Superior lithium storage properties of Fe₂(MoO₄)₃/MWCNT composite with a nanoparticle (0D)–nanorod (1D) hetero-dimensional morphology

Synthesis of nanostructures with pre-designed morphology has recently gained tremendous research attention for achieving enhanced performance. Herein, we report synthesis of hetero-dimensional hybrid nanostructure of Fe₂(MoO₄)₃ consisting of nanorods (length 90–170 nm, dia ∼30 nm) in which spherical nanoparticles (dia 5–10 nm) are embedded. We also report the electrochemical properties of synergic Fe₂(MoO₄)₃/MWCNT composites as lithium-ion battery anode for the first time. Here, 1D Fe₂(MoO₄)₃ nanorods serve as a strain accommodative matrix imparting stability while the entrenched 0D Fe₂(MoO₄)₃ nanoparticles offer a large number of active sites yielding high capacity. Due to high surface to volume ratio of the composites, the Li⁺ ion diffusion length is shortened leading to a faster kinetics and improved the rate performance. Moreover, MWCNT provides an effective conduction network for electron transport during lithiation/delithiation process and at the same time, serves as a strain-buffer preserving mechanical integrity of the composite electrode. This three-way strategy results in a specific capacity of 1321 mAh g⁻¹ for a 50:50 wt% composite of Fe₂(MoO₄)₃ and MWCNT. Even at a high current density of 1.0 mA cm⁻² (1200 mA g⁻¹), capacity of 600 mAh g⁻¹ could be obtained. Further, 82% retention of capacity is observed after 200 cycles at 0.1 mA cm⁻². Importantly, no appreciable change in morphology is observed with discharge-charge cycling.