Multi-walled Carbon Nanotube Improve The Proformance Of Li/CFx Primary Batteries

In the system of commercial primary batteries,lithium/fluorinated graphite?Li/CF₁?primary battery has the highest theoretical specific capacity,about 865mAh/g.In addition,the Li/CF₁ primary batteries have the advantages of long shelf life and low self-discharge,which has a great advantage in the field of battery application.However,the discharge rate and efficiency of Li/CF₁ primary batteries are restricted by the poor electrical conductivity of fluorinated graphite,and the reaction product LiF is insulative,which limit the wide application of Li/CF₁ primary batteries.In order to minimize those shortcomings,in which fluorinated multi-walled carbon nanotubes instead of fluorinated graphite was used as the positive active material,and flexible paper composite of fluorinated graphite,paper fiber and carbon nanotubes was used as electrode.The main research results are as follows:?1?The electrochemical properties of fluorinated multi-walled carbon nanotubes are vary from the fluorine content.When the content of fluorine is relatively low?CFx,x?1?,the electrochemical properties?the specific capacity and the stability of the voltage plateau?of fluorinated multi-walledl carbon nanotubes improve with the increase of fluorine content.On the contrary,the conductivity of multi-walled fluorinated carbon nanotubes is extremely low when the fluorine content is higher?CFx,x>1?,the performance of prepared battery using high fluorine content is very poor.?2?The multi-walled fluorinated carbon nanotubes have the space structure of shell nuclei,which can provide more contact area between active material and electrolyte.Under the low discharge rate,compared with fluorinated graphite electrode,the performance has not been improved obviously when the multi-walled fluorinated carbon nanotubes were used as electrode active materials,On the contrary,the performance has been greatly improved at the high rate.The multi-walled fluorinated carbon nanotube electrode achieved a discharge specific capacity of 375.4mAh/g at the 2 C discharge rate,which has a capacity increasing of 32.3%higher than fluorinated graphite electrode of 283.7 mAh/g.Under the 2 C discharge rate,fluorinated graphite and fluorinated multi-walled carbon nanotubes electrode exhibited 54.3%and 63.9%capacity attenuation compared with 0.05 C,respectively.Fluorinated multi-walled carbon nanotubes instead of fluorinated graphite as the anode can largely improve discharge specific capacity of Li/CF₁ primary battery,and a certain extent slow down the attenuation rate of discharge specific capacity.?3?The flexible carrier of active material was prepared by paper fiber,multi-walled carbon nanotubes and fluorinated graphite.The flexible carrier can reduce the electron transfer resistance between active material and interface metal.In addition,paper fiber can provide a frame structure,increase the contact space of active materials and electrolyte.The unique tubular structure of multi-walled carbon nanotubes allows lithium-ions and electrons enter the channel Around the active material.The flexible carrier used as electrode can increase the electrochemical reaction effect and reduce the polarization effect of battery,further improve the utilization rate of the active material,the battery capacity and the stability of voltage plateau.