Simple Ball Milling Process Research Articles

Effect of synthesis method on the morphological and electrochemical characteristics of sulfur/MWCNT composite cathode

Sulfur-multi-walled carbon nanotube composites were synthesized via two different strategies of a simple ball-milling process (S/MWCNT-1) and a two-step procedure of liquid-phase infiltration and melt diffusion (S/MWCNT-2). The influence of preparation method on the structure of the composite materials was investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). As compared to the S/MWCNT-1 composite, the sulfur in the S/MWCNT-2 composite was highly dispersed and partially embedded into the pores and hollow tubes of carbon nanotubes, leading to suppress the shuttle mechanism and therefore improve the discharge capacity and the cycle stability. The S/MWCNT-2 composite showed an initial discharge capacity of 866mAhg−1 and a capacity retention of 69% after 50cycles at 0.5C rate, much higher than S/MWCNT-1 composite. The impact of morphology of the composite electrodes on the electrochemical performance was further investigated by electrochemical impedance spectroscopy (EIS) and SEM techniques. Compared with the S/MWCNT-1 composite, the S/MWCNT-2 cathode well maintained its homogeneous and porous morphology after 50cycles and a less formation of passive layer on the cathode surface was observed.

G-C3N4/conductive carbon black composite as Pt-free counter electrode in dye-sensitized solar cells

The composites of g-C3N4 and conductive carbon black (CCB) were prepared by a simple ball-milling process and explored as the counter electrode for dye-sensitized solar cells (DSCs). The enhanced electrocatalytic activity for I3− reduction can be demonstrated when CCB was incorporated into g-C3N4. The charge-transfer resistance of g-C3N4/CCB (1:1, mass ratio) composite electrode was 2.4Ωcm2, which is much lower than those of the individual g-C3N4 and CCB electrodes, indicating predominant synergistic effect of g-C3N4 and CCB in electrocatalytic activity. Under illumination of 100mWcm−2, the DSC with g-C3N4/CCB (1:1) composite counter electrode achieved a conversion efficiency of 5.09%, which is comparable to that of the cell with Pt counter electrode.

Spectral Investigation of Structural and Optical Properties of Mechanically Synthesized TiO2-V2O5 Nanocomposite Powders

TiO2-V2O5 nanocomposite powders are prepared by simple ball milling process at room temperature. The structural and optical properties of the synthesised sample powders are characterised by Powder X-Ray diffraction (PXRD), SEM with EDS, Fourier Transform Infrared (FT-IR) Spectroscopy, UV Vis, Raman spectroscopy, TGA and DTA techniques. The X-ray diffraction (XRD) pattern contains a series of peaks corresponds to the tetragonal phase structure of both TiO2 and V2O5 which are well matched with JCPDS data. The surface morphologies are revealed by SEM images. The average crystallite size is calculated by the scherrer's formula and is found to be 10nm. SEM images at different parameters are taken and revels the spherical like structures with little agglomeration. FT-IR shows the fundamental vibration modes of TiO2-V2O5. The band-gap energies are calculated from the UV Vis spectra. Raman analysis provided the qualitative information about the structure of the mixed oxide composite. The weight loss and temperature stability of the powders were analysed by TG and DTA analysis.

Mechanical Ball-Milling Preparation of Fullerene/Cobalt Core/Shell Nanocomposites with High Electrochemical Hydrogen Storage Ability

The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process.

Ball-milling preparation of one-dimensional Co–carbon nanotube and Co–carbon nanofiber core/shell nanocomposites with high electrochemical hydrogen storage ability

Owing to the special honeycomb structures and excellent electrical characters of carbon nanotube (CNT) and carbon nanofiber (CNF), they are extensively considered as ideal cornerstones for hydrogen storage materials. Herein, metal cobalt has been uniformly coated on CNT's and CNF's surfaces in nanoscale through a simple ball milling process. Accordingly their X-ray diffraction, scanning electron microscope and transmission electron microscopy measurements clarify the satisfying composite structures. And their electrochemical experimental results demonstrate that the as-obtained CNT/Co and CNF/Co composites have excellent electrochemical hydrogen storage reversibility and considerably high storage capacities of 717.3 mAh g−1 (2.62 wt% hydrogen) and 739.4 mAh g−1 (2.70 wt% hydrogen) under room temperature and ambient pressure, which are much higher than the capacities of individual CNT (29.9 mAh g−1, 0.11 wt% hydrogen) and CNF (49.0 mAh g−1, 0.18 wt% hydrogen) measured in this work. Furthermore their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible CNT (CNF)/Co ↔ CNT (CNF)/Co–Hx reaction is the dominant cycle process.

Facile and economical mass production of graphene dispersions and flakes

A facile and economical strategy for the bulk production of aqueous graphene dispersions and high-quality few-layer graphene flakes via a simple ball milling process assisted with non-ionic industrial surfactant.

