Ultra‐stable carbon‐coated sodium vanadium phosphate as cathode material for sodium‐ion battery

Abstract Based on the excellent sodium ion mobility of sodium superionic conductor structures, Na 3 V 2 (PO 4 ) 3 materials have become promising cathode materials in sodium‐ion batteries (SIBs). However, inadequate electronic transport of Na 3 V 2 (PO 4 ) 3 limits the cycling stability and rate performances in SIBs. In this work, high‐performance conductive carbon‐coated Na 3 V 2 (PO 4 ) 3 materials are obtained via a simple and facile ball‐milling assisted solid‐state method by utilizing citric acid as carbon sources. The carbon‐coated composite electrodes display a high initial specific capacity of 111.6 mAh·g −1 , and the specific capacity could retention reach 92.83% after 100 cycles at 1C with the high coulombic efficiency (99.95%). More importantly, the capacity of conductive carbon‐coated nano‐sized Na 3 V 2 (PO 4 ) 3 can remain 48.5 mAh·g −1 at 10C after 3000 cycles (initial capacity of 101.2 mAh·g −1 ). At the same time, high coulombic efficiency (near 100%) has little decay even at a high rate of 20C during 1000 cycles, demonstrating the excellent cycling stability and remarkable rate performances, and showing potential in large‐scale productions and applications.