A novel coprecipitation method towards the synthesis of Ni<Subscript>x</Subscript>Mn<Subscript>x</Subscript>Co<Subscript>(1–2x)</Subscript>(OH)<Subscript>2</Subscript> for the preparation of lithium metal oxides

A series of mixed metal hydroxide (Ni _x Mn _x Co_(1–2x)(OH)₂) precursors for the preparation of lithiated mixed metal oxides (LiNi _x Mn _x Co_(1–2x)O₂) were prepared using a novel coprecipitation approach based on the thermal decomposition of urea. Three different methods were used to achieve the temperature required to decompose urea and subsequently precipitate the hydroxides. The first two methods consisted of either a hydrothermal or microwave-assisted hydrothermal synthesis at 180 °C and elevated pressures. The final method was an aqueous reflux at 100 °C. A complete series (x = 0.00–0.50) was prepared for each method and fully characterized before and after converting the materials to lithiated metal oxides (LiNi _x Mn _x Co_(1–2x)O₂). We observed the formation of a complex structure after the coprecipitation of the hydroxides. Scanning electron micrographs images demonstrate that the morphology and particle size of the hydroxide particles varied significantly from x = 0.00–0.50 under hydrothermal synthesis conditions. There is also a significant change in particle morphology as the urea decomposition method is varied. The X-ray diffraction profiles of the oxides synthesized from these hydroxide precursors all demonstrated phase pure oxides that provided good electrochemical performance.     

Suppressing the P2–O2 Phase Transition of Na0.67Mn0.67Ni0.33O2 by Magnesium Substitution for Improved Sodium‐Ion Batteries

Room‐temperature sodium‐ion batteries (SIBs) have shown great promise in grid‐scale energy storage, portable electronics, and electric vehicles because of the abundance of low‐cost sodium. Sodium‐based layered oxides with a P2‐type layered framework have been considered as one of the most promising cathode materials for SIBs. However, they suffer from the undesired P2–O2 phase transition, which leads to rapid capacity decay and limited reversible capacities. Herein, we show that this problem can be significantly mitigated by substituting some of the nickel ions with magnesium to obtain Na_0.67Mn_0.67Ni_0.33?xMg_xO₂ (0≤x≤0.33). Both the reversible capacity and the capacity retention of the P2‐type cathode material were remarkably improved as the P2–O2 phase transition was thus suppressed during cycling. This strategy might also be applicable to the modulation of the physical and chemical properties of layered oxides and provides new insight into the rational design of high‐capacity and highly stable cathode materials for SIBs.     

Recent advances in layered LiNi x CoyMn1−x−y O2 cathode materials for lithium ion batteries

Lithium cobalt oxide, LiCoO₂, has been the most widely used cathode material in commercial lithium ion batteries. Nevertheless, cobalt has economic and environmental problems that leave the door open to exploit alternative cathode materials, among which LiNi _x Co_yMn_{1 − x − y} O₂ may have improved performances, such as thermal stability, due to the synergistic effect of the three ions. Recently, intensive effort has been directed towards the development of LiNi _x Co _y Mn_{1 − x − y} O₂ as a possible replacement for LiCoO₂. Recent advances in layered LiNi _x Co_yMn_{1 − x − y} O₂ cathode materials are summarized in this paper. The preparation and the performance are reviewed, and the future promising cathode materials are also prospected.     

Comprehensive study of the process of formation of the ceramic material with the composition 1.5MgO·0.5RO·2Al<Subscript>2</Subscript>O<Subscript>3</Subscript>·5SiO<Subscript>2</Subscript> [R = Mn(II), Fe(II), Cu(II), or Zn]

The results of the study of ceramic materials obtained by partial substitution of MgO in the 2MgO×2Al₂O₃×5SiO₂ (cordierite) with transition metal oxides FeO, MnO, CuO and ZnO, are presented The modification of the magnesium-aluminosilicate system led to intensification of the phase formation and improved the ceramics properties. In the systems modified with the oxides basic by their chemical nature (MnO, FeO) solid solutions formed Mg_2−y R _y Al₄Si₅O₁₈ (0.5 < y <1.5), which, according to X-ray analysis, are close to high-and low-temperature modifications of cordierite, where R is Mn(II) or Fe(II). The qualitative phase composition of the materials modified with oxides of amphoteric nature (ZnO, CuO) is characterized by the presence of silicate and aluminate solid solutions Mg_1−x R _x Al₂O₄ (0.25 < x < 0.75), where R is Cu(II) or Zn. The activation energies of the studied processes and standard heats of formation of products were determined.     

