Exceptional lithium storage performance achieved by iron-based nanostructures upon extended high-rate cycling

Highlights: • Lithium storage performance of FeOOH NRs, Fe₂O₃ NTs and FeP NTs, investigated. • Lithiation induced activation in Fe-based nanostructures and excellent electrochemical cycling stability. • Upon cycling, the capacity of Fe-based nanostructures exceeded their theoretical values. • Very high specific capacity and exceptional rate capability is achieved. -- Abstract: Lithium storage performance of low-cost iron-based nanostructures including FeOOH nanorods (NRs) as well as Fe₂O₃ and FeP nanotubes (NTs) at high charge/discharge rates is comprehensively investigated. Although they show a low specific capacity at a rate of 1000 mA g⁻¹ in the beginning of cycling test, it is found that the specific capacity increases as the cycling proceeds, and can eventually reach an exceptionally high value of 1670, 1644 and 1897 mAh g⁻¹ for FeOOH NRs, Fe₂O₃ NTs and FeP NTs, respectively, after 1200 charge/discharge cycles. Moreover, even at a higher charge/discharge current density of 3000 mA g⁻¹, FeOOH NRs, Fe₂O₃ NTs and FeP NTs can still deliver an impressive specific capacity of 419.4, 459.7 and 603.4 mAh g⁻¹, respectively, upon 1400 charge/discharge cycles. The lithiation-induced activation process reported here offers a new perspective in designing high-performance anodes for long-lived lithium-ion batteries.