【摘要】 采用A型扫描超声脉冲反射技术,对40℃Li-Ga液态金属电池放电过程进行实时原位检测.通过辨识正极界面超声信号指纹区,发现正极界面的回波声压随液态金属电池放电容量的增加而增大,表明放电产物Li₂Ga₇的声阻抗大于液态金属Ga;当放电产物Li₂Ga₇完全覆盖正极表面时,正极界面的回波声压较初始状态增大约45%；归纳了不同放电阶段超声回波声压随放电容量的变化规律,提供了判断电池状态的依据.采用全聚焦相控阵超声三维成像技术,对放电产物Li₂Ga₇在正极界面的形成过程进行可视化分析,发现放电产物优先在正极界面中心区形成并聚集,与放电1.4 mA·h的光学成像结果吻合,揭示了Li-Ga液态金属电池放电过程中正极界面的传质特性.总结归纳了超声回波信号与电池放电容量间的耦合关系,建立了定量分析的工作曲线,发展了一种液态金属电池正极界面过程原位无损检测的新方法.更多还原

【Abstract】 Due to the specific working mechanism of liquid metal battery（LMB）,substance change only happens at the cathode interface during charge and discharge process. For better understanding the dynamic property of mass transport process inside LMB noninvasively,the A-scan type ultrasonic pulse echo technology was used to investigate discharge process of 40 ℃ Li-Ga LMB. By comparing the change of ultrasonic echo signal before and after discharge,the acoustic pressure value with specific time of flight was identified as the signal reflected from the liquid Ga/electrolyte interface. The results show that the acoustic pressure value increases proportionally to the discharge capacity.When the solid Li₂Ga₇interphase forms and entirely covers the liquid Ga cathode,the acoustic pressure value will finally increase about 45% compared with the original state. The quantitative relationship between discharge capacity and ultrasonic pressure value was calculated,which means that ultrasonic pulse echo signal can be used to diagnose discharge state of Li-Ga LMB. Moreover,in order to illustrate the mass transport mechanism at the liquid Ga cathode interface,the formation process of Li₂Ga₇solid interphase at the initial stage of discharge process was recorded by ultrasonic confocal phased array three-dimensional imaging system. It was found that Li₂Ga₇solid interphase firstly form at the central part of the liquid Ga cathode interface,which is in accordance with the optical result obtained after 1.4 mA·h capacity discharged. This work provides a novel in-situ and non-destructive interface analysis method for liquid metal battery.更多还原