Co-precipitation Preparation Research Articles

Core–shell and concentration-gradient cathodes prepared via co-precipitation reaction for advanced lithium-ion batteries

In this review, the design principles, formation mechanism and recent advances in co-precipitation preparation core–shell and concentration-gradient cathodes for advanced LIBs are summarized. The remaining challenges and possible solutions are also discussed.

Preparation of AZO nanoparticles, ceramic targets and thin films by a Co-precipitaition method

We comprehensively study the co-precipitation preparation of aluminum doped zinc oxide (AZO) nanoparticles, ceramic target and thin film deposition. The When the calcination temperature exceeded 700 °C, ZnAl2O4 phase appeared. The resistivity and relative density of the AZO target pressed from nanoparticles were 3×10-3 Ω∙cm and 99.1%, respectively. The minimum resistivity of AZO thin films prepared by DC sputtering of the ceramic target reached 4.1×10–4 Ω∙cm with the mobility of 33 cm2/v∙s and the carrier concentration of 4.5 ×1020 cm-3. The average optical transmittance of the AZO thin films in the visible wavelength range (400-800 nm) was more than 80%.

Carbonate coprecipitation preparation of Li-rich layered oxides using the oxalate anion ligand as high-energy, high-power and durable cathode materials for lithium-ion batteries

A green, highly efficient and low cost ligand oxalate anion is successfully introduced to prepare spherical precursors for high-energy, high-power and durable cathode materials.

Synthesis of Nd:GGG Powder by Liquid Phase Co-Precipitation or Solid State Method and Preparation of its Transparent Ceramic

Neodymium-doped gadolinium gallium garnet (Nd:GGG) precursor and ceramic were prepared by liquid phase co-precipitation or solid-state methods, and the properties were studied. The results indicate that the precursor prepared with the liquid phase co-precipitation method has a small particle size. The sub-transparent ceramic was obtained after the body sintered for 2-3h at 1650°C at 1100Pa using liquid-phase co-precipitation method. When the body was sintered at 1750°C for 2-3h, a sintered body with non-transparency was obtained. The absorption spectrum and fluorescence spectrum of the sub-transparent ceramic were measured with the cross section at 807nm was calculated as1×10-20cm2 and the strongest emission peak located at 1061nm.

Influence of Li2O content on the structural and electrochemical properties of layered-layered-spinel composite cathode materials LixMn4/6Ni1/6Co1/6O(1.75+0.5x)

The layered-layered-spinel composite cathode materials LixMn4/6Ni1/6Co1/6O(1.75+0.5x) with different content of Li2O have been synthesized by the two-step co-precipitation method and evaluated in lithium cells. Powder X-ray diffraction provides the evidence that the structures of LixMn4/6Ni1/6Co1/6O(1.75+0.5x) composite transform from ‘layered-layered’ to ‘layered-layered-spinel’ as the content of Li2O decreasing. Electrochemical charge/discharge profiles suggest that Li1.3Mn4/6Ni1/6Co1/6O2.4 electrode with low content of Li2O delivers a large initial discharge capacity which is about 305.3 mAh·g−1, and that the discharge capacities of Li1.3Mn4/6Ni1/6Co1/6O2.4 electrode change little at the first three cycles, because of that a considerable amount of spinel phase in electrode facilitating Li ions diffusion. Nevertheless, the discharge capacities of Li1.4Mn4/6Ni1/6Co1/6O2.45 and Li1.5Mn4/6Ni1/6Co1/6O2.5 electrode in the first three cycles gradually rise as cycles continuing, which is expected to be that Li ions diffusion paths are not fully opened. The irreversible electrochemical reaction that Li2O component separates from Li2MnO3 to form MnO2 happens at the first charge at 4.7V, and the structure of layered Li2MnO3 component converts into the spinel component during continuously cycles. The LixMn4/6Ni1/6Co1/6O(1.75+0.5x) composites also display good cycling performance and rate performance. The capacity retention of LixMn4/6Ni1/6Co1/6O(1.75+0.5x) composites exceeds 100%, and its coulombic efficiency is greater than 98% after 50 cycles. We conclude that electrochemical performances of LixMn4/6Ni1/6Co1/6O(1.75+0.5x) composites are improved by using the two-step co-precipitation preparation method, especially in terms of large discharge capacity of Li1.3Mn4/6Ni1/6Co1/6O2.4 composite due to the appearance of spinel components.

Co-precipitation preparation, characterization and optical properties of blue CaSb2O6: Bi3+ nano-phosphor

Bi3+ doped CaSb2O6 nanoparticles were prepared by the co-precipitation technique followed by heat-treatment. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectra. It was found that the CaSb2O6:xBi nano-crystals exist in the hexagonal phase, and show sphere-like shape with diameters of 60–80nm. The CaSb2O6:xBi exhibited a strong emission band with peak wavelength of 437nm at room temperature, which can be effectively excited both at 295 and 336nm. It is believed that the formation of defect clusters such as [(BiCa)−(VCa)]′ and/or [(BiCa)−(VCa)−(BiCa)] would play an important role on the optical properties of CaSb2O6:xBi phosphors. The intense blue emission and a higher quenching concentration suggested the potential application of nano-scaled CaSb2O6:xBi for lighting and display devices.

