PDF(Pubmed)
Abstract：
Lithium stripping is a crucial process coupled with lithium deposition during the cycling of Li metal batteries. Lithium deposition has been widely studied, whereas stripping as a subsurface process has rarely been investigated. Here we reveal the fundamental mechanism of stripping on lithium by visualizing the interface between stripped lithium and the solid electrolyte interphase (SEI). We observed nanovoids formed between lithium and the SEI layer after stripping, which are attributed to the accumulation of lithium metal vacancies. High-rate dissolution of lithium causes vigorous growth and subsequent aggregation of voids, followed by the collapse of the SEI layer, i.e., pitting. We systematically measured the lithium polarization behavior during stripping and find that the lithium cation diffusion through the SEI layer is the rate-determining step. Nonuniform sites on typical lithium surfaces, such as grain boundaries and slip lines, greatly accelerated the local dissolution of lithium. The deeper understanding of this buried interface stripping process provides beneficial clues for future lithium anode and electrolyte design.
摘要：
锂剥离是在Li金属电池循环期间与锂沉积结合的关键过程。锂沉积已被广泛研究，而剥离作为地下过程很少被研究。在这里，我们通过可视化剥离的锂与固体电解质界面（SEI）之间的界面来揭示锂剥离的基本机理。我们观察到剥离后锂和SEI层之间形成的纳米空隙，这归因于锂金属空位的积累。锂的高速溶解导致剧烈生长和随后的空隙聚集，接着是SEI层的坍塌，即，点蚀。我们系统地测量了剥离过程中的锂极化行为，发现锂阳离子通过SEI层的扩散是速率决定步骤。典型锂表面上的不均匀位点，如晶界和滑移线，大大加速了锂的局部溶解。对这种掩埋界面剥离过程的更深入了解为未来的锂阳极和电解质设计提供了有益的线索。
