Preparation Of Metal Oxides Nanomaterials Applied In Li-ion Battery

Metal oxide nanostructure materials, which show excellent physical and chemicalproperties due to the shape anisotropy, have attracted worldwide attention for theirintrinsic performance different from the bulk materials. As the lithium ion batteryanode material, the metal oxide nanostructure materials are though to be the mostpromising anode material in place of the carbon material in the future, for their goodperformance such as high capacity, large energe density, low cost and stability etc. Thedevelopment of nanomaterials and lithium-ion battery and oxide materials arereviewed in details in our report. In this thesis, most metal oxide nanostructures wereprepared by simple solution-based route, the Co₃O₄nanoarray and parachute-likemorphology; the SnO₂nanosphere; the a-Fe₂O₃nanorods, peanut-like and sphere-likemorphologies. The microstructure and physicochemical properties of theas-synthesized Metal oxide nanomaterials were characterized by X-ray diffraction（XRD）, scanning electron microscopy （SEM）, transmission electron microscopy（TEM）, BET analysis, the frustrated total internal reflection （FTIR） andthermogravimetric analysis （TGA）. Furthermore, the lithium-ion battery properties ofthese as-synthesized metal oxide nanomaterials were also studied. The details aresummarized as follows.In chapter2, the cobalt compounds of （Co（CO3）0.5（OH）0.11H2O） were synthesizedby a simple solution route at low temperature. Through calcining the as-synthesizedcobalt compounds, two kinds of Co₃O₄porous nanostructures （nanoarray andparachute-like） were obtained. It reveals that the morphology of as-synthesized cobaltcompounds can be tuned by adjusting the concentrations of reactants. And after beingconverter into Co₃O₄nanostructures, they were no significant alterations inmorphology. As anode materials for lithium-ion batteries （LIBs）, they show betterperformance. At a discharge current density of0.1C, they are of capable to retain aspecific capacity of797,761mAh/g over50cycles. As for the rate capacity test, thedischarge rate is modified on2C; the retaining specific capacity is700mAh/g fornanoarray, and760mAh/g for nano-parachute. In this chapter, the formationmechanism of different structures and their improved lithium performance are studied.In chapter3, we report the synthesis of SnO₂nanosphere and its lithiumproperties. The SEM and TEM reveal that SnO₂nanospheres were assembled by numerous tetragonal nanocubes with an average size of8nm. When tested as thelithium anode materials, it can release drastic specific volume change during thecharge and discharge process, which lead to a better stability and show superiorelectrochemical performance to commercial SnO₂.In chapter4, the a-Fe₂O₃nanomaterials are successfully realized by evaporatingaqueous FeCl₃solution. This green route is facile and low cost, which can be scaled upeasily in industry. By just simply changing the reaction temperature and time,nanorods, peanut-like and sphere-like morphologies of a-Fe₂O₃could be obtainedunder the selected temperature of120,150,180℃. The elemental nanorods have awidth range of10-20nm. On the basis of time-dependent experiments, the formationmechanisms of various nanostructures were proposed. When tested as anodes, theas-obtained a-Fe₂O₃nanostructures showed structure-dependent electrochemicalproperties.