Self-Assembled Nanoparticle Supertubes as Robust Platform for Revealing Long-Term, Multiscale Lithiation Evolution

Herein, free-standing supertubes, composed of a single layer of close-packed carbon-coated nanoparticles, are fabricated by a confined-epitaxial-assembly strategy. Benefiting from the tubular geometry, monolayer superlattice structure, and uniform and conformal carbon coating, such free-standing supertubes promise high electrochemical performance while simultaneously serving as a robust platform for reliably elucidating the structure-performance relationship of lithium-ion batteries (LIBs). As a model, Fe 3 O 4 supertubes, when used as LIB anodes, can deliver a capacity of ∼800 mAh g −1 after 500 cycles at 5 A g −1 , outperforming most Fe 3 O 4 -based materials reported previously. More importantly, the structural evolution of Fe 3 O 4 supertubes is revealed at meso-/nano-/atomic scales simultaneously upon lithiation and delithiation, which correlates well with the battery's capacity reactivation, stabilization, and degradation behaviors during the course of 500 cycles.