Grain boundary optimization in Li–Mg alloy anodes via controlled cooling rates and cold rolling,Journal of Materials Chemistry A

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Grain boundary optimization in Li–Mg alloy anodes via controlled cooling rates and cold rolling
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2024-09-06 , DOI: 10.1039/d4ta02636e
Chae Yeon Yeom ₁ , Woo Seok Choi ₁ , Seung Ho Lee ₁ , Sin Hyong Joo ₁ , Jong Hoon Kim ₂ , Jong Hyeon Lee _{1,

3}

Affiliation

The commercialization of Li-metal batteries is primarily hindered by the poor stability and safety risks associated with the use of Li-metal anodes. As an alternative, research is being conducted to improve the stability of anodes using Li–Mg alloys. However, after Li stripping, Li-poor Li–Mg alloys lower the usability of Li; moreover, the mechanism by which the cycling characteristics improve when the grain boundary density increases remains obscure. In this study, we controlled the grain size of Li–Mg alloys by adjusting the cold rolling and solidification rates, and investigated the effect of grain boundaries on the deposition and stripping characteristics of Li⁺ ions. Thus, an Li-rich Li–Mg phase was formed at the grain boundaries when casting Li–Mg alloys. As the grain boundary density increased, more sites with preferential Li⁺ deposition and stripping were observed, leading to a reduction in the overpotential and improved cycling characteristics. An optimized grain size was discovered through symmetric cell tests of the Li–Mg alloys with various grain sizes ranging from 7 to 298 μm, and a superior cycling performance of up to 1500 h (375 cycles) was achieved at the optimal grain size. These results are expected to provide an important foundation for the development of stable and safe Li-metal anodes using Li–Mg alloys.

中文翻译：

通过控制冷却速率和冷轧优化锂镁合金阳极的晶界

锂金属电池的商业化主要受到与使用锂金属负极相关的稳定性差和安全风险的阻碍。作为替代方案，正在进行研究以提高使用锂镁合金的阳极的稳定性。然而，脱锂后，贫锂锂镁合金降低了锂的可用性；此外，当晶界密度增加时循环特性改善的机制仍然不清楚。在本研究中，我们通过调节冷轧和凝固速率来控制Li-Mg合金的晶粒尺寸，并研究了晶界对Li ⁺离子沉积和剥离特性的影响。因此，在铸造Li-Mg合金时，在晶界处形成了富Li的Li-Mg相。随着晶界密度的增加，观察到更多的Li ⁺优先沉积和剥离位点，导致过电势降低并改善循环特性。通过对各种晶粒尺寸范围为 7 至 298 μm 的锂镁合金进行对称电池测试，发现了优化的晶粒尺寸，并且在最佳晶粒尺寸下实现了高达 1500 小时（375 个循环）的优异循环性能。这些结果有望为使用锂镁合金开发稳定、安全的锂金属负极提供重要基础。

更新日期：2024-09-11

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