Research on Redox Properties of Novel Electronically Conducting Materials and Their Application

本研究项目的主题是通过分子偶联有机硫化合物和导电聚合物来开发具有新颖或改进功能的电活性材料。在高能量密度锂二次电池正极材料的应用中，考察了这些复合材料的应用前景。有机硫功能化吡咯单体的合成和电聚合将硫醇和二硫化物等有机硫官能团共价引入到吡咯单体中，以提高导电聚合物对有机硫氧化还原反应的电催化活性。成功地合成了附着二硫基团的吡咯单体，并在电极表面进行了电聚合。得到的聚吡咯衍生物的电活性高于在相同条件下制备的未经修饰的原始聚吡咯，这表明由于聚吡咯链的电催化作用，二硫基团的氧化还原反应被激活。然而，迄今为止，从拉曼光谱和电化学石英晶体微天平中还没有得到二硫化物与硫醇氧化还原转化的明确证据。该聚合物的进一步表征目前正在进行中。有机硫化合物在聚（3,4-乙烯二氧噻吩）（PEDOT）上的电催化氧化还原反应本研究首次证实了聚（3,4-乙烯二氧噻吩）（PEDOT）对有机硫氧化还原反应的高电催化活性。观察到有机硫化合物如2,5-二巯基-1,3,4-噻二唑（DMcT）在pedot修饰的碳电极上有效地激活了氧化还原反应。PEDOT还电催化了DMcT二聚体和低聚物的氧化还原反应。DMcT氧化还原反应的加速对有机硫化合物在电池中的实际应用至关重要，这归因于DMcT加入PEDOT基体的电子特性。时间电位测定结果表明，在PEDOT修饰的电极上，DMcT的氧化还原反应足够快，即使在1.0 mA/cm^2的电解电流下，DMcT的库仑效率几乎为100%。少

The subject of this research project is to develop electroactive materials with novel or improved functionality by molecularly coupling organosulfur compounds and conducting polymers. The promise of these composite materials was examined in the application to a cathode material for lithium secondary batteries with high energy density.1.Synthesis and Electropolymerization of Organosulfur-Functionalized Pyrrole MonomersOrganosulfur functional groups such as thiols and disulfides were covalently introduced to a pyrrole monomer in an attempt to enhance electrocatalytic activity of conducting polymers toward organosulfur redox reactions. Pyrrole monomer, to which disulfide group was attached, was successfully synthesized and further electropolymerized at electrode surfaces. A polypyrrole derivative thus obtained showed higher electroactivity compared to that of unmodified, pristine polypyrrole prepared under the same condition, which suggested that the redox reaction of the disulfide group … More was activated due to electrocatalysis of polypyrrole chain. However, clear evidences for the redox transformation between disulfide and thiol have not so far obtained from Raman spectroscopy and electrochemical quartz crystal microbalance. Further characterization of the polymer is currently under way.2.Electrocatalytic Redox Reactions of Organosulfur Compounds on Poly(3,4-ethylenedioxythiophene) (PEDOT)In this study, high electrocatalytic activity of poly(3,4-ethylenedioxythiophene) (PEDOT) toward organosulfur redox reactions was confirmed for the first time. It was observed that redox reactions of an organosulfur compound such as 2,5-dimercapto-1,3,4-thiadiazole (DMcT) was efficiently activated at a PEDOT-modified carbon electrodes. PEDOT also electrocatalyzed the redox reactions of DMcT dimer and oligomers. Such acceleration of the DMcT redox reactions, which is essential to practical application of organosulfur compounds to batteries, was ascribed to electronic properties of PEDOT matrix, into which DMcT was incorporated. Chronopotentiometric results indicated that the redox reactions of DMcT were enough fast at PEDOT modified electrodes to sustain an electrolysis current even at 1.0 mA/cm^2 and coulombic efficiency for DMcT was virtually 100%. Less