Alkali ions pre-intercalated layered vanadium oxide nanowires for stable magnesium ions storage

Owing to the high energy density, high security and low price, rechargeable magnesium batteries (RMBs) are promising candidate for the next generation of high-performance batteries. However, the development of cathode materials for RMBs is hindered by the intensive polarization of Mg2+, which tends to destroy the stability of crystal structure and results in the degradation of batteries. Pre-intercalating the different alkali ions in crystal structure is an effective strategy to improve the layered structure stability and electrochemical performance of materials. Herein, the alkali ions (Li+, Na+, K+) pre-intercalation is presented to improve the structure stability of layered vanadium oxide (A-V3O8) for Mg2+ storage. From the result, the cycling performance of cathode is promoted with the pre- intercalation radius increase. To explain the optimizing principle, we use density functional theory (DFT) calculation to simulate the interaction effect between pre- intercalated cation and layered structure. Among intercalation compounds A-V3O8 (A = Li, Na, K), the electrochemical performance of Na+ pre-intercalated materials (NaV3O8) is better than the most of cathode materials for RMBs. Besides, the reaction mechanism of NaV3O8 is demonstrated. This work confirms that the pre- intercalation of appropriate alkali cation is an efficient strategy to improve the electrochemical performance of layered cathode materials for RMBs.