In situ hybridization of α-Fe2O3 nanorods with a mesoporous carbon matrix for reversible lithium-ion batteries

Abstract

Carbon/metal oxide composites, particularly those with iron oxide nanostructures, have been extensively studied for lithium-ion batteries (LIBs) because of their substantial theoretical specific capacity. Nevertheless, achieving electrochemical stability over extended cycling continues to be a challenge, primarily due to issues related to electrode structure, including size, morphology, and aggregation. In this work, we employed an in situ hydrothermal method to control the growth of hematite nanorods achieving a diameter of 42 ± 5 nm and an aspect ratio of about 7 on mesoporous carbon featuring a surface area of about 1700 m².g⁻¹. We demonstrate that this approach facilitates hybridization between the iron oxide and carbonaceous matrix through C-O interfacial bonds. As a result, the resulting anode material, comprising approximately 50 % rhombohedral Fe₂O₃ nanorods, exhibits improved electrical conductivity, rapid electrochemical reactions, and enhanced cycling stability due to its hybrid microporous nanostructure. Moreover, this structure accommodates more lithium ions while reducing diffusion lengths and enlarging the electrolyte/electrode interface. This distinctive architecture promotes efficient electron transport and accommodates volume changes, yielding an initial discharge capacity of 735.82 mAh.g⁻¹ (0.1 C)—nearly twice compared to graphite (372 mAh g⁻¹) and around 50 % of α- Fe₂O₃ (1007 mAh g⁻¹) electrodes. After 100 charge-discharge cycles, the hybrid electrode maintains a capacity of 479.90 mAh.g⁻¹, demonstrating improved stability (∼65 %) compared to the pristine constituents. We propose that the controlled growth of metal oxides on mesoporous carbonaceous materials, along with surface hybridization, provides engineered anode materials for reversible LIBs.