Herein,the core-shell structured N-doped carbon coated Fe7S8 nano-aggregates(Fe7S8@NC)were controllably prepared via a simple three-step synthesis strategy.The appropriate thickness of N-doped carbon layer outside Fe7...Herein,the core-shell structured N-doped carbon coated Fe7S8 nano-aggregates(Fe7S8@NC)were controllably prepared via a simple three-step synthesis strategy.The appropriate thickness of N-doped carbon layer outside Fe7S8 nano-aggregates can not only inhibit the particle pulverization induced by the big volume changes of Fe7S8,but can increase the electron transfer efficiency.The hierarchical Fe7S8 nano-aggregates composed of some primary nanoparticles can accelerate the lithium or sodium diffusion kinetics.As anode materials for Li-ion batteries(LIBs),the well-designed Fe7S8@NC nanocomposites exhibit outstanding lithium storage performance,which is better than that of pure Fe7S8,Fe3O4@NC and Fe7S8@C.Among these nanocomposites,the N-doped carbon coated Fe7S8 with carbon content of 26.87 wt.%shows a high reversible specific capacity of 833 mAh·g^−1 after 1,000 cycles at a high current density of 2 A·g^−1.The above electrode also shows excellent high rate sodium storage performance.The experimental and theoretical analyses indicate that the outstanding electrochemical performance could be attributed to the synergistic effect of hierarchical Fe7S8 nanostructure and conductive N-doped carbon layer.The quantitative kinetic analysis indicates that the charge storage of Fe7S8@NC electrode is a combination of diffusion-controlled battery behavior and surface-induced capacitance behavior.展开更多
基金The authors thank the National Natural Science Foundation of China(No.51772257)the Major Basic Research Project of Shandong Natural Science Foundation(No.ZR2018ZC1459)Doctor Foundation of Shandong Province(No.ZR2017BB081)for financial support.
文摘Herein,the core-shell structured N-doped carbon coated Fe7S8 nano-aggregates(Fe7S8@NC)were controllably prepared via a simple three-step synthesis strategy.The appropriate thickness of N-doped carbon layer outside Fe7S8 nano-aggregates can not only inhibit the particle pulverization induced by the big volume changes of Fe7S8,but can increase the electron transfer efficiency.The hierarchical Fe7S8 nano-aggregates composed of some primary nanoparticles can accelerate the lithium or sodium diffusion kinetics.As anode materials for Li-ion batteries(LIBs),the well-designed Fe7S8@NC nanocomposites exhibit outstanding lithium storage performance,which is better than that of pure Fe7S8,Fe3O4@NC and Fe7S8@C.Among these nanocomposites,the N-doped carbon coated Fe7S8 with carbon content of 26.87 wt.%shows a high reversible specific capacity of 833 mAh·g^−1 after 1,000 cycles at a high current density of 2 A·g^−1.The above electrode also shows excellent high rate sodium storage performance.The experimental and theoretical analyses indicate that the outstanding electrochemical performance could be attributed to the synergistic effect of hierarchical Fe7S8 nanostructure and conductive N-doped carbon layer.The quantitative kinetic analysis indicates that the charge storage of Fe7S8@NC electrode is a combination of diffusion-controlled battery behavior and surface-induced capacitance behavior.
