Dendrite‐free lithium and sodium metal anodes with deep plating/stripping properties for lithium and sodium batteries

Although lithium (Li) and sodium (Na) metals can be selected as the promising anode materials for next‐generation rechargeable batteries of high energy density, their practical applications are greatly restricted by the uncontrollable dendrite growth. Herein, a platinum (Pt)–copper (Cu) alloy‐coated Cu foam (Pt–Cu foam) is prepared and then used as the substrate for Li and Na metal anodes. Owing to the ultrarough morphology with a three‐dimensional porous structure and the quite large surface area as well as lithiophilicity and sodiophilicity, both Li and Na dendrite growths are significantly suppressed on the substrate. Moreover, during Li plating, the lithiated Pt atoms can dissolve into Li phase, leaving a lot of microsized holes on the substrate. During Na plating, although the sodiated Pt atoms cannot dissolve into Na phase, the sodiation of Pt atoms elevates many microsized blocks above the current collector. Either the holes or the voids on the surface of Pt–Cu foam what can be extra place for deposited alkali metal, what effectively relaxes the internal stress caused by the volume exchange during Li and Na plating/stripping. Therefore, the symmetric batteries of Li@Pt–Cu foam and Na@Pt–Cu foam have both achieved long‐term cycling stability even at ultrahigh areal capacity at 20 mAh cm−2. Pt–Cu foams improve the electrochemical properties of Li metal batteries due to the ultrarough morphology with a 3D porous structure and lithiophilic properties as well as quite‐large surface area.