Lithium Storage in Bowl-like Carbon: The Effect of Surface Curvature and Space Geometry on Li Metal Deposition

Dendrite growth severely hinders the practical use of lithium metal as an ideal battery anode. To realize controlled Li plating, tremendous efforts have been focused on modifying the lithiophilicity chemistry of the anode hosts. Instead, we attempt to address this issue from a geometry perspective. We herein adopt carbon nanobowls (CBs) as a model host to study the geometry-guided Li growth behaviors by in situ electron microscopy. The strong effect of surface curvature is clearly demonstrated: Li metal is always guided to deposit on the concave surface of an isolated CB instead of the convex surface. The fully confined hollow cavity is more favorable for Li deposition in comparison to the partially confined spaces, such as the hemispherical concavity of a CB and interstitial voids between neighboring CBs. Density functional theory calculations elucidate that the geometry-guided Li growth is driven by the energy minimization associated with the formation of low-energy Li/C interfaces.