Layered Na-birnessites are promising cathode materials for aqueous sodium-ion batteries due to their high theoretical capacity, low cost, and environmental benignity. However, the general O′3 Na-birnessites possess low Na content and dominant inactive {001} exposed facets, which compromise their Na storage capability and cycling stability. Herein, we develop a high-Na-content P′3-Na_0.71MnO₂·0.15H₂O with highly enriched {010} active facets by a hydrothermal conversion method. In comparison with the O′3 Na-birnessite, the P′3 Na-birnessite with a high ratio of {010}/{001} exposed facets provides greatly increased open channels for Na⁺ diffusion, while the P′3 stacking affords a lower Na⁺ diffusion barrier, resulting in improved electrode kinetics with a large specific capacity of 176 mAh g^–1 at 0.2 A g^–1. More importantly, the P′3 Na-birnessite manifests solo Na⁺ intercalation/deintercalation with extraordinary cycling stability in an aqueous electrolyte, achieving 90.5% capacity retention after 60,000 cycles. When coupled with the NaTi₂(PO₄)₃ anode, the P′3 Na-birnessite-based full cell delivers both high energy density and long cycle life, demonstrating the potential application in aqueous sodium-ion batteries. This study demonstrates an efficient method to prepare high-Na-content P′3 birnessite with tunable exposed facets and provides important insights into developing highly stable layered cathodes for sustainable aqueous sodium-ion batteries.

中文翻译：

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通过 P′3 堆叠获得高 Na 含量的伯恩斯石，具有可调谐的有源刻面，用于先进的水系钠离子电池


层状 Na-birnesite 因其高理论容量、低成本和环境友好性而成为水系钠离子电池的正极材料。然而，一般的 O′3 Na-birnesite 具有低 Na 含量和主要的非活性{001}暴露的刻面，这损害了它们的 Na 储存能力和循环稳定性。在此，我们通过水热转化方法开发了一种高 Na 含量的 P′3-Na_0.71MnO₂·0.15H₂O，具有高度富集{010}活性刻面。与 O'3 Na-birnesite 相比，具有高 {010}/{001} 暴露面比率的 P'3 Na-birnessite 为 Na⁺ 扩散提供了大大增加的开放通道，而 P'3 堆叠提供了较低的 Na⁺ 扩散屏障，从而改善了电极动力学，在 0.2 A g^–1 下具有 176 mAh g^–1 的大比容量。更重要的是，P′3 Na-birnesite 在水性电解质中表现出单独的 Na⁺ 嵌入/去嵌入，具有非凡的循环稳定性，在 60,000 次循环后实现 90.5% 的容量保留。当与 NaTi₂（PO₄）₃ 负极耦合时，基于 P′3 钠钴石的全电池可提供高能量密度和长循环寿命，展示了在水系钠离子电池中的潜在应用。本研究展示了一种制备具有可调暴露面的高 Na 含量 P′3 钡石的有效方法，并为为开发用于可持续水系钠离子电池的高度稳定的层状阴极提供了重要见解。