. However, with lithium hydroxide (LiOH) as an electrolyte, the cell becomes rechargeable. Furthermore, the incorporation of bismuth into MnO2 in the LiOHcell was found to result in significantly longer cycle life, compared with cells using undoped MnO2. The Bi-doped cell exhibited a greater capacity after 100 discharge cycles, than the undoped cell after just 40 cycles. X-ray diffraction and the microscopic analysis suggest that the presence of Bi3+ ions reduces the magnitude of structural changes occurring in MnO2 during cycling. Comparison with additives assessed in our previous studies (titanium disulfide (TiS2); titanium boride (TiB2)) shows that the best rechargeability behavior is obtained for the current Bi-doped MnO2. As the size of Bi3+ ions (0.96 A) is much larger than Mn3+ (0.73 A) or Mn2+ (0.67 A) they have effectively prevented the formation of non-rechargeable products.

Titanium tetraisopropoxide reacts with hydrogen sulfide in butylamine solvent at room temperature to form an amorphous titanium alkoxy-sulfide which can be converted to crystalline titanium disulfide by heat treatment in a flowing hydrogen sulfide gas stream. The reaction has been studied using infrared and Raman spectroscopy, gas chromatography-mass spectrometry, X-ray diffractometry and energy-dispersive X-ray analysis measurements. Based on these studies, it is shown that a partially thiolysed alkoxide precursor forms through the replacement of a limited number of alkoxy groups by hydrosulfide moieties. This alkoxy-hydrosulfide is believed to form following a thiolysis-condensation mechanism similar to the hydrolysis-condensation process that occurs during the corresponding oxide sol-gel reaction. The alkoxy-hydrosulfide species can then be completely thiolysed at 800 °C in a stream of hydrogen sulfide to yield pure, hexagonal titanium disulfide in either film or particulate form.

Titanium disulfide thin films are grown by atomic layer deposition (ALD) at 400–500 °C using TiCl4 and H2S as precursors. Soda-lime glass, silicon, and thin films of TiN, ZnS, Rh, Ir, Pd, Pt, and Ru are used as substrates. Hexagonal (001)-oriented TiS2 is deposited on ZnS at 400 °C with growth rates of between 0.15 and 0.20 A per cycle. Randomly oriented, hexagonal, platelike crystals are deposited on glass and TiN with a growth rate of 0.26 A per cycle. Significant variations in surface morphologies were detected in TiS2 films on various noble metals. TiS2 was also grown on the pore walls of an alumina membrane.

The reaction of TiCl4 with pyridine- and pyrimidine-thiol has been investigated. Reaction of TiCl4 with 3 equiv. of 2-mercaptopyridine and 3 equiv. of tert-butylpyridine in toluene at room temperature resulted in the formation of the tris(pyridine-2-thiolate) complex [TiCl(SC5H4N)3] (1). The related reaction between TiCl4 with 3 equiv. of 2-mercaptopyrimidine and 3 equiv. of tert-butylpyridine in toluene at room temperature resulted in the isolation of the complex [TiCl(SC4H3N2)3] (2). Compound 2 has been characterised by X-ray crystallography. Low pressure CVD of 1 and 2 produced brown/gold films of TiS2/TiO2 on glass substrates at 550 and 600 °C.

We reported the synthesis of titanium disulfide (TiS 2 ) whiskers on Ni-coated Si wafer via a simple vapor transport deposition method at 630 °C. To our knowledge, this is the first time to report the synthesis of TiS 2 whiskers with exact stoichiometric composition. By gently controlling the configuration of S and Ti sources and Si substrate during vapor reaction, TiS 2 whiskers could be successfully acquired. TiS 2 whiskers are single crystalline with exact stoichiometric composition. This kind of solid sulfide source method also can be used for synthesis of other transitional metal dichalcogenide whiskers. We believe that the successful growth of TiS 2 whiskers would provide significant theoretical and experimental opportunities for researchers.

A room-temperature low-cost TiS2 p-type contact material is applied for the first time as the hole-transporting material (HTM) in perovskite solar cells, with power conversion efficiencies surpassing 13.5%. Synthesized by a simple two-step hot-injection method, it presents a much lower price per m2 than octakis(4-methoxyphenyl)-9,9′-spirospirobi[9H-fluorene]-2,2′,7,7′-tetramine (spiro-OMeTAD), 30 times lower in price ($0.046 for TiS2 and $1.36 for spiro-OMeTAD at 13.54% efficiency), standing out over most of the reported HTM alternatives.

The synthesis of inorganic fullerene (IF) nanoparticles and IF hollow spheres of titanium disulfide by a simple colloidal route is reported. The injection temperature of the titanium precursor into the solvent mixture was found to be important in controlling the morphology.

