Enhanced Performance of Ternary NASICON-Type Na 3.5- X Mn 0.5 V 1.5- X Zr X (PO4)3/C Cathodes for Sodium-Ion Batteries

Sodium-ion batteries (SIBs) are widely studied for energy storage applications, but achieving cathode materials with balanced high energy density, stability, and fast charge/discharge performance remains a key challenge. In this study, we successfully synthesized a series of NASICON-type Na 3.5- X Mn 0.5 V 1.5- X Zr X (PO 4 ) 3 /C, incorporating Mn, V, and Zr to investigate their impact on electrochemical performance. By introducing Zr alongside Mn and V, we developed a novel strategy to activate V 4+ /V 5+ redox reactions, achieving high energy density. Moreover, this substitution promotes Na-ion migration by widening the migration pathways and generating additional Na vacancies, which greatly enhances electrode reaction kinetics and boosts overall performance. Na 3.4 Mn 0.5 V 1.4 Zr 0.1 (PO 4 ) 3 /C demonstrates superior stability, retaining 90% of its capacity after 800 cycles, and delivers high-rate performance (84 mAh center dot g-1 at 20C), significantly outperforming pristine Na3.5Mn0.5V1.5(PO4)3/C. These advancements highlight a potential approach for developing efficient and sustainable SIBs.