Preparation And Properties Of Porous Carbon As Anode Material For Lithium-ion Batteries

Nowadays,the commercial anode materials for lithium-ion batteries are based on graphite,but the specific capacity of graphite materials is very low,only 372 mAh/g and the charge and discharge performance is poor under large magnification.Because porous carbon materials have high specific surface area,large pore volume,good electrical conductivity and excellent mechanical properties as anode of lithium ion battery,the capacity and rate of the battery can be greatly improved.In this paper,the porous carbon were focused on improving he lithium-ion battery capacity,the performance of the rate and the cycle life.Porous carbon anode materials for lithium ion batteries were prepared by using polyvinylpyrrolidone(PVP)and sodium chloride(NaCl)as raw materials.1.Polyvinyl pyrrolidone(PVP)was used as a carbon source to prepare PVP nanofibers by electrospinning and then carbonized at high temperature to obtain C nanofibers.The resulting carbon nanofibers were etched in air for different times to obtain a multi-cavity surface.Carbon nanofibers can clearly see through their electron micrographs that there are a lot of cavities on the surface of carbon nanofibers.The material was assembled into a button cell and tested for electrochemical performance.The results showed that the electrochemical performance of the fiber material obtained by air etching for 20 min was the best.The first charge capacity was as high as 1138 mAh/g at 0.1 C rate,and the long cycle at 5C rate.After 1000 cycles,the battery has a reversible capacity of 278 mAh/g and the capacity retention reach up to 87.51%.2.Polyvinyl pyrrolidone(PVP)as carbon source,sodium chloride(NaCl)as pore-forming agent,PVP/NaCl nanofibers were prepared by electrospinning,and carbon/NaCl nanofibers were obtained after high temperature carbonization.The NaCl nanofibers were rapidly washed with water and NaCl dissolving obtain porous carbon nanofiber membrane electrode materials.Through its electron micrograph,it can be clearly seen that there are a large number of mesopores on the surface and inside of carbon nanofibers.The material was assembled into a button cell and tested for electrochemical performance.The results showed that the obtained porous carbon nanofiber material had good electrochemical performance.The first charge capacity was as high as 1150 mAh/g at 0.1 C rate,and long cycle 1700 at 5 C rate.After the battery reversible capacity up to 208.8 mAh/g,capacity retention rate as high as 83.5%.3.Polyvinyl pyrrolidone(PVP)was used as the carbon source,sodium chloride(NaCl)was used as the pore-forming agent.PVP/NaCl composites were prepared by simple mechanical mixing,and then C/NaCl composites were obtained by high-temperature carbonization to obtain the C/NaCl composites.The material was rapidly washed with water and NaCl was dissolved to obtain a three-dimensional coral-like porous carbon electrode material.Through its electron microscope image,it can be clearly seen that there are a large number of cubic cavities in the material,and there are a large number of hole-like defects on the walls of the cavity.The material was assembled into a button cell for electrochemical performance testing.The results showed that the electrode material with a PVP/NaCl mass ratio of 2:1 had better electrochemical performance,and the first charge capacity was as high as 800 mAh/g at 0.1 C rate,at 2 C.The battery has a reversible capacity of up to 188.8 mAh/g after a long cycle of 1200 cycles at a large rate,and the capacity retention rate is as high as 85.81%.