Simple co-precipitation synthesis of high-voltage spinel cathodes with different Ni/Mn ratios for lithium-ion batteries

The high-voltage spinel is a promising cathode material in next generation of lithium-ion batteries. Samples LiNi_0.5???xMn_1.5?+?xO₄ (x?=?0, 0.05, 0.1) are synthesized by a simple co-precipitation method, in which pH value and temperature conditions do not need control. In the simple co-precipitation method, NaHCO₃ solution is poured into transition metal solution to produce precursor. Ni and Mn are distributed uniformly in the products. The as-prepared samples are composed of ~?200 nm primary particles. Samples LiNi_0.5???xMn_1.5?+?xO₄ (x?=?0, 0.05, 0.1) are also tested to study the effects of different Ni/Mn ratios. Sample LiNi_0.5Mn_1.5O₄ delivers discharge capacities of 130 mAh g^?1 at 0.2 C. The decreasing of Ni/Mn ratio in samples reduces specific capacity. With the decreasing of Ni/Mn ratios in spinel, amount of Mn³⁺ are increased. Attributed to its high Mn³⁺ contents, sample LiNi_0.4Mn_1.6O₄ delivers the highest discharge capacity of 106 mAh g^?1 at a large current density of 15 C, keeping 84.5% of that at 0.2 C rate. With the increasing of Ni/Mn ratios in spinel, cycling performance is improved. Sample LiNi_0.5Mn_1.5O₄ shows the best cycling stability, keeping 94.4% and 90.4% of the highest discharge capacities after 500 cycles at 1 C and 1000 cycles at 5 C.     

Hydrodynamic Sequential Injection Spectrophotometric System for Determination of Manganese in Soil

ABSTRACT

A novel hydrodynamic sequential injection (HSI) spectrophotometric system for determination of manganese was developed. It is based on the complexation of Mn(II) with formaldoxime in basic solution (pH ≥ 10) to produce product that could be monitored spectrophotometrically at 450 nm. Based on the HSI concept, both sample and reagents were aspirated through solenoid valves to fill a defined volumes conduit between 3-way connectors connected in series, forming stacked zones of solutions similar to those in normal SI. The concept was successfully demonstrated for manganese determination. A linear calibration graph over a range of 0.5 to 30 mg L^?1 Mn(II) with a detection limit of 0.2 mg L^?1 was obtained. Relative standard deviations for 11 replicated injections of 5 and 20 mg Mn L^?1 were 5.6% and 2.4%, respectively. A sample throughput of 45 h^?1 was achieved. The results from investigation of exchangeable manganese in soil samples by the developed method were found to be in good agreement with the results obtained by a batch spectrophotometric method, despite the proposed system employed simpler and more cost-effective devices/instruments, had higher degrees of automation with full microcontroller control of the operation, and consumed smaller amounts of chemicals (250 µL each of hydroxylamine, sample, and formaldoxime solutions and 2.5 mL of buffer carrier solution per operation cycle).     

Synthesis,Spectral Characterization,DNA Binding Studies and Antimicrobial Activity of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) Complexes with 4-Aminoantipyrine Schiff Base of Ortho-Vanillin

A series of transition metal complexes of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) have been synthesized involving the Schiff base, 2,3-dimethyl-1-phenyl-4-(2-hydroxy-3-methoxy benzylideneamino)-pyrazol-5-one(L), obtained by condensation of 4-aminoantipyrine with 3-methoxy salicylaldehyde. Structural features were obtained from their FT-IR, UV–vis, NMR, ESI Mass, elemental analysis, magnetic moments, molar conductivity and thermal analysis studies. The Schiff base acts as a monovalent bidentate ligand, coordinating through the azomethine nitrogen and phenolic oxygen atom. Based on elemental and spectral studies six coordinated geometry is assigned to Co(II), Ni(II), Fe(III) and VO(IV) complexes and four coordinated geometry is assigned to Zn(II) complex. The interaction of metal complexes with Calf thymus DNA were carried out by UV–VIS titrations, fluorescence spectroscopy and viscosity measurements. The binding constants (K_b) of the complexes were determined as 5?×?10⁵ M^?1 for Co(II) complex, 1.33?×?10⁴ M^?1 for Ni(II) complex, 3.33?×?10⁵ M^?1 for Zn(II) complex, 1.25?×?10⁵ M^?1 for Fe(III) complex and 8?×?10⁵ M^?1 for VO(IV) complex. Quenching studies of the complexes indicate that these complexes strongly bind to DNA. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through groove. The ligand and it’s metal complexes were screened for their antimicrobial activity against bacteria. The results showed the metal complexes to be biologically active, while the ligand to be inactive.     

