2, Gyeongsang National University, Seoul, , Korea (the Republic of)
3, RIST, Seoul, , Korea (the Republic of)
As the importance of renewable energy grows, Sodium/β”-alumina(BASE) cell has been recognized as one of the most effective energy storage device because of its high specific energy, high efficiency of charge/discharge and long cycle life. For better operation of Sodium-BASE cell, poor wettability, which is caused by moisture and impurity in the BASE such as calcium, of electrolyte on liquid sodium anode should be enhanced. However, the formation of the oxide film, which is related to moisture absorbed on the BASE surface, impedes sodium dissolution, thereby hindering an accurate determination of wetting behavior. In this study, the sessile drop technique under controlled moisture and O2 environment is used as a type of an artificial Sodium-BASE cell system to study the issue of water interface formed onto the BASE. To separate water interface, BASE surface need to be coated by metal that can form an alloy with sodium and therefore completely isolate its surface in a way that emulate the sealed and complete real cell. Bi is chosen as protect layer and sodium alloy with Bi is impervious to water yet does not interfere with sodium conductivity. By the enhanced wettability, the Sodium-BASE batteries can be operated at lower temperature with solving the safety issues and to use low cost polymeric seals.