Electrolytic iron sulfides for thin-layer lithium-ion batteries

Thin-layer electrolytic iron sulfides synthesized on stainless steel substrates were studied in prototype lithium and lithium-ion batteries with an electrolyte composed of ethylene carbonate, dimethyl carbonate, and 1 M LiClO₄. A two-volt lithium-ion system with electrolytic iron sulfide and LiCoO₂ as negative and positive electrodes, respectively, was suggested. The discharge capacity of the prototype system is 350–400 mA h g⁻¹ Fe sulfide.     

Environmentally compatible dimethyl sulfoxide: an alternative to N-methylpyrrolidone for electrochemical performance of recycled LiMn1/3Ni1/3Co1/3O2 in lithium-ion battery

The effect of recycling and doping LiMn_1/3Ni_1/3Co_1/3O₂ of lithium-ion battery with dimethyl sulfoxide (DMSO) instead of N-methylpyrrolidone (NMP) on the electrochemical performance of the battery has been investigated for the first time. Observation shows that preparing the cathode active materials with dimethyl sulfoxide will increase the conductivity of the battery. The results show that the as-recovered LiMn_1/3Ni_1/3Co_1/3O₂ modified with LiOH · H₂O calcined at 450°C delivers discharge capacities of about 247 mA h g^?1 in the first cycle with discharge efficiency of 83.1% in sample doped with dimethyl sulfoxide, and 189 mA h g^?1 with discharge efficiency of 82.7% in N-methylpyrrolidone at the rate of 0.2 C. The asrecovered samples calcined at 800 and 850°C deliver 149 and 217 mA h g^?1 in the fourth cycles respectively in dimethyl sulfoxide. The capacity loss observed in dimethyl sulfoxide faded with increase in cycle numbers. In general, for the samples doped with dimethyl sulfoxide, better performances were evident with high discharge capacities in powders calcined at a lower temperature than higher temperature in accordance with particle sizes shown by the SEM images. On the basis of better cyclic performance of lithium metal cathode and environmental safety, it is evident that relatively cheap dimethyl sulfoxide could replace N-methylpyrrolidone in battery formulations. The X-ray diffraction patterns revealed that LiMn_1/3Ni_1/3Co_1/3O₂ was successfully recycled by dimethyl sulfoxide.     

Influence of iron ions on the structural properties of Zn-borosilicate glasses

The effects of iron on the structural properties of Zn-borosilicate glasses have been studied using X-ray diffraction, IR spectroscopy and⁵⁷Fe Mössbauer spectroscopy. Zn-borosilicate glasses were doped with α?Fe₂O₃. In the systems Na₂O?ZnO?B₂O₃?SiO₂?Fe₂O₃ the presence of only one crystalline phase, ZnFe₂O₄, was detected. X-ray diffraction showed that crystallization is more pronounced in the systems ZnO?B₂O₃?SiO₂?Fe₂O₃. In these systems the presence of different crystalline phases, such as ZnO, γ?Fe₂O₃, Fe₃O₄, ZnFe₂O₄ and Fe₃BO₅, was detected. The crystallization of α?Zn₂SiO₄ in the system ZnO?B₂O₃?SiO₂ was confirmed by X-ray diffraction and IR spectroscopy. The valence state and coordination of iron in Zn-borosilicate glasses were determined by⁵⁷Fe Mössbauer spectroscopy.     

A facile method to prepare bi-phase lithium vanadate as cathode materials for Li-ion batteries

Bi-crystal lithium vanadate is synthesized with starting materials of V₂O₅ and LiF by one-step solid-state reaction. Since fluorine reacts with crucible made of silica, Li_0.3V₂O₅-liked and LiV₃O₈-liked phases without F coexist in the produces. The stoichiometric proportion of two phases depends on the amount of dopant LiF. These are confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM). Charge and discharge curves of bi-crystal materials present better reversibility of voltage plateaus than that of pure V₂O₅. The initial discharge capacity of Li_0.3V₂O₅-liked phase dominated bi-crystal material is higher than pure V₂O₅. LiV₃O₈-liked phase dominated bi-crystal material has lower initial discharge capacity but delivers better cycling performance. Electrochemical impedance spectroscopy (EIS) measurements are performed to evaluate electrochemical kinetics of the bi-crystal materials. The results indicate that bi-crystal phase benefit the transfer resistance, interior diffusion resistance, and structure stability. Cathodes with different bi-phase structures have variable charge transfer resistance and lithium-ion diffusion speed due to this special structure.     

