A continuous vapor de-alloying strategy for a hundred-gram scale fabrication of silicene is developed by etching CaSi2 using waste polyvinyl chloride (PVC). The as-obtained few-layered silicene can be readily assembled with carbon nanotubes into flexible electrodes for lithium storage with excellent performance, which stably deliver a high capacity and stability. This strategy can be extended to other silicon analogs with various structures by selecting precursors such as Mg2Si and Al/Si alloy.