Olivine LiFePO4/C composite cathode materials were synthesized by a solid state method in N2 ＋ 5vol% H2 atmosphere. The effects of different iron sources, including Fe（OH）3 and FeC2O4·2H2O, on the performance ...Olivine LiFePO4/C composite cathode materials were synthesized by a solid state method in N2 ＋ 5vol% H2 atmosphere. The effects of different iron sources, including Fe（OH）3 and FeC2O4·2H2O, on the performance of as-synthesized cathode materials were investigated and the causes were also analyzed. The crystal structure, the morphology, and the electrochemical performance of the prepared samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, laser particle-size distribution measurement, and other electrochemical techniques. The results demonstrate that the LiFePO4/C materials obtained from Fe（OH）3 at 800℃ and FeC2O4·2H2O at 700℃ have the similar electrochemical performances. The initial discharge capacities of LiFePO4/C synthesized from Fe（OH）3 and FeC2O4·2H2O are 134.5 mAh.g^-1 and 137.4 mAh.g^-1 at the C/5 rate, respectively. How- ever, the tap density of the LiFePO4/C materials obtained from Fe（OH）3 are higher, which is significant for the improvement of the capacity of the battery.展开更多
Treated FeS2 samples were prepared by natural FeS2 samples which were ground first, heated in nitrogen and then washed in acid. The levels of impurity elements, primarily present as metallic oxides and sulfides, are h...Treated FeS2 samples were prepared by natural FeS2 samples which were ground first, heated in nitrogen and then washed in acid. The levels of impurity elements, primarily present as metallic oxides and sulfides, are higher in the natural FeS2 than those in the treated sample. Scanning electron microscopy shows that the grain sizes of treated FeS2, particles are smaller than those of natural FeS2 particles. The electrochemical performance of Li/treated FeS2 cells is attributed to the smaller grain sizes and higher purity of treated FeS2 particles in comparison to the natural FeS2 sample.展开更多
基金supported by the Science and Technology Research Item of Guangzhou, China (No.2007Z3-D0021)
文摘Olivine LiFePO4/C composite cathode materials were synthesized by a solid state method in N2 ＋ 5vol% H2 atmosphere. The effects of different iron sources, including Fe（OH）3 and FeC2O4·2H2O, on the performance of as-synthesized cathode materials were investigated and the causes were also analyzed. The crystal structure, the morphology, and the electrochemical performance of the prepared samples were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, laser particle-size distribution measurement, and other electrochemical techniques. The results demonstrate that the LiFePO4/C materials obtained from Fe（OH）3 at 800℃ and FeC2O4·2H2O at 700℃ have the similar electrochemical performances. The initial discharge capacities of LiFePO4/C synthesized from Fe（OH）3 and FeC2O4·2H2O are 134.5 mAh.g^-1 and 137.4 mAh.g^-1 at the C/5 rate, respectively. How- ever, the tap density of the LiFePO4/C materials obtained from Fe（OH）3 are higher, which is significant for the improvement of the capacity of the battery.
基金SUPPORTED BY NATIONAL NATURAL SCIENCE FOUNDATION OF CHINA( NO. 20273047)DOCTOR FOUNDATION OF MINISTRY OF EDUCATION ( NO. 20020056045).
文摘Treated FeS2 samples were prepared by natural FeS2 samples which were ground first, heated in nitrogen and then washed in acid. The levels of impurity elements, primarily present as metallic oxides and sulfides, are higher in the natural FeS2 than those in the treated sample. Scanning electron microscopy shows that the grain sizes of treated FeS2, particles are smaller than those of natural FeS2 particles. The electrochemical performance of Li/treated FeS2 cells is attributed to the smaller grain sizes and higher purity of treated FeS2 particles in comparison to the natural FeS2 sample.