Electrolytic binary Co and Ni sulfides in electrodes of lithium and lithium-ion low—temperature batteries

Electrolytic binary e-Co, Ni-sulfides are synthesized on aluminum supports and studied in laboratory lithium and lithium-ion batteries with the electrolytes of ethylene carbonate—dimethyl carbonate—1 M LiClO₄ and propylene carbonate—dimethoxyethane—1 M LiClO₄. The discharge capacity of binary sulfides in laboratory cells is higher than in the case of the corresponding individual sulfides. A 2 V lithium-ion system with e-Co, Ni sulfide and LiMn₂O₄ as the negative and positive electrodes, accordingly, is suggested. The discharge capacity of a lithium-ion batteries exceeds 400 mA h/g of e-Co, Ni sulfide. A relationship is established between the surface morphology of the synthesized sulfides and their discharge characteristics.     

Synthesis of high-purity LiMn2O4 with enhanced electrical properties from electrolytic manganese dioxide treated by sulfuric acid-assisted hydrothermal method

Using sulfuric acid-assisted hydrothermal treatment, β-MnO₂ particles were obtained from the electrolytic manganese dioxide (EMD). Via high-temperature solid-phase reactions, spinel lithium manganese oxides (LiMn₂O₄) were produced using the obtained β-MnO₂ particles as precursor mixed with LiOH·H₂O for the lithium-ion battery cathodes. Atomic absorption (AAS) shows that after the hydrothermal treatment, the contents of impurity ions, such as Na⁺, K⁺, Ca²⁺, and Mg²⁺, caused by the limitation of preparation technology of EMD are greatly reduced. X-ray diffraction and scanning electron microscopy show that β-MnO₂ is highly alloyed consisting of nano sticks. Spinel lithium manganese (LiMn₂O₄) synthesized by the β-MnO₂ precursor has high crystallinity with a well 111 face grow and presents a regular and micron-sized octagonal crystal. When used as cathode materials for lithium-ion batteries, LiMn₂O₄ synthesized by the β-MnO₂ precursor has greater discharge capacity, better cycle performance, and better high-rate capability when compared with LiMn₂O₄ synthesized by the EMD precursor. Cyclic voltammetry and electrochemical impedance spectroscopy indicate that LiMn₂O₄ synthesized by the β-MnO₂ precursor has better electrochemical reaction reversibility, greater peak current, higher lithium-ion diffusion coefficient, and lower electrochemical impedance.     

Steady-state polarization measurements of lithium insertion electrodes for high-power lithium-ion batteries

Steady-state polarization measurements of lithium titanium oxide (LTO; Li[Li_1/3Ti_5/3]O₄) were carried out using the 0-V lithium-ion cells consisting of two identical LTO-electrodes with a parallel-plate symmetrical electrode configuration. The sinusoidal voltage with the peak amplitude of 1.0 V was imposed at 0.1 Hz upon the 0-V cells and the current response was measured as a function of time. The steady-state polarization, obtained by plotting the current versus applied voltage, was linear in current up to approximately 60 mA cm^?2 or 4 A g^?1 based on the LTO weight and suggested the resistance polarization only for the lithium insertion electrode of the LTO. The method was also applied to lithium aluminum manganese oxide (LAMO; Li[Li_0.1Al_0.1Mn_1.8]O₄) and the resistance polarization of the LAMO-electrode was determined for currents up to approximately 25 mA cm^?2 or 2 A g^?1 based on the LAMO weight. The validity of the results was examined for the polarization measurements of the 2.5-V lithium-ion battery consisting of LTO and LAMO, and the significance of the polarization measurements of lithium insertion electrodes for high-power applications was discussed.     