Isoelectric points of plasma‐modified and aged silicon oxynitride surfaces measured using contact angle titrations

Acid‐base properties of metal oxides and polymers can control adhesion properties between materials, electrical properties, the physical structure of the material and gas adsorption behavior. To determine the relationships between surface isoelectric point, chemical composition and aging effects, plasma‐surface treatment of amorphous silicon oxynitride (SiO_xN_y) substrates was explored using Ar, H₂O vapor, and NH₃ inductively coupled rf plasmas. Overall, the Ar plasma treatment resulted in nonpermanent changes to the surface properties, whereas the H₂O and NH₃ plasmas introduced permanent chemical changes to the SiO_xN_y surfaces. In particular, the H₂O plasma treatments resulted in formation of a more ordered SiO₂ surface, whereas the NH₃ plasma created a nitrogen‐rich surface. The trends in isoelectric point and chemical changes upon aging for one month suggest that contact angle and composition are closely related, whereas the relationship between IEP and composition is not as directly correlated. Copyright © 2010 John Wiley & Sons, Ltd.     

Pilot-Scale Experiment for Simultaneous Dioxin and NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> Removal from Garbage Incinerator Emissions Using the Pulse Corona Induced Plasma Chemical Process

A pilot-scale pulse corona induced plasma chemical process (PPCP) reactor for controlling gas-phase dioxins and NO _x simultaneously is installed in a garbage incineration plant. The flow rate of the sampled flue gas is 5,000 Nm³/h (N: standard state) in maximum at the PPCP reactor, which consists of 22 wire-cylinder electrodes and is energized by a 50 kW nanosecond pulse high voltage generator. With an applied plasma energy density of 2.9–6.1 Wh/Nm³, the decomposition efficiency for dioxins is 75–84% based on TEQ (toxic equivalents); the conversion efficiency of NO to NO₂ is ~93% at maximum. The flue gas treated by the PPCP reactor is introduced at a rate of 50 Nm³/h to a wet-type chemical reactor, which uses an aqueous solution of sodium sulfite (Na₂SO₃). More than 90% of NO _x is reduced to nitrogen, with negligible byproducts such as NO₂ ⁻ or NO₃ ⁻ ions left in the solution.     

Recent Progress of P2-Type Layered Transition-Metal Oxide Cathodes for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) have attracted much attention due to their abundance, easy accessibility, and low cost. All of these advantages make them potential candidates for large-scale energy storage. The P2-type layered transition-metal oxides (Na_xTMO₂; TM=Mn, Co, Ni, Ti, Fe, V, Cr, and a mixture of multiple elements) exhibit good Na⁺ ion conductivity and structural stability, which make them an excellent choice for the cathode materials of SIBs. Herein, the structural evolution, anionic redox reaction, some challenges, and recent progress of Na_xTMO₂ cathodes for SIBs are reviewed and summarized. Moreover, a detailed understanding of the relationship of chemical components, structures, phase compositions, and electrochemical performance is presented. This Review aims to provide a reference for the development of P2-type layered transition-metal oxide cathode materials for SIBs.     

Synthesis and Isolation of Titanium Metal Cluster Complexes and Ligand-Coated Nanoparticles with a Laser Vaporization Flowtube Reactor

A new laser vaporization flow reactor (LVFR) is described consisting of a laser ablation cluster source combined with a fast flowtube reactor for the production and isolation of ligand-coated metal clusters. The source includes high repetition rate laser vaporization with a 100 Hz KrF (248 nm) excimer laser, while cluster growth and passivation with ligands takes place in a flowtube with ligand addition via a nebulizer spray. Samples are isolated in a low temperature trap and solutions containing the clusters are analyzed with laser desorption time-of-flight mass spectrometry. Initial experiments with this apparatus have trapped Ti _x (ethylenediamine) _y complexes which apparently have linear metal units with octahedral ligand coordination. Other experiments have produced and isolated clusters of the form Ti _x O _y (THF) _z that apparently have linear metal oxide cores and larger (TiO₂) _x (THF) _y nanoparticle species. The isolation of these new cluster species suggest that the LVFR instrument has considerable potential for the production of new nanocluster materials.     

