Quantitative Understanding on Lithium Nucleation Process to Unveil the Performance-Limiting Interfaces

Quantitatively understanding the lithium (Li) nucleation and growth process is crucial for optimizing the performance of lithium metal batteries. Here we investigate the roles of two interfaces within the Li nucleation process: Li/electrolyte (SEI) and Li/substrate. With a theoretical description that describes the nucleation process, we identify which of the two interfaces controls Li nucleation for different electrolytes and substrates. Different SEI properties leads to SEI-controlled vs., Substrate-controlled Li nucleation. For substrate-controlled nucleation, we derive a math model that elucidates the requirement for a substrate to promote uniform dendrite-free Li nucleation. We also reveal that Li nucleation modes have a strong impact on Li plating/stripping reversibility. Simultaneous fast transport through the SEI and fast Li adatom movement on the substrate are essential for achieving dense Li deposition and long-cycle life lithium metal batteries.