Long lifespan lithium metal anodes enabled by Al2O3 sputter coating

Abstract Lithium metal is a Holy Grail anode for high energy density lithium ion batteries. While, its high chemical reactivity and high tendency to form dendrites hinder its wide applications. Here, in this study, we stabilize lithium metal by engineering an artificial SEI layer, namely fabricating a conformal nano-meter thickness amorphous Al2O3 thin film via magnetron sputtering technique on its surface. The obtained Al2O3 modified Li metals present robust chemical surface stability and effectively restrain the dendrite growth. 20 nm-thick Al2O3 film modified lithium metal in an all-solid-state battery Li/PEO-LiTFSI/Li ensures a cycle life of 660 h at a current density of 0.1 mA/cm2. Contradicting to a traditional belief of lithium plating at the current collector side via crossing the Al2O3 film, it directly plates on the Al2O3 film next to the separator side. Al2O3 film plays a crucial role as a “surfactant” in inducing a layer-by-layer film growth mode.