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

为了更好地了解铅锡硅酸盐玻璃固态氧化还原反应的反常行为，1997-1998财政年度进行了研究。由于X射线衍射是无特征的，因此需要新的方法来可视化和跟踪发生在固体基质中的现象。因此，我们集中开发了以下新方法：(1)使用光学显微镜和CCD摄像机来观察微米尺度上发生的事情；(2)利用我们实验室设计和制造的带有声传感器和换能器的原位电化学池进行声发射组织测量，以检测铅锡硅酸盐玻璃颗粒的破裂声音；(3)使用自制的带有原位电化学池的膨胀仪来检测0.1微米精度的尺寸变化。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。将该方法应用于锂、过渡金属和氧离子组成的锂插层材料，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作为锂离子电池的负极材料，但用声发射组织计量学方法消除破裂声还需要改进。如上所述，我们成功地可视化了迄今尚未检测到的现象，为先进的锂离子电池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.