Electrochemical Characteristics of Coal Tar Pitch Prepared By Chemical Activation for Lithium Ion Battery

Abstract

In recent years, carbon-based materials have been extensively investigated as an anode material for Li-ion battery (LIB). Because of their low material cost, abundance, nontoxicity and good capacity, carbon materials have been considered promising materials for LIB anodes in portable electronic devices and electric/hybrid vehicles. Despite these advantages, the practical application of carbon-based materials in many electronic device and electric/hybrid vehicles is still limited by its poor electrochemical performances . To enhance these electrochemical performances, we have performed the surface modification of coal tar pitch (CTP) by the chemical activation with KOH and K2CO3 . Coa l tar pitch (CTP) as an industrial by-product, composed of cyclical hydrocarbons of various molecular weights and configurations. The preparation method has been optimized through the analysis of diverse experimental variables. The results obtained confirm the importance of the activating chemical agents to CTP ratio and the flow rate of gas during carbonization on the development of porosity. In addition, it shows that chemical activation with KOH and K2CO3 can be successfully used to develop CTP with high surface area and mean pore size. In this study, the effect of activating chemical agent /CTP weight ratio, CTP particle size and vinylene carbonate (VC) as an electrolyte additive on electrochemical performances was investigated. The prepared modified CTP was analyzed by BET, XRD, FE-SEM and XPS. Also the electrochemical performances of modified CTP as the anode were investigated by constant current charge/discharge, cyclic voltammetry and electrochemical impedance tests in the electrolyte of LiPF6 dissolved in organic solvents(EC:DMC=1:1 vol%). The coin cell using modified CTP( KOH /CTP = 1 : 5 in weight) has better initial capacity (421 mAh/g) than that of other composition coin cells. Also, modified CTP anode appeared a high capacity of 4 11 mAh/g on the second cycle and the retention rate capability of 2C/0.1C was 83 % after 30 cycle. It is found that prepared CTP anode showed improved cycling and rate capacity performance.