Methods to visualize solid-state redox reaction of lead-tin silicate glass and their use to explore new materials for advanced lithium batteries

为了更好地理解铅锡硅酸盐玻璃固态氧化还原反应的异常行为，在1997-1998财政年度进行了研究。由于x射线衍射没有特征，因此需要新的方法来可视化和跟踪在固体基质中发生的现象。因此，我们集中开发了以下新方法：(1)光学显微镜，使用光学显微镜和CCD相机在微米尺度上观察发生了什么；(2)声发射组织测量，使用原位电化学电池与声传感器和传感器，在我们的实验室设计和制造，检测铅锡硅酸盐玻璃颗粒的破裂声；(3)采用自制的原位电化学电池膨胀仪，测量尺寸变化的精度为0.1微米。这些新方法很好地可视化和表征了铅锡硅酸盐（或硼酸盐）玻璃的异常行为。将该方法应用于由锂、过渡金属和氧离子组成的锂插入材料，并与铅锡硅酸盐玻璃的结果进行了比较。根据我们的研究结果，铅锡硅酸盐玻璃或硼酸盐玻璃可以应用于锂离子电池的负极材料，尽管需要通过声发射组织测量法进行一些改进以消除破裂声。如上所述，我们已经成功地可视化了迄今为止尚未发现的现象，并为先进锂电池的材料化学家提供了有用的信息。

Research directed toward the better understanding of anomalous behavior on solid-state redox reactions of lead-tin silicate glass was carried out in the fiscal year of 1997-1998. Since X-ray diffraction was featureless, new methods to visualize and follow the phenomena took place in a solid matrix were necessary. Therefore, we have intensively developed the following new methods :(1) optical microscopy using optical microscope with CCD camera to see what are going on in a micrometer scale,(2) acoustic emission histometry using in-situ electrochemical cells with acoustic sensor and transducer, which is designed and fabricated in our laboratory, to detect cracking sounds of lead-tin silicate glass particles, and(3) dilatometry using home-made dilatometer with in-situ electrochemical cells which was designed to detect dimensional changes in 0.1 micrometer accuracy.These new methods worked very well to visualize and characterize the anomalous behaviors of lead-tin silicate (or borate) glass. The methods were also applied to lithium insertion materials consisting of lithium, transition metal, and oxygen ions, and the results were compared with those from lead-tin silicate glass. According to our results, lead-tin silicate glass or borate glass can be applied to a negative electrode material for lithium ion batteries although some improvement would be needed to erase cracking sound by acoustic emission histometry.As were stated above, we have successfully visualized phenomena which have not detect so far and gave useful information to materials chemists for advanced lithium batteries.