Preparation And Properties Of Polypyrrole-based Materials As Anodes Of Lithium Secondary Batteries Via Chemical Oxidative Polymerization

Lithium/polymer secondary batteries have big developing spaces in capacity, shape, charge-discharge property, security and enviroment. Polypyrrole is one of the candidate materials as anode of lithium secondary battery for its good stability, easily synthesis, high conductivity and good electrical redox property.PPy and PPy-based composites synthesized by chemical oxidative polymerization were tried to use as anode of lithium secondary battery. Some fundamental problems related to its electrochemical properties were studied in order to resolve the difficulties in mass production and stripping when using electrochemical method. Phsical and electrochemical properties of PPy, PPy/SiO2 and PPy/V2O5 composites were studied.PPy were first synthesized by chemical oxidative polymerization in water. Conditions of polymerization such as reaction temperature, amount of oxidant, kind and amount of dopants were optimized. The highest conductivity of PPy was 58.82S/cm. Using powder PPy as anode for the first time, the process of coating and fabricating of button battery was found out. The separator, electrolyte and adhesive matched for anode were chosen. The influencial actors of anode material on battery properties were studied and using band theory to explane the higher the conductivity the higher the capacity. The principle of charge-discharge of Li/PPy secondary battery was tested and verified. The charging-discharging of PPy anode were realized by doping-undoping of anions. The highest capacity was 95mAh/g and the cyclability was good.PPy/SiO2 composites used as anode of lithium secondary battery were studied. In order to improve the conductivity and coating propery of anode material, nanosilica were induced. Conditions were optimized in its polymerization. The relation between material and battery properties was studied from its chemical compositon and mophology. The adding of silica improved the conductivity and coating property more than the battery capacity. The highest discharge capacity of the battery was 85.02mAh/g and the cyclability was good.On the basis of above work, in order to improve the electro-chemical property of anode, V2O5 was induced to prepare PPy/V2O5 composites. The polymerization conditions were optimized. Now the highest discharge capacity of PPy/V2O5 composite was 230mAh/g. The charging-discharging principle was studied from new angel of view. The PPy/V2O5 anode realized charging-discharging by doping-undoping of anions and insertion-disinsertion of lithium ions. The cooperative action principle of PPy with V2O5 was also studied. The PPy/V2O5 composites have great research value and laten capacity in actual use. More effort would be paid on these materials in the future for more progress.