Solid state reaction of metal halides MXn (n = 1 or 2) with stoichiometric amounts of sodium chalcogenide (Na2S2 or Na2E where E = S, Se or Te) at 300 °C for 48 h in evacuated ampoules affords a range of transition and main-group metal chalcogenides: ME2 (M = Fe or Co, E = S or Te); M(1 − x)E (M = Fe or Co, E = S); Ag2E (E = S, Se or Te), Ni(1 − x)E (E = S, Se or Te); NiS2, MnS, FeSe, SnSe and SnTe along with co-formed salt. Washing of the highly sintered, fused product mixture with water resulted in isolation of crystalline binary chalcogenides, typically of a single phase in good yield (90%). The products were characterised by X-ray powder diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA) and i nfrared spectroscopy.

The role of intercalation/insertion reactions in battery electrodes was first recognized just over 25 years ago. From the first prototypical titanium disulfide cells, the technology has more recently been commercialized by Sony in the Li-ion cell using a cobalt oxide insertion cathode and a carbon insertion anode. These cells have proved themselves highly successful in the field in small devices, such as cellular phones and portable computers. However, their energy density is no higher than the titanium sulfide system and they are too expensive for large-scale application. Therefore, the search is on for lower cost cathodes that have at least double the energy density of the present systems. The research trends and future prospects are discussed.

Mixed conductors show significant mobility of both electronic and ionic species and were the subject of an earlier review in MRS Bulletin. The current review is restricted to those mixed conductors of interest for use in lithium batteries, with an emphasis on commercialization. The first lithium batteries were primary cells using pure lithium anodes and carbon monofluoride or manganese oxide as the cathode. Both were developed in Japan, the former for use in fishing floats and the latter for calculators and similar small devices. Such primary cells based mainly on MnO{sub 2} or FeS{sub 2} cathodes are still extensively used in watches, cameras, and so on. Lithium primary cells are also the main power source for many medical devices, such as pacemakers. In some of these applications, silver vanadate is the cathode. The recognition of the role of intercalation/ insertion reactions in battery electrodes just over 25 years ago allowed significant progress to be made in secondary (rechargeable) lithium batteries. From the first prototypical titanium disulfide cells, the technology has more recently been commercialized by Sony Corp. in the Li-ion cell, using a cobalt oxide insertion cathode and a carbon insertion anode. In the former, commercialized by Exxon, the reactionmore » is the simple intercalation of lithium ions between sheets of TiS{sub 2}.« less

A study of the electronic structure and chemical bonding of the transition-metal intercalated titanium disulfide, MTiS 2 (M = Cr and Fe), is performed by a first-principles molecular-orbital method using a model cluster composed of 75 atoms. The discrete-variational (DV)-Xα method was employed and Mulliken's population analyses were thoroughly conducted. The intercalation in the so-called van-der-Waals gap is found to change the local electronic structure significantly in the following manner: The net charge of the intercalated M-layer is decreased by 0.559 and 0.307 when M = Cr and Fe, respectively. The bond overlap population (BOP), a measure of the covalent bond-strength, decreases by approximately 20% as for the Ti-S bond. Both the BOPs of the Cr-S and Fe-S bonds are found to be as large as that of the Ti-S bond.

Electron diffraction has been used to observe in situ HgxTiS2 (1.24 > x ≥ 0.00) guest-layer structural behavior as a function of temperature. At low temperature (−170 °C), Hg forms well-ordered inc...

Investigations pertaining to the synthesis of titanium disulfide (TiS 2 ) have so far been focused on solid state reactions, low temperature chemical techniques and vapor phase reactions using titanium tetrachloride (TiCl 4 ) as the starting material. In this paper, we have investigated the potential of titanium tetraalkoxides [Ti(OR) 4 ], which have been widely used for the synthesis of oxides by the sol-gel approach, for the synthesis of TiS 2 via the thio-sol-gel process. The mechanism of the reaction of titanium isopropoxide {Ti(OPr i ) 4 } with H 2 S in benzene has been studied using infrared spectroscopy (FTIR), gas chromatography (GC) and chemical analysis. Based on these studies, it has been determined that the precipitate obtained from the reaction forms following a thiolysis-condensation mechanism similar to the hydrolysis-condensation mechanism that operates in the oxide sol-gel process. The precipitate, which is an alkoxysulfide, can be converted to TiS 2 by heat treatments in flowing H 2 S. The influence of modifying agents, the role of solvents and the alkoxy group [in Ti(OR) 4 ] on the formation of the alkoxysulfide precipitate have also been presented and discussed. Finally, the applicability of this process for the synthesis of NbS 2 has also been demonstrated.