Synthetic control over polymorph formation in the d-band semiconductor system FeS2

Pyrite, also known as fool''s gold is the thermodynamic stable polymorph of FeS₂. It is widely considered as a promising d-band semiconductor for various applications due to its intriguing physical properties. Marcasite is the other naturally occurring polymorph of FeS₂. Measurements on natural crystals have shown that it has similarly promising electronic, mechanical, and optical properties as pyrite. However, it has been only scarcely investigated so far, because the laboratory-based synthesis of phase-pure samples or high quality marcasite single crystal has been a challenge until now. Here, we report the targeted phase formation via hydrothermal synthesis of marcasite and pyrite. The formation condition and phase purity of the FeS₂ polymorphs are systematically studied in the form of a comprehensive synthesis map. We, furthermore, report on a detailed analysis of marcasite single crystal growth by a space-separated hydrothermal synthesis. We observe that single phase product of marcasite forms only on the surface under the involvement of H₂S and sulphur vapor. The availability of high-quality crystals of marcasite allows us to measure the fundamental physical properties, including an allowed direct optical bandgap of 0.76 eV, temperature independent diamagnetism, an electronic transport gap of 0.11 eV, and a room-temperature carrier concentration of 4.14 × 10¹⁸ cm⁻³. X-ray absorption/emission spectroscopy are employed to measure the band gap of the two FeS₂ phases. We find marcasite has a band gap of 0.73 eV, while pyrite has a band gap of 0.87 eV. Our results indicate that marcasite – that is now synthetically available in a straightforward fashion – is as equally promising as pyrite as candidate for various semiconductor applications based on earth abundant elements.

Pyrite, also known as fool''s gold is the thermodynamic stable polymorph of FeS₂.     

Hydrothermal synthesis of nanotubular Mg-Fe hydrosilicate

Magnesium iron hydrosilicate nanotubes with a chrysotile ((Mg,Fe)₃Si₂O₅(OH)₄) structure have been synthesized hydrothermally at t = 250–450°C and p = 30–100 MPa. In the hydrothermal synthesis of (Mg,Fe)₃Si₂O₅(OH)₄ chrysotile, part of the Fe²⁺ ions oxidize to Fe³⁺ and are incorporated into the octahedron and tetrahedron layers of the chrysotile structure. The limiting iron content of chrysotile has been determined up to which cylindrically rolled layers can form to yield nanotubes. The hydrothermal treatment of precursors richer in FeO yields platelike hydrosilicates. The iron ions present in the starting components affect the synthesis parameters, morphology, size, optical properties, and thermal stability of the nanotubes.     

Co3O4/SiO2 nanocomposites for supercapacitor application

In this study, Co₃O₄/SiO₂ nanocomposites have been successfully synthesized by citrate–gel method by utilizing SiO₂ matrix for Co₃O₄ embedment. Spectroscopy analyses confirm the formation of high crystalline Co₃O₄ nanoparticles; meanwhile, microscopy findings reveal that the Co₃O₄ nanoparticles are embedded in SiO₂ matrix. Electrochemical properties of the Co₃O₄/SiO₂ nanocomposites were carried out using cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) in 5 M KOH electrolyte. The findings show that the charge storage of Co₃O₄/SiO₂ nanocomposites is mainly due to the reversible redox reaction (pseudocapacitance). The highest specific capacitance of 1,143 F g ^?1 could be achieved at a scan rate of 2.5 mV s^?1 in the potential region between 0 and 0.6 V. Furthermore, high-capacitance retention (>92 %) after 900 continuous charge–discharge tests reveals the excellent stability of the nanocomposites. It is worth noting from the EIS measurements that the nanocomposites have low ESR value of 0.33 Ω. The results manifest that Co₃O₄/SiO₂ nanocomposites are the promising electrode material for supercapacitor application.     

