Zhu Yuanqiang, Xu Hui, Bao Yuanhai, Li Siyao, Chen Yong
College of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, China.
Key Laboratory of Low Carbon Energy and Chemical Engineering of Gansu Province, Lanzhou 730050, China.
ACS Appl Mater Interfaces. 2025 Feb 5;17(5):7581-7594. doi: 10.1021/acsami.4c15767. Epub 2025 Jan 22.
Na superionic conductor (NASICON)-structure NaMnV(PO) (NVMP) electrode materials reveal highly attractive application prospects due to ultrahigh energy density originating from two-electron reactions. Nevertheless, NVMP also encounters challenges with its poor electronic conductivity, Mn dissolution, and Jahn-Teller distortion. To address this issue, utilizing N-doped carbon layers and carbon nanotubes (CNTs) for dual encapsulation enhances the material's electronic conductivity, creating an effective electron transport network that promotes the rapid diffusion and storage of Na. On this basis, partially substituting Mn in NVMP with Fe, a new sodium superionic conductor (NASICON) structured cathode material has been designed to alleviate Jahn-Teller distortion and prolong the cycling life. The synergistic effect of N-doped double nanocarbon encapsulation and multielectron reactions is employed to promote the optimized NaVMnFe(PO)/NC@CNTs (NVMnFeP/NC@CNTs) electrode material to deliver fast Na diffusion kinetics, high reversible capacity (110.2 mAh g at 0.1 C), and long-term cyclic stability (80.1% of the capacity at 10 C over 2000 cycles). Besides, the electrochemical properties of NVMnFeP/NC@CNTs composites were investigated in detail at high loads and high window voltages to evaluate their potential for practical applications. The reduction/oxidation processes involved in Fe/Fe, Mn/Mn, and V/V redox couples and a solid-solution and biphasic reaction mechanism upon repeated de- and re-intercalation processes are revealed via ex-situ XRD and XPS characterization. Finally, the assembled NVMnFeP/NC@CNTs ∥ hard carbon full cell manifests high capacity (101.1 mAh g at 0.1 C) and good cycling stability (98.2% capacity retention at 1 C after 100 cycles). The rational design with multimetal ion substitution regulation has the potential to open up new possibilities for high-performance sodium-ion batteries.
钠超离子导体（NASICON）结构的NaMnV(PO)（NVMP）电极材料因其源于双电子反应的超高能量密度而展现出极具吸引力的应用前景。然而，NVMP也面临着电子导电性差、Mn溶解和 Jahn-Teller 畸变等挑战。为解决这一问题，利用 N 掺杂碳层和碳纳米管（CNTs）进行双重封装可提高材料的电子导电性，构建有效的电子传输网络，促进 Na 的快速扩散和存储。在此基础上，通过用 Fe 部分替代 NVMP 中的 Mn，设计了一种新型钠超离子导体（NASICON）结构的正极材料，以减轻 Jahn-Teller 畸变并延长循环寿命。采用 N 掺杂双纳米碳封装与多电子反应的协同效应，促进优化后的 NaVMnFe(PO)/NC@CNTs（NVMnFeP/NC@CNTs）电极材料实现快速的 Na 扩散动力学、高可逆容量（0.1 C 时为 110.2 mAh g）和长期循环稳定性（10 C 下 2000 次循环后容量保持率为 80.1%）。此外，还在高负载和高窗口电压下详细研究了 NVMnFeP/NC@CNTs 复合材料的电化学性能，以评估其实际应用潜力。通过非原位 XRD 和 XPS 表征揭示了 Fe/Fe、Mn/Mn 和 V/V 氧化还原对所涉及的还原/氧化过程以及反复脱嵌过程中的固溶体和双相反应机制。最后，组装的 NVMnFeP/NC@CNTs∥硬碳全电池表现出高容量（0.1 C 时为 101.1 mAh g）和良好的循环稳定性（1 C 下 100 次循环后容量保持率为 98.2%）。多金属离子取代调控的合理设计有潜力为高性能钠离子电池开辟新的可能性。
