Microsized alloying particles have broad application prospects as anodes of high energy density batteries, but their fast charging and long cyclic stability are seriously affected by the sluggish bulk diffusivity, poor stress response and uncontrolled electrode/electrolyte interface. Herein, we develop a microsized Bi-Sn alloying particle model system with the engineered eutectic phase boundaries (PBs) that provide high energy density, fast charging capability, and long cyclic stability for sodium ion batteries (SIBs). PBs with spacious atomic misalignment can effectively promote the bulk diffusivity, which facilitates the fast ion diffusion. The asynchronous multi-step alloying mechanism induced by PBs can not only maintain the permanent alloying driving force of particles by releasing stress, but also improve the mechanical robustness and interface stability of particles by changing the process of structure evolution. The Bi6Sn4 anode delivers a fast charging capability of 407 mAh g−1 at 8 A g−1 (20C), comparable even to the reported nano-sized alloy anodes. The electrode can also achieve a high tap density of 2.1 g cm−3 and a volumetric capacity of 1226 mAh cm−3, indicating a practical potential. The present results offer insights into the fast charging and durability for high energy SIBs by PBs engineering of microsized alloying particles.

中文翻译：

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具有工程共晶相边界的微尺寸合金颗粒可实现快速充电和持久的钠储存


微尺寸合金颗粒作为高能量密度电池的负极具有广阔的应用前景，但其快速充电和长循环稳定性受到体扩散率缓慢、应力响应差和电极/电解质界面不受控制的影响。在此，我们开发了一种具有工程共晶相界 （PB） 的微型 Bi-Sn 合金颗粒模型系统，可为钠离子电池 （SIB） 提供高能量密度、快速充电能力和长循环稳定性。具有宽敞原子错位的 PBs 可以有效地促进体扩散率，从而促进离子的快速扩散。PBs诱导的异步多级合金化机制不仅可以通过释放应力来保持颗粒的永久合金化驱动力，还可以通过改变结构演变过程来提高颗粒的力学稳健性和界面稳定性。Bi6Sn4 阳极在 8 A g-1 （20C） 下提供 407 mAh g-1 的快速充电能力，甚至与已报道的纳米级合金阳极相当。该电极还可以实现 2.1 g cm-3 的高振实密度和 1226 mAh cm-3 的体积容量，表明具有实际潜力。目前的结果为微尺寸合金颗粒的 PBs 工程对高能 SIB 的快速充电和耐久性提供了见解。