Development of Novel Organic Materials with High Energy and Power Densities

具有高能量和功率密度的二次电池有望进一步发展电动汽车和许多其他电子仪器。本研究的目的是开发高性能二次电池用新型有机材料。首先，我们研究了硫醇（2,5-二巯基-1,3,4-噻二唑，DMcT）和导电聚合物（聚苯胺，PAn）之间的电子转移。结果表明，它们之间的可逆电子转移是可能的。我们已经发现DMcT-PAn复合材料可以作为二次电池的高能量密度正极材料。然而，电池的充电电流和放电电流都不够大，无法实际使用。然后，我们在复合阴极上使用了铜集流器，而不是传统的碳集流器。在前几个循环中，在充电过程中可以看到铜集流器的溶解。同时，放电容量也有所增加。由于充放电容量可以超过理论容量，这是由DMcT和PAn的量计算出来的，溶解的铜离子必须作为阴极活性物质。这表明铜离子与DMcT之间形成了某种配合物。充电/放电电流足够高，可以实际使用。虽然我们目前还没有明确的证据证明这种配合物的形成，但我们观察到加入DMcT后Cu (ClO_4)_2溶液的可见光谱发生了一些变化。Cu (I)和Cu （II）与DMcT以及其他过渡金属离子形成络合物已被报道。其他噻二唑也能与铜和其他金属离子形成配合物。该复合物作为二次电池正极材料具有广阔的应用前景。

Secondary batteries with high energy and power densities is expected for further development of electric vehicles and many other electric instruments. Objective of the present work is developing novel organic materials for high performance secondary batteries. First we examined electron transfer between a thiol (2,5-dimercapto-1,3,4-thiadiazole, DMcT) and a conducting polymer (polyaniline, PAn). As a result, it was found that the reversible electron transfer is possible between them. We have already found that the DMcT-PAn composite can serve as a high energy density cathode material for a secondary battery. However, charging current and discharging current of the battery were not high enough for the practical use. Then, we used a copper current collector for the composite cathode instead of a conventional carbon current collector. In the first few cycles, dissolution of the copper current collector was seen during the charging process. Simultaneously, an increase in the discharge capacity was seen. Since the charge-discharge capacity can exceed the theoretical capacity, which is calculated from amounts of DMcT and PAn, dissolved copper ion (s) must function as cathode active material. This suggests that some complex is formed between copper ion (s) and DMcT.Charging/discharging currents were high enough for the practical use. Although we have no clear evidence for the complex formation at present, we observed some change in the visible spectrum of a Cu (ClO_4)_2 solution upon addition of DMcT.Complex formation of Cu (I) and Cu (II) with DMcT has been reported as well as other transition metal ions. Other thiadiazoles also form complexes with copper and other metal ions. The complexes should be promising as cathode materials for secondary batteries.