A Novel Strategy for the Synthesis of Fe3(PO4)2 Using Fe-P Waste Slag and CO2 Followed by Its Use as the Precursor for LiFePO4 Preparation.

A novel method whose starting materials was Fe-P waste slag and CO2 using a closed-loop carbon and energy cycle to synthesize LiFePO4/C materials was proposed recently. In the first step, Fe-P slag was calcinated in a CO2 atmosphere to manufacture Fe3(PO4)2, in which the solid products were tested by XRD (X-ray diffraction) analysis and the gaseous products were analyzed by the gas detection method. In the second step, as-synthesized Fe3(PO4)2 was further used as the Fe and P source to manufacture LiFePO4/C materials. Also, the influence of the preparation conditions of Fe3(PO4)2, including calcination time and calcination temperature, on the energy storage properties of as-obtained LiFePO4/C was investigated. It was found that the LiFePO4/C materials, which was synthesized from Fe3(PO4)2 obtained by calcining Fe-P waste slag at 800 °C for 10 h in CO2, exhibited a higher capacity, better reversibility, and lower polarization than other samples. The discharge capacity of as-obtained LiFePO4/C can reach 145 mAh/g at 0.1 C current rate. This work puts forward an environment-friendly method of manufacturing LiFePO4/C cathode materials, which has a closed-loop carbon and energy cycle.

The phase transfer effect of sulfur in lithium-sulfur batteries.

Lithium-sulfur (Li-S) batteries are considered to be among the most promising energy storage technologies owing to their high theoretical capacity (1675 mA h g-1). At present, however, discharge mechanisms are complicated and remain a controversial issue. In this work, elemental sulfur, used as an electrical insulator for the cathode, was introduced into batteries for its potential chemical reactions in the electrolyte. A film, prepared by loading elemental sulfur onto glass fiber, was introduced as an interlayer in a Li-S battery. The results demonstrate that elemental sulfur may be reduced to polysulfides even when it functions as an electrical insulator for the cathode. Furthermore, it can improve the overall capacity of the Li-S battery and cycle life. This was verified by simulating the phase equilibrium of the chemical system in Li-S batteries using HSC Chemistry software. We hypothesize that the insulating elemental sulfur could be reduced by polysulfides generated on the cathode, after which they are dissolved in the electrolyte and participate in cathode reactions. This phase transfer effect of sulfur in Li-S batteries revealed a chemical equilibrium in the electrolyte of the Li-S battery, which may form a chemical path embedded into the discharge process of Li-S batteries.

Fluoridated hydroxyapatite/titanium dioxide nanocomposite coating fabricated by a modified electrochemical deposition.

Fluoridated hydroxyapatite/titanium dioxide nanocomposite coating was successfully fabricated by a modified electrochemical deposition technique. F(-) ions, nanoscaled TiO(2) particles and 6% H(2)O(2) was added into the electrolyte, and ultrasonication was also performed to prepare this nanocomposite coating. The microstructure, phase composition, dissolution rate, bonding strength and in vitro cellular responses of the composite coating were investigated. The results show that the composite coating was uniform and dense owing to the effects of H(2)O(2) and ultrasonication. The thickness of the composite coating was ~5 mum and scanning electron microscopy revealed that nanoscaled TiO(2) particles were imbedded uniformly between FHA crystals. The addition of F(-) and TiO(2) reduced the crystallite size and increased the crystallinity of HA in FHA/TiO(2) composite coating. In addition, the composite coating shows higher bonding strength and lower dissolution rate than pure HA coating, and the in vitro bioactivity of FHA/TiO(2) composite coating was not affected as compared with pure HA coating.