Since Vecht and Quddus have reported the preparation of alkaline earth sulfides by using the reaction between alkaline earth alkoxides and H 2 S in 1976, a thio sol-gel process has been reported for the synthesis of metal sulfides using alkoxides or thiolates. The thio sol-gel process in which metal alkoxides act as the metal source uses H 2 S for a thiolysis reaction similar to H 2 O for the hydrolysis reaction in the conventional sol-gel process as follows

A relationship has been ascertained between the conditions of synthesis, physicochemical properties and electrochemical activity of sulfide cathodic materials (TiS2, V2S2, MoS3) in lithium batteries with an aprotic electrolyte. The existence of two forms of titanium disulfide has been shown for the first time, a ‘soft’ and ‘hard’ form (TiS2(s) and TiS2(h)) that differ essentially in their structure, conductivity, electrochemical activity and mechanism of intercalation. TiS2(s) synthesized under non-stationary conditions with a considerable disorderliness has greater specific capacity (210 mAh/g) and better lithium transport properties than TiS2(h) synthesized under long stationary conditions. It has been shown that the effectiveness of solid-phase cathodic materials in lithium batteries is caused by their macro- and microstructure and depends on their preparation conditions, the stoichiometry of active cathodic substances is not the basic criterion. The other cathodic materials obtained by the methods of non-stationary synthesis also possess extremely high specific properties: MoS3: ∼ 400 mAh/g and V2S2: 240–260 mAh/g.

A novel type of solid-state lithium rocking-chair battery, employing titanium disulfide as the negative lithium sink electrode, lithium cobalt oxide as the lithium source positive electrode, and a highly conductive gel-type polymer membrane as the electrolyte has been fabricated and evaluated. The data reported here demonstrate that the rocking-chair concept may be applied to various combinations, which, starting from the well-established C-LiMO[sub 2] (M = Co, Ni) may expand to others involving alternative electrode materials of which TiS[sub 2] is a promising example.

Sulfides of transition metals (titanium, molybdenum, vanadium, tungsten, etc.) represent an important class of materials well-known for their catalytic and electrochemical properties. The catalytic properties make them potentially useful in hydrodesulfurization reactions, and their electrochemical response makes them suitable as active cathodes in rechargeable batteries. A thio sol-gel process for the synthesis of titanium disulfide using titanium alkoxide as the metal source is demonstrated. The alkoxide reacts at room temperature with H[sub 2]S to form a precipitate which is a precursor to the sulfide. Through infrared spectroscopy and chemical analysis of the powder and gas chromatographic analysis of the liquid byproducts of the reaction, it is shown that a partially sulfidized alkoxide precursor forms through the displacement of alkoxy groups from the alkoxide by sulfur-bearing thiol groups. This thiolysis reaction is very similar to that which occurs in the case of sol-gel reactions to form oxides. The alkoxy-thiol species then undergo condensation-polymerization by the liberation of H[sub 2]S. When it is heat-treated in H[sub 2]S, this precursor transforms to TiS[sub 2] at [approximately]700 C. Systematic heat treatments have been performed and the formation of TiS[sub 2] has been observed using X-ray diffractometry. The change in the morphology has also beenmore » studied using scanning electron microscopy.« less

The present paper describes the fabrication and characterization of a novel type of a solid-state, thin-layer lithium rocking chair battery. The battery utilizes titanium disulfide, TiS2, as the negative ‘lithium sink’ electrode, lithium cobalt dioxide, LixCoO2, as the positive ‘lithium source’ electrode, and a composite lithium ion-conducting polymer membrane as the electrolyte. Our initial studies on this novel system involved characterization of the charge/discharge behaviour and a.c. impedance responses.

A rocking-chair ambient temperature rechargeable organic electrolyte cell employing thin films of titanium disulfide and lithium cobalt oxide as the negative and positive electrodes, respectively, is described. A 1.52 M solution of lithium hexafluoroarsenate in acetonitrile with a conductivity of 0.0522 S/cm at 25 o C was used as the electrolyte. The cell was assembled in the discharged state and after charging exhibited an open-circuit potential of 2.1 V. The discharge characteristics of the cell are presented at current densities between 2 to 20 mA/cm 2 . The cell also exhibited good cycle life and delivered 500 cycles

Titania (TiO2) and sodium titanate nanostructures with controllable phases and morphologies were synthesized by hydrothermal method with titanium disulfide (TiS2) as the starting material. Sodium 5 titanate nanobelts could be synthesized under a relatively low alkaline concentration (1 mol L-1 NaOH) and short duration (6 hours). At 3 mol L-1 HCl, rutile TiO2 nanorods were synthesized. Anatase TiO2 nanoparticles were obtained under pH values ranged between 2 to 13. FTIR analysis confirmed the phase change as the pH of the reacting medium increased from highly acidic to highly alkaline condition. The adsorption of methylene blue (MB) on the as-synthesized sodium titanate nanobelts 10 fitted well with the Langmuir monolayer model, with an adsorption capacity as high as 312.5 mg g-1. The kinetics of MB adsorption was found to be pseudo-second-order kinetic model. In brief, this study demonstrates a simple method to control the phase and morphology of titanium-based oxides. Excellent performance has been shown in the MB adsorption test by the sodium titanate nanostructures. Accepted version

