Regulating bifunctional flower-like NiFe₂O₄/graphene for green EMI shielding and lithium ion storage

Environment and energy are the eternal hot topics in the world, multiloculated microscale materials have attracted great attention in the field of electromagnetic interference (EMI) shielding and lithium ions storage. Herein, a novel flower-like NiFe₂O₄/graphene composite with adjustable structure was fabricated as EMI shielding material and anode material of lithium-ion batteries. NiFe₂O₄/graphene composite is a potential green EMI shielding material. The EMI shielding effectiveness (SE) increases with the increase of graphene content in NiFe₂O₄/graphene composite, and the total EMI SE of NiFe₂O₄/graphene with 73.6 wt.% graphene increases from 26.5 to 40.6 dB with the increase of frequency in 2–18 GHz. Furthermore, it exhibits long-life and large capacity lithium storage performance at high current density. The capacity reaches 732.79 mAh g⁻¹ after 100 cycles at 0.1 A g⁻¹, recovering to more than 139% from the minimum capacity value. After 300 cycles at 0.5 A g⁻¹, the capacity increases to 688.5 mAh g⁻¹. The initial capacities at 2 and 5 A g⁻¹ are 704.9 and 717.8 mAh g⁻¹, and remain 297.9 and 203.2 mAh g⁻¹ after 1000 cycles. The distinguished EMI shielding performance and electrochemical performance are mainly ascribed to the structure regulation of NiFe₂O₄/graphene composite, as well as the synergistic effect of graphene and NiFe₂O₄. This research opens up infinite opportunities for the application of multifunctional and interdisciplinary materials.