In situ construction of amorphous hierarchical iron oxyhydroxide nanotubes via selective dissolution-regrowth strategy for enhanced lithium storage

The low-cost and high-capacity metal oxides/oxyhydroxides possess great merits as anodes for lithium-ion batteries (LIBs) with high energy density. However, their commercialization is greatly hindered by insufficient rate capability and cyclability. Rational regulations of metal oxides/oxyhydroxides with hollow geometry and disordered atomic frameworks represent efficient ways to improve their electrochemical properties. Herein, we propose a fast alkalietching method to realize the in-situ fabrication of iron oxyhydroxide with one-dimensional (1D) hierarchical hollow nanostructure and amorphous atomic structure from the iron vanadate nanowires. Benefiting from the improved electron/ ion kinetics and efficient buffer ability for the volumetric change during the electro-cycles both in nanoscale and atomic level, the graphene-modified amorphous hierarchical FeOOH nanotubes (FeOOH-NTs) display high rate capability (similar to 650 mA h g(-1) at 2000 mA g(-1)) and superior long-term cycling stability (463 mA h g(-1) after 1800 cycles), which represents the best cycling performance among the reported FeOOH-based materials. More importantly, the selective dissolutionregrowth mechanism is demonstrated based on the time tracking of the whole transition process, in which the dissolution of FeVO4 and the in-situ selective re-nucleation of FeOOH during the formation of FeOOH-NTs play the key roles. The present strategy is also a general method to prepare various metal (such as Fe, Mn, Co, and Cu) oxides/oxyhydroxides with 1D hierarchical nanostructures.