Facile Synthesis of Amino-functionalized Mesoporous Fe3O4/rGO 3D Nanocomposite by Diamine compounds as Li-ion Battery Anodes

Abstract

Being an essential part of lithium-ion batteries, the development of novel anode materials currently receives much attention. Among these, the high theoretical capacity of Fe3O4 (924 mAh g−1) makes it highly promising. However, massive volumetric changes and particle aggregation during repeated insertion/de-insertion of lithium ions damage the electrode structure and destroy the electrical connection with the current collectors, resulting in rapid and significant capacity losses. One strategy to overcome this problem is the employment of graphene-based compounds as a substrate in an interconnected porous conductive network using a crosslinker (e.g., ethylene diamine) to adjust the distance between the graphene layers. Such a 3D framework creates enough available space for the lithium ions to be inserted or de-inserted respectively to or from the electrode during the charge-discharge process. Moreover, this strategy prevents large electrode volume changes and the accumulation of Fe3O4 during cycling. Herein, an ex situ method was used to synthesize amino-functionalized mesoporous Fe3O4/graphene-based nanocomposites. In the first step, Fe3O4 nanoparticles were synthesized with the addition of ethylenediamine (EDA), whereby mesoporous Fe3O4 nanoparticles were obtained (Fe3O4-E). In the second step, Fe3O4-E/rGO nanocomposites were prepared with the help of electrostatic interactions. The Fe3O4-E/rGO nanocomposite showed good cycling performance vs. Li-metal and a high reversible capacity (∼465 mAh g−1) and average coulombic efficiency of ∼98% after 250 cycles at the current density of 1000 mA g−1. These promising results can be attributed to the presence of EDA in the formation of mesoporous nanoparticles and the 3D structure of the resulting composite. Itprevents the fragmentation of Fe3O4 particles induced by the formation of mesoporous structures and the restacking of rGO sheets generated by adjusting the layer spacing.