P2-Type Layered Cathode Materials for Sodium-Ion Rechargeable Batteries with High Initial Coulombic Efficiency

Sodium-ion rechargeable batteries (SIBs) have attracted great attention as promising next-generation rechargeable batteries, especially for large-scale energy storage systems (ESS), owing to the natural abundance of Na resources and the similarities in their chemical structure and reaction mechanism to commercial lithium-ion batteries (LIBs). Thus, enormous efforts have been made to improve the electrochemical performance of SIBs through the development of novel cathode materials. According to the previous literatures, P2-type layered cathode materials for SIBs have suffered from their low initial coulombic efficiency, which inevitably requires the pre-sodiation of carbon anode materials under full cell systems. In this regard, we focused on how to increase their initial charge capacity with sacrificial salts in the level of electrode fabrication. Actually, the suppression of irreversible capacity of P2-type layered cathode materials are challenging without specific electrode design. Thus, in the present study, we suggest new electrode fabrication process with sacrificial salts (i.e. NaN3) to reduce the high initial irreversible capacity of P2-type layered cathode materials for SIBs.