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<p>Sodium superionic conductor (NASICON)-type materials are promising cathodes for sodium-ion batteries due to their stable multi-channel frameworks and exceptional ionic conductivity. Among them, Na<sub>3</sub>V<sub>2</sub>(PO<sub>4</sub>)<sub>2</sub>F<sub>3</sub> (NVPF) has attracted significant attention. However, the low electronic conductivity and phase impurities limit its sodium storage capability. Herein, we present a Fe and Mn dual-doped NVPF (FM-NVPF) cathode with improved phase purity, electronic conductivity, and electrochemical activities. Detailed ex-situ analyses and density functional theory calculations reveal that Fe and Mn dopants induce defect energy levels and modulate the electronic structure, resulting in a direct-to-indirect bandgap transition in NVPF, which in turn increases carrier concentration and lifetime, accelerates ionic/electronic transport, and improves structural stability. As a result, the FM-NVPF cathode delivers a high capacity of 126.6&#xa0;mAh g⁻<sup>1</sup> at 0.1&#xa0;C (1&#xa0;C = 128&#xa0;mAh g⁻<sup>1</sup>) and outstanding high-rate capability of 67.6&#xa0;mAh g⁻<sup>1</sup> at 50&#xa0;C, corresponding to 1.2&#xa0;min per charge. Furthermore, Na ion full cells assembled with the FM-NVPF cathodes and hard carbon anodes exhibit a high energy density of about 175&#xa0;Wh kg<sup>−1</sup><sub>cathode+anode mass</sub> and appealing cyclic stability. This work provides an efficient strategy for developing high-purity and high-performance NVPF cathode materials for advanced sodium-ion batteries.</p>

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Iron–Manganese Dual-Doping Tailors the Electronic Structure of Na3V2(PO4)2F3 for High-Performance Sodium-Ion Batteries

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月5日

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  • Jien Li,
  • Shuang Luo,
  • Renjie Li,
  • Yingkai Hua,
  • Linlong Lyu,
  • Xiangjun Pu,
  • Jun Fan,
  • Zheng-Long Xu

摘要

Sodium superionic conductor (NASICON)-type materials are promising cathodes for sodium-ion batteries due to their stable multi-channel frameworks and exceptional ionic conductivity. Among them, Na3V2(PO4)2F3 (NVPF) has attracted significant attention. However, the low electronic conductivity and phase impurities limit its sodium storage capability. Herein, we present a Fe and Mn dual-doped NVPF (FM-NVPF) cathode with improved phase purity, electronic conductivity, and electrochemical activities. Detailed ex-situ analyses and density functional theory calculations reveal that Fe and Mn dopants induce defect energy levels and modulate the electronic structure, resulting in a direct-to-indirect bandgap transition in NVPF, which in turn increases carrier concentration and lifetime, accelerates ionic/electronic transport, and improves structural stability. As a result, the FM-NVPF cathode delivers a high capacity of 126.6 mAh g⁻1 at 0.1 C (1 C = 128 mAh g⁻1) and outstanding high-rate capability of 67.6 mAh g⁻1 at 50 C, corresponding to 1.2 min per charge. Furthermore, Na ion full cells assembled with the FM-NVPF cathodes and hard carbon anodes exhibit a high energy density of about 175 Wh kg−1cathode+anode mass and appealing cyclic stability. This work provides an efficient strategy for developing high-purity and high-performance NVPF cathode materials for advanced sodium-ion batteries.