3D Hierarchical Porous Cu-Based Composite Current Collector with Enhanced Ligaments for Notably Improved Cycle Stability of Sn Anode in Li-Ion Batteries

A 3D porous Cu current collector used in Li-ion batteries can improve the cycling performance of Sn anodes with high specific capacity because of the accommodation of large volume expansion by the pores. However, the pure Cu ligament is too soft to endure enough stress from volume expansion, and then it leads to the fast fade of capacity because of the formation of cracks or the collapse of the 3D porous structure. In this study, a novel micro-nano 3D hierarchical porous Cu-based composite current collector with enhanced ligaments has been fabricated by one-step dealloying of the Cu-34Zn-6Al (wt %) precursor and subsequent heat treatment. The pore and microstructure evolutions during dealloying and heat treatment have been studied by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. To confirm the validity of the 3D porous Cu/β/γ composite current collector, Sn has been directly electroless plated on it in comparison with the porous pure Cu and the common Cu foil. It is found that the Sn-coated 3D hierarchical porous Cu/β/γ composite current collector with higher hardness shows significantly improved cycling stability compared with the Sn-coated 3D porous Cu current collector and the planar copper foil.