A Modified Natural Graphite Negative Materials Of Lithium Ion Battery With Phosphorus-containing Phenol Resin

Natural spherical graphite, is considered to be one of the most important anode materials because it is superior to other carbon candidates in terms of high conductivity,high crystallinity ,low cost high theoretical lithium intercalating capacity, flat and low profile of charge and discharge potential. Nevertheless, its disadvantages, such as its bad compatibility with electrolytes, the low capacity of the first charge-discharge,the poor cycle performance,can't bear high current charge-discharge. In order to overcome these disadvantages, we modified graphite by coating it with pyrolysis of phenolic resin, We found:1.Using Orthogonal Test to find the optimized the covering amount and heat treatment temperature is respectively 15% and 900℃.2.pyrolytic carbon of phenol resins coating on natural spherical graphite can develop its initial charge/discharge efficiency, cycle performance and charge discharge capacity. Natural pherical graphite whose initial reversible capacity charge-discharge efficiency is 278mAh/g and 67.5% respectively,while 340mAh/g and 88.9% when doped with phosphorus and heated at 900℃.after ten cycles its reversible capacity also contain 331mAh/g while Natural pherical graphit 174mAh/g3.Then doped with phosphorus in the inhibitory coating .By analyzing its performance of electrochemical,we find the electrochemical properties of the modified natural graphite have been obviously improved, reversible capacity and coulomb efficiency is 362mAH/g and 95.8% respectively.