Tailored crystal structure via Zr-chemistry in Na3V2(PO4)3 cathodes for high-performance Na-ion storage

In this work, a Zr-chemistry modulation approach is presented to precisely alter the electronic structure of Na3V2(PO4)3 (NVP) via atomic-level doping under controlled conditions. Our findings reveal that Zr substitution triggers a significant anisotropic expansion along the c axis, thereby enhancing Na+ diffusion pathways. Additionally, in situ x-ray diffraction reveals that the expanded pathway facilitates a transition from a three-phase process to a two-phase process during operation, significantly enhancing structural reversibility and stability. Benefiting from this structural design, the optimized NVP cathode exhibits excellent Na-ion storage performance, achieving a high specific capacity of 110.3 mA h g−1 at 0.2 C and retaining 78.6 mA h g−1 after 1000 cycles at 20 C, corresponding to 87.1% capacity retention.