P2-type Ni/Mn-based layered oxides are regarded to be promising cathode materials for advanced sodium-ion batteries (SIBs) owing to their rapid sodium ion diffusion kinetics, high working voltage, and high theoretical capacity. However, P2-type Ni/Mn-based layered oxides are prone to phase transition during charging and discharging processes, resulting in serious capacity fading. Here, introduction of Zn and Ti into transition-metal layers of P2-type layered NaNiMnO can effectively inhibit P2–O2 phase transition at high voltage, leading to the improved cycling endurance. When being used as cathode materials for SIBs, NaNiZnMnTiO (NNZMT) can deliver a discharge specific capacity of 106.6 mAh g, with 95.17% capacity retention after the 100th cycle at 100 mA g within 2.1–4.3 V, which are much higher than those (58.4 mAh g and 45.2%) of Zn/Ti-undoped NaNiMnO (NNM). Besides, NNZMT displays a much better rate capability compared to the NNM sample. The full cell, based on P2-type layered NNZMT as cathode material and hard carbon as anode material, can provide an initial discharge specific capacity of 94.1 mAh g, with a capacity retention of 75.6% after 100 cycles at 100 mA g within 1.0–4.2 V. This research work confirms that low-lost Zn/Ti co-doping strategy is an effective approach for designing and preparing cathode materials for advanced SIBs.

中文翻译：

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Zn/Ti共掺杂协同效应抑制先进钠离子电池P2型Ni/Mn基层状氧化物的P2-O2相变

P2型Ni/Mn基层状氧化物由于其快速的钠离子扩散动力学、高工作电压和高理论容量而被认为是先进钠离子电池（SIB）的有前途的正极材料。然而，P2型Ni/Mn基层状氧化物在充放电过程中容易发生相变，导致严重的容量衰减。在P2型层状NaNiMnO的过渡金属层中引入Zn和Ti可以有效抑制高电压下的P2-O2相变，从而提高循环耐久性。当用作SIBs正极材料时，NaNiZnMnTiO（NNZMT）的放电比容量为106.6 mAh g，在2.1-4.3 V内以100 mA g-1循环100次后容量保持率为95.17%，远高于那些（NNZMT）。 58.4 mAh g 和 45.2% 的 Zn/Ti 未掺杂的 NaNiMnO (NNM)。此外，与 NNM 样本相比，NNZMT 显示出更好的速率能力。该全电池以P2型层状NNZMT为正极材料，硬碳为负极材料，首次放电比容量为94.1 mAh g，在1.0–100 mA g-1下循环100次后容量保持率为75.6%。 4.2 V.这项研究工作证实，低损失的Zn/Ti共掺杂策略是设计和制备先进SIB阴极材料的有效方法。