Large-Scale Porous Hematite Nanorod Arrays: Direct Growth on Titanium Foil and Reversible Lithium Storage

Abstract

Porous single-crystalline hematite (α-Fe 2 O 3 ) nanorod array has been synthesized on large-area Ti foil via a facile hydrothermal method followed by a simple annealing treatment in Ar gas at 450 °C. The nanorods attained from 6 h hydrothermal reaction are average 30 nm in diameter and 450 nm in length. When used directly as additive-free anode for lithium ion batteries (LIBs), the α-Fe 2 O 3 nanorod array demonstrates excellent cycling performance up to 50 times (∼562 mAh g −1 retained at C/5) and good rate capability, in distinct contrast to α-Fe 2 O 3 nanorod powder-based electrode. The improved electrochemical performance could be ascribed to the enhanced electron transport and Li + diffusion that result from the well-defined array architecture and the porous nature of the single-crystalline nanorods. Fe 3 O 4 and C/α-Fe 2 O 3 nanorod arrays are further prepared to improve the lithium storage property. Our work represents a successful example of fabricating iron oxide 1D nanostructure arrays directly on nonreactive current collector. Once optimized, the array electrode may hold great promise in thin-film LIBs and other microelectronic systems.