PREPARATION AND SODIUM STORAGE PERFORMANCE OF THE K + /Al 3+ /SiO 4 4- CO-DOPED Na 3 V 2 (PO 4 ) 3 /CNTs COMPOSITES

Abstract

To address the issue of low intrinsic conductivity in sodium-ion battery cathode material Na3V2(PO4)3(NVP), a sol-gel method combined with carbon nanotube (CNTs) composite technology was employed to successfully synthesize K+, Al3+, and SiO44-triple-doped NVP/C@CNTs composites. Systematic structural characterization revealed that the prepared composites exhibit a typical NASICON structure. The tripledoping strategy induced lattice expansion, which lowered the Na+migration barrier, while grain refinement shortened the ion diffusion pathway. Additionally, CNTs incorporation effectively suppressed NVP particle agglomeration and constructed a three-dimensional conductive network, significantly enhancing the overall electrochemical performance of NVP-based materials. The results demonstrate that the triple-doped K0.04Na3.06V1.96Al0.04(PO4)2.9(SiO4)0.1/C@5%CNTs composite achieves an initial discharge specific capacity of 114.18 mAh g-1 at 0.1C (reaching 97.09% of the theoretical capacity), with a capacity retention of 95.36% (104.80 mAh g-1) after 200 cycles at 1C and 93.25% capacity retention at 10C (relative to 0.3C), demonstrating superior electrochemical performance. The synergistic strategy of triple-doping combined with CNT compositing provides a novel approach for developing high-performance cathode materials for sodium-ion batteries.