Novel simple methods for the synthesis of single-phase valentinite Sb2O3

Several methods with solid and dissolved reactants were investigated as possible routes for synthesis of single-phase valentinite Sb₂O₃. The methods are based on simple chemical reaction between SbCl₃ and NaOH. The method with solid state reactants was established on self-propagating room temperature reaction (SPRT), while wet syntheses were based on the same chemical reaction, and performed in either distilled water or absolute ethanol. The prepared powders were characterized by X-ray powder diffraction, scanning electron microscopy and field emission scanning electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction (SAED) and UV/vis diffuse reflectance spectroscopy. SPRT and aqueous solution syntheses resulted in single-phase valentinite Sb₂O₃, but with significantly different morphologies. In the case of SPRT method the obtained powder contains well crystallized prismatic shaped submicronic particles, with hexagonal or lozenge basis typical for valentinite crystal structure, while aqueous solution synthesis resulted in powder containing micronic agglomerates. The ethanolic solution synthesis product was Sb₂O₃ with cubic senarmontite as predominant phase and traces of orthorhombic valentinite. It was confirmed that not only the aggregate state, but also the choice of solvent has a great influence on the structural and optical characteristics of synthesized Sb₂O₃ powders.     

X-Ray diffraction data for new ferrites ErMFe<Subscript>2</Subscript>O<Subscript>5</Subscript> (M = Li,Na, K)

New ferrites ErMFe₂O₅ (M = Li, Na, K) were synthesized from erbium and iron(III) oxides and lithium, sodium, and potassium carbonates by solid-state annealing. According to X-ray powder diffraction, these compounds crystallize in the orthorhombic system with the following unit cell parameters: ErLiFe₂O₅, a = 10.510 Å, b = 10.776 Å, c = 14.270 Å, V ⁰ = 1616.16 ų; Z = 16, V _subcell ⁰ = 101.01 ų, ρ_X = 6.01 g/cm³, ρ_pycn = 5.97 ± 0.05 g/cm³; ErNaFe₂O₅, a = 10.519 Å, b = 10.785 Å, c = 15.510 Å, V ⁰ = 1759.56 ų, Z = 16, V _subcell ⁰ = 109.90 ų, ρ_X = 5.77 g/cm³, ρ_pycn = 5.72 ± 0.08 g/cm³; ErKFe₂O₅, a = 10.050 Å, b = 11.320 Å, c = 15.480 Å, V ⁰ = 1937.33 ų, Z = 16, V _subcell ⁰ = 121.08 ų, ρ_X = 5.46 g/cm³, ρ_pycn = 5.41 ± 0.04 g/cm³.     

In situ Mössbauer spectroscopy studies of the electrochemical reaction of lithium with KFeS2

In situ Mössbauer spectroscopy has been used to study the electrochemical reaction of lithium with KFeS₂. Compositions KLi_xFeS₂ with Δx = 0.25 were obtained by coulometric titration for one complete discharge and recharge. Mössbauer spectra were obtained at each composition. Three new iron sites are identified in addition to Fe³⁺ in KFeS₂. A mechanism to account for the electrochemical and Mössbauer data is proposed. The end product KLiFeS₂ has been synthesized and found to be body-centered tetragonal with a = 3.938(2) Å and c = 13.135(5) Å.     

