Papers by Author: Dong Ye Yao

Abstract: Based on the empirical electron theory (EET) of solids and molecules, the valence electron structures (VESs) of TiC-Mo(Ni)-Fe system were calculated by building proper structure model. The results indicate that additives of Mo and Ni improve the interface conjunction factors of the cermets in different ways. By adding Mo, the VESs of the ceramic phase are improved for the formation of the rim phase (Ti1-xMox)C, which leads to the enhancement of the interface conjunction, while the improvement of the VESs on metal phase by adding Ni is due to the formation of the Fe100-yNiy. Mo and Ni additives increase the interface electron density of cermets, that is, the adding of the Mo and Ni enhance the overlapping grade of the electron cloud on interface and increase the binding energy of the interface, which is propitious to the wettability. The best wettability was found at x=0.5 or y=30.

Abstract: Well-crystallized LiFePO4 cathode materials were synthesized by NaCl-KCl molten salt method. The effect of heating time on the structure, morphology and electrochemical properties of the materials were studied in detail. Single olivine-type LiFePO4 phase was obtained, and the morphology and particle size of the powders could be controlled by changing the synthesis conditions. It was shown that LiFePO4 cathode material synthesized at 680°C for 3h with the salt content N=2 (defining the molar ratio of NaCl-KCl/LiFePO4 as N) had a narrow particle-size distribution and spherical or quasi-spherical shape. Meanwhile, the tap density of the cathode material reached the maximum of 1.501gcm-3. The charge-discharge test indicated that the initial charge and discharge specific capacity reached 138mAhg-1 and 125mAhg-1 respectively at the current density of 0.3mAcm-2.