Secondary Battery: Lithium Ion and Sodium Ion Conductions

Abstract

Lithium ion battery has been widely in many electronic devices. Due to flammability of liquid organic electrolyte, solid electrolyte has been explored from the viewpoint of battery safety. To investigate the mechanism of lithium ion conduction in solid electrolyte of La2/3−x Li3x TiO3 perovskite, hybrid-DFT calculation is performed. From the obtained potential energy curve, the activation energy for lithium ion conduction can be estimated. From chemical bonding rule, it is found that lithium ion forms ionic bonding during lithium ion conduction. Based on the knowledge, K x Ba(1−x)/2MnF3 perovskite was designed as thermally stable lithium ion conductor. Recently, sodium ion battery has attracted much interest, because of abundant sodium resource. However, as sodium ion has larger ionic radius, it is more difficult to design sodium ion conductor. In this chapter, our designed sodium ion conductors such as CsMn(CN)3, Al(CN)3 and NaAlO(CN)2 are introduced. In CsMn(CN)3, Al(CN)3, sodium ion migrates through counter cation vacancy, as same as La2/3−x Li3x TiO3 perovskite. In NaAlO(CN)2, the anisotropic sodium ion conduction occurs. Sodium ion can migrates through only Al4(CN)4 bottleneck.