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Transition metal oxides have recently been demonstrated as highly attractive anodes for high-capacity lithium ion batteries, whose electrochemical properties could be further improved through rational architecture design and incorporating reliable conductive network. Herein, mesoporous γ-Fe2O3 spheres/graphene aerogel composites were synthesized via a solvothermal pathway followed by suitable annealing. Experimental results reveal the uniform mesoporous structure and well-dispersed γ-Fe2O3 spheres with the size of 300−400 nm embedded in the mesopores of the graphene aerogel network. Compared with α-Fe2O3/graphene aerogel and pure γ-Fe2O3, the as-synthesized composite delivers, at the first cycle, a high discharging capacity of 1080 mAh g−1 at current density of 200 mA g−1. Even at much higher current density of 8000 mA g−1, satisfactory discharging capacities of 421.5 mAh g−1 can still be achieved. Upon 100 charging-discharging cycles, the specific capacity of as high as 890.5 mAh g−1 at 200 mA g−1 is maintained. The enhanced electrochemical properties could be attributed to their favorable three-dimensional graphene aerogel network, which accounts for the improved structural stability and electronic conductivity of γ-Fe2O3 during the lithiation/delithiation process. [ABSTRACT FROM AUTHOR]

Transition metal oxides have recently been demonstrated as highly attractive anodes for high-capacity lithium ion batteries, whose electrochemical properties could be further improved through rational architecture design and incorporating reliable conductive network. Herein, mesoporous γ-Fe 2 O 3 spheres/graphene aerogel composites were synthesized via a solvothermal pathway followed by suitable annealing. Experimental results reveal the uniform mesoporous structure and well-dispersed γ-Fe 2 O 3 spheres with the size of 300-400 nm embedded in the mesopores of the graphene aerogel network. Compared with α-Fe 2 O 3 /graphene aerogel and pure γ-Fe 2 O 3 , the as-synthesized composite delivers, at the first cycle, a high discharging capacity of 1080 mAh g -1 at current density of 200 mA g -1 . Even at much higher current density of 8000 mA g -1 , satisfactory discharging capacities of 421.5 mAh g -1 can still be achieved. Upon 100 charging-discharging cycles, the specific capacity of as high as 890.5 mAh g -1 at 200 mA g -1 is maintained. The enhanced electrochemical properties could be attributed to their favorable three-dimensional graphene aerogel network, which accounts for the improved structural stability and electronic conductivity of γ-Fe 2 O 3 during the lithiation/delithiation process.