Electrochemical and Computational Insights into Lithium Nucleation at Ni(111) and Cu(111) Surfaces for Anode-free Li-metal Batteries

Abstract

The high energy density of anode-free Li-metal batteries (AFLMBs) stems from eliminating the graphite anode, allowing lithium (Li) to be directly electrodeposited onto the current collector during charging. Although copper (Cu) foil is widely employed as a current collector, it often experiences Li dendritic growth, which can cause system failures. Nickel (Ni) foil is a promising alternative as a current collector, meeting the general requirements; however, the in-depth behaviour of Li deposition on Ni remains unclear. Here, we compare the initial stages of Li deposition on model Cu(111) and Ni(111) single crystals by calculating the apparent rate coefficients of Li deposition (k app (t,E)). In addition, we apply density functional theory (DFT) calculations to clarify the experimentally observed trends in kinetic parameters. Our results reveal that the overall k app (t,E) on Ni(111) are lower than on Cu(111) with a decreasing trend with increasing overpotential and deposition time. Further, we show that Ni(111) exhibits higher lithiophilicity than Cu(111) as the adsorption energy on the former is lower (more negative values), while maintaining a similar surface diffusion barrier. A subsequent second layer Li deposition is theoretically examined to have higher adsorption energy on Ni(111) than on Cu(111) for dense configurations, which can facilitate lateral diffusion of Li adatoms, leading to smoother Li growth as shown experimentally. What is more, we show Ni(111) exhibits a higher corrosion resistance, rendering it a preferred material choice as a current collector.