Soft-templated synthesis of core–shell heterostructured Ni3S2@polypyrrole nanotube aerogels as anode materials for high-performance lithium ion batteries

Building additional functionality into self-assembled conductive polymer nanotubes with high electrical conductivity, fast charge/discharge capability, and high mechanical strength is of great interest for energy storage materials and applications. Well-defined core–shell heterostructured Ni3S2@polypyrrole (Ni3S2@PPy) nanotube aerogels, hollow polypyrrole nanotubes wrapped by uniform Ni3S2 layers, were fabricated via a facile two-step process, chemical oxidative polymerization assisted by a lithocholic acid soft-template and a biomolecule-assisted hydrothermal process. With the unique core–shell nanotube network structure, the PPy nanotubes would offer the largest surface area, short paths for Li+ diffusion and numerous active sites, while the PPy nanotube matrix would prefer fast charge transportation and buffer the volume change of Ni3S2 during lithiation/delithiation processes. When directly used as an anode material for lithium-ion batteries, the as-prepared core–shell heterostructured Ni3S2@PPy nanotube aerogel electrode exhibits high reversible capacity, good rate capability, and improved cycling stability. A reversible capacity of 645.4 mA h g−1 is sustained at a current density of 100 mA g−1 after 1000 cycles, showing better cycling stability than the Ni3S2 powder pasted electrode. The low densities, large surface areas, and three-dimensional network features of the resulting Ni3S2@PPy nanotube aerogels render them attractive for potential energy conversion/storage devices.