Effect of ultrasonic irradiation on the structure and electrochemical properties of cathode material LiNi 0.5Mn 0.5O 2 for lithium batteries

Substituting mechanical stirring by ultrasonic irradiation in co-precipitation method, cathode material LiNi 0.5Mn 0.5O 2 for lithium batteries with better layered structure and crystallinity has been successfully synthesized. The physicochemical and electrochemical properties of ultrasonic co-precipitation (UCP) prepared material were compared with those of the mechanical stirring co-precipitation (MSCP) prepared material by thermogravimetery analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), and galvanostatic charge–discharge testing in detail. UCP prepared LiNi 0.5Mn 0.5O 2 presents better rate discharge capability, cyclic stability and reversibility, resulting from smaller electrochemical polarization during electrode reaction and easier lithium ion insertion/desertion. Application of ultrasonic irradiation during the co-precipitation preparation process is beneficial to produce samples with better physicochemical and electrochemical properties.

Preparation and Properties of Zinc Oxide and Titanium Oxide Ultra-Fine Composite Particles for Attenuation of Ultraviolet Radiation

A co-precipitation preparation method and the properties of an ultraviolet (UV)-attenuating agent are described in this paper. The composite particles of ultra-fine zinc oxide and titanium oxide are used to attenuate UV radiation. Preparation of TiOSO4, ZnCl2 solution and the co-precipitation of the composite particles by alkali are included during the process. Various types of surfactants have been used to modify the composite particles. Particle sizes are determined by laser particle analyzer, and reflectance and absorption coefficient are determined by UV-VIS spectrophotometer. Results show that particle size of the composite particles as well as total reflectance and absorption coefficient depend on the surfactants, pH value, and carline temperature. The average sizes of zinc oxide and titanium oxide ultra-fine particles range from39 to 65 nm. Attenuation capability of ultraviolet radiation becomes stronger when the particle average sizes becomes smaller. Composites less than 40 nm with titanium oxide of rutile phase attenuate most effectively the ultraviolet radiation ranging from 280 nm to 390 nm.

A Low Temperature Co-Precipitation Preparation of Nano-Sized Zinc Containing β-Tricalcium Phosphate Powders

Nano-sized zinc containing β-tricalcium phosphate (ZnTCP) powders were synthesized by a co-precipitation method. The co-precipitation took place in an ice-water bathed beaker, after further washing, freezing, lyophilizing and calcining at 800°C, the precipitates transformed to ZnTCP powders. The XRD pattern of the ZnTCP powders demonstrated a pure β-TCP phase. TEM observation revealed the particle size is about 100-120nm, which is favorable for TCP particles to form composites, such as polymer based composite, and as well to attain a desired microstructure. It was found zinc incorporation could eventually result in the decrease of particle size, thus be beneficial for its further application.

Coprecipitation preparation and voltage sensitive characteristics of doped ZnO varistor

A process of preparing ZnO voltage-sensitive ceramics doped with some oxides by coprecipitation was described in the paper. The thermal properties of ZnO nanometer powders and the current-voltage characteristics of the ceramics have been investigated. The results showed that the six-additive ZnO powders with hexagonal system were homogeneous grain size distribution in microstructure, the optimal reaction pH is 6.90±0.05, the temperature for calcining and sintering was at about 500 °C and 1100 °C, respectively. The powders were also examined by SEM, IR and XRD etc, and the effect of doping La2O3 on the electrical properties of ZnO varistor was investigated too.

Effects of Surface Fluorination on Catalytic Activities and Surface Compositions of TiO2–Al2O3 and TiO2–SiO2–Al2O3

Abstract Studies showed that the ternary oxide having the atomic ratio of Ti/Si/Al=47.5/47.5/5 exhibited a high catalytic activity for cumene cracking after a surface fluorination using 1 wt% hydrofluoric acid. The catalytic activity for CH3OH conversion into olefins was highly dependent on the preparation method. That is, the ternary mixed oxide promoted olefin formation slightly when the mixed oxide was prepared only by coprecipitation. Surface treatment, using gaseous CF3Cl was effective in enhancing catalytic activity. Although the binary oxide, TiO2–Al2O3, itself, was catalytically inactive for olefin formation, TiO2–Al2O3 prepared by coprecipitation became active after the treatment using CF3Cl. Such an enhancement was found also for the ternary oxide, TiO2–SiO2–Al2O3, and is ascribable to increased acid strength, as determined by NH3 adsorptions at various temperatures. The XPS measurements showed that F atoms introduced into mixed metal oxides by the fluorination using CF3Cl, selectively combined with Al atoms on the mixed oxides prepared by coprecipitation. The XPS measurements of the mixed oxides before and after fluorination using CF3Cl showed that the coprecipitation preparation is more preferable than the impregnation method in maintaining surface composition during fluorination.