A Universal Molten Salt Method for Direct Upcycling of Spent Ni-rich Cathode towards Single-crystalline Li-rich Cathode

With ever-increasing pursuit for high-value output in recycling spent lithium-ion batteries (LIBs), traditional recycling methods of cathodes tend to be obsolete because of the complicated procedures. Herein, we first upcycle spent polycrystal LiNi_0.88Co_0.095Al_0.025O₂ (S-NCA) to high value-added single-crystalline and Li-rich cathode materials through a simple but feasible LiOH-Na₂SO₄ eutectic molten salt strategy. The in situ X-ray diffraction technique and a series of paratactic experiments record the evolution process of upcycling and prove that excessive Li occupies the transition metal (TM) layers. Beneficial from the single-crystalline and Li-rich nature, the regenerated NCA (R-NCA) exhibits remarkably enhanced electrochemical performances in terms of long-term cyclability, high-rate performance and low polarization. This approach can also be successfully extended to other cathode materials e.g., LiNi_xCo_yMn_zO₂ (NCM) and mixed spent NCAs with varied degree of Li loss.     

Effectiveness of nitric oxide ozonation

Attempts to develop new technologies of NO _x (NO + NO₂) emission reduction are still carried out all around the world. One of the relatively new approaches is the application of ozone injection into the exhaust gas stream followed by the absorption process. Ozone is used to transform NO _x to higher nitrogen oxides which yield nitric acid with better effectiveness. The main objective of this paper was to study the influence of mole ratio (MR) O₃/NO used in the ozonation process of NO _x on the effectiveness of NO _x oxidation to higher oxides. The ozonation process was carried out in a flow reactor for concentrations of nitric oxide in the range of 1.5 × 10⁻⁵−7.7 × 10⁻⁵ mol dm⁻³ and varying O₃/NO mole ratios. Measurements were conducted with the use of a FTIR spectrometer. The results obtained prove that for MR higher than 1, the oxidation effectiveness of nitric oxides generally reaches 95 %, whereas for MR higher than 2, oxidation of NO _x to higher nitrogen oxides is completed.     

Thermodynamic Stability of Transition‐Metal‐Substituted LiMn2−xMxO4 (M=Cr,Fe, Co,and Ni) Spinels

The formation enthalpies from binary oxides of LiMn₂O₄, LiMn_2?xCr_xO₄ (x=0.25, 0.5, 0.75 and 1), LiMn_2?xFe_xO₄ (x=0.25 and 0.5), LiMn_2?xCo_xO₄ (x=0.25, 0.5, and 0.75) and LiMn_1.75Ni_0.25O₄ at 25 °C were measured by high temperature oxide melt solution calorimetry and were found to be strongly exothermic. Increasing the Cr, Co, and Ni content leads to more thermodynamically stable spinels, but increasing the Fe content does not significantly affect the stability. The formation enthalpies from oxides of the fully substituted spinels, LiMnMO₄ (M=Cr, Fe and Co), become more exothermic (implying increasing stability) with decreasing ionic radius of the metal and lattice parameters of the spinel. The trend in enthalpy versus metal content is roughly linear, suggesting a close‐to‐zero heat of mixing in LiMn₂O₄—LiMnMO₄ solid solutions. These data confirm that transition‐metal doping is beneficial for stabilizing these potential cathode materials for lithium‐ion batteries.     

Electrochemical reduction of CO_2 in solid oxide electrolysis cells

The effort on electrochemical reduction of CO_2 to useful chemicals using the renewable energy to drive the process is growing fast recently. In this review, we introduce the recent progresses on the electrochemical reduction of CO_2 in solid oxide electrolysis cells(SOECs). At high temperature, only CO is produced with high current densities and Faradic efficiency while the reactor is complicated and a better sealing technique is urgently needed. The typical electrolytes such as zirconia-based oxides, ceria-based oxides and lanthanum gallates-based oxides, anodes and cathodes are introduced in this review, and the cathode materials, such as conventional metal–ceramics(cermets), mixed ionic and electronic conductors(MIECs) are discussed in detail. In the future, to gain more value-added products, the electrolyte, cathode and anode materials should be developed to allow SOECs to be operated at temperature range of 573–873 K. At those temperatures, SOECs may combine the advantages of the low temperature system and the high temperature system to produce various products with high current densities.     

