Preparation and evaluation of lithium secondary batteries by using thin film technology

从2005年到2006年对氧化锰薄膜的制备工艺进行了研究。在开始本研究之前，已经发现用反应蒸发法制备了用于锂二次电池的氧化锰（Mn_3O_4）薄膜。坩埚中的金属锰由于在氧气环境中蒸发而遭受氧化。因此，沉积速率随沉积行程的增加而降低。本研究提出了一种在反应蒸发过程中使Mn蒸发剂远离氧气气氛的技术。通过我们的研究开发了三种类型的分离器：钼分离器，不锈钢电池（SUS电池）和石英安瓿。它们已经安装在Mn坩埚的底部。利用这些装置制备的Mn_3O_4薄膜具有较高的重现性。在评价Mn_3O_4薄膜时，发现必须制备含锂的氧化锰薄膜。2006年开始用溅射法制备LiMn_2O_4薄膜。结果表明，该方法可以在室温的衬底温度下制备LiMn_2O_4薄膜。这种材料在性价比上优于其他材料，而且无毒。采用快速热退火（RTA）工艺可以改善晶体性能。通过这项研究，制备过程变得更加复杂。这项研究目前正在进行中。

The preparation procedure of manganese oxide films have been investigated from 2005 through 2006. Before starting this research, it was found that manganese oxide (Mn_3O_4) films for lithium secondary batteries have been prepared using a reactive evaporation method. The metallic Mn in the crucible suffers oxidation since it is evaporated in the oxygen atmosphere. So the deposition rate is deteriorated with increasing deposition run.This research shows a technique which keeps off the Mn evaporant from oxygen atmosphere during the reactive evaporation process. Three types of separators have been developed through our studies: a Mo separator, a stainless steel cell (SUS cell), and a quartz ampoule. They have been installed in the bottom of the Mn crucible. The Mn_3O_4 films could be prepared with high reproducibility with these devices.During the evaluation of Mn_3O_4 films, it was found that manganese oxide films which involve Li have to be prepared. Preparation of LiMn_2O_4 thin films using a sputtering method was started on 2006. It was found that LiMn_2O_4 thin films could be prepared even at the substrate temperature of room temperature (R.T.) by this method. This material is superior to other materials in the cost performance as well as non-toxic. The crystal properties could be improved after a rapid thermal annealing (RTA) process. The preparation procedure has been sophisticated through this study. The study is now under way.