Magnetic-Field Modulation of Na3V2(PO4)3 Crystal Orientation for Enhanced Sodium-Ion Battery Performance

Na 3 V 2 (PO 4 ) 3 (NVP) is a promising electrode material that exhibits magnetic anisotropy; however, the potential of this magnetic anisotropy to optimize battery performance has been largely unexplored. This study proposes a cost-effective and efficient method to induce the alignment of NVP along the (113) crystal plane by applying a vertical magnetic field during the slurry coating process, thereby enhancing its battery performance. Comprehensive structural characterizations and theoretical analysis elucidate the structure-activity relationship between the preferred crystal orientation and ion transport kinetics, facilitating the formation of more ordered Na + deintercalation pathways in NVP electrodes. This alignment reduces electrode tortuosity, enhances interfacial compatibility, and substantially improves battery performance, particularly in terms of high-rate cycling capability. As a result, the magnetic-field-modulated NVP (NVP−M⊥) electrode exhibits a high capacity retention of 85.1% after 500 cycles at 5 C, significantly surpassing that of the pristine electrode. The NVP−M⊥ electrode also demonstrates considerable reversible capacity at 40 C and maintains excellent stability under high temperature and prolonged cycling conditions. Furthermore, superior battery performance is observed in the assembled NVP−M⊥||hard−carbon pouch cell and commercial NVP electrode following magnetic-field modulation, thereby validating the efficacy of this method. Consequently, this magnetic-field-induced crystal-orientation optimization strategy provides an innovative approach for low-cost and high-throughput preparation of high-performance sodium-ion batteries.