Electrochemical performances of Sn anode electrodeposited on porous Cu foam for Li-ion batteries

A three-dimensional Sn electrode is fabricated by the electrodeposition of Sn on a porous Cu foam substrate that consists of grape-like Cu nanodeposits. It is revealed from the XRD results that a small amount of Cu ₆Sn ₅ is formed at the interface of Sn deposits and the Cu foam, thereby forming Sn-Cu ₆Sn ₅/Cu foam electrode. The electrode shows better cyclic performance and higher charge capacity than the Sn electrode electrodeposited on a smooth Cu foil does. The improved electrochemical performances of the Sn-Cu ₆Sn ₅/Cu foam electrode is due to the fact that the porous Cu foam accommodates the volumetric expansion of Sn-Cu ₆Sn ₅, and hence inhibits the pulverization or delamination of the active materials from the substrate. Furthermore, ex situ XRD analysis and SEM observation demonstrate that Sn deposits electrodeposited on the Cu foam are gradually blended with the Cu deposits, causing the transformation of Sn into Cu ₆Sn ₅. The phase transformation of Sn into Cu ₆Sn ₅ enhances the bonding force between the Sn and the Cu foam, and reducing the volume changes of active materials during cycling.