Refining grains and optimizing grain boundaries by Al2Yb to enable a dendrite-free lithium anode

Abstract

Effective lithium (Li) metal alloying in adjusting its crystallization process offers a reliable approach to refine the grain size and alter the grain boundary composition, consequently enhancing its stripping/plating behavior. Key requisites for the alloying composition include a high melting point, which aids in heterogeneous nucleation of lithium metal, and a robust adsorption of lithium ions. Using the Bramfitt equation as a basis, this study demonstrates that Al₂Yb facilitates heterogeneous nucleation with Li, leading to grain refinement and an increase in active sites. Al₂Yb's superior adsorption energy compared to Li is noteworthy, enabling the dense deposition of lithium ions on the electrode surface, forming a flat surface that effectively suppresses side reactions. Consequently, the Li–3Al–1Yb electrode exhibits exceptional material structural stability, electrochemical cycling stability, and rate performance in various cell configurations, including Li–Li symmetrical coin cells, Li‖NCM811 cells, and pouch cells. This investigation not only offers insights into addressing challenges related to dendrite growth in metal lithium but also contributes to the improvement of both electrochemical and mechanical properties.