Hongmei Dai, Zhian Yang, Tingting Xie, Ziheng Zhao, Yongfei Shang, Changchun Ai,* and Qun Yi*

ADVANCED FUNCTIONAL MATERIALS//doi.org/10.1002/adfm.202505185

Abstract：Na4Fe3(PO4)2(P2O7) (NFPP) is a promising cathode material for sodium-ion batteries (SIBs) due to its low cost, facile synthesis, environmental compatibility, high structural stability, and suitable operating voltage. However, its practical application is hindered by poor cycling stability, limited rate capability, and low electronic/ionic conductivity. Herein, these challenges are addressed by strategically incorporating Zr4+ ions at the Fe1 site of NFPP (denoted as NZFPP-X, where X represents the Zr/Fe ratio). The optimized NZFPP-0.05 exhibits significantly enhanced thermodynamic stability and electrochemical performance. Zr substitution induces depolarization effects, which promote electron mobility, thereby improving conductivity, cycling stability, and rate performance. Specifically, NZFPP-0.05 delivers an exceptional capacity retention of 86.6% after 6000 cycles at 10 C and a remarkable rate capability of 58.5 mAh g−1 at 50 C. These advancements are attributed to the reduced energy barrier and accelerated kinetics of NZFPP-0.05 compared to pristine NFPP. This work presents a novel Zr-substitution strategy to enhance the performance of NFPP cathodes and introduces NZFPP-0.05 as a cost-effective, ultra-stable, and high-rate cathode material for SIBs.

Na₄Fe₃(PO₄)₂(P₂O₇)（NFPP）因其低成本、合成简便、环境友好、结构稳定性高以及适中的工作电压，成为钠离子电池（SIBs）中一种有前景的正极材料。然而，其实际应用受到循环稳定性差、倍率性能有限以及电子/离子电导率低的限制。本文通过在 NFPP 的 Fe1 位点有策略地引入 Zr⁴⁺ 离子来解决这些问题，所得材料记为 NZFPP-X（其中 X 表示 Zr/Fe 摩尔比）。优化后的 NZFPP-0.05 表现出显著增强的热力学稳定性和优异的电化学性能。Zr 的掺杂诱导了去极化效应，促进了电子迁移，从而提高了材料的导电性、循环稳定性和倍率性能。具体而言，NZFPP-0.05 在 10C 倍率下经过 6000 次循环后仍保持 86.6% 的容量，在 50C 倍率下仍具有 58.5 mAh g⁻¹ 的高比容量。这些性能的提升归因于 NZFPP-0.05 相较于原始 NFPP 具有更低的能量势垒和更快的动力学过程。本研究提出了一种新颖的 Zr 掺杂策略，有效提升了 NFPP 正极材料的性能，并将 NZFPP-0.05 推广为一种成本低廉、超稳定且具备高倍率特性的钠离子电池正极材料。