A series of F‐substituted Na_2/3Ni_1/3Mn_2/3O_2−xF_x (x = 0, 0.03, 0.05, 0.07) cathode materials have been synthesized and characterized by solid‐state ¹⁹F and ²³Na NMR, X‐ray photoelectron spectroscopy, and neutron diffraction. The underlying charge compensation mechanism is systematically unraveled by X‐ray absorption spectroscopy and electron energy loss spectroscopy (EELS) techniques, revealing partial reduction from Mn⁴⁺ to Mn³⁺ upon F‐substitution. It is revealed that not only Ni but also Mn participates in the redox reaction process, which is confirmed for the first time by EELS techniques, contributing to an increase in discharge specific capacity. The detailed structural transformations are also revealed by operando X‐ray diffraction experiments during the intercalation and deintercalation process of Na⁺, demonstrating that the biphasic reaction is obviously suppressed in the low voltage region via F‐substitution. Hence, the optimized sample with 0.05 mol f.u.⁻¹ fluorine substitution delivers an ultrahigh specific capacity of 61 mAh g⁻¹ at 10 C after 2000 cycles at 30 °C, an extraordinary cycling stability with a capacity retention of 75.6% after 2000 cycles at 10 C and 55 °C, an outstanding full battery performance with 89.5% capacity retention after 300 cycles at 1 C. This research provides a crucial understanding of the influence of F‐substitution on the crystal structure of the P2‐type materials and opens a new avenue for sodium‐ion batteries.

中文翻译：

---

F替代钠离子电池用F替代的P2型氧化物阴极的增强的循环和速率性能的见解

合成了一系列F-取代的Na _2/3 Ni _1/3 Mn _2/3 O _{2- x} F _x（x = 0、0.03、0.05、0.07）阴极材料，并通过固态¹⁹ F和^23进行了表征Na NMR，X射线光电子能谱和中子衍射。X射线吸收光谱和电子能量损失光谱（EELS）技术系统地揭示了潜在的电荷补偿机制，揭示了从Mn ⁴⁺到Mn ^3+的部分还原F替代后。据揭示，不仅Ni而且Mn也参与氧化还原反应过程，这是通过EELS技术首次证实的，从而有助于提高放电比容量。在Na ⁺的嵌入和脱嵌过程中，通过操作X射线衍射实验还揭示了详细的结构转变，表明在低压区域中通过F取代明显抑制了两相反应。因此，具有0.05 mol fu ^-1氟取代的优化样品可提供61 mAh g ^-1的超高比容量 在30°C下经过2000次循环后在10°C下保持良好的循环稳定性，在10°C和55°C下经过2000次循环后具有75.6％的容量保持率，在1°C进行300次循环后具有89.5％的容量保持率。这项研究对F取代对P2型材料的晶体结构的影响提供了至关重要的理解，并为钠离子电池开辟了一条新途径。