Novel Bioactive Co(II), Cu(II), Ni(II) and Zn(II) Complexes with Schiff Base Ligand Derived from Histidine and 1,3-Indandione: Synthesis,Structural Elucidation,Biological Investigation and Docking Analysis

Novel bioactive complexes of Co(II), Cu(II), Ni(II) and Zn(II) metal ions with Schiff base ligand derived from histidine and 1,3-indandione were synthesized and thoroughly characterized by various analytical and spectral techniques. The biological investigations were carried out to examine the efficiency of the binding interaction of all the complexes with calf thymus DNA (CT-DNA). The binding properties were studied and evaluated quantitatively by K_b and K_sq values using UV-visible, fluorescence spectroscopy and voltammetric techniques. The experimental results revealed that the mode of binding of all the complexes with CT-DNA is via intercalation. It is further verified by viscosity measurements and thermal denaturation experiments. From the results of the cleavage study with pUC19 DNA it is inferred that all the complexes possess excellent cleaving ability. The present investigation proved that the binding interaction of all the complexes are significantly strong and the order of binding strength of the complexes is [Ni(L)₂] (K_b = 3.11 × 10⁶ M^?1) > [Co(L)₂] (K_b = 2.89 × 10⁶ M^?1) > [Cu(L)₂] (K_b = 2.64 × 10⁶ M^?1) > [Zn(L)₂] (K_b = 2.41 × 10⁵ M^?1). The complexes were also screened for antibacterial and anticandidal activity. The in vitro cytotoxicity of the ligand and complexes on the NIH/3 T3 mouse fibroblast cell lines were examined using CellTiter-Blue® (CTB) Cell viability assay, which unveiled that all the complexes exhibit more potent activities against NIH/3 T3 cells. Among all the complexes [Zn(L)₂] complex showed the maximum efficiency.     

The role of zirconium oxide as nano-filler on the conductivity,morphology, and thermal stability of poly(methyl methacrylate)–poly(styrene-co-acrylonitrile)-based plasticized composite solid polymer electrolytes

The plasticized composite solid polymer electrolytes (CSPE) involving polymer blends poly(methyl methacrylate)-poly(styrene-co-acrylonitrile) (PMMA-SAN), plasticizers ethylene carbonate (EC), and propylene carbonate (PC) with lithium triflate (LiCF₃SO₃) as salt and varying concentration of composite nano-filler zirconium oxide (ZrO₂) is prepared by solution casting technique using THF as solvent. The powder X-ray diffraction (XRD) studies reveal amorphous nature of the CSPE samples. Fourier transform infrared (FT-IR) spectroscopy studies reveal interaction of Li⁺ ion with plasticizers, both C=O and OCH₃ group of the PMMA, while nitrile group of SAN is inert. AC impedance and dielectric studies reveal that the ionic conductivity (σ), dielectric constant (ε’), and dielectric loss (ε”) of the prepared CSPE samples increase with increasing content of ZrO₂ nano-filler up to 6 wt% and decrease with further additions. The temperature dependence of ionic conductivity follows Arrhenius relation and indicates ion-hopping mechanism. The sample Z2 (6 wt% ZrO₂) with relaxation time τ of 8.13?×?10^–7 s possess lowest activation energy (E_a?=?0.23 eV) and highest conductivity (2.32?×?10^–4 S cm^?1) at room temperature. Thermogravimetric analysis (TGA) reveals thermal stability of highest conducting sample Z2 up to 321 °C after complete removal of residual solvent, moisture, and its impurities. Differential scanning calorimetric (DSC) studies reveal absence of glass transition temperature (T_g) corresponding to atactic PMMA for the CSPE Z2, while isotactic PMMA component shows T_g around 70 °C, which is due to increased interaction of filler with PMMA leading to change in its tacticity. Scanning electron microscopy (SEM) analysis reveals blending of PMMA/SAN polymers and lithium triflate salt. The incorporation of nano-filler ZrO₂ leads to change in surface topology of polymer matrix. Rough surface of the CSPE Z2 leads to new pathway for ionic conduction leading to maximum ionic conductivity.     

