One-Pot Synthesis of Pomegranate-Structured Fe₃O₄/Carbon Nanospheres-Doped Graphene Aerogel for High-Rate Lithium Ion Batteries

A unique hierarchically nanostructured composite of iron oxide/carbon (Fe₃O₄/C) nanospheres-doped three-dimensional (3D) graphene aerogel has been fabricated by a one-pot hydrothermal strategy. In this novel nanostructured composite aerogel, uniform Fe₃O₄ nanocrystals (5-10 nm) are individually embedded in carbon nanospheres (ca. 50 nm) forming a pomegranate-like structure. The carbon matrix suppresses the aggregation of Fe₃O₄ nanocrystals, avoids direct exposure of the encapsulated Fe₃O₄ to the electrolyte, and buffers the volume expansion. Meanwhile, the interconnected 3D graphene aerogel further serves to reinforce the structure of the Fe₃O₄/C nanospheres and enhances the electrical conductivity of the overall electrode. Therefore, the carbon matrix and the interconnected graphene network entrap the Fe₃O₄ nanocrystals such that their electrochemical function is retained even after fracture. This novel hierarchical aerogel structure delivers a long-term stability of 634 mA h g^-1 over 1000 cycles at a high current density of 6 A g^-1 (7 C), and an excellent rate capability of 413 mA h g^-1 at 10 A g^-1 (11 C), thus exhibiting great potential as an anode composite structure for durable high-rate lithium-ion batteries. Graphene aerogel electrode: A unique hierarchically nanostructured composite of Fe₃O₄/carbon nanospheres-doped three-dimensional (3D) graphene aerogel has been fabricated by a one-pot hydrothermal strategy (see scheme). This material delivers superior cycling performance and excellent rate capability as an anode composite structure for durable high-rate lithium-ion batteries.