A three-dimensional hierarchical structure of cyclized-PAN/Si/Ni for mechanically stable silicon anodes

The main challenges associated with silicon anodes are their poor conductivity and severe structural degradation during cycling. Here we design a three-dimensional sandwich hierarchical structure that tackles these problems, and we demonstrate its use in flexible, large-area silicon anode assemblies. The design of the electrode is achieved via plasma enhanced chemical vapor deposition of silicon nanoparticles onto three-dimensional nickel foam followed by conformal coating of cyclized-PAN on the silicon surface, thus forming a sandwiched cyclized-PAN/Si/Ni hierarchical structure. The three-dimensional networks provide abundant electroactive zones and conductive transport paths, the conformal coating of cyclized-PAN accommodates volume change during cycling, and the monolithic electrode configuration without additional binders or conductive agents improves the energy density of the whole electrode. Furthermore, as a result of the sandwich hierarchical arrangement, the solid-electrolyte interface of the anode remains stable and spatially confined, leading to an increased reversible capacity and improved cycling stability (910 mA h g^-1 after 100 cycles at 1.0 A g^-1).