High-rate reactive magnetron sputtering of zirconia films for laser optics applications

ZrO₂ exhibits low optical absorption in the near-UV range and is one of the highest laser-induced damage threshold (LIDT) materials; it is, therefore, very attractive for laser optics applications. This paper reports explorations of reactive sputtering technology for deposition of ZrO₂ films with low extinction coefficient k values in the UV spectrum region at low substrate temperature. A high deposition rate (64 % of the pure metal rate) process is obtained by employing active feedback reactive gas control which creates a stable and repeatable deposition processes in the transition region. Substrate heating at 200 °C was found to have no significant effect on the optical ZrO₂ film properties. The addition of nitrogen to a closed-loop controlled process was found to have mostly negative effects in terms of deposition rate and optical properties. Open-loop O₂ gas-regulated ZrO₂ film deposition is slow and requires elevated (200 °C) substrate temperature or post-deposition annealing to reduce absorption losses. Refractive indices of the films were distributed in the range n = 2.05–2.20 at 1,000 nm and extinction coefficients were in the range k = 0.6 × 10^?4 and 4.8 × 10^?3 at 350 nm. X-ray diffraction analysis showed crystalline ZrO₂ films consisted of monoclinic + tetragonal phases when produced in Ar/O₂ atmosphere and monoclinic + rhombohedral or a single rhombohedral phase when produced in Ar/O₂ + N₂. Optical and physical properties of the ZrO₂ layers produced in this study are suitable for high-power laser applications in the near-UV range.     

Aerosol characterization and lung deposition of synthesized TiO2 nanoparticles for murine inhalation studies

This study presents a novel exposure protocol for synthesized nanoparticles (NPs). NPs were synthesized in gas phase by thermal decomposition of metal alkoxide vapors in a laminar flow reactor. The exposure protocol was used to estimate the deposition fraction of titanium dioxide (TiO₂) NPs to mice lung. The experiments were conducted at aerosol mass concentrations of 0.8, 7.2, 10.0, and 28.5 mg m^?3. The means of aerosol geometric mobility diameter and aerodynamic diameter were 80 and 124 nm, and the geometric standard deviations were 1.8 and 1.7, respectively. The effective density of the particles was approximately from 1.5 to 1.7 g cm^?3. Particle concentration varied from 4 × 10⁵ cm^?3 at mass concentrations of 0.8 mg m^?3 to 12 × 10⁶ cm^?3 at 28.5 mg m^?3. Particle phase structures were 74% of anatase and 26% of brookite with respective crystallite sized of 41 and 6 nm. The brookite crystallites were approximately 100 times the size of the anatase crystallites. The TiO₂ particles were porous and highly agglomerated, with a mean primary particle size of 21 nm. The specific surface area of TiO₂ powder was 61 m² g^?1. We defined mice respiratory minute volume (RMV) value during exposure to TiO₂ aerosol. Both TiO₂ particulate matter and gaseous by-products affected respiratory parameters. The RMV values were used to quantify the deposition fraction of TiO₂ matter by using two different methods. According to individual samples, the deposition fraction was 8% on an average, and when defined from aerosol mass concentration series, it was 7%. These results show that the exposure protocol can be used to study toxicological effects of synthesized NPs.     

