PAn/PEO-LiClO_4界面的交流阻抗研究

IMPENDANCE ANALYSIS FOR THE INTERFACE OF POLYANILINE AND PEO-LiClO_4 COMPLEX

近年来,交流阻抗方法已成功地应用于固体电极-电解质界面电化学性能的研究.特别是最近几年,聚氧化乙烯-锂盐复合物(PEO-LiX)系列高分子电解质材料研究的深入,研制以高分子电解质为隔膜的全固态锂电池的设想已成可能.前人用交流阻抗方法对Li/PEO-LiX和钒氧阴极/PEO-LiX界面行为研究已作了大量工作,并获得相关锂电池电极界面电化学性能的理论数据.本文用化学氧化法合成聚苯胺(PAn)阴极材料和本室改进的PEO-LiClO_4复合物作室温固体电解质,研究PAn/PEO-LiClO_4电极界面的电化学性能,获得一些新的结果。

Poly(aniline) (PAn) was synthesized by chemical oxidation with (NH_4)_2S_2O_8 as oxidant, and the interface between PAn and an improved PEO-LiClO_4 complex was investigated using ac impedance technique. In the interface a salt-rich passiva-tion film arising from the self-diffusion of ClO_4^- anions exists.During film formationthe thickness of the film may be expressed in terms of L=Kt^(0.14) where K is aconstant related to the intrinsic properties of the film. The passivation film has anionic conductivity of 2. 2×10^(-6)S·cm^(-1) at 15℃,suggesting that it causes no unfavorableeffect on the electrochemical reversibility of the PAn. The constancy of R_pC_p valueswith time implies that the storage time does not affect the structure or componentsof the passivation film during the thickening of the film. The relationship of tem-perature-conductivity,silimar to that observed in other amorphous PEO-MX complexes,can be described by VTF equation.