Carbon-coated Fe3O4 nanoparticles in situ grown on 3D cross-linked carbon nanosheets as anodic materials for high capacity lithium and sodium-ion batteries

Abstract

Fe₃O₄ nanomaterials with desired electrochemical properties in energy conversation and storage are considered a potential substitute for the graphite anode because of their high lithium (Li) ion and sodium (Na) ion storage in a new system of green secondary batteries. In this work, 3D cross-linked Fe₃O₄@C composites (Fe₃O₄@N/C) comprising Fe₃O₄ nanoplates coated on C nanosheets were prepared in one step by a solvent-free method and they showed porous structures with a high special surface area. The porous hierarchical structures could not only enhance the electron/ion transport in the electrochemical charge/discharge process but also reduce the spatial effect in long-term use. At the same time, the carbon-coated Fe₃O₄ hierarchical structures could slow down the volume change caused by Li⁺/Na⁺ embedment and prostration, and effectively prevent the structure from crushing in the continuous application. Besides, the additional organic nitrogen in situ doping from the added amino acids of the starting materials into the porous hierarchical structures could enhance the conductivity of the disordered carbon matrix by changing the structure of the electron cloud to improve the performance in the energy storage application. The Fe₃O₄@N/C as the anode material of Li-ion batteries (LIBs) showed a remarkable property of lithium storage at about 1200 mA h g⁻¹ after 350 cycles at 1 A g⁻¹. Meanwhile, the material as the anode material of Na-ion batteries (SIBs) exhibited a high capacity of up to 236.4 mA h g⁻¹ and 176 mA h g⁻¹ at 5 A g⁻¹ and 10 A g⁻¹. Our work provides a convenient strategy to relieve the volume changes of the electrode materials to achieve better electrochemical performance for Li⁺/Na⁺ ion electrochemical energy storage.