Degradation pathways of dissolved carbon in landfill leachate traced with compound-specific 13C analysis of DOC

The isotopic compositions of carbon compounds in landfill leachate provide insights into the biodegradation pathways that dominate the different stages of waste decomposition. In this study, the carbon geochemistry of different carbon pools, environmental stable isotopes and compound-specific isotope analysis (CSIA) of leachate dissolved organic carbon (DOC) fractions and gases show distinctions in leachate biogeochemistry and methane production between the young area of active waste emplacement and the old area of historical emplacement at the Trail Road Landfill (TRL).

The active area leachate has low DOC concentrations (<200 mg l^?1) dominated by fulvic acid (FA=160 mg l^?1), and produces CH₄ dominantly by CO₂ reduction (D? excess=20.6‰). Leachate generated in the area of older waste has high DOC (>4770 mg l^?1) dominated by FA (4482 mg l^?1) and simple fatty acids (acetic=1008 mg l^?1 and propionic=608 mg l^?1), and produces CH₄ by the acetate fermentation pathway (D? excess=9.8‰). CSIA shows an advanced degradation and a progressive accumulation of ¹³C of fatty acids in leachate from the older area. The enriched ¹³C value of FA (?20 and?26‰ for the older and active parts, respectively,) and of low molecular weight DOC (?8 and?27‰) as well as of the bulk DOC (?21 and?25‰) shows more advanced degradation in the older part of the landfill, which is consistent with the shift in the humic/FA ratios (0.05 and 0.18). The ¹³C enrichment of acetate (?12‰) above the ¹³C of DOC (?21‰) and of propionic acid (?19‰), in older leachate, suggests that this acetate has not evolved from the simple degradation of larger organic molecules, but by homoacetogenesis from the enriched dissolved inorganic carbon (DIC) pool (8‰) and H_2, which produce a more enriched ¹³C of acetate. In contrast, the ¹³C of the minor acetate in the active area (?17‰) indicates that CO₂-reducing bacteria must be the primary consumers of H₂, which has resulted in enriched ¹³C_DIC (10‰) and depleted ¹³C_CH4 (?58‰).     

Synthesis and characterization of nanostructure hydrous iron–titanium binary mixed oxide for arsenic sorption

Synthesis of nanostructure hydrous iron–titanium binary mixed oxide (NHITBMO) had been reported by a simple method, and characterized by the X-ray diffraction (XRD), thermal analysis, transmission electron microscope (TEM), Föurier Transform Infrared (FTIR), surface area, and zero surface charge pH (pHzpc). The synthetic oxide was hydrated and microcrystalline with 77.8 m² g^?1 BET surface area. The particle size (nm) calculated using XRD peak table and TEM image was ~10–13 and 6–8, respectively. The pH_zpc value was 6.0 (±0.05) for the oxide. The NHITBMO showed pH dependent good sorption affinity for arsenic from the aqueous solution and, the Langmuir monolayer capacity (mg g^?1) was 80.0 and 14.6, respectively, for the As(III) and As(V). The pseudo-second order equation described the room temperature arsenic sorption kinetic data well. The minimum dose required was 1.6 g NHITBMO per L of water (As_total = 0.24 mg L^?1) to reduce the arsenic level below 0.01 mg L^?1 in batch treatment process.     

Synthesis and electrochemical behavior of Li2CoSiO4 cathode with pyrrolidinium-based ionic liquid electrolyte for lithium ion batteries

Li₂CoSiO₄, a silicate olivine cathode for lithium rechargeable batteries, is synthesized for the first time by sol–gel method using polyacrylic acid (PAA) as the chelating agent. Coupled thermal and vibrational analysis of the gel and also the X-ray diffraction pattern confirms the formation of the sample at 800 °C. 1-Butyl-1-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (BMPyTFSI) solutions of lithium bis(trifuloromethansulfonyl)imide (LiTFSI) having a concentration of 0.2 mol kg^?1 is used as electrolyte. The electrochemical stability window of this electrolyte is found to be >5 V by linear sweep voltammetry technique. The compatibility of Li₂CoSiO₄ with 0.2 mol kg^?1 LiTFSI-BMPyTFSI electrolyte is tested by charge–discharge cycles which show charging and discharging capacities of about 204 and 32 mAh g^?1, respectively, in the first cycle.     

