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

为了改善聚苯胺阴极非水电池的放电和充电特性，提出了苯胺电聚合的新方法。在酸性水溶液中采用电聚合法制备了聚苯胺。该制备方法可方便地获得活性聚苯胺。然而，制备的聚苯胺被部分氧化，并且含有大量的水。这些特性不适用于非水电池的正极材料。本研究采用非水电解质对苯胺进行电聚合。从反应机理看，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。本研究以四氟硼酸苯胺（ATFB）为原料。在这种情况下，苯胺和质子同时被提供给电解质。在含ATFB的电解液中进行了苯胺的恒流聚合。在电极上得到了聚苯胺，并通过红外光谱进行了验证。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。然而，在大放电电流下，非水溶液中制备的聚苯胺的放电容量比水溶液中制备的小。这可能是由于聚苯胺的形态不同所致。聚苯胺的形态取决于溶剂的种类。以乙腈为溶剂，制得具有纤维结构的聚苯胺。即使在大放电电流下，其电化学活性也优于在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.