Li–Mg alloys are important because of their beneficial role in fostering uniform plating and stripping of lithium in all-solid-state batteries. The alloy LixMg1−x${\mathrm{Li}}_x{\mathrm{Mg}}_{1-x}$ forms a solid solution on the BCC crystal structure when the lithium content is greater than x ≈ 0.3. The activation barriers of lithium and magnesium exchanges with a vacancy, crucial for substitutional diffusion, are predicted to be exceptionally low and almost identical, with negligible dependence on the alloy composition. The equilibrium vacancy concentration at room temperature is predicted to be very low, and it also remains almost constant with no dependence on Mg content in the alloy (for xLi≥0.5$x_{\mathrm{Li}}\ge 0.5$). Nevertheless, both experiments and kinetic Monte Carlo simulations indicate that the tracer diffusion coefficients decrease by almost an order of magnitude with the addition of Mg to the alloy. In this contribution, the crucial role that chemical short-range order plays in affecting the diffusion coefficients is studied. Chemical short-range order is found to increase the effective activation barrier for lithium and magnesium diffusion by making successive atomic hops with vacancies correlated.

中文翻译：

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短程有序对 Li-Mg 合金扩散系数的影响


Li-Mg 合金很重要，因为它们在促进全固态电池中锂的均匀电镀和剥离方面发挥着有益的作用。当锂含量大于 x ≈ 0.3 时，合金 LixMg 1-x 在 BCC 晶体结构上形成固溶体。锂和镁交换的活化势垒与空位对取代扩散至关重要，预计极低且几乎相同，对合金成分的依赖性可以忽略不计。预计室温下的平衡空位浓度非常低，并且几乎保持恒定，不依赖于合金中的 Mg 含量（对于 xLi≥0.5）。尽管如此，实验和动力学蒙特卡洛模拟都表明，向合金中添加 Mg 后，示踪剂扩散系数几乎降低了一个数量级。在这篇文章中，研究了化学短程有序在影响扩散系数中起的关键作用。发现化学短程有序通过使具有空位的连续原子跃迁相关联来增加锂和镁扩散的有效活化屏障。