Field-Responsive Dynamic Monolayer Regulated Interphase for Enhanced Lithium Metal Batteries.

Lithium metal batteries offer high energy density but suffer from persistent interphase instability, where continuous corrosion, solid electrolyte interphase (SEI) growth and poor lithium deposition morphology remain key barriers to long cycle and calendar life. Here, we introduce a novel concept of dynamic monolayers on Li metal anodes, consisting of electric field-responsive molecules that assemble into packed, structured layers at the lithium interphase under an applied voltage. We employed electrochemical quartz crystal microbalance with dissipation monitoring for in situ verification of the field responsiveness and packing behavior of these molecules. Dynamic monolayers with stronger packing are found to promote more inorganic-rich SEI and chunkier lithium growth, as directly observed by cryogenic X-ray photoelectron spectroscopy and operando optical microscopy. Together, these interfacial improvements translate into enhanced Coulombic Efficiency, reduced overpotential, and improved long-term cycling stability across Li||Cu, Li||Li, ultrathin lithium (20 μm) and anode-free NMC811 configurations. Dynamic monolayers potentially provide a broadly applicable approach for tackling interfacial challenges across a range of alkali metal battery systems.