Tailored engineering of Fe3O4 and reduced graphene oxide coupled architecture to realize the full potential as electrode materials for lithium-ion batteries

Developing advanced electrode materials with appropriate compositions and exquisite configurations is crucial in fabricating lithium-ion batteries (LIBs) with high energy density and fast charging capability plateau. Herein, a Fe3O4@reduced graphene oxide (Fe3O4@rGO) coupled architecture was rationally designed and in-situ synthesized. Monodispersed mesoporous Fe3O4 nanospheres were homogeneously formed and strongly bound on interconnected macroporous rGO frameworks to form well-defined three-dimensional (3D) hierarchical porous morphologies. This tailored Fe3O4@rGO coupled architecture fully exploited the advantages of Fe3O4 and rGO to overcome their inherent challenges, including spontaneous aggregating/excessive restacking tendency, sluggish ions diffusion/electrons transportation, and severe volume expansion/structural collapse. Benefitting from their synergistic effects, the optimized Fe3O4@rGO composite electrode exhibited an improved electrochemical reactivity, electrical conductivity, electrolyte accessibility, and structural stability. The optimized composite electrode displayed a high specific capacity of 1296.8 mA h g-1 at 0.1 A g-1 after 100 cycles, even retaining 555.1 mA h g-1 at 2 A g-1 after 2000 cycles. The electrochemical kinetics analysis revealed the predominantly pseudocapacitive behaviors of the Fe3O4@rGO heterogeneous interfaces, accounting for the excellent electrode performance. This study proposes a viable strategy for use in engineering hybrid composites with coupled architectures to optimize their potential as high-performance electrode materials for use in LIBs.