Synthesis And Electrochemical Properties Of LiFePO4/G/CNTs/C Cathde Composite Materials

This paper focus on the modification of Li Fe PO4 by constructing a threedimensional conductive network by means of graphene and carbon nanotubes.Li Fe PO4 is a kind of lithium ion battery cathode material with excellent performance,which is an Olivine-type polyanionic compound.The cell made by it shows excellent cycle stability, relatively high discharge voltage platform and theoretical capacity. The compound is environmentally friendly and cheap cathode material with extensive sources. Because its disadvantages are poor intrinsic electronic conductivity, low tap density and lithium ion migration rate, Li Fe PO4 lithium-ion battery is still not widely used in vehicle as a new power.The research of improving the material’s conductivity were done as follows:1 、 The Li Fe PO4/G/C composite materials were prepared by in-situ polymerization method. The influence of additon amount of GO were discussed by studying on the microstructure and electrochemical properties of the composite. The result show the Li Fe PO4/G/C composite material containing 3%GO has the best microstructure and electrochemical performance2 、 The Li Fe PO4/CNTs/C composite materials were synthesized by a homogeneous precipitation method. The effect of additon amount of CNTs to the composite were investigated by studying on the microstructure and electrochemical properties. The result show the Li Fe PO4/CNTs/C composite material containing2%CNTs has the best microstructure and electrochemical performance.Its discharge specific capacity at various rate were 158.84 m Ah/g(0.1C),133.56 m Ah/g(0.5C),129.73 m Ah/g(1C), 123.21 m Ah/g(2C), 97.95 m Ah/g(5C),75.18 m Ah/g(10C).3 、 The Li Fe PO4/CNTs/G/C composite material were synthesized by a homogeneous precipitation method. We researched on the influence of the microstructure and electrochemical properties of the composites adding different amount of CNTs and GO.Whether the charge and discharge platform or discharge specific capacity, the sample adding 1%CNTs and 1%GO was better than othersamples.It had smaller voltage difference between charge and discharge plateau.Under different rate, its discharge specific capacity was 159.73 m Ah/g(0.1C),138.00 m Ah/g(0.5C), 130.21 m Ah/g(1C), 120.34 m Ah/g(2C), 102.81 m Ah/g(5C),83.11 m Ah/g(10C). At rate of 5C and 10 C,its Specific capacity retention was 92.52%and 92.36% respectively after 100 cycles.