Mechanism of lithium dendrite growth on iron surfaces toward high-performance and safe anode-free lithium metal batteries

Abstract

Developing higher-energy-density and long-lifetime lithium-based batteries is essential for rapid energy delivery and recharging in emerging electric vehicles and grid energy-storage technologies. Anode-free lithium metal batteries (LMBs) possess an advanced cell configuration with only a bare anode metal foil current collector and no other negative electrode material that can maximize the energy density at the battery-pack level. However, capacity fading and operational safety risks caused by the formation of lithium (Li) dendrites impede the practical application of anode-free LMBs. Herein, we evaluated the growth of Li dendrites on an iron (Fe) substrate surface by performing a series of systematic molecular dynamics (MD) simulations based on the embedded-atom method (EAM) force field to investigate the effects of multiple surface morphologies on the Li atomic deposition and Li dendrite self-healing processes. The kinetics of Li dendrite growth on the atomic scale demonstrate that selecting the Fe(111) surface lattice orientation, reducing undesirable surface cracks, and controlling the surface nanogroove structures can be applied to effectively prevent the formation of irreversible Li dendrites on the surface of the Fe collector, resulting in better battery cell cycling. This work indicates that understanding the mechanism of Li growth on metal surfaces to search for an anode current collector that can significantly improve cell cycling stability is crucial for developing new anode-free LMBs.