Synthesis of iron oxide cubes/reduced graphene oxide composite and its enhanced lithium storage performance

Fe₃O₄ is considered as a promising electrode material for lithium-ion batteries (LIBs) due to its low cost and high theoretical capacity (928 mAh/g). Nevertheless, the huge volume expansion and poor conductivity seriously hamper its practical applications. In this study, we use a facile hydrothermal reaction together with a post heat treatment to construct the three-dimensional heterostructured composite (Fe₃O₄/rGO) inwhich reduced graphene oxide sheets wraped the Fe₃O₄ submicron cubes as the conductive network. The electric conduction and electrode kinetics of lithium ion insertion/ extraction reaction of the composite is enhanced due to the assist of conductive rGO, and thus the Li-storage performance is obviously improved. The composite exhibits a reversible charge capacity of 772.1 mAh/g at the current density of 0.1 A/g, and the capacity retention reaches 70.3% after 400 cycles at 0.5 A/g, demonstrating obviously higher specific capacity and rate capability over the Fe₃O₄ submicron cubes without rGO, and much superior cycling stability to the parent Fe₂O₃ submicron cubes without rGO. On the other hand, as a synergic conductive carbon support, the flexible rGO plays an important role in buffering the large volume change during the repeated discharge/charge cycling.