Electrode/Electrolyte Interfaces in Sodium-Ion Battery

Sodium-ion batteries (SIBs) have attracted a significant interest as large-scale energy storage candidates due to their naturally available sodium resources and low cost. Since the accelerated growth of the last decade, commercial requirements for SIBs have been focused on applications for energy storage systems. However, the lack of knowledge of the physical and chemical dynamics occurring at the electrode-electrolyte interface is the greatest obstacle to the advancement of existing battery technology and the creation of new ones. Similar to LiBs, the most important problem to improve lifetime, power capability, and even the safety of SIBs is understanding the chemical electrode surface. In this chapter, we begin with a discussion on the chemical composition and structure of the Na-ion solid electrolyte interphase (SEI). We also review the current understanding of the mechanism of SEI formation on different types of anodes and the existence of the SEI in ether-based electrolytes to emphasize how the enhanced stability of the SEI fundamentally affects the efficiency and reversibility of electrochemical reactions. Therefore, the built-up of the appropriate SEI layer is a necessary step in optimizing the combination of anode-electrolyte-cathode for Na-ion batteries (NABs), either focusing on finding the new materials or developing novel ones. Furthermore, the understanding of the analysis techniques used to characterize the SEI-layer properties is also provided in this chapter. Finally, we discuss the SEI layer’s perspective and challenges in the schedule for developing commercial Na-rechargeable batteries.