| The development of low-cost and high-performances electrode materials for lithium-ion batteries employed in EVs is significant. Electrochemical performances of intercalation/deintercalation of Li+ in natural graphite(NG)-based composite materials modified by different methods are studied, also the changes of kinetics parameters of part carbon anode materials during the intercalation process of Li+ are investigated in this dissertation.NG materials have a good structure for the storage of Li+. However, the compatibility of NG with ordinary electrolyte solutions is poor. The reasons for making the charge/discharge performances worse are as follows:(i) the poor-quality SEI film, which is formatted during 1st intercalation process of lithium ions; (ii) the exfoliation from solvated Li+ intercalating into the carbon layers;(iii) the exfoliation from the expanding and shrinking of distance between graphite layers during intercalation/deintercalation process of Li+. The capacity of intercalation/deintercalation of Li+ rapidly descends at larger current density because of polarization.The proper oxidation disposals of NG have been proved to be effective on improvement of it's electrochemical performances. Better electrochemical performances of NG can be obtained, while NG is modified by the combination method of proper thermal oxidization in air, chemical oxidation in concentrated HNO3 and artificially imposed Solid Electrolyte Film in LiOH solution. The 1st deintercalation capacity of 340mAh/g, and 1st cycling efficiency of 84% can be gained in model cell: Carbon/lmol -L"1 LiPF6/EC+DMC(l : 1 )/Li(voltage cut off: 0~2.8V(vs.Li/Li+),current density: 15mA/g) when Natural flake graphite is treated by the above method, and almost there is no decay of capacity for the 1st twenty cycles after the 1st cycle. However, Oxidation disposals methods are ineffective on electrochemical performances at larger current density.Double coating treatment is proved to be beneficial to the improvement of electrochemical intercalation/deintercalation Li+ of NG at larger current density. A better technics I, by which high-performances NG-based composite materials can be prepared, has been obtained by orthogonal experimental methods. The technics is as follows: during first coating process, the content of phenlic resin is 10% of NG by weight, the pyrolysis temperature is 1000℃, the content of H3PO4 in resin is 30% by weight; during the second coating process, the pyrolysis temperature is 700℃, the content of phenlic resin is 10-15% of NG by weight; during the 1st and 2nd process, the following parameters are the same: Ar flow rate is 300mL/min, heating rate is 1℃/min, soak time is Ih. Natural flake graphite-basedcomposite material prepared by the technics has a 1st deintercalation Li capacity of 228mAh/g,and 1st cycling efficiency of 72% at current density of 300mA/g ,and the 1st ten cycling capacities can almost be retained in our experimental conditions. However, the 1st cycling efficiency is still too low.Several NG-Metal or metal compounds composite materials have been prepared by a lot of methods such as electroless, thermal decomposition,' and physical mix. Electrochemical performances of these composite materials have been researched in our laboratory. Obviously, the electrochemical performances of intercalation/deintercalation of Li+ in these NG-based composite materials have improved because of metals or metal compounds. We find electroless Ag is the best method. And the weight content of metals should be less than 10%.Different metals or metal compounds have different mechanisms on the improvement of electrochemical performances. The lithiation reactions between metal(Ag,Zn) and Li"1" are beneficial to formation of stable SEI film on the surface of carbon electrode, accordingly the cycling performances of composite materials has been enhanced. Cu and Ni deposited on the surface of NG by electroless can effectively block the intercalation of solvated Li+ into NG, and so stability of structure is maintained during intercalat...
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