Long lifespan lithium metal anodes enabled by Al2O3 sputter coating

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 Al 2 O 3 thin film via magnetron sputtering technique on its surface. The obtained Al 2 O 3 modified Li metals present robust chemical surface stability and effectively restrain the dendrite growth. 20   nm-thick Al 2 O 3 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/cm 2 . Contradicting to a traditional belief of lithium plating at the current collector side via crossing the Al 2 O 3 film, it directly plates on the Al 2 O 3 film next to the separator side. Al 2 O 3 film plays a crucial role as a “surfactant” in inducing a layer-by-layer film growth mode.