Li metal coated with amorphous Li3PO4 via magnetron sputtering for stable and long-cycle life lithium metal batteries

Lithium metal with high theoretical capacity (3860 mAh/g) and low operational voltage (−3.04 V vs. standard hydrogen electrode) reflects to be one of the most high energy density anodes for energy storage devices. While, its high chemical activity to continuously react with electrolytes causing low coulombic efficiency and formation of lithium dendrites leading safety concern limits practical applications. To conquer these challenges, amorphous Li 3 PO 4 thin films with thickness of 0–200 nm are directly coated on the surface of Li metal foil via magnetron sputtering . The as-prepared Li 3 PO 4 has almost insulated property with electronic conductivity of 1.4 × 10 −10  S/cm and ionic conductivity of 2.8 × 10 −8  S/cm. The conformal coating layer Li 3 PO 4 can successfully suppress the lithium dendrites growth and improve its life span. The remarkable improvements of the Li 3 PO 4 -coated Li electrodes are mainly attributed to high chemical stability as well as amorphous nature of Li 3 PO 4 , which leads layer-by-layer growth Li film rather than islands form dendrites.