A Hybrid Bilayer Design to Control Lithium Nucleation and Dendrite Growth in Lithium Metal Batteries

Lithium metal batteries have gained renewed attention after a recent surge in high-energy battery systems. Lithium metal, known for its exceptional specific capacity and voltage, suffers from dendrite formation, which affects the cell performance and poses a severe safety threat, like internal short circuits and thermal runaway. Artificial solid electrolyte (ASEI) has emerged as an effective strategy to guide uniform lithium deposition, but only a few studies have explored the correlation between the interfacial kinetics and the nucleation behavior at the molecular level. In our work, we developed an inorganic-organic hybrid bilayer protective coating on the lithium anode, enabling over 1000 h of Li/Li symmetric cell cycling at 0.5 mA/cm2 (0.5 mAh/cm2) with low overpotentials. The impact of this bilayer on the nucleation behavior has been addressed using chronoamperometric studies and a modified SEI model based on S-H classical nucleation. Ab initio molecular dynamics (AIMD) simulations revealed the role of bilayer components in homogenizing the lithium flux by decreasing the coordination number of lithium ions and promoting lateral growth. These led to a relatively uniform lithium deposition morphology with better capacity retention of more than 80% after 80 cycles for protected lithium (p-Li)/NMC-622 half-cells cycled at 1.7 C with a high loading of 23 mg/cm2. Our findings establish the importance of interface engineering in controlling the nucleation kinetics of lithium deposition for the development of high-voltage lithium metal batteries.