Study of Specific Interaction between bis(<Emphasis Type="Italic">p</Emphasis>-phenylene)-34-crown-10-based Substituted Macrocycle and Ni<Superscript>2+</Superscript>

A novel macrocyclic host has been synthesized for the determination of Ni (II) ions in aqueous solution (H₂O-CH₃CN, v/v?=?1:1). Its molecular structure has been verified by ¹H-NMR, ¹³C NMR and mass spectrometry (ESI).This probe shows selectivity towards the presence of Ni (II) ion among various alkali, alkaline earth, and transition metal ions. The formation of a new fluorescence band at 311 nm has been detected due to possible complex formation with increasing Ni²⁺ concentration in the range of 10^?5–10^?4 M. The detection limit is calculated to be 5.22 μM. To our knowledge, it will be the first case for bis(p-phenylene)-34-crown-10 based molecules to recognize Ni²⁺ ions.     

Novel synthesis and characterization of ZnCo<Subscript>2</Subscript>O<Subscript>4</Subscript> nanoflakes grown on nickel foam as efficient electrode materials for electrochemical supercapacitors

ZnCo₂O₄ nanoflakes were directly grown on Ni foam via a two-step facile strategy, involving cathodic electrolytic electrodeposition (ELD) method and followed by a thermal annealing treatment step. The results of physical characterizations exhibit that the mesoporous ZnCo₂O₄ nanoflakes have large electroactive surface areas (138.8 m² g^?1) and acceptable physical stability with the Ni foam, providing fast electron and ion transport sites. The ZnCo₂O₄ nanoflakes on Ni foam were directly used as integrated electrodes for supercapacitors and their electrochemical properties were measured in 2 M KOH aqueous solution. The ZnCo₂O₄ nanoflake electrode exhibits a high capacitance of 1781.7 F g^?1 at a current density of 5 A g^?1 and good rate capability (62% capacity retention at 50 A g^?1). Also, an excellent cycling ability at various current densities from 5 to 50 A g^?1 was obtained and 92% of the initial capacitance maintained after 4000 cycles. The results demonstrate that the proposed synthesis route is cost-effective and facile and can be developed for preparation of electrode materials in other electrochemical supercapacitors.     

Substitution effects on the bulk and surface properties of (Li,Ni)Mn<Subscript>2</Subscript>O<Subscript>4</Subscript>

Manganese oxides of spinel structure, LiMn₂O₄, Li_1-x Ni _x Mn₂O₄ (0.25 ≤ x≤ 0.75), and NiMn₂O₄, were studied by EDS, XRD, SEM, magnetic (M-H, M-T), and XPS measurements. The samples were synthesized by an ultrasound-assisted sol-gel method. EDS analysis showed good agreement with the formulations of the oxides. XRD and Rietveld refinement of X-ray data indicate that all samples crystallize in the Fd3m space group characteristic of the cubic spinel structure. The a-cell parameter ranges from a = 8.2276 Å (x = 0) to a = 8.3980 Å (x = 1). SEM results showed particle agglomerates ranging in size from 2.3 μm (x = 0) down to 0.8 μm (x = 1). Hysteresis magnetization vs. applied field curves in the 5–300K range was recorded. ZFC-FC measurements indicate the presence of two magnetic paramagnetic-ferrimagnetic transitions. The experimental Curie constant was found to vary from 5 to 7.1 cm³ K mol^?1 for the range of compositions studied (0 ≤ x ≤ 1). XPS studies of these oxides revealed the presence of Ni²⁺, Mn³⁺, and Mn⁴⁺. The experimental Ni/Mn atomic ratios obtained by XPS were in good agreement with the nominal values. A linear relationship of the average oxidation state of Mn with Ni content was observed. The oxide’s cation distributions as a function of Ni content from x = 0 ?Li⁺[Mn³⁺Mn⁴⁺]O₄ to x = 1 \( {\mathrm{Ni}}_{0.35}^{2+}{\mathrm{Mn}}_{0.65}^{3+}\left[{\mathrm{Ni}}_{0.65}^{2+}\right.\left.{\mathrm{Mn}}_{1.35}^{3+}\right]{\mathrm{O}}_4 \) were proposed.     

