From 0D to 3D: Hierarchical structured high-performance free-standing silicon anodes based on binder-induced topological network architecture

Abstract

Free-standing silicon anodes with high proportion of active materials have aroused great attention; however, the mechanical stability and electrochemical performance are severely suppressed. Herein, to resolve the appeal issues, a free-standing anode with a “corrugated paper” shape on micro-scale and a topological crosslinking network on the submicron and nano-scale is designed. Essentially, an integrated three-dimensional electrode structure is constructed based on robust carbon nanotubes network with firmly anchored SiNPs via forming interlocking junctions. In which, the hierarchical interlocking structure is achieved by directional induction of the binder, which ensures well integration during cycling so that significantly enhances mechanical stability as well as electronic and ionic conductivity of electrodes. Benefiting from it, this anode exhibits outstanding performance under harsh service conditions including high Si loading, ultrahigh areal capacity (33.2 mA h cm−2), and high/low temperatures (−15–60 °C), which significantly extends its practical prospect. Furthermore, the optimization mechanism of this electrode is explored to verify the crack-healing and structure-integration maintaining along cycling via a unique self-stabilization process. Thus, from both the fundamental and engineering views, this strategy offers a promising path to produce high-performance free-standing electrodes for flexible device applications especially facing volume effect challenges.