Regulating the growth of lithium dendrite by coating an ultra-thin layer of gold on separator for improving the fast-charging ability of graphite anode

With the ever-growing application of lithium-ion batteries (LIBs), their fast-charging technology has attracted great interests of scientists. However, growth of lithium dendrites during fast charge of the batteries with high energy density may pose great threats to the operation and cause serious safety issues. Herein, we prepared a functional separator with an ultra-thin (20 nm) layer of Au nanoparticles deposited by evaporation coating method which could regulate growth direction and morphology of the lithium dendrites, owing to nearly zero overpotential of lithium meal nucleation on lithiated Au. Once the Li dendrites are about to form on the graphite anode during fast charging (or lithiation), they plate predominantly on the Au deposited separator rather than on the graphite. Such selective deposition does not compromise the electrochemical performance of batteries under normal cycling. More importantly, it enables the better cycling stability of batteries at fast charge condition. The Li/Graphite cells with Au nanoparticles coated separator could cycle stably with a high areal capacity retention of 90.5% over 95 cycles at the current density of 0.72 mA cm−2. The functional separator provides an effective strategy to adjust lithium plating position at fast charge to ensure high safety of batteries without a compromise on the energy density of LIBs.