Nonlinear optical characteristics of CdS and ZnS nanoparticles implanted into zirconium oxide thin films

The nonlinear refractive indices γ and nonlinear absorption coefficients of ZrO₂ films doped with CdS or ZnS nanoparticles, as well as with various metals, are measured. The effects of semiconductor and metal nanoparticles and annealing on the nonlinear optical properties of films are studied. The structural parameters of films, determined by electron microscopy and x-ray dispersion spectroscopy, are compared to the optical and nonlinear optical characteristics of these media. The high magnitude of γ of the films ((3±0.6)×10^?11 cm² W^{? 1}) is attributed to the surface enhancement effect in semiconductor nanoparticles. On the basis of Z-scan data obtained at different intensities of radiation, it is shown that the variations in γ of the ZrO₂:CdS(Cr) and ZrO₂:ZnS(Mn) films are related to the generation of free carriers.     

Oral intake of zirconia nanoparticle alters neuronal development and behaviour of <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

Zirconia nanoparticles (ZrO₂ NPs) have been extensively used in teeth and bone implants and thus get a chance to interact with the physiological system. The current study investigated the oral administration of various concentrations of ZrO₂ NPs synthesized by the hydrothermal method (0.25 to 5.0 mg L^?1) on Drosophila physiology and behaviour. The size of the currently studied nanoparticle varies from 10 to 12 nm. ZrO₂ NPs accumulated within the gut in a concentration-dependent manner and generate reactive oxygen species (ROS) only at 2.5 and 5.0 mg L^?1 concentrations. ROS was detected by nitroblue tetrazolium (NBT) assay and 2′,7′-dichlorofluorescein (H2DCF) staining. The ROS toxicity alters the larval gut structure as revealed by DAPI staining. The NP stress of larvae affects the Drosophila development by distressing pupa count and varying the phenotypic changes in sensory organs (eye, thorax bristle, wings). Besides phenotypic changes, flawed climbing behaviour against gravity was seen in ZrO₂ NP-treated flies. All together, for the first time, we have reported that a ROS-mediated ZrO₂ NP toxicity alters neuronal development and functioning using Drosophila as a model organism.

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Simple microwave synthesis and improved electrochemical performance of Nb-doped MnO<Subscript>2</Subscript>/reduced graphene oxide composite as anode material for lithium-ion batteries

Niobium-doped MnO₂/reduced graphene oxide (Nb-MnO₂/RGO) composite has been successfully synthesized via a simple microwave radiation method. The samples were systematically studied by X-ray diffraction (XRD), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscope (TEM), and electrochemical measurements. As the anode material for lithium-ion batteries, the Nb-MnO₂/RGO (molar ratio of Mn/Nb?=?50:1) (NMG50) showed an outstanding reversible discharge capacity of 556.6 mAh g^?1 after 50 cycles with a capacity retention of 77% at a charge-discharge rate of 0.1 A g^?1 and the reversible discharge capacity can still retain 223.3 mAh g^?1 at a current of 1 A g^?1, which is much higher than those for Nb-MnO₂/RGO (molar ratio of Mn/Nb?=?10:1) (NMG10) and undoped MnO₂/RGO (MG). The improved electrochemical performance could be attributed to the proper amount of Nb doping, which could enhance both the conductivity and the structure stability of MnO₂.     

