The high theoretical capacity of Sb-based intermetallic alloys makes them attractive potential anode materials for sodium-ion batteries (SIBs) with high energy density. However, their cycling stability is greatly restricted by the huge volumetric variations resulted from the intrinsic (de-)alloying mechanism. Herein, we demonstrate a unique lattice softening mechanism, which enables highly reversible sodium storage and stable cycling of the as-prepared Bi-Sb alloy/carbon nanofibers electrodes. Theoretical analyses show that the elastic modulus of Bi-Sb alloys is reduced whereas the toughness is enhanced by tuning the lattice chemistry of rhombohedral Bi-Sb alloys, which is of great importance in relieving the concentrated stress during the continuous (de-)sodiation processes. In-situ characterization and electrochemical evaluations demonstrate that the electrodes made of BiSb₃/C nanofibers exhibit high anti-pulverization capability upon Na-cycling and extraordinary long-life cyclability. Specifically, a highly reversible capacity of 233.2 mAh g^–1 at 2 A g^–1 is achieved over 2500 cycles. Moreover, a full cell assembled with the pre-sodiated BiSb₃/C anode and a Na₃V₂(PO₄)₃/C cathode delivers a high reversible capacity of 333.2 mAh g^–1 at 0.2 A g^–1 over 200 cycles. This present work provides further understandings and new solution for developing high-performance alloying-based anodes for SIBs.

Sb基金属间合金的高理论容量使其成为具有高能量密度的钠离子电池（SIB）极具吸引力的潜在阳极材料。但是，它们的循环稳定性受到固有（脱合金）机理导致的巨大体积变化的极大限制。在这里，我们展示了一种独特的晶格软化机制，该机制能够实现高度可逆的钠存储，并使所制备的Bi-Sb合金/碳纳米纤维电极稳定循环。理论分析表明，通过调整菱形Bi-Sb合金的晶格化学，Bi-Sb合金的弹性模量降低，而韧性得到提高，这对于缓解连续（去）渗析过程中的集中应力非常重要。 。₃ / C纳米纤维在Na循环中显示出高抗粉化能力，并具有超长的循环寿命。具体而言，在2500次循环中，在2 A g ^–1时可实现233.2 mAh g ^–1的高度可逆容量。此外，将全电池与预先饱和的BiSb ₃ / C阳极和Na ₃ V ₂（PO ₄）₃ / C阴极组装在一起，可在200个循环中以0.2 A g ^–1提供333.2 mAh g ^–1的高可逆容量。。本工作为开发用于SIB的高性能合金基阳极提供了进一步的理解和新的解决方案。