Yin Zhou-lan

Synthesis and characterization of triclinic structural LiVPO4F as possible 4.2 V cathode materials for lithium ion batteries

AbstractA potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction (CTR) process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V3+ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with LiF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure(space group p % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfKttLearuqr1ngBPrgarmWu51MyVXgatC% vAUfeBSjuyZL2yd9gzLbvyNv2CaeHbd9wDYLwzYbItLDharyavP1wz% ZbItLDhis9wBH5garqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbb% L8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yqaqpe% pae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabeqaam% aaeaqbaaGcbaWaa0aaaeaacqaIXaqmaaaaaa!3BCC!

Synthesis and characterization of high-voltage cathode material LiNi0.5Mn1.5O4 by one-step solid-state reaction

\overline 1

Preparation of Bi-system superconductor using sol-gel method

), isostructural with the naturally occurring mineral tavorite, LiFePO4·OH. SEM image exhibits that the particle size is about 2 μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V (vs Li/Li+), and the capacity retains 89 mA·h/g after 30 cycles.

Identification of arsenato antimonates in copper anode slimes

TiO2/Nb2O5 photocatalyst loaded with WO3 (WO3-TiO2/Nb2O5) was prepared by a modified hydrolysis process, and characterized by X-ray diffractometry, transmission electron microscopy, Raman spectra and UV-Vis diffuse refraction spectroscopy. The photocatalytic activity of WO3-TiO2/Nb2O5 was investigated by employing splitting of water for O2 evolution. The results indicate that WO3 loading can pronouncedly improve the photocatalytic activity of TiO2/Nb2O5 by using Fe3+ as an electron acceptor under UV irradiation. The optimum molar fraction of the loaded WO3 is 2%, and the largest speed of O2 evolution for 2% WO3-TiO2/Nb2O5 catalyst is 151.8 µmol/(L·h).

Study on the photocatalytic activity of K2La2Ti3O10 doped with zinc(Zn)

LiNi0.5Mn1.5O4 was prepared under various conditions by one-step solid-state reaction in air and its properties were investigated by X-ray diffractormetry (XRD), scanning electron microscopy (SEM) and electrochemical measurement. XRD patterns show that LiNi0.5Mn1.5O4 synthesized under various conditions has cubic spinel structure. SEM images exhibit that the particle size increases with increasing calcination temperature and time. Electrochemical test shows that the LiNi0.5Mn1.5O4 calcined at 700 °C for 24 h delivers up to 143 mA · h/g, and the capacity retains 132 mA · h/g after 30 cycles.

Study on the kinetics of the thermal decompositions of ammonium molybdates

A new process of separating sulfur with different valance from polysulfide mixtures was developed. Sulfide, sulfite and sulfur were separated by adding acetic acid in one step. The polysulfide mixture, sulfite solution and sulfur were oxidized to sulfate by hydrogen peroxide. The products were measured by X-ray Fluorescence Spectrometer(XRF) using filter method preparative specimen. The measurement needs only one set of standard sample. The effects of temperature and pH values on the separation were discussed. The results show that the recoveries range from 98.0% to 101.3% of sulfidic sulfur S(-II), 97.0% to 103.0% for sulfite S(IV) and 98.4% to 100.4% for polysulfidic sulfur S(0).

Synthesis and characterization of arsenate antimonic acid AAAc(1 : 1)

The citrate gel of (Bi, Pb), Sr, Ca and Cu and the (Bi, Pb)-Sr-Ca-Cu-(O, F) superconductor were prepared using citrate as the organic complex agent and 2-ethyl hexanol as the dehydrating agent. The starting material was a high-purity nitrate solution containing the desired ions in the appropriate atomic ratio. The optimum temperature and pH to obtain the homogeneous gel precursor were estimated. IR and DSC were employed to study the thermal decomposition and the calcination of the precursor material. After the calcined powder was sintered, a nearly single-phase (Bi, Pb)2Sr2Ca2Cu3Ox superconductor with the transition temperature 105 K was synthesized. The effect of the doping of Pb and F was also studied in the paper.