Abstract Sn-based anodes are potential replacements for commercial carbon-based lithium-ion battery anodes. Moreover, alloying with Cu improves the cyclability of Sn. This study directly grows Cu6Sn5 crystals on polycrystalline Cu current collectors via a solid-liquid reaction with molten Sn alloys. The Cu6Sn5 crystals grown when a molten Sn-Cu alloy was used have a preferred orientation along the η-Cu6Sn5 (101). In this study, the crystals are tailored to grow along the η-Cu6Sn5 (2-12) preferred orientation by excluding Cu in the molten Sn alloy used as a starting material. The (2-12) oriented electrodes show significantly improved electrochemical properties, displaying a 50th cycle discharge capacity of 762 mAh g-1, a 55% increase over the (101) electrode under the same cycling conditions. The (101) electrode ceased to function at 1C and above, while the (2-12) electrode retained around 480 mAh g-1 at 2C. In addition, the (101) electrode shows the formation of 3-fold superstructures in the crystal lattice; while the (2-12) electrode shows atomic arrangements of a higher crystal symmetry, further facilitating the transportation of Li-ions. Density functional theory calculations confirm that Li-ions prefer to adsorb onto Sn in η-Cu6Sn5 and diffuse through the structure in a zig-zag pattern along the [111] channels with a low barrier energy of 0.705 eV.

中文翻译：

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具有定制晶体取向和有序原子排列的电化学增强型 Cu6Sn5 阳极，用于锂离子电池应用

摘要 Sn 基负极是商用碳基锂离子电池负极的潜在替代品。此外，与Cu合金化提高了Sn的循环性能。本研究通过与熔融 Sn 合金的固液反应，在多晶 Cu 集流体上直接生长 Cu6Sn5 晶体。使用熔融 Sn-Cu 合金时生长的 Cu6Sn5 晶体具有沿 η-Cu6Sn5 (101) 的择优取向。在这项研究中，通过排除用作起始材料的熔融 Sn 合金中的 Cu，晶体被调整为沿着 η-Cu6Sn5 (2-12) 择优取向生长。(2-12) 取向电极显示出显着改善的电化学性能，第 50 次循环放电容量为 762 mAh g-1，在相同循环条件下比 (101) 电极增加 55%。(101) 电极在 1C 及以上停止工作，而 (2-12) 电极在 2C 时保持约 480 mAh g-1。此外，（101）电极在晶格中形成了3重超结构；而（2-12）电极显示出更高晶体对称性的原子排列，进一步促进了锂离子的传输。密度泛函理论计算证实，锂离子更喜欢吸附在 η-Cu6Sn5 中的 Sn 上，并以 0.705 eV 的低势垒能量沿着 [111] 通道以锯齿形图案扩散通过结构。