Encapsulating ultrafine Fe3O4 nanoparticles into interconnected 3D multiporous carbon for superior Li-ion energy storage

Abstract

Although Fe3O4 has low cost and high theoretical capacity, its low electrical conductivity and significant volume changes during the reaction process result in poor electrochemical performance, particularly cycling performance, which limit its application as anode materials. To overcome these limitations, this study created Fe3O4@3D cellular carbon composites (Fe3O4@3D cellular carbon: Fe3O4@3D-CC) by homogeneously embedding ultrafine Fe3O4 nanoparticles of size around 10 nm in a three-dimensional cellular carbon skeleton using a template-assisted method. The porous structure enables for large volumes of electrolyte to be stored and features a dual continuous transport channel for ions and electrons, which can considerably improve the conductivity of the Fe3O4. Furthermore, 3D cellular carbon locks Fe3O4 nanoparticles, allowing them to adapt to volume changes during charge-discharge process and preventing structural degradation. Due to the aforementioned structural properties, this material has a first discharge-specific capacity of 2534 mA h g−1 at a rate of 0.1 C and can still reach 1011 mA h g−1 after 400 cycles at a high rate of 2 C. This keeps the theoretical capacity at 109 % and distinctly enhances the electrochemical performance of Fe3O4, particularly the cycling performance.