Synthesis Of Co-based Compounds Nanowire(Nanotube)and Electrochemistry Performance

Electrochemical energy is considered to be an ideal alternative to conventional energy because it could be cycled and more environmentally friendly.In electrochemical system,Li-ion batteries and supercapacitors have attracted worldwide attention in the past decades because of their outstanding advantages such as fast charge,long cycle life,low coat and clean.Due to it's wide variety of patterns,metal oxide nanomaterials have become one of the most important materials for electrode materials.In this thesis,three kinds of cobalt based metal oxides nanomaterial are prepared by facile hydrothermal method and electrospinning method,combined with relatively low temperature annealing process following.Supercapacitors and Lithium-ion batteries are synthesized based on cobalt based metal oxides electrodes,and their electrochemical performances are tested.Main research contents are as following:With Cu(NO3)2 and Co(NO3)2 act as reactants,CuCo2O4 nanowire arrays were successfully grown on the surface of nickel foam via a hydrothermal route without template,and the nanowire arrays on nickel foam were used as working electrodes for electrochemical capacitors.Such nanoarray-based electrodes exhibited remarkable electrochemical performance with a high specific capacitance of 61 1 F g-1 at a charge and discharge current density of 1.7 A g-1(60%of its theoretical value which is 984 F g-1),an excellent cycling ability of 94.8%conservation rate after 8000 cycles.The superior electrochemical performances could be attributed to the fully reversible electrochemical properties as well as nanowire arrays with three-dimensional structure characteristics,low resistance,multiply channel.With Ni(NO3)2 and Co(NO3)2 act as reactants,NiCo2O4 nanowire arrays were successfully grown on the carbon cloth,and the unique array architectures were applied as working electrodes directly in Li-ion batteries.NiCo2O4 nanowire arrays yielded high performance during the test.While the current density is 100 mA g-1,the first cycle discharge capacitance reached 1295.3 mAh g-1,the first cycle charge capacitance reached 832 mAh g-1,corresponding first Coulomb efficiency is 64.2%.The specific capacitance is much higher than commercial carbon material.After 200 cycles,the specific capacitance of NiCo2O4 nanowire array based flexible electrode is 750 mAh g-1 The results of electrochemical characteristics measurements reveal that as synthesized nanoarray on carbon cloth is potential in flexible supercapacitors,which could be contributed to its multiply channel and 3D structure.With SnCl4 and CoCl2 act as reactants,PVP as template,Co3O4/SnO2 nanotubes were synthesized by subtle electrospinning method and following annealing.Li ion battery electrodes were then made based on the nanofiber.Electrochemical measurements were taken and the excellent rate performance shows its potential in applications.While the current density is 100 mA g-1,the first cycle discharge capacitance reached 1900 mAh g-1,the first cycle charge capacitance reached 1500 mAh g-1,corresponding first Coulomb efficiency is as high as 79.2%,shows its potential in fast charge devices.The high performance of as prepared nanofiber would be attributed to its hollow structure and its large surface area.