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<p>The development of Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> (NVP) as a cathode material for sodium-ion batteries is significantly hindered by its intrinsically low electronic conductivity, structural instability during cycling, and poor kinetics. To address these issues, a novel strategy of co-doping NVP with Al and Y ions via a sol–gel method is proposed in this study. While substituting V<sup>3+</sup>(0.64 Å) with Al<sup>3+</sup> (0.51 Å) enhances electronic conductivity, thereby improving rate capability, this smaller ionic radius may compromise ionic conductivity. Simultaneously, introducing a small amount of larger Y<sup>3+</sup> (0.90 Å) for V<sup>3+</sup>(0.64 Å) stabilizes the crystal structure by expanding the unit cell volume, which facilitates Na⁺ diffusion. The synergistic effect of Al and Y co-doping systematically enhances the structural stability of NVP, effectively improves electron transfer and ion diffusion kinetics, and boosts structural robustness. Consequently, the optimized Na<sub>3</sub>V<sub>1.793</sub>Al<sub>0.2</sub>Y<sub>0.007</sub>(PO<sub>4</sub>)<sub>3</sub>/C sample exhibits superior electrochemical and kinetic performance. It delivers a high reversible capacity of 116.1 mAh/g at 0.1 C and retains 83.9 mAh/g even at 30 C. Furthermore, the optimized Na<sub>3</sub>V<sub>1.76</sub>Al<sub>0.2</sub>Y<sub>0.04</sub>(PO<sub>4</sub>)<sub>3</sub>/C sample shows an initial capacity of 103.5 mAh/g at 1 C and maintains 98 mAh/g after 500 cycles, corresponding to an impressive capacity retention of 94.68%. This work provides a promising approach for developing high-performance cathode materials for sodium-ion batteries, advancing their application potential in energy storage systems.</p>

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Enhanced electrochemical performance of Na3V2(PO4)3 cathodes enabled by the synergistic effect of Al/Y co-doping

  • 期刊论文

  • 发表日期：

    2025年9月30日

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  • Guankai Lin,
  • Yujie Cheng,
  • Jie Lei

摘要

The development of Na3V2(PO4)3 (NVP) as a cathode material for sodium-ion batteries is significantly hindered by its intrinsically low electronic conductivity, structural instability during cycling, and poor kinetics. To address these issues, a novel strategy of co-doping NVP with Al and Y ions via a sol–gel method is proposed in this study. While substituting V3+(0.64 Å) with Al3+ (0.51 Å) enhances electronic conductivity, thereby improving rate capability, this smaller ionic radius may compromise ionic conductivity. Simultaneously, introducing a small amount of larger Y3+ (0.90 Å) for V3+(0.64 Å) stabilizes the crystal structure by expanding the unit cell volume, which facilitates Na⁺ diffusion. The synergistic effect of Al and Y co-doping systematically enhances the structural stability of NVP, effectively improves electron transfer and ion diffusion kinetics, and boosts structural robustness. Consequently, the optimized Na3V1.793Al0.2Y0.007(PO4)3/C sample exhibits superior electrochemical and kinetic performance. It delivers a high reversible capacity of 116.1 mAh/g at 0.1 C and retains 83.9 mAh/g even at 30 C. Furthermore, the optimized Na3V1.76Al0.2Y0.04(PO4)3/C sample shows an initial capacity of 103.5 mAh/g at 1 C and maintains 98 mAh/g after 500 cycles, corresponding to an impressive capacity retention of 94.68%. This work provides a promising approach for developing high-performance cathode materials for sodium-ion batteries, advancing their application potential in energy storage systems.