An all solid-state cell employing lithium tetrachloroaluminate (LiAlCl 4 ) as the lithium ion conducting solid electrolyte and using lithium intercalating compounds, titanium disulfide (TiS 2 ), and lithium cobalt(III) oxide (LiCoO 2 ), as the electroactive materials in the rocking chair' configuration is described. Thin films of TiS 2 were prepared by chemical vapor deposition onto aluminum substrates while thin films of LiCoO 2 on aluminum were prepared by organometallic decomposition and used as the negative and positive electrodes, respectively. On charge, LiCoO 2 was delithiated and the lithium ions were transported through the solid electrolyte to the TiS 2 electrode where theyr were intercalated and formed lithiated titanium disulfide (Li x TiS 2 )

Titanium disulfide and niobium triselenide are two well-studied candidate materials for positive electrodes in rechargeable lithium cells. A comparative study of the kinetics of intercalation of lithium in both the cathodes is made here based on various electrochemical techniques, i.e., linear polarization, potentiodynamic polarization, and ac impedance under different experimental conditions such as prismatic or disk configuration of fresh, partially discharged, or cycled electrode. Further, the diffusion coefficients of lithium ions in these cathodes are estimated under these conditions using conventional techniques, i.e., ac impedance, chronocoulometry, chronoamperometry, and current pulse relaxation. Based on the values of the diffusion coefficients, the applicability of these methods for the determination of diffusion coefficients is discussed.

A study has been made of the influence of the sulfide substrate on the rate and direction of thermal decomposition, in an argon atmosphere, of Fe3(CO)12 deposited on the surface of crystalline MoS2, TiS2, and Co0.5TiS2 in amounts K=0.5−10 monolayers. It has been shown that the decomposition rate increases in the series MoS2

The chemical, D , and self diffusion, D, coefficients for lithium transport within the cubic polymorph of TiS2 have been determined as a function of temperature and composition by ac impedance measurements. Both D and D vary with the lithium content, reaching maxima at 23°C of 5.6 × 10−10 and 6.9 × 10−9 cm2sec−1, respectively. The Arrhenius plots for the self diffusion coefficient are linear; however, the preexponential factor and activation energy vary significantly with composition displaying a broad minimum centered at x = 0.5. This behavior is associated with interactions between the mobile ions; two possible models for ion interactions are presented, either or both of which may be important in these systems.

Testing of AA size rechargeable cells for underwater vehicle and other naval applications is complete for AT&T's lithium/niobium triselenide (Li/NbSe/sub 3/) and Moli Energy's lithium/molybdenum disulfide (Li/MoS/sub 2/) and is in progress on Moli Energy's lithium/manganese dioxide (Li/MnO/sub 2/) and W.R. Grace's lithium/titanium disulfide (Li/TiS/sub 2/). Cell cycling was performed at various discharge rates, temperatures, and depths of discharge. At 25 degrees C and 1 mA/cm/sup 2/ (roughly the C/4 rate), delivered energy densities were about 40 Wh/lb for NbSe/sub 3/, TiS/sub 2/, and MnO/sub 2/ and 22 Wh/lb for MoS/sub 2/. Under the same conditions, nickel/cadmium (Ni/Cd) cells deliver only 10 Wh/lb. However Ni/Cd cycles much longer and the lithium cells are far more vulnerable than Ni/Cd to performance loss in low temperature, high discharge rate cycling. The NbSe/sub 3/ data and the (limited) TiS/sub 2/ data indicate that these cells tend to accept excessive charge which is often associated with lithium dendrite shorting and considered potentially hazardous. At 1 mA/cm/sup 2/ and 25 degrees C, discharge plateaus ranged from 2.9 V for MnO/sub 2/ to 1.8 V for MoS/sub 2/. >

Reaction of [Nb(NMe(2))(5)] with 10 equiv of 2,6-Me(2)C(6)H(3)SH in toluene results in the formation of red crystals of [Nb(SC(6)H(3)Me(2)-2,6)(5)]. Crystal structure analysis of [Nb(SC(6)H(3)Me(2)-2,6)(5)] showed that the niobium center adopts a distorted trigonal bipyramidal geometry. Niobium disulfide, NbS(2), has been successfully prepared via a thio "sol-gel" process using [Nb(SC(6)H(3)Me(2)-2,6)(5)] as the metal source. In contrast, vapor phase thin-film studies revealed that [Nb(SC(6)H(3)Me(2)-2,6)(5)] functions as a single-source precursor to NbS films.