Guiding Smooth Li Plating and Stripping by a Spherical Island Model for Lithium Metal Anodes.

Lithium metal anodes are considered as promising candidates for next-generation high-energy-density batteries. However, the dendrite formation of Li metal anodes during charge-discharge results in some serious issues. Herein, we show a simple way to flatten the Li metal deposition surface on Ag-modified Cu foil using a spherical island model. In this model, Ag nuclei induce the deposition of Li atoms with low nucleation potentials at the initial heterogeneous nucleation stage. Then, Li homogeneously grows around the spherical islands and these regular islands overlap each other and form a flat Li surface. On the bare Cu foil surface, the Li growth behavior is random, and the deposition surface is porous and covered with dendrites. Stable long-term plating/stripping of a symmetric battery over 800 h at 1 mA cm was achieved. Moreover, the super flat Li structure can be achieved by constructing islands into a three-dimensional (3D) current collector using the spherical island model. Benefiting from the spherical island model, Li||LiFePO and Li||O batteries with this 3D anode structure can obtain a stable performance.