TiOx Films Deposited by Plasma Enhanced Chemical Vapour Deposition Method in Atmospheric Dielectric Barrier Discharge Plasma

The plasma enhanced chemical vapour deposition method applying atmospheric dielectric barrier discharge (ADBD) plasma was used for TiO_x thin films deposition employing titanium (IV) isopropoxide and oxygen as reactants, and argon as a working gas. ADBD was operated in the filamentary mode. The films were deposited on glass. The films?? chemical composition, surface topography, wettability and aging were analysed, particularly the dependence between precursor and reactant concentration in the discharge atmosphere and its impact on TiO_x films properties. Titanium in films near the surface area was oxidized, the dominating species being TiO₂ and substoichiometric titanium oxides. The films exhibited contamination with carbon, as a result of atmospheric oxygen and carbon dioxide reactions with radicals in films. No relevant difference of the film surface due to oxygen concentration inside the reactor was determined. The films were hydrophilic immediately after deposition, afterwards their wettability diminished, due to chemical reactions of the film surface and chemical groups involved in the atmosphere.     

Molybdenum Substitution for Improving the Charge Compensation and Activity of Li2MnO3

Lithium‐rich layer‐structured oxides xLi₂MnO₃? (1?x)LiMO₂ (0<x<1, M=Mn, Ni, Co, etc.) are interesting and potential cathode materials for high energy‐density lithium ion batteries. However, the characteristic charge compensation contributed by O^2? in Li₂MnO₃ leads to the evolution of oxygen during the initial Li⁺ ion extraction at high voltage and voltage fading in subsequent cycling, resulting in a safety hazard and poor cycling performance of the battery. Molybdenum substitution was performed in this work to provide another electron donor and to enhance the electrochemical activity of Li₂MnO₃‐based cathode materials. X‐ray diffraction and adsorption studies indicated that Mo⁵⁺ substitution expands the unit cell in the crystal lattice and weakens the Li?O and Mn?O bonds, as well as enhancing the activity of Li₂MnO₃ by lowering its delithiation potential and suppressing the release of oxygen. In addition, the chemical environment of O^2? ions in molybdenum‐substituted Li₂MnO₃ is more reversible than in the unsubstituted sample during cycling. Therefore molybdenum substitution is expected to improve the performances of the Li₂MnO₃‐based lithium‐rich cathode materials.     

Efficient Deposition of Semiconductor Powders for Photoelectrocatalysis by Airbrush Spraying

Powder catalysts were deposited as thin films on transparent conductive oxides (TCO) by means of an airbrush spray coating technique. Photoelectrocatalytic properties of the powder catalysts were characterized using photocurrent spectroscopy at different wavelengths demonstrating on the one hand the stability of the films and on the other hand the electrical connection with the electrode surface. The morphology and thickness of the deposited powder catalyst films on TCO were characterized using scanning electron microscopy. Aiming at photocatalytic water splitting, semiconductor powders like gallium oxide (Ga₂O₃) and zinc oxide (ZnO) were used as test samples to optimize the deposition technique resulting in thin homogeneous layers and good adhesion on the conductive substrate. The proposed airbrush deposition technique of powder catalysts allows closing an experimental gap between microheterogeneous systems and modified electrodes for finding suitable materials for photoelectrochemical water splitting.     

CF_x-Ru复合阴极材料的制备及在锂一次电池中的应用（英文）

首次采用简单的原位化学改性方法合成了CFx-Ru复合阴极材料并应用于锂一次电池。与原始CFx材料相比,CFx-Ru在5C的放电倍率下放电容量、放电电压平台和最大功率密度可分别高达605 mAh·g^-1、2 V、8727 W·kg^-1。通过X射线衍射、X射线光电子能谱、扫描电子显微镜和透射电子显微镜对阴极材料结构、化学环境和形貌进行了研究。研究发现,在CFx-Ru复合材料中,nF/nC和C-F2键与C-F共价键的峰面积比都有所降低,这可能是由于RuO2与CFx材料表面或边缘的CF2惰性基团反应所致。这种原位化学反应消耗了非活性的CF2,产生了导电元素钌,并由于气相产物的演化而增加了比表面积。这些特性有助于改善阴极材料的电化学性能。电化学阻抗谱和N2吸附-脱附测试结果也进一步证实了改性材料拥有较大的比表面积和优异的电导率。     

