高容量锂离子电池电极材料研究的新进展.ppt
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1、Exploration research of new cathode materials with high capacity for Li-ion battery,Yong Yang State Key Lab of Physical Chemistry of Solid Surface, Xiamen University China,Whatare the major players of the cathode materials,Electrode materials,High energy density,High power density,Layered oxide cath
2、ode materials,Polyanion: LFePO4,Spinel, LiMn2O4,High energy density,Li2FeMnSiO4; Organic-type Fluorides,Further improvement of layered oxide-based cathode materials,1) Nickel-based layered cathode materials: Lattice-doping Surface coating 1) H. S. Liu, et al ; Electrochimica Acta, 2004, 49:1151-1159
3、; Solid State Ionics, 2004, 166:317-325 2) Z.R.Zhang, et al; J Power Sources, 2004, 129(1):101-106; J. Phys. Chem. B; 2004, 108, 17546-17552 2) Li-rich Li-Ni-Co-Mn-O system; Very promising system, still more study are needed. E.g. first cycle efficiency, rate capability, safety issues, how choose su
4、itable anode systems.,High-Capacity LiLi(1-x)/3Mn(2-x)/3Nix/3Co3/xO2 Cathode,Charge/discharge at 18 mA/g, 2.0 4.8 V,The initial discharge capacity is 249 mAh/g, about 100 mAh/g higher than that of LiCoO2.,Layered Oxide-type Cathode Materials,High energy density batteries,Layered oxide cathode materi
5、als Li2MnO3. LiNixCoyMn1-x-y O2 : 270mAh/g or even higher,Gas evolution, e.g. O2, CO2,High capacity cathode materials,Charging to high voltage,In-situ Electrochemical Mass spectroscopic techniques and Its use in Li-ion batteries,AlF3 coating layer provides a buffer layer to make oxygen atoms with hi
6、gh activity combine together to form O2 molecules with low oxidation capability to electrolytes.,1/4,5 times,Advantages: Low cost excellent thermal stability no oxygen evolved at low amount Li+ intercalated Disadvantages: Lower capacity and low electronic conductivity,Phosphate should be developed a
7、s High Power Density and Safe Cathode Materials,Polyanion compounds(i.e. LiFePO4) with stable framework is one of the excellent candidate as new generation cathode materials in lithium-ion batteries,Olivine type: LiMPO4 (PO4)3- Orthosilicates: Li2MSiO4 (SiO4)4- The redox potential of Mn+/n+1 can be
8、modulated by the coordinated polyanion group Lower inductive effects of silicate anions compared with phosphate anion, but higher inductive effects than oxide anion is expected.,Why do we choose Silicates ? orthosilicate materials (Li2MSiO4): Two lithium ions should be reversible extracted or insert
9、ed in principle without distinctively changes of the crystal structure.,A novel cathode materials with more than one electron exchange: Li2MnSiO4,Rietveld plot of Li2MnSiO4/C composite.,Y. X. Li, Z.L.Gong, Y. Yang; J. Power Sources, 174(2), 528-532, 2007 Y.Yang, Y.X.Li, Z.L.Gong; Chinese Patent CN 2
10、00610005329,Li2MnSiO4正极材料循环性能的研究,Cyclic stability of Li2MnSiO4 material is poor!,The first charge/discharge profiles of Li2Mn1-xFexSiO4/C at a current density of 10 mA g-1.*,* Z.L. Gong, Y.X. Li, Y. Yang, Electrochem. Solid-State Lett. 9 (2006) A542.,Li2Mn1-xFexSiO4/C,Cyclic performance of improved
11、Li2Mn0.5Fe0.5SiO4,Current density: 10mA/g (C/16), Temperature:30 oC,Evidence for fading mechanism of Li2MnSiO4,870cm-1,SiO44-,SiO44-,SiO44-,SiO32-,Solid MAS 7Li NMR of Li2MnSiO4 at different charged states,From ex-situ NMR spectra, it is proposed that the rate of deintercalation of Li+ at different
12、sites are different, and some Li2SiO3 are newly formed,Questions,Can we get better cyclic performance in SiO44- framework with more than one electron for transition metal ions ? What are main factors control the capacity and cyclic stability of the silicates materials? Whats the reaction step and me
13、chanism for mixed system, i.e. Li2Fe1-xMnxSiO4 (0 x1) In-situ or ex-situ XAS, Solid MAS NMR, Mossbauer ,XRD pattern of Li2Fe0.5MnSiO4,SEM images of Li2Fe0.5Mn0.5SiO4,Structure and morphology of Li2Fe0.5Mn0.5SiO4/C,Electrochemical performances of Li2 Fe0.5Mn0.5SiO4,The initial two cycles at 5 mA/g be
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