The anionic redox reaction (ARR) is a promising charge contributor to improve the reversible capacity of layered-oxide cathodes for Na-ion batteries; however, some practical bottlenecks still need to be eliminated, including a low capacity retention, large voltage hysteresis, and low rate capability. Herein, we proposed a high-Na content honeycomb-ordered cathode, P2–Na5/6[Li1/6Cu1/6Mn2/3]O2 (P2-NLCMO), with combined cationic/anionic redox. Neutron powder diffraction and X-ray diffraction of P2-NLCMO suggested P2-type stacking with rarely found P6322 symmetry. In addition, advanced spectroscopy techniques and density functional theory calculations confirmed the synergistic stabilizing relationship between the Li/Cu dual honeycomb centers, achieving fully active Cu3+/Cu2+ redox and stabilized ARR with interactively suppressed local distortion. With a meticulously regulated charge/discharge protocol, both the cycling and rate capability of P2-NLCMO were significantly improved, demonstrating reasonable capacity and eliminating voltage hysteresis. Overall, this work contributes a well-defined layered oxide cathode with combined cationic/anionic redox towards rational designing advanced Na-ion batteries.

中文翻译：

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使用 Li/Cu 双蜂窝中心促进可逆阴离子氧化还原反应


阴离子氧化还原反应 （ARR） 是一种很有前途的电荷贡献者，可以提高钠离子电池层状氧化物阴极的可逆容量;然而，一些实际的瓶颈仍然需要消除，包括低容量保持、大电压滞后和低速率能力。在此，我们提出了一种高 Na 含量的蜂窝有序阴极 P2-Na5/6[Li1/6Cu1/6Mn2/3]O2 （P2-NLCMO），具有阳离子/阴离子复合氧化还原。P2-NLCMO 的中子粉体衍射和 X 射线衍射表明 P2 型堆叠，P6322 对称性很少见。此外，先进的光谱技术和密度泛函理论计算证实了 Li/Cu 双蜂窝中心之间的协同稳定关系，实现了完全活性的 Cu3+/Cu2+ 氧化还原和稳定的 ARR，并具有交互抑制的局部畸变。通过精心调节的充电/放电协议，P2-NLCMO 的循环和倍率能力都得到了显著提高，展示了合理的容量并消除了电压滞后。总体而言，这项工作有助于合理设计先进的钠离子电池，形成定义明确的层状氧化物阴极和阳离子/阴离子氧化还原的组合。