Synthesis and Microstructure of Anodic Spark Deposited SrZrO3

 The advanced plasma electrochemical process of anodic spark deposition was used to prepare polycrystalline strontium zirconate layers on metal surfaces by an anodic conversion of the zirconium metal substrate and the metal ions in an aqueous electrolyte. On the metal substrate a thin passivating barrier film of zirconia first forms, which subsequently changes to the perovskite structure of SrZrO₃ during the anodic spark process. The typical surface morphology was characterized by scanning electron microscope. X-ray diffraction studies showed that the layers are composed of polycrystalline strontium zirconate and microcrystalline phases of zirconium oxides. The chemical state of zirconium was investigated by X-ray photoelectron spectroscopy.     

Physicochemical properties and catalytic performance of Pr2 − x SrxCoO4 ± y mixed oxides for NO reduction by CO

Using the polyglycol gel method, a series of Pr_{2 − x} Sr_xCoO_{4 ± y} (0.2 ≤ x ≤ 1.0) mixed oxides were prepared, and their catalytic activities were studied in the test reaction of NO reduction by CO. The solid-state physicochemical properties, including crystal structure, defect structure, IR spectrum, valence state of B-site ions, nonstoichiometry oxygen (y), oxygen species, and redox properties, were characterized by means of XRD, IR, TPD, TPR, XPS, and chemical analysis. The results show that all mixed oxides display a K₂NiF₄ structure. When x = 0.2 and 1.0, the obtained samples still have little uncertain mixed oxides; however, the mixed oxides (x = 0.4, 0.6, 0.8) all represent a single A₂BO₄ phase. With the increase of x, lattice parameters, unit-cell volume, and average crystalline size decrease gradually, whereas microstrain density, the concentration of Co³⁺, the amounts of lattice oxygen released and the concentration of oxygen vacancy increase. The catalytic activities of Pr_{2 − x} Sr_xCoO_{4 ± y} catalysts for NO reduction by CO are closely correlated with oxygen vacancy and the concentration of Co³⁺. Published in Russian in Kinetika i Kataliz, 2006, Vol. 47, No. 3, pp. 431–437. The text was submitted by the authors in English.     

Synthesis and X-ray diffraction study of complex oxides of the Zn2 ? x(ZraSnb)1 ? xFe2xO4 composition

A multicomponent system of complex refractory oxides of the composition Zn_{2 − x} (Zr _a Sn _b )_{1 − x} Fe_2x O₄ (a + b = 1; a: b = 1: 5, 1: 4, 1: 3, 1: 2, 1: 1, 2: 1, 3: 1, 4: 1; x = 0−1.0; Δx = 0.05) was studied by X-ray diffraction. The samples were prepared from oxides of appropriate metals by low-temperature plasma synthesis (hydrogen-oxygen flame). Two phases with wide homogeneity ranges were identified: α phase crystallized in the crystal system of inverse cubic spinel and β phase with the structure of tetragonal spinel. The phase boundaries were found. Structural data are presented for about 100 solid solutions.     

Structure Design and Performance of LiNixCoyMn1‐x‐yO2 Cathode Materials for Lithium‐ion Batteries: A Review

Lithium‐ion batteries are now considered to be the technology of choice for future hybrid electric and full electric vehicles to address global warming. One of the challenges for improving the performance of lithium ion batteries to meet increasingly demanding requirements for energy storage is the development of suitable cathode materials. The recent advancement of lithium nickel cobalt manganese oxides are investigated as advanced positive cathode materials for lithium‐ion batteries. This review aims at providing the reader with an understanding of the critical scientific challenges facing the development of LiNi_xCo_yMn_1‐x‐yO₂ materials, the latest developments in crystal structure, synthesis methods, and structure designs to unravel the mechanisms of charge and mass transport processes associated with battery performance, and the outlook for future‐generation batteries that exploit gradient structures materials for significantly improved performance to meet the ever‐increasing demands of emerging technologies.