Preparation and characterization of polyaniline as cathode material of rechargeable battery in nonaqueous electrolyte

为了改善以聚苯胺为正极的非水电池的充放电性能，提出了一种新的苯胺电聚合方法。在酸性水介质中，采用电聚合法制备了聚苯胺。该方法制备活性聚苯胺非常方便。但是，制备的聚苯胺被部分氧化，并包含大量的水。这些性质不适合作为非水电池的正极材料。本文研究了苯胺在非水电解液中的电聚合。从反应机理来看，质子源是获得活性聚苯胺的必要条件。然而质子不存在于非质子溶剂中。在这项研究中，苯胺四氟硼酸盐（ATFB）被用作起始材料。在这种情况下，苯胺和质子同时被供应到电解质。在含ATFB的电解液中进行了苯胺的恒电流电聚合。红外光谱证实了聚苯胺在电极上的存在。所制备的聚苯胺的电化学活性略优于水溶液中制备的聚苯胺。但在大电流放电时，非水溶液中制备的聚苯胺的放电容量小于水溶液中制备的聚苯胺。这一事实可能是由于聚苯胺形态的差异。聚苯胺的形貌取决于溶剂的种类。当乙腈用作溶剂时，获得具有原纤结构的聚苯胺。即使在高放电电流下，其电化学活性也优于水溶液中制备的聚苯胺。

The new method for the electropolymerization of aniline was developed in order to improve the discharge and charge characteristics of the nonaqueous battery with polyaniline cathode. Polyaniline has been prepared using the electropolymerization in acidic aqueous media. This preparation method is very convenient to obtain the active polyaniline. However, the prepared polyaniline was partly oxidized and included a large amount of water. These properties are not suitable for the cathode material of nonaqueous battery. In this study, the electropolymerization of aniline using nonaqeous electrolyte was performed. From the reaction mechanisms, the proton source is necessary to obtain the active polyaniline. However proton dose not exist in an aprotic solvent. In this study, aniline tetrafluoroborate (ATFB) was used as an starting material. In this case, both aniline and proton are supplied to the electrolyte, simultaneously. The galvanostatic electropolymerization of aniline in the electrolyte containing ATFB was conducted. The polyaniline was obtained on the electrode, that was confirmed by FT-IR spectra. The electrochemical activity of the prepared polyaniline was slightly better than that of polyaniline prepared in aqueous solution. However, at high discharge current, the discharge capacity of polyaniline prepared in nonaqueous solution was smaller than that prepared in aqueous solution. This fact may be due to the difference in the morphology of polyaniline. The morphology of polyaniline depends the kind of solvent. When acetnitrile was used as a solvent, polyaniline having the fibril structure was obtained. The electrochemical activity was better than polyaniline prepared in aqueous solution even at high discharge current.