Fe/amorphous SnO2 core–shell structured nanocapsules for microwave absorptive and electrochemical performance

Abstract

Fe nanocapsules with an Fe nanoparticle core and an amorphous SnO₂ shell have been synthesized by the modified arc discharge method. The microwave absorption properties and electrochemical performances of Fe/amorphous SnO₂ nanocapsules were investigated. The synergistic effect of magnetic loss in the Fe nanoparticles core and dielectric loss in the SnO₂ shell gave the Fe/SnO₂ nanocapsules excellent microwave absorption properties. The reflection loss (RL) value of the Fe/SnO₂ nanocapsule–paraffin composite is −39.2 dB at 16.8 GHz at the absorbent thickness of 2 mm and the absorption bandwidth with the RL below −20 dB is up to 10.6 GHz (from 7.4 to 18 GHz) for the absorber with the thickness of 2–3.8 mm. When evaluated as anode materials for lithium-ion batteries, the Fe/amorphous SnO₂ nanocapsules deliver an initial discharge of 1558.7 mA h g⁻¹ at 38 mA g⁻¹ and maintain a reversible capacity of 698.2 mA h g⁻¹ over 100 cycles, which is attributed to the amorphous SnO₂ nanoshell.