By The Spinning Technique Preparation Of Micro-and Nano Structural Materials And Their Applications

Due to unique physical and chemical properties, micro-nanostructured materials play a key role in energy-saving devices. In this dissertation, we explored a new way to prepare mcro-nanostructured materials and thoroughly studied their structure and property. We successfully prepared mcro-nanostructured carbon materials and metal oxides with the delicate control of their sizes, morphologies, compositions and structures through wet-spinning and electrospinning techniques. The main point of this dissertation is as follows:1. Preparation of hierarchically porous carbon fibers (HPCFs) through wet-spinning technique:One-dimentional (ID) hierarchically porous carbon fibers (HPCFs) were synthesized by controlled carbonization of wet-spun alginic acid fibers. The as-obtained HPCFs consist of a 3D network of nano-sized carbon particles with diameter less than 10 nm and exhibit a hierarchically porous architecture composed of both micropores and mesopores. Due to their unique structure, HPCFs possess excellent rate capability and capacity retention compared with commercial graphite when employed as anode materials for Li-ion batteries.2. Preparation of carbon coated Mn3O4 composite fibers through wet-spinning technique: carbon coated Mn3O4 composite (Mn3O4@C) fibers consisting of carbon coated Mn3O4 nanoparticles were prepared from thermal decomposition of manganese alginate fibers produced by wet-spinning technique. The as-obtained Mn3O4@C fibers consist of plenty of nano-sized Mn3O4 crystals with even diameter of 10-15 nm and carbon coating layer with a thickness of 1-2 nm. The composite fibers exhibit also a porous structure consisting of both micropores and mesopores. Due to the nano-dimension of Mn3O4 particles, the thin carbon coating layer and the nanopores existing among Mn3O4@C nanoparticles, Mn3O4@C fibers possess a higher specific capacitance and superior rate capability when used as electrode materials for supercapacitor compared with commercial Mn3O4.3. Preparation of micro-nanostructured V2O5 through electrospinning technique: micro-nanostructured V2O5 materials were prepared from thermal decomposition of non-woven cloth of electrospun nanofibers. We thoroughly studied the effect of the solution system, voltage and collector on the morphology of nanofibers. After optimizing the electrospinning condition, we discussed the effect of thermal decomposition on the morphology and property of V2O5 nanofibers. The as-obtained micro-nanostructured V2O5 nanofibers possess good electrochemical property when used as cathode materials for lithium battery.