The Preparation And Application Of SnO₂ Nanotubes And Sn/C Composite Nanofibers

Nowadays, rechargeable high capacity lithium-ion batteries are needed direly with the rapid development of mobile devices and new energy technology, which is also one of the key fields studied by scientists around the world. Tin-based material has high charge and discharge capacity, but the volume of tin-based material would change with the intercalating and deintercalating progress of lithium-ion, which limits its application in lithium-ion batteries. However, if tin-based material is in nanostructure, its volume changing effect would be avoided, which is expected to replace carbon in lithium-ion battery as cathode material to improve performance of battery.In this paper, the basic connotation, properties, preparation methods of nanomaterials and the fundamental of lithium-ion battery are systematically introduced firstly. Then the preparations of one-dimensional nanomaterials, SnO₂ nanotubes and Sn/C nanometer compound fibers were described detailedly, and their morphology, microstructure, and electrochemical character are tested under SEM, XRD, EDX, TEM and constant current charge/discharge experiments; at last, the results of these tests are discussed. The specific research are shown as follows:1. One-dimensional nano-materials were made successfully with the main raw materials of PVP and pinksalts (SnCl₂·2H₂O and C₁₆H₃₀O₄Sn), in the method of high voltage electrostatic spinning, as well as combining the calcined technique. The result shows that the thickness of SnO₂ nanotubes in this nano-material increases with the adding of SnCl₂ gradually. The reason that SnCl₂ transformed into SnO₂ nanotubes might be the hydrolyzation of SnCl₂ in the air. The product is SnO₂ nanofiber if SnCl₂ is replaced by C₁₆H₃₀O₄Sn, which don't hydrolyze in the air.2. Sn/C composite nanofiber was successfully made in the method of high voltage electrostatic spinning and deoxidizing by high temperature H₂, with the main raw materials of PAN and pinksalt (SnCl4 and C₁₆H₃₀O₄Sn). The number of Sn particles in fiber and their diameter increase gradually with the adding of pinksalt.3. Standard CR2032 button cells were assembled using nanotubes and Sn/C composite nanofiber as lithium-ion battery cathode materials, and constant current charge/discharge test was carried out. The results show that batteries made of SnO₂ nanotube material has large initial charge and discharge capacity in the first charging, but the attenuation is also greatly. This shows that the nanostructure of SnO₂ nanotube could not avoid the powders or concentration of Li in its implanting and emerging process. The charge and discharge capacity of Sn/C composite nano-fibre batteries is also large, and the capacity tends to a stable level after 10 times cycling, which shows that Sn/C composite nano-fibre has a better electrochemical behavior, and it is a good material for cathode of lithium-ion battery.