Modified surfaces on metal anodes for batteries can help resist formation of malfunction-inducing surface defects. The modification can include application of a protective nanocomposite coating that can inhibit formation of surface defects. such as dendrites, on the anode during charge/discharge cycles. For example, for anodes having a metal (M′), the protective coating can be characterized by products of chemical or electrochemical dissociation of a nanocomposite containing a polymer and an exfoliated compound (Ma′Mb″Xc). The metal, M′, comprises Li, Na, or Zn. The exfoliated compound comprises M′ among lamella of Mb″Xc, wherein M″ is Fe, Mo, Ta, W, or V, and X is S, O, or Se.