An experimental and theoretical study on the structure and photoactivity of XFe2O4 (X = Mn,Fe, Ni,Co, and Zn) structures

XFe₂O₄ magnetic nanoparticles (X = Mn, Fe, Co, Ni, and Zn) were prepared by using two methods: coprecipitation and hydrothermal. The synthesized nanoparticles were compared according to the separation in an external magnetic field and finally, the hydrothermal method was specified as a better synthesis method. The magnetic nanoparticles were characterized by physico-chemical analysis methods such as Vibrating Sample Magnetometer (VSM), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), nitrogen adsorption-adsorption isotherm and Transmission Electron Microscopy (TEM). Magnetic properties of synthesized nanoparticles were studied by ab-initio theoretical methods to confirm and compare with the experimental results. According to the VSM analysis, all of magnetic nanoparticles had good magnetization while CoFe₂O₄ nanoparticles showed the ferromagnetic behavior. The magnetic properties of XFe₂O₄ configurations were studied using Density Functional Theory ab-initio method. The theoretical results were consistent with experimental magnetizations in the absence of external field. Finally, the photocatalytic behavior of prepared samples was investigated in the presence of oxone as an accelerated agent for degradation of an azo dye.     

Preparation and characterization of electrospun nanofiber-coated membrane separators for lithium-ion batteries

Nanofiber-coated membrane separators were prepared by electrospinning polyvinylidene fluoride-co-chlorotrifluoroethylene (PVDF-co-CTFE) nanofibers onto three different microporous membrane substrates. The nanofibers on the membrane substrates showed uniform morphology with average fiber diameters ranging from 129 to 134 nm. Electrolyte uptakes, ionic conductivities, and interfacial resistances were studied by soaking the nanofiber-coated membrane separators with a liquid electrolyte solution of 1 M lithium hexafluorophosphate in ethylene carbonate/dimethylcarbonate/ethylmethyl carbonate (1:1:1 by volume). Compared with uncoated membranes, nanofiber-coated membranes had greater electrolyte uptakes and lower interfacial resistances to the lithium electrode. It was also found that after soaking in the liquid electrolyte solution, nanofiber-coated membranes exhibited higher ionic conductivities than uncoated membranes. In addition, lithium-ion half cells containing nanofiber-coated membranes were evaluated with a LiFePO₄ cathode for charge–discharge capacities and cycle performance. The cells containing a nanofiber-coated separator membrane showed high discharge specific capacities and good cycling stability at room temperature. Results demonstrated that coating PVDF-co-CTFE nanofibers onto microporous membrane substrates is a promising approach to obtain new and high-performance separators for rechargeable lithium-ion batteries.     

Synthesis and Crystal Structure of the Coordination Polymer of Ni-Mo8-Pyrazinecarboxylic Acid

An inorganic–organic hybrid compound [Ni₄(pzac)₄(H₂O)₈(β-Mo₈O₂₆)]·2H₂O (1), pzac = 2- pyrazinecarboxylic acid, was synthesized hydrothermally and characterized by IR spectrum, TGA, X-ray single-crystal diffraction. Photoluminescence property has been investigated. In 1 pzac coordinates to Ni1 with a chelating mode and bridges Ni2 forming a one-dimensional undulate chain structure. Ni atom accepts a terminal oxygen atom of [β-Mo₈O₂₆]^4? anion with a little longer Ni–O distances of 2.685 Å and 2.767 Å. [β-Mo₈O₂₆]^4? anion links four Ni atoms of four chains, forming a three-dimensional covalent framework. Lattice water molecules fill the vacancies of the framework.     

Co-precipitation spray-drying synthesis and electrochemical performance of stabilized LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.5</Subscript>O<Subscript>4</Subscript> cathode materials

In this paper, the LiNi_0.5Mn_1.5O₄ cathode materials of lithium-ion batteries are synthesized by a co-precipitation spray-drying and calcining process. The use of a spray-drying process to form particles, followed by a calcination treatment at the optimized temperature of 750 °C to produce spherical LiNi_0.5Mn_1.5O₄ particles with a cubic crystal structure, a specific surface area of 60.1 m² g^?1, a tap density of 1.15 g mL^?1, and a specific capacity of 132.9 mAh g^?1 at 0.1 C. The carbon nanofragment (CNF) additives, introduced into the spheres during the co-precipitation spray-drying period, greatly enhance the rate performance and cycling stability of LiNi_0.5Mn_1.5O₄. The sample with 1.0 wt.% CNF calcined at 750 °C exhibits a maximum capacity of 131.7 mAh g^?1 at 0.5 C and a capacity retention of 98.9% after 100 cycles. In addition, compared to the LiNi_0.5Mn_1.5O₄ material without CNF, the LiNi_0.5Mn_1.5O₄ with CNF demonstrates a high-rate capacity retention that increases from 69.1% to 95.2% after 100 cycles at 10 C, indicating an excellent rate capability. The usage of CNF and the synthetic method provide a promising choice for the synthesis of a stabilized LiNi_0.5Mn_1.5O₄ cathode material.

