Reduced Graphene Oxide (rGO)-Supported and Pyrolytic Carbon (PC)-Coated γ-Fe₂ O₃ /PC-rGO Composite Anode Material...

As a high-capacity anode material for lithium ion batteries, γ-Fe₂ O₃ is a promising alternative to conventional graphite among multifarious transition metal oxides owing to its high theoretical specific capacity (1007 mAh g^-1 ), abundant reserves, good safety and low cost. However, improving the electrical conductivity and overcoming the morphological damage caused by the severe volume expansion during cycling are still the tricky problems to be solved. Herein, a three-dimensional heterostructure composite (γ-Fe₂ O₃ /PC-rGO₆₀ ) was prepared by a facile solvothermal reaction followed by heat treatment in inert atmosphere. This composite material exhibits a reversible charge specific capacity of 1035 mAh g^-1 at the current density of 0.1 A g^-1 . After 100 cycles at 0.2 A g^-1 , the capacity is increased from 966.2 to 1091.1 mAh g^-1 . Even cycled for 200 cycles at 1 A g^-1 , the capacity is only decreased from 751.4 to 670.6 mAh g^-1 , giving capacity retention of 89.3%. The rGO network supported flexible composite architecture is beneficial for accommodating the volume expansion of the γ-Fe₂ O₃ active material during the lithiation/delithiation process. Besides, the conductive rGO network and the in-situ formed pyrolytic carbon (PC) can provide a smooth electron transmission path and a favorable lithium ion transport channel.