An Amorphous Red Phosphorus/Carbon Composite as a Promising Anode Material for Sodium Ion Batteries

An amorphous red phosphorus/carbon composite is obtained through a facile and simple ball milling process, and its electrochemical performance as an anode material for Na ion batteries is evaluated. The composite shows excellent electrochemical performance including a high specific capacity of 1890 mA h g(-1), negligible capacity fading over 30 cycles, an ideal redox potential (0.4 V vs. Na/Na(+)), and an excellent rate performance, thus making it a promising candidate for Na ion batteries.

Doctor-bladed Cu2ZnSnS4 light absorption layer for low-cost solar cell application

The doctor-blade method is investigated for the preparation of Cu2ZnSnS4 films for low-cost solar cell application. Cu2ZnSnS4 precursor powder, the main raw material for the doctor-blade paste, is synthesized by a simple ball-milling process. The doctor-bladed Cu2ZnSnS4 films are annealed in N2 ambient under various conditions and characterized by X-ray diffraction, ultraviolent/vis spectrophotometry, scanning electron microscopy, and current-voltage (J—V) meansurement. Our experimental results indicate that (i) the X-ray diffraction peaks of the Cu2ZnSnS4 precursor powder each show a red shift of about 0.4°; (ii) the high-temperature annealing process can effectively improve the crystallinity of the doctor-bladed Cu2ZnSnS4, whereas an overlong annealing introduces defects; (iii) the band gap value of the doctor-bladed Cu2ZnSnS4 is around 1.41 eV; (iv) the short-circuit current density, the open-circuit voltage, the fill factor, and the efficiency of the best Cu2ZnSnS4 solar cell obtained with the superstrate structure of fluorine-doped tin oxide glass/TiO2/In2S3/Cu2ZnSnS4/Mo are 7.82 mA/cm2, 240 mV, 0.29, and 0.55%, respectively.

Electrochemical hydrogen absorbing properties of graphite/AB 5 alloy composite electrode

Graphite is an inexpensive carbon material, but its hydrogen absorbing performance has attracted little attention. In this paper, in order to lower the cost of nickel metal-hydride (Ni-MH) battery, graphite is used as a hydrogen absorbing material in its negative electrode. The results of charge–discharge tests show that the graphite electrode has poor electrochemical hydrogen absorbing performance. The capacity of the graphite/AB 5 alloy (90 wt%) composite electrode is close to AB 5 alloy (298 mAh/g), but it has higher charge–discharge polarization and difficulty in activation. When graphite is modified with metal nickel powder by a simple ball milling process, the capacity of the composite electrode reaches to 315 mAh/g and its activation is accelerated. The results of electrochemical impedance spectroscopy (EIS) tests show that hydrogen diffusion in the modified composite electrode is more rapid than in AB 5 alloy, thereby resulting in lower charge–discharge polarization and better discharge performance at large currents.

Polyvinyl Alcohol 폴리머 용액법으로 합성한 스포듀민 분말의 특성연구

【LAS-system ceramic powder, spodumene ( $Li_2O{\cdot}Al_2O_3{\cdot}4SiO_2$ ), was successfully synthesized by a chemical solution technique employing PVA(polyvinyl alcohol) as an organic carrier. The PVA content affected the microstructure of porous precursor gels and the crystalline development. The optimum PVA content contributed to homogeneous distribution of metal ions in the precursor gel and it resulted in the synthesis of glass free $\beta$ -spodumene powder having a specific surface area of $7.57\;m^2/g$ . The agglomerated $\beta$ -spodumene powders were also enough soft to grind to fine powders by a simple ball milling process. The microstructures of the densified powder compacts were strongly dependant on the minor phases of spodumene solid solution and amount of liquid phase, which were formed from the inhomogeneous precursors.】

Electrical Conductive CNT-PVA/PC Nanocomposites with High Tensile Elongation

Electrically conductive CNT reinforced polycarbonate matrix nanocomposites with high strain-to-failure were fabricated by inserting polyvinylalcohol as a surface modifier through a melt blending process. The addition of PVA by coating the CNT through a simple ball milling process before melt blending with a polycarbonate matrix resulted in an increased percolation limit as compared to that prepared using uncoated CNTs, while the electrical conductivity was maintained at a similar level of 2 x 10(-2) S/cm. However, tensile elongation was considerably improved by the addition of PVA and remained at 81% even though 5 wt% of the CNTs were added for electrical conductivity, while elongation dropped to 25% when the CNTs were not coated with PVA. The addition of PVA induces homogeneous dispersion of CNTs during the melt blending process and can enhance both electrical conductivity and mechanical durability.

Ball milled cobalt oxyhydroxide coat on the surface of nickel hydroxide

Cobalt oxyhydroxide coat on the surface of nickel hydroxide particles is finished employing a simple ball milling process. The structure, morphology, and surface composition of the coated Ni(OH)2 particles is characterized by using X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy tests. The results show that numerous strip-like particles of a mixture of Ni(OH)2 and CoOOH aggregate on the surface of the Ni(OH)2 particles, and a structure of β-Ni(OH)2 is preserved. Compared to the Ni(OH)2 electrodes with a mixed CoO additive, the electrochemical activity of the electrodes with ball milled CoOOH coat can be improved as shown by using electrochemical impedance spectroscopy test, thus resulting in charge–discharge and cycle life performance improvement of the electrodes.