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Graphical Abstract Micro/nanostructured LiNi_0.5Mn_0.5O₄ cathode materials with enhanced electrochemical performances for high voltage lithium-ion batteries are synthesized by a co-precipitation spray-drying and calcining routine and using carbon nanofragments (CNFs) as additive.

     

Use of drinking water sludge in the production process of zeolites

This study reports the synthesis of zeolites A, X, and P, cancrinite, and sodalite using sludge generated in a drinking water plant. Two experimental steps were carried out: (1) fusion and (2) hydrothermal treatment. Crystallization was achieved by means of a 2³ experimental design with central point with the following factors: temperature, time, and solid/liquid ratio. The sludge presented Si and Al contents (SiO₂/Al₂O₃ = 1.7) which allow the synthesis of zeolites with high cation exchange capacity. The content of organic matter was considerable (loss on ignition 26.1 %), but is eliminated in the fusion step at 550 °C. This process also permits the conversion of the initial aluminosilicates into zeolite precursors (sludge–NaOH mix of 1:0.785 g/g). Hydrothermal treatment then permits the crystallization of the aforementioned zeolites. These materials showed high cation exchange capacities as compared to other commercial and experimentally synthesized zeolites, and can be used in the removal of heavy metals such Cd²⁺, Pb²⁺, Cu²⁺, Fe²⁺, and ammonium present in water, providing an interesting new option in wastewater treatment and remediation of soils.     

Gel-assisted synthesis of anatase TiO2 nanoparticles and application for electrochemical determination of L-tryptophan

Anatase titanium dioxide nanoparticles (TiO₂-NPs) were synthesized with and without gelatin via the sol-gel method. The TiO₂-NPs were characterized by a number of techniques, such as thermogravimetric analysis (TGA), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR) and ultraviolet visible spectroscopy (UV-Vis). The particle sizes of the TiO₂-NPs prepared with and without gelatin were ～13 and ～17 nm, respectively. The main advantage of using gelatin as a stabilizing agent is that it provides long-term stability for nanoparticles by preventing particles agglomeration. The results indicated that gelatin was a reliable green stabilizer, which can be used as a polymerization agent in the sol-gel method for synthesis of tiny size TiO₂-NPs. Moreover, the composite film was prepared by synthesized TiO₂-NPs nanoparticles and multi wall carbon nanotube (MWNT) on glassy carbon electrode (TiO₂-MWNT/GCE). The TiO₂-MWNT/GCE responded linearly to L-tryptophan (L-Trp) in the concentration of 1.0 × 10^?6 to 1.5 × 10^?4 M with detection limit of 5.2 × 10^?7 M at 3 using amperometry. The studied sensor exhibited good reproducibility and long-term stability.     

Synthesis of amino-containing meso-aryl-substituted porphyrins and their conjugates with the closo-decaborate anion

Amphiphilic meso-aryl-substituted porphyrins containing an amino group and long-chain hydrophobic substituents were synthesized. Two strategies of the synthesis of asymmetric amino-containing porphyrins using p-acetamidobenzaldehyde and p-nitrobenzaldehyde were developed and investigated. A series of new substituted porphyrin-containing closo-decaborates were prepared based on the synthesized porphyrins and nitrilium derivatives of the closo-decaborate anion [B₁₀H₁₀]^2?.