高容量锂离子电池电极材料研究的新进展优质课件.ppt

* * * * The inverse of the magnetic susceptibility agrees well with paramagnetism for sample B. the arrow point out the anomalies characteristics of an antiferromagnetic ordering of Li2FeSiO4 below TN = 20 K. the curve agree well with Curie-Weiss law * * * * * * The material can not only supply large capacity under high-rate conditions, but can also maintain good cycling stability. The discharge capacity first increases slightly and then remains stable. The capacity does not tend to decline after 50 cycles. * * * * * * * * * * * * * * * * At our synthesis conditions, two modifications of Li2CoSiO4 (βⅡ, and βⅠ) which are derivatives of low temperature Li3PO4 were obtained. a: βⅡ; Oorthorhombic and space-group Pmn21. b: βⅠ orthorhombic The XRD profiles of the Li2CoSiO4 powers prepared at different conditions. Co-silicates-- Li2CoSiO4 L. Gong, Y. X. Li, Y. Yang; J Power Sources, 2007, 174(2), 524-527, S. Q. Wu, J. H. Zhang, Z. Z. Zhu and Y. Yang, Curr. Appl. Phys. 2007, 7, 611 * The temperature dependence of the inverse molar magnetic susceptibility 1/χm for Li2CoSiO4 powers prepared at 873 K. The magnetization curves M (H) at 2 K for Li2CoSiO4 powers prepared at 873 K. Magnetic property * Galvanostatic charge–discharge curves for Li2CoSiO4-based cathodes at current rate 16 mA/g. Electrochemical performance * space-group: Pmn21 SiO4 - MO4 LiO4 SiO4 - MO4 Corrugated layer First-principles investigations on the structural and electronic properties Structure of Li2MSiO4 Reference: S.Q.Wu, et al; Computational Materials Science, 2009, 44, 1243-1251 O – Co - O O – Si - O * Conclusions A series of silicates cathode materials such as Li2FeSiO4, LiFexMn1-xSiO4, Li2CoSiO4 with and without carbon coating have been synthesized, some of them could achieve more than 1-1.6 Li+ reversible exchange. e.g. Li2Mn0.5Fe0.5SiO4 with 235 mAh/g has been achieved. We have made a carbon-coated nanostructured Li2FeSiO4 material with excellent rate performance, it shows a promis