A Promising High-Voltage Cathode Material Based on Mesoporous Na3V2(PO4)3/C for Rechargeable Magnesium Batteries

Graphical Cathode for magnesium-ion batteries : An electrochemically desodiated phase NaV 2 (PO 4 ) 3 /C has been developed as a high-voltage cathode material (ca. 2.5 V vs. Mg 2+ /Mg) for rechargeable magnesium batteries, offering good cycle performance. The electrochemical reaction involves an intercalation mechanism and shows good reversibility. The lack of suitable high-voltage cathode materials has hindered the development of rechargeable magnesium batteries (RMBs). Here, mesoporous Na 3 V 2 (PO 4 ) 3 /C (NVP/C) spheres have been synthesized through a facile spray-drying–annealing method, and their electrochemically desodiated phase NaV 2 (PO 4 ) 3 /C (ED-NVP/C) has been investigated as an intercalation host for Mg 2+ ions. The obtained ED-NVP/C exhibits an average discharge voltage of around 2.5 V (vs. Mg 2+ /Mg), higher than those of most previously reported cathode materials. In addition, it can deliver an initial discharge capacity of 88.8 mA h g −1 at 20 mA g −1 , with good cycling stability. Ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results demonstrate that the electrochemical reaction is based on an intercalation mechanism and shows good reversibility. Galvanostatic intermittent titration technique (GITT) data have revealed that the intercalation process involves a two-phase transition. The reported ED-NVP/C cathode material with high working voltage offers promising potential for application in RMBs.