Ionic Rectification across Ionic and Mixed Conductor Interfaces

In electrochemical devices, it is important to control the ionic transport between the electrodes and solid electrolytes. However, it is difficult to tune the transport without applying an electric field. This paper presents a method to modulate the transport via tuning of the electrochemical potential difference by controlling the electronic states at the interfaces. We fabricated thin-film solid-state Li batteries using LiTi₂O₄ thin films as positive electrodes. The spontaneous Li-ion transport between the solid electrolyte and LiTi₂O₄ is controlled by tuning the electrochemical potential difference via use of an electrically conducting Nb-doped SrTiO₃ substrate. This study establishes the foundation for rectifying the ionic transport via electronic energy band alignment.