Aiming for promoting the capacity and cycling stability of O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM), the cathode material of sodium ion batteries (SIBs) with the most potential for industrialization, Na(Ni_1/3Fe_1/3Mn_1/3)_0.99Mo_0.01O_1.99F_0.01 (NFM-MoF), Na(Ni_1/3Fe_1/3Mn_1/3)_0.99Mo_0.01O₂ (NFM-Mo) and NaNi_1/3Fe_1/3Mn_1/3O_1.99F_0.01 (NFM-F) were successfully synthesized by solid phase method. The electrochemical performance of the doped samples was compared with that of the pristine NFM. The mechanism of the single- or dual-doping was explored by XRD Rietveld refinement and XPS. The NFM-MoF exhibits the highest initial specific discharge capacity of 137mAhg⁻¹ at 1 C with a retention of 91.97% after 100 cycles and the smallest polarization (0.32 V), which could be contributed to the highest Ni²⁺ content and highest $D_{{\mathit{Na}}^{+}}$ (7.335 ×10⁻¹³ cm²·s⁻¹) caused by the synergistic effect of Mo and F dual-doping. The highest Fe³⁺ content in the NFM-Mo leads to the higher initial discharge capacity of ¹36 mAhg⁻¹ at 1 C with a relative lower retention of 83.38%, which is due to the structure instability resulting from Fe migration and the lowest Mn content, than that of the NFM-F (85.31%). It illustrates that the Mn⁴⁺ plays a crucial role in stabilizing the structure during Na⁺ migrating. The superiority of the discharge capacity of the NFM-Mo become narrow with rates rise, due to its lower $D_{{\mathit{Na}}^{+}}$ (4.229 ×10⁻¹³ cm²·s⁻¹) than that of the NFM-F $D_{{\mathit{Na}}^{+}}$ (5.681 ×10⁻¹³ cm²·s⁻¹). It verifies that it is a diffusion control process at high rates. Mo and F dual-doping in NFM was proved to amplify the benefit of Ni²⁺ increasing, meanwhile restrain undesirable Fe increasing due to the synergistic effect.

旨在提高O3型NaNi _1/3 Fe _1/3 Mn _1/3 O ₂ (NFM)的容量和循环稳定性，这是最具产业化潜力的钠离子电池(SIBs)正极材料Na(Ni _1/3 Fe _1/3 Mn _1/3 ) _0.99 Mo _0.01 O _1.99 F _0.01 (NFM-MoF), Na(Ni _1/3 Fe _1/3 Mn _1/3 ) _0.99 Mo _0.01 O ₂ (NFM-Mo)和 NaNi _1/3 Fe _1/3 Mn _1/3 O _1.99固相法成功合成了F _{0.01 (NFM-F)。}将掺杂样品的电化学性能与原始 NFM 的电化学性能进行了比较。通过 XRD Rietveld 精修和 XPS 探索了单掺杂或双掺杂的机理。NFM-MoF 在 1 C 下表现出最高的初始比放电容量，为 137mAhg ^-1，循环 100 次后保持率为 91.97%，极化最小（0.32 V），这可能是 Ni ²⁺含量最高和最高$D_{{\mathit{钠}}^{+}}$(7.335 ×10 ^-13 cm ² ·s ^-1 )由Mo和F双掺杂的协同效应引起。NFM-Mo 中最高的 Fe ³⁺含量导致在 1 C 时具有较高的初始放电容量¹ 36 mAhg ^-1，而保持率相对较低，为 83.38%，这是由于 Fe 迁移导致的结构不稳定性和最低的Mn含量，高于NFM-F（85.31%）。这说明Mn ^{4+在Na +}迁移过程中对稳定结构起着至关重要的作用。NFM-Mo 的放电容量优势随着倍率的升高而变窄，由于其较低的$D_{{\mathit{钠}}^{+}}$(4.229 ×10 ^-13 cm ² ·s ^-1 ) 比 NFM-F$D_{{\mathit{钠}}^{+}}$(5.681 ×10 ^-13 cm ² ·s ^-1 )。它证实这是一个高速率的扩散控制过程。NFM中Mo和F的双掺杂被证明可以放大Ni ²⁺增加的好处，同时由于协同效应抑制不希望的Fe增加。