The development of anode materials with high-rate capability is critical to high-power lithium batteries. T-Nb₂O₅ has been widely reported to exhibit pseudocapacitive behavior and fast lithium storage capability. However, the other polymorphs of Nb₂O₅ prepared at higher temperatures have the potential to achieve even higher specific capacity and tap density than T-Nb₂O₅, offering higher volumetric power and energy density. Here, micrometer-sized H-Nb₂O₅ with rich Wadsley planar defects (denoted as d-H-Nb₂O₅) is designed for fast lithium storage. The performance of H-Nb₂O₅ with local rearrangements of [NbO₆] octahedra blocks surpasses that of T-Nb₂O₅ in terms of specific capacity, rate capability, and stability. A wide range variation in the valence of niobium ions upon lithiation was observed for defective H-Nb₂O₅ via operando X-ray absorption spectroscopy. Operando extended X-ray absorption fine structure and ex situ Raman spectroscopy analyses reveal a large and reversible distortion of the structure in the two-phase region. Computation and ex situ X-ray diffraction analysis reveal that the shear structure expands along major lithium diffusion pathways and contracts in the direction perpendicular to the shear plane. Planar defects relieve strain through perpendicular arrangements of blocks, minimizing volume change and enhancing structural stability. In addition, strong Li adsorption on planar defects enlarges intercalation capacity. Different from nanostructure engineering, our strategy to modify the planar defects in the bulk phase can effectively improve the intrinsic properties. The findings in this work offer new insights into the design of fast Li-ion storage materials in micrometer sizes through defect engineering, and the strategy is applicable to the material discovery for other energy-related applications.

中文翻译：

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用于大功率锂离子电池的具有剪切结构和平面缺陷的铌氧化物

开发具有高倍率能力的负极材料对于大功率锂电池至关重要。据报道，T-Nb ₂ O ₅表现出赝电容行为和快速的锂存储能力。然而，在更高温度下制备的 Nb ₂ O ₅的其他多晶型物有可能实现比 T-Nb ₂ O ₅更高的比容量和振实密度，从而提供更高的体积功率和能量密度。在这里，具有丰富的 Wadsley 平面缺陷（表示为 dH-Nb ₂ O ₅）的微米级 H-Nb ₂ O ₅设计用于快速锂存储。H-Nb的性能₂ ø ₅与本地重排[NbO的₆ ]八面体块赶超该T-的Nb ₂ Ó ₅中的比容量，倍率性能和稳定性方面。通过操作X 射线吸收光谱观察到有缺陷的 H-Nb ₂ O ₅ 锂化时铌离子的化合价有很大范围的变化。Operando扩展 X 射线吸收精细结构和非原位拉曼光谱分析揭示了两相区域中结构的大且可逆的畸变。计算和异地X 射线衍射分析表明，剪切结构沿主要的锂扩散路径扩展，并在垂直于剪切平面的方向上收缩。平面缺陷通过块的垂直排列来缓解应变，最大限度地减少体积变化并增强结构稳定性。此外，平面缺陷上强烈的锂吸附扩大了嵌入能力。与纳米结构工程不同，我们修改体相平面缺陷的策略可以有效地改善本征性质。这项工作的发现为通过缺陷工程设计微米尺寸的快速锂离子存储材料提供了新的见解，该策略适用于其他能源相关应用的材料发现。