The Study Of Polyaniliene As Positive Material For Lithium Secondary Batteries

As a representative conducting polymer, polyaniline has attracted attention widely because of its unique advantages such as electrochemical stability, easy synthesis, low price and environment-friendly features in the field of battery. In this paper, polyaniline in the doped state was prepared by protonic acids and lithium salts as dopants. According to the characterization of the structure, it determined the active point position of the doping reaction in polyaniline. It was also studied that the factors including the type of doping anionic, the quantity of doping anionic, the kinds of diaphragm, pressure strength, the thickness of positive and the time of immersing, which affected the performance of the battery based on the feedback of the battery charge and discharge testing.Moreover, it was studied preliminarily about the feasibility of the amplification synthesis of polyaniline.Polyaniline was doped either with a protonic acid and the electrical conductivity results show that the conductivity of the approximately insulated polyaniline increased obviously by8order of magnitude. The XRD test findings of polyaniline doped with hydrochloride turned out that diffraction peak shape became more acute after doping with proton acids and the crystallinity increased from8.20%to24.82%. In the FT-IR spectrum, the absorption of C=N in emeraldine base shifted from1140cm-1to1109cm-1in the doping polyaniline with the biggest range and the strongest absorption peak, which represented that the acid doping reaction was happened at the structure of C=N in quinoid of polyaniline. Simultaneously the test results of XRD and SEM revealed that PANi can also obtain the high crystallinity by doping with lithium salt in the organic system. Apart from these, the outcome of XPS test implied that the N1S peak strength of N atoms in quinoid structure decreased significantly, while it represented the opposite tendency in the cation radicals structure after doping lithium, which illustrated that lithium doping reaction occured in the structure of C=N.EA and DMC as electrolyte additives were determined by observing the swelling and crackling phenomenon of PANi wafer in the electrolyte. The study of PANi doped with various anion implied that PANi doped ClO4-had a good cycle performance and the capacity was up to75mAh/g. In addition, the optimum anion doping process, which consisted of6hours of reaction, the reaction temperature of25℃and the acidity of1.5mol/L was adopted by a set of four factors three levels orthogonal test. What‘s more, according to the results of battery performance, the optimum process factors were identified with the AGM/polypropylene composite diaphragm, immersing for48h, positive wafer thickness varying from0.7mm to1.0mm, and pressure strength of4MPa. Amplification of PANi synthesis and battery assembly and test were studied, and it was found that amplification synthesis of PANi obtained the good crystallinity by observing its morphology with SEM. Capacity of the battery assembled with the amplification synthesis production was up to80mAh/g. Furthermore, the charging and discharging of the assembled battery lasted for more than80000min with almost no attenuation capacity in the top40cycle.Finally, the current market of secondary battery was analysed and the cost of PANi synthesized in laboratory was20yuan per kilogram, whose price advantage was obvious.