Ni(II) and Zn(II) Complexes Containing Alkynyl Functionalized Salicylaldimine Ligand and Heterocyclic Coligand: Synthesis,Characterization and Luminescence Properties

Some nickel(II) and zinc(II) complexes of the type [Ni(L)(phen/bipy)]X (1a–6a) and [Zn(L) (phen/bipy)]X (1b–6b) (where L = 2-{(E)-[(4-trimethylsilylethynylphenyl)imino]methyl}-4-(4-nitro phenylethynyl)phenol; phen = 1, 10-phenanthroline, bipy = 2, 2´-bipyridine; X = ClO₄ ^?, BF₄ ^?, PF₆ ^?) have been prepared and characterized on the basis of elemental analyses, FTIR, ¹H NMR and mass spectral studies. The molecular structure of L was determined by single crystal X-ray diffraction studies. The electrochemical behaviour of the Ni(II) complexes indicate that the phen complexes appears at more positive potential as compared to those for bipy complexes, as a consequence of its strong π-acidic character. TGA was carried out to study the thermal behavior of the complexes. Room temperature luminescence is observed for all complexes corresponds to π → π* ILCT transition. The size of the counter anion and heterocyclic coligands phen and bipy shows marked effect on emission properties of the complexes.     

The optimal condition for H<Subscript>2</Subscript>TiO<Subscript>3</Subscript>–lithium adsorbent preparation and Li<Superscript>+</Superscript> adsorption confirmed by an orthogonal test design

An orthogonal test design was applied to confirm the optimum condition for H₂TiO₃–lithium adsorbent preparation and Li⁺ adsorption. Extraction and adsorption mechanism and cycle performance were studied. The verified optimal condition is confirmed as the Li⁺ concentration, adsorption temperature, molar ratio of Li/Ti, reaction, and pre-calcination temperature are 4.0 g L^?1, 60 °C, 2.2, and 650 and 25 °C, respectively. Under the optimal condition, the adsorptive capacity reaches 57.8 mg g^?1. Adsorptive capacity of the adsorbent maintains in 5 cycles, typically 25–30 mg g^?1.     

Acacia gum-assisted co-precipitating synthesis of LiNi<Subscript>0.5</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.3</Subscript>O<Subscript>2</Subscript> cathode material for lithium ion batteries

LiNi_0.5Co_0.2Mn_0.3O₂ particles of uniform size were prepared through carbonate co-precipitation method with acacia gum. The precursor of carbonate mixture was calcined at 800 °C, and a well-crystallized Ni-rich layered oxide was got. The phase structure and morphology were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The micro-sized particles delivered high initial discharge capacity of 164.3 mA h g^?1 at 0.5 C (1 C?=?200 mA g^?1) between 2.5 and 4.3 V with capacity retention of 87.5 % after 100 cycles. High reversible discharge capacities of 172.4 and 131.4 mA h g^?1 were obtained at current density of 0.1 and 5 C, respectively. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed to further study the LiNi_0.5Co_0.2Mn_0.3O₂ particles. Anyway, the excellent electrochemical performances of LiNi_0.5Co_0.2Mn_0.3O₂ sample should be attributed to the use of acacia gum.     

Lithium-rich layered nickel–manganese oxides as high-performance cathode materials: the effects of composition and PEG on performance

Lithium-rich layered nickel–manganese oxide (LRL-NMO) as a cathode material for rechargeable lithium-ion batteries was successfully prepared using an oxalic acid co-precipitation method, with polyethylene glycol (PEG1000) as an additive. The effects of the Ni/Mn ratio and of PEG on the phase purity, morphology, and electrochemical performance of LRL-NMO were investigated with X-ray diffraction, scanning electron microscope, electrochemical impedance spectroscopy, and charge/discharge testing. Li[Li_0.167Ni_0.25Mn_0.580]O₂ delivered the best electrochemical performance among the various Li[Li_1/3?2x/3Ni _x Mn_2/3?x/3]O₂ (0?<?x?<?0.5) materials. Furthermore, the sample to which an appropriate amount of PEG had been added showed much smaller and more uniform particle size, higher discharge capacity and energy density, better cycling stability, and lower resistance. The material prepared by adding 9 wt% PEG exhibited high discharge capacity and stability; after 100 cycles at 2 C, it still delivered a discharge capacity of 125.6 mAh g^?1, which was 50 % higher than that of a sample prepared without PEG.