The Investigation Of Metal Oxide Nanocomposites As Anode Materials For Lithium Ion Batteries

Increasing energy demands have stimulated extensive research on alternative anode materials for lithium ion batteries ?LIBs?. Metal oxide materials ?including tin, iron, cobalt oxide and its binary oxide material? have a higher reversible specific capacity than carbon material, are ideal anode materials for lithium ion battery. However, the weak structural stability, large volume variation during charge and discharge of batteries, poor electrical conductivity and low temperature performance, hamper their potential practical usage in LIBs. Up to now, the development of high-performance anode materials is mainly through synthetic nano structure and carbon composite as well as metal decoration, thus to maintain stable material structure, improve the electrical conductivity, enhance performance at low temperature.Based on the above, this dissertation studies around about three parts as follow:Firstly, homogeneous composites of pomegranate-structured SnO₂@C/Cu have been prepared by a simple hydrothermal reaction coupled with wet-chemical reduction, and directly used as anode materials for lithium ion batteries ?LIBs?. SnO₂@C/Cu anodes exhibit much better room-temperature and low-temperature electrochemical performance including reversible capacity, cycling performance and rate performance. This unique configuration can prevent the agglomeration of active materials and facilitate electron conduction especially at a relative low temperature, and obtain the capacity stability in cycling process for LIBs.Secondly, composites of pomegranate-structured SnO₂ nanospheres mixed with GO and SWNTs with unique nanostructure has been fabricated form SnO₂-GO-SWNT composites. This composite used as anode for LIBs can deliver high reversible capacities and good rate capability. The superior performance could be mainly attributed to the synergistic effects of the conductance contribution of GO and SWNT supporters and the stability of restricted SnO₂ nanospheres.Finally,composites of Ag-incorporated carbon nanofibers ?CNFs? confined with CoFe₂O₄ nanoparticles ?Ag-CoFe₂O₄ CNFs? have been synthesized through an electrospinning method and evaluated as anodes for lithium batteries ?LIBs?. Benefiting from the synergistic effect of the CNF matrix and the conducting Ag incorporating, the Ag-CoFe₂O₄ CNFs electrode displays superior cyclic stability and excellent rate performance at room temperature. These preliminary results indicate the great potential application of CNF-supported coupled with Ag incorporating synthesis of metal oxide anodes for high-performance LIBs. In addition, this work is a preliminary study, which will provide a substantial reference for the subsequent modified composite electrode.