Gradient electrospinning and controlled pyrolysis derived Fe_xO_y@N-doped carbon nanorods towards enhanced lithium storage

The rational structural design of the anode material plays a vital role in the performance of lithium-ion batteries (LIBs). Herein, a novel one-dimensional carbon based anode material, consisting of ultra-fine hollow Fe_xO_y nanoparticles (NPs) uniformly anchored on the porous N-doped carbon nanorods (donated as Fe_xO_y@PN-CNR) has been fabricated via electrospinning technique combined with controlled pyrolysis. Under the Kirkendall-type diffusion, Fe₃C is transformed into hollow Fe_xO_y NPs. This unique structure could effectively prevent the aggregation, dissolution, and pulverization of iron oxide NPs, maintaining the structural integrity of the electrode. Additionally, it also provides a connected hierarchical conducting network with doped N for electron transport and offers abundant accessible porous channels for fast Li⁺ diffusion. As a consequence, the resulting Fe_xO_y@PN-CNR composite delivers an ultra-high reversible specific capacity of 1198.6 mA h g⁻¹ at 1000 mA g⁻¹ over 100 cycles as anode in LIBs. Remarkably, a stable cycle life (800 mA h g⁻¹ after 200 cycles with a nearly 100% coulombic efficiency) can be obtained even at a large rate of 5000 mA g⁻¹. The present study provides a promising strategy for the construction of nanostructured anode materials toward prominent electrochemical performance of LIBs.