Robust 3D nanowebs assembled from interconnected and sandwich-like C@Fe3O4@C coaxial nanocables for enhanced Li-ion storage

An ideal electrode material of Li-ion batteries (LIBs) is expected to not only involve nanoscale subunits, but also possess a stable 3D porous hierarchical microstructure. Herein, a green and bottom-up approach is developed for fabricating robust 3D nanowebs assembled from interlinked and sandwich-like carbon@Fe3O4@carbon coaxial nanocables. The uniform growth of iron oxide precursors on carbon substrates is achieved with the assistance of a layer-by-layer assembled polyelectrolyte, which is demonstrated to be a strategy applicable to the preparation of various carbon-based functional composites. The carbon components of the hybrid materials are in situ doped with nitrogen due to the utilization of nitrogen-containing polymers as carbon sources. In such rationally nanoengineered materials, the 3D nitrogen-doped carbon nanowebs can provide a continuous pathway for electron transport, reduce the diffusion length of Li-ions, and improve the structural integrity and stability of the whole electrode. Accordingly, the obtained materials exhibit impressive Li-storage properties including high capacity, long cycle life, and superior rate performance.