Construction Of Carbon Coated Iron Series Oxide Micro-nanostructures And Their Lithium Storage Properties

Nowadays, energy crisis is the prime problem in the 21st century. As the storage of non-renewable resources declines and the ecological environment keeps worsening, traditional energy sources, such as coal, oil and natural gas can’t meet the increasing demands any more. Under such a prospect, it is an urgent task to search for new types of clean energy source. The lithium ion batteries (LIBs), have attracted a lot of attention of researchers due to its potential applications in environmental-friendly energy storing devices. Therefore, it is a great challenge to explore novel environmental-friendly electrode materials with longer cycle life and higher capacity to improve the performance of lithium ion batteries.The transition metal oxides attracted a lot of attention due to its high theoretical specific capacity. Thus, fabricating nano-structures with controlled morphology can bring a better electrochemical performance for the LIBs; In addition, composite oxides also enhanced the electrochemical performance because of the combined advantages of different components. However, transition metal oxides suffer large volume variation during discharge and charge cycles; hence, we need to modify structures to improve their electrochemical performance.In this paper, we try to improve the electrochemical performance from the perspective of preparation and post-modification of electrode materials. Fe3O4@C core-shell nanotubes and Co2SnO4@C yolk-shell nanocubes had been prepared successfully as anode materials in lithium ion batteries. The nanostructures are characterized by powder X-ray diffraction (XRD), scanning electron electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectra and transmission electron microscopy (TEM). The main contributions are as follows:1. Fe2O3 nanotubes were synthesized through hydrothermal method, firstly. Resorcinol-formaldehyde resin sol-gel method was applied to fabricate Fe2O3@RF, which was annealed at Ar flow to obtain Fe3O4@C nanotubes. Electrochemical tests showed that the carbon coating can effectively improve the material electrochemical cycle performance and rate performance.2. CoSn(OH)6 nanocubes used as precursor were attained through coprecipitation reaction at the room temperature. After that, SiO2 and resorcinol-formaldehyde resin (RF) shells were coated on its surface in sequence. Then the as-obtained sample was annealed at Ar flow and washed by the NaOH solution to obtain the carbon coated Co2SnO4@C yolk-shell nanotubes. Electrochemical tests showed that this composite can effectively improve the material electrochemical cycle performance and rate performance.