In this research, P2-type with high-entropy configurations and superlattice structures, Na0.78Mg0.12Ni0.12Nb0.02Li0.13Mn(IV)0.14Mn(III)0.47O2-xFx (NMNNLM-OFx, x = 0, 0.05, 0.08, 0.1), were synthesized. The charge compensation mechanism was elucidated through X-ray absorption spectroscopy (XAS). The findings demonstrate that increasing the covalency of transition metal-oxygen bonds strengthens lattice oxygen activation, thereby improving rate performance and cycling stability. Additionally, both Ni and Mn were found to participate in redox reactions and charge compensation. Structural transformations were investigated in detail using in situ X-ray diffraction (In situ-XRD). The NMNNLM-OF0.1 cathode material successfully inhibited the O2/OP4 phase transition in the high-voltage and reduced Jahn-Teller distortion in the low-voltage, achieving high reversible capacities of 145.3/150.5 mAh g–1 at 0.3C within the 1.5–4.3/4.5 V voltage window and exceptional high-rate performance, delivering discharge capacities of 87.2/79.5 mAh g–1 at 20C. After 100 cycles at 1C in the 1.5–4.3V/4.5 V voltage window, the capacity retention rates were 95.87% and 83.53%, respectively. At 20C, the full battery NMNLMM-OF0.1//HC retained a discharge specific capacity of 56.9 mAh g⁻¹, after 90 cycles at 1C, the capacity retention rate was 79.42%. This study offers significant insights into the development of fluoride-substituted manganese-rich high-entropy P2-type cathode materials for high-voltage sodium-ion batteries, providing a promising direction.

中文翻译：

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高熵富氧氟化物金属氧键的共价调控提高了钠离子电池在高压下的高倍率和长寿命性能

本研究合成了具有高熵构型和超晶格结构的 P2 型 Na0.78Mg0.12Ni0.12Nb0.02Li0.13Mn（IV）0.14Mn（III）0.47O2-xFx（NMNNLM-OFx， x = 0， 0.05， 0.08， 0.1）。通过 X 射线吸收光谱 （XAS） 阐明了电荷补偿机制。研究结果表明，增加过渡金属-氧键的共价可增强晶格氧活化，从而提高速率性能和循环稳定性。此外，发现 Ni 和 Mn 都参与氧化还原反应和电荷补偿。使用原位 X 射线衍射 （In situ-XRD） 详细研究了结构转变。NMNNLM-OF0.1 正极材料成功抑制了高压下的 O2/OP4 相变，减少了低压下的 Jahn-Teller 失真，在 1.5–4.3/4.5 V 电压窗口内实现了 145.3/150.5 mAh g–1 在 0.3C 下的可逆容量和 4.5 倍率性能，在 20C 下提供 87.2/79.5 mAh g–1 的放电容量。在 1.5–4.3V/4.5 V 电压窗口下 1C 下循环 100 次后，容量保持率分别为 95.87% 和 83.53%。在 20C 时，满电池 NMNLMM-OF0.1//HC 保持了 56.9 mAh g⁻¹ 的放电比容量，在 1C 下循环 90 次后，容量保持率为 79.42%。本研究为开发用于高压钠离子电池的氟化物取代富锰高熵 P2 型正极材料提供了重要的见解，为开发提供了有前途的方向。