P2-type layered Mn-based oxides are promising cathode materials for sodium-ion batteries (SIBs), but it is still challenging to achieve both high capacity and stability because of complex phase transitions and irreversible oxygen release at high voltage. To address these challenges, an optimal P2-type Na0.67Mn0.8Cu0.15Ti0.05O2 (NMCT) cathode with a complete solid-solution reaction and reversible oxygen redox reaction over a wide voltage range was developed. The introduction of the Na–O–Ti configuration leads to fewer delocalized electrons on oxygen and thus enhances oxygen redox activity, while the high energetic overlap between O 2p and Cu 3d states and the increased Mn–O hybridization strengthen the rigidity of oxygen framework to achieve reversible and stable oxygen redox reaction. In addition, the reinforced TM–O interaction, combined with the ameliorated Mn3+ Jahn-Teller distortion and disrupted Na+/vacancy ordering, synergistically eliminate the undesired P2–OP4 phase transition and lead to a complete solid-solution reaction, which greatly facilitates Na+ transport kinetics and stabilizes structural integrity. As a consequence, improved rate performance and cycling stability are achieved for NMCT. Our present study provides a promising avenue for simultaneously utilizing the reversible oxygen redox activity and maintaining the structural integrity to accomplish the capacity-stability trade-off of Mn-based oxide cathodes for constructing practical SIBs.

中文翻译：

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使用可逆氧氧化还原在层状阴极中实现完全固溶反应，用于高稳定性钠离子电池


P2 型层状 Mon 基氧化物是很有前途的钠离子电池 （SIB） 正极材料，但由于复杂的相变和高压下不可逆的氧释放，要实现高容量和稳定性仍然具有挑战性。为了应对这些挑战，开发了一种最佳的 P2 型 Na0.67Mn0.8Cu0.15Ti0.05O2 （NMCT） 阴极，该阴极在较宽的电压范围内具有完整的固溶反应和可逆氧氧化还原反应。Na-O-Ti 构型的引入导致氧上的离域电子减少，从而提高氧氧化还原活性，而 O 2p 和 Cu 3d 态之间的高能重叠以及 Mn-O 杂化增加加强了氧框架的刚性，以实现可逆和稳定的氧氧化还原反应。此外，增强的 TM-O 相互作用，结合改善的 Mn3+ Jahn-Teller 畸变和破坏的 Na+/空位有序，协同消除不需要的 P2-OP4 相变并导致完整的固溶反应，这极大地促进了 Na+ 传输动力学并稳定了结构完整性。因此，NMCT 实现了更好的速率性能和循环稳定性。我们目前的研究为同时利用可逆氧氧化还原活性和保持结构完整性以实现 Mn 基氧化物阴极的容量-稳定性权衡以构建实用的 SIB 提供了一种有前途的途径。