Effects of short residence time oxidation and pressure-driving carbonization on microstructure and electrochemical performance of pitch-based carbon materials

Abstract

In this work, coal tar pitch (CTP) is subjected to short residence time air oxidization at varying temperatures, followed by heat treatment under pressure to obtain green cokes with the aim of promoting mesophase development. Then, the green cokes are carbonized to prepare anode materials of lithium-ion batteries (LIBs). The correlation between the microstructure of the carbonized products and the electrochemical performance is investigated. The results reveal that short residence time oxidation facilitates the formation of hydrogen bonds of OH and O of the ether of the pitch. The pressure driving enhances the orientation of the carbon layer of the green cokes, which leads to increased graphene layer size of the subsequent carbonization product. When used as LIB anode materials, the carbonization product displays a high reversible specific capacity of 278 mAh/g at the current density of 2 A/g with stable cycling performance after 1000 cycles. Therefore, appropriate oxidation time and pressure driving at low temperatures are crucial for the growth of the carbon layer during the carbonization.