Intercalation mechanisms of
lithium into graphitized needle cokes
lithium into graphitized needle cokes
(1. Department of Materials Science and Engineering,
Central South University, Changsha 410083, P.R.China;
2. Institute of New carbon materials, Hunan University,
Changsha 410082, P.R.China)
Central South University, Changsha 410083, P.R.China;
2. Institute of New carbon materials, Hunan University,
Changsha 