Fig. 1. Schematic illustration of the expected growth behavior of Li when plating on bare Cu foil and microspansule-modified Cu foil.

(A) Behavior of Li nucleation and dendrite growth during Li plating on bare Cu foil. (B) Upon Li plating on microspansule-modified Cu foil, the in situ formation of M layer derived from dissolved metal ions of microspansules can effectively guide dendrite-free Li deposition. Meanwhile, with the concurrent supply of fluoride ions, a steady and LiF-rich SEI is formed outside the plated Li, leading to a uniform distribution of Li⁺ ion flux and stable Li electroplating.