Preparation And Electrochemical Properties Of Metal Oxide/Carbon Composite Fibers

Lithium-ion batteries are the primary energy storage devices in the communications,transportation and renewable-energy sectors. As the cost of materials account for about70%in lithium-ion battery, it is critical to select suitable materias to improve andenhance the performance of lithium-ion battery. The traditional graphite anode has thedisadvantages of low energy density and safety issues related to lithium deposition. Thus,there is necessary to research and develop of new alternative graphite anode materials, inorder to adapt the future demand of lithium-ion battery.Recently, electrospinning technique has been used to fabricate electrode materials.Variety of nanostructures can be designed by electrospinning technique. Meanwhile,carbon material has good cycle stability and metal oxides have gained much attentionowing to their relatively higher specific capacity and energy density. Hence, thecombination of the advantages of carbon materials and metal oxides via electrospinningtechnique, metal oxides/carbon composite fibers will be a potential anode material forlithium-ion battery. The main contents are as follows:1. Porous CoFe₂O₄/C composite fibers were synthesized via electrospinningtechnology, following carbonization treatment. TEM shows that the diameter of CoFe₂O₄nanograin is about42nm. Electrochemical test demonstrates that the first dischargecapacity reached to1827mAh·g^-1at a rate of0.1C and it maintained1100mAh·g^-1after100cycles, which was82%of the second discharge capacity. The EIS test reveals that theCoFe₂O₄/C composite fibers have superior conductivity compared with the CoFe₂O₄fibers obtained at the same temperature.2. In this chapter, ZnFe₂O₄/C composite nanofibers were fabricated by similarmethod with the third chapter and the cobalt which is electrochemical inactive is replacedby zinic that can react with lithium via alloying-de-alloying. It exhibited a dischargecapacity reached of1343mAh·g^-1during the first charge-discharge process. It still has adischarge capacity of726mAh·g^-1after100cycles, the charge-discharge efficient wasreached to96.7%. Except the good specific capacity and cyclic stability, the compositenanofibers also show outstanding rate performance. At the rate of0.1C0.2C0.5C1.0C and2.0C, the average discharge capacity was750mAh·g^-1650mAh·g^-1580mAh·g^-1520mAh·g^-1and450mAh·g^-1, respectively. 3. The ZnV₂O₆/C composite fibers were fabricated by electrospinning methodcombined with carbonazition processing. The effect of calcination temperature wereinvestigated. The ZnV₂O₆/C composite nanofibers obtained at700showed the bestelectrochemical performance. It showed that ZnV₂O₆/C composite nanofibers maintaineda capacity of800mAh·g^-1after500cycles, which exhibited high rate capacity and goodcapacity rentention. Furthemore, the CoV₂O₆/C, MnV₂O₆/C, composite fibers were alsoobtained at700and preliminarily investigated their electrochemical performance.