Grain Growth Behavior and Characteristics of Multiphase Ceramic Composites Fabricated by Organic-Inorganic Solution Technique

Multi-component ceramic composites consisting of two, three and four phases, based on duplex microstructures of zirconia and alumina, were fabricated by a polymer complexation route employing polyethylene glycol (PEG) as a polymeric carrier. The polymer complexation route provided porous and soft powders and they were sintered after a simple ball milling process. In this study, the microstructures and flexural strengths of the multi-component (Al2O3-ZrO2-Y2O3-SrO) ceramic composites were examined on the processing variations of mole ratio and sintering temperature. The composites showed various grain morphologies according to the sintering temperature, and flexural strength of 410 MPa was obtained in the Al2O3·ZrO2·0.5Y2O3·0.4SrO composite sintered at 1600 °C for 1 h. In particular, needle-shape grains were observed in the four-component composites sintered at 1500 °C.

Characteristics of Porous YAG Powders Fabricated by PVA Polymer Solution Technique

Pure and stable YAG (Y3Al5O12) powders were synthesized by a PVA (polyvinyl alcohol) polymer solution technique. PVA was used as an organic carrier for the precursor ceramic gel. The PVA affected crystallization behavior, powder morphology, specific surface area and crystalline size of the synthesized powders. The precursor gels were crystallized to YAG at relatively a low temperature of 900 °C. The synthesized powders, which have nano-sized primary particles, were soft and porous, and the porous powders were ground to sub-micron size by a simple ball milling process. The ball-milled powders were densified to 94% relative density at 1500 °C for 1h. In this study, the characteristics of the synthesized YAG powders were examined by using X-ray diffractometer, simultaneous differential scanning calorimetry and electrophoretic light scattering spectrophotometer. And the morphologies of the powders and the densified samples were observed by scanning electron microscopy.

Fabrication of Nano-Sized Titanate Powders by an Ethylene Glycol Solution Route

Several titanate powders (Al2TiO5, SrTiO3, etc.) were synthesized by an ethylene glycol solution route. Titanium isopropoxide and nitrate salts were dissolved in stoichiometric proportions in liquid-type ethylene glycol without any precipitation. The parent precursor sols were dried to porous gels, and then the gels were calcined and crystallized. All synthesized titanate powders had stable crystallization behavior at low temperature and high specific surface area after a simple ball-milling process. A three-component PZT (Pb(Zr0.52·Ti0.48)O3) powder was also synthesized successfully by the ethylene glycol method. In this study, the characteristics of the multi-component titanate powders by the ethylene glycol method are examined.

Nano-sized ceria particles prepared by spray pyrolysis using polymeric precursor solution

Nano-sized ceria particles were prepared from the aqueous solution containing the polymeric precursors by ultrasonic spray pyrolysis at the severe preparation conditions such as high flow rate of carrier gas and short residence time. The key idea to produce nanoparticles was to prepare hollow ceria particles which are easily turned to aggregates of nano-sized primary particles during the post-thermal treatment and thereafter disintegrate such aggregates to nano-sized particles by a simple ball milling process. It was found that using the polymeric precursor strongly influences the crystallization characteristics and morphological changes of the as-prepared particles during the post-thermal treatment. The as-prepared particles prepared from the polymeric precursor solution had non-spherical shape and fractured structure with a thin shell, whereas the as-prepared and calcined ceria particles obtained from the aqueous solution had spherical shape and hollow morphology with a thick shell. Also, nano-sized ceria particles prepared from the polymeric precursor solution had less aggregated structure than those prepared from the aqueous solution. For the ceria particles prepared from the polymeric precursor solution, the degree of aggregation between the primary particles was reduced as increasing the calcination temperature. As a result, aggregation-free nano-sized ceria particles were obtained above 1200 °C without a milling process. The mean size of the primary particles increased from several tens nanometer to submicrometer size as the calcination temperature changed from 800 to 1300 °C.

Preparation of nano-sized BaTiO 3 particle by citric acid-assisted spray pyrolysis

Nano-sized BaTiO 3 particles were prepared by citric acid (CA)-assisted spray pyrolysis. It was found that controlling the spray solution with an organic additive made great differences in the structure and morphology of BaTiO 3 particles during the calcination. High agglomerated particles of irregular shape were produced after the calcination at 1050 °C when they were prepared from the nitrate solution without organic additive. In contrast, coarse aggregates consisting of nano-sized BaTiO 3 primary crystallites were obtained when we used the nitrate solution containing an organic additive (citric acid, CA). The coarse aggregates were successfully disintegrated to nano-sized BaTiO 3 particles with narrow particle size distribution after a simple ball-milling process. The use of CA additive also affected the crystallographic behavior of the BaTiO 3 nanoparticles. The CA additive prevented phase separation of barium and produced phase-pure BaTiO 3 particles at the as-prepared state and enhanced the phase transformability of metastable cubic phase to the tetragonal one during calcination. Consequently, BaTiO 3 nanoparticles of about 150 nm with good tetragonality were successfully obtained by simple ball milling the coarse aggregates that were prepared from the CA-assisted spray pyrolysis and calcination at 1050 °C.