Enhanced Stability of Lithium Metal Anode by using a 3D Porous Nickel Substrate

Lithium (Li) metal is considered as the holy grail anode for high energy density batteries, but its applications in rechargeable Li metal batteries are still hindered by the formation of Li dendrites and low coulombic efficiency for Li plating/stripping. An effective strategy to stabilize Li metal is to embed a Li metal anode in a three-dimensional (3D) current collector. Here, a highly porous 3D Ni substrate is reported to effectively stabilize a Li metal anode. By using a galvanostatic intermittent titration technique combined with scanning electron microscopy, the underlying mechanism of the improved stability of the Li metal anode is revealed. It is clearly demonstrated that the porous 3D Ni substrate can effectively suppress the formation of dead Li and support the generation of a dense surface passivation layer, while a highly porous dead Li layer is accumulated on the two-dimensional (2D) Li metal, which eventually limits mass transport. X-ray photoelectron spectroscopy results further reveal the compositional differences in the solid-electrolyte interphase layer formed on the Li metal embedded in the porous 3D Ni substrate and the 2D Li metal substrate. These results indicate that the use of 3D conductive host is critical for the long-term stability of Li metal batteries.