Verification of the fracture mechanism of β″-aluminas caused by large current density

Abstract

β″-aluminas which transmit sodium ions and do not conduct electrons are expected to be applied in practice for solid electrolytes and separators in sodium-sulfur batteries. It is known that a large sodium ion current density fractures β″-aluminas instantly. To clarify this fracture mechanism, the temperature and thermal stress distributions in a β″-alumina tube generated by transmitting sodium ions were calculated. Then using β″-alumina tubes, experiments were carried out in which β″-alumina were cracked by a large current density. The values of thermal stress in these experiments wre solved using upper calculation. These values were almost equal to those of the mechanical strength of β″-aluminas. The fracture mechanism of β″-aluminas by transmission of a large sodium ion current density is thermal stress generated by Joule loss in β″-aluminas.