Preparation of road-petroleum-asphalt derived carbon-coated Fe3O4 composites by two-step pyrolysis method and its lithium storage performance
In this paper,asphalt-derived carbon nanosheets coated Fe3O4 composites(C@Fe3O4)were prepared by two-step pyrolysis and template-assisted method by selecting cheap emulsified asphalt as the carbon precur-sor,while ammonium ferric citrate was used as the iron source,and sodium chloride was used as the template.The chemical composition and microstructural morphology of C@Fe3O4 composites were characterized by SEM,TEM,XRD and XPS,and the electrochemical properties were characterized by galvanostatic charge-discharge test,cyclic voltammetry,electrochemical impedance spectroscopy and galvanic intermittent titration technique(GITT).The results show that Fe3O4 nanoparticles produced by ammonium ferric citrate in pyrolysis are uni-formly encapsulated in graphitized asphalt-derived carbon nanocages.As an anode of lithium-ion batteries,the optimized C@Fe3O4-3 composite delivers an excellent reversible capacity of 910.85 mAh/g after 100 cycles at a current density of 0.1 A/g,and retains an excellent reversible capacity of 517.76 mAh/g after 240 cycles at a high current density of 1 A/g.Such excellent cycling stability is mainly attributed to its well-designed structure:the highly graphitized petroleum asphalt-based carbon nanocage not only improves the electrical conductivity of the Fe3O4 material,but also effectively suppresses the volume expansion of Fe3O4 during charge/discharge cyc-ling,thus providing enhanced electrochemical stability.This work not only realizes the high value-added utiliza-tion of low-cost petroleum asphalt,but also can be extended to the application of other transition metal oxide-based anodes.
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