Abstract
Sodium ion batteries have drawn extensive attentions for large-scale energy storage to replace lithium ion batteries primarily due to the natural abundance of sodium resource and low cost, but their energy density and electrochemical performance are hindered by the sluggish diffusion kinetics of sodium ion. Herein, free-standing nitrogen-doped graphene aerogel has been fabricated via hydrothermal reaction as the potential anode material for sodium ion batteries. The three dimensional porous network structure of the graphene aerogel provides sufficient interstitial space for sodium ion accommodation, allowing fast and reversible ion intercalation/de-intercalation. The nitrogen doping could introduce defects on the graphene sheets, making the feasible transport of large-sized sodium ion. Benefiting from the effective structure and nitrogen doping, the obtained material demonstrates high reversible capacities, good cycling performance (287.9 mA h g−1 after 200 cycles at a current density of 100 mA g−1), especially superior rate capability (151.9 mA h g−1 at a high current density of 5 A g−1).
Highlights
Lithium ion batteries have been regarded as the most competitive choice for high power sources and electric vehicles because of the high energy density, the limited lithium source driven researcher to explore the substitutes for lithium ion batteries[1,2,3]
The atomic structure and layers stacking of N-doped graphene aerogel was investigated by High-resolution electron microscopy (HRTEM)
3D free-standing nitrogen-doped graphene aerogel was synthesized by hydrothermal reaction and annealing treatment
Summary
Lithium ion batteries have been regarded as the most competitive choice for high power sources and electric vehicles because of the high energy density, the limited lithium source driven researcher to explore the substitutes for lithium ion batteries[1,2,3]. Many carbonaceous material with different structures have been investigated in the electrochemical performance as anode materials for sodium ion batteries, such as carbon fibers[9, 10], nanowires[11], carbon nanospheres[12], reduced graphene oxide[13,14,15], and porous carbon composites[16] Among these materials, graphene is the most attractive anode material for sodium ion batteries due to its extraordinary electric conductivity, high surface area, and remarkable mechanical flexibility. Based on the first-principle’s calculation, the defects can facilitate lithium ion diffusion from the vacancy and go through the graphene sheets due to the lower diffusion barrier around defect sites[21] These appealing merits driven the study of nitrogen doped graphene as an anode material in the field of sodium ion batteries. The superior electrochemical performance makes the N-doped graphene aerogel material have a promising prospect in practical applications
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