Sodium‐ion batteries (SIBs) have drawn remarkable attention due to their low cost and the practically inexhaustible sodium sources. The major obstacle for the practical application of SIBs is the absence of suitable negative electrode materials with long cycling stability and high rate performance. Here, sulfur‐doped double‐shell sodium titanate (Na₂Ti₃O₇) microspheres constructed from 2D ultrathin nanosheets are synthesized via a templating route combined with a low‐temperature sulfurization process. The resulting double‐shell microspheres deliver a high specific capacity (≈222 mAh g⁻¹ at 1 C), excellent cycling stability (162 mAh g⁻¹ after 15 000 cycles at 20 C), and superior rate capability (122 mAh g⁻¹ at 50 C) as anode for SIBs. The improved electrochemical properties originate from synergistic effects between the unique double‐shell nanostructures built from 2D nanosheets architecture and sulfur doping. This synergistic effect not only stabilize Na₂Ti₃O₇‐based electrode during the cycling, but also improve the sluggish Na insertion/extraction kinetics by narrowing the bandgap of Na₂Ti₃O₇. The synthesis strategy proposed here can be developed into a technical rationale for generating high‐performance sodium‐storage devices.

中文翻译：

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通过硫掺杂促进二维二维超薄纳米片构建的双壳钛酸钠微球的钠存储

钠离子电池（SIB）的价格低廉，而且钠源几乎用不完，因此备受关注。SIB实际应用的主要障碍是缺乏合适的负极材料，其具有长的循环稳定性和高倍率性能。在这里，由二维超薄纳米片构建的掺硫双壳钛酸钠（Na ₂ Ti ₃ O ₇）微球是通过模板法结合低温硫化过程合成的。所得的双壳微球具有较高的比容量（在1 C下约为222 mAh g ^-1），出色的循环稳定性（在20 C下进行15 000次循环后为162 mAh g ^-1）和出色的倍率能力（122 mAh g）在50 C时为^-1）作为SIB的阳极。改善的电化学性能源自于由二维纳米片结构构建的独特双壳纳米结构与硫掺杂之间的协同效应。这种协同作用不仅可以在循环过程中稳定基于Na ₂ Ti ₃ O ₇的电极，还可以通过缩小Na ₂ Ti ₃ O ₇的带隙来改善缓慢的Na插入/引出动力学。此处提出的合成策略可以发展成为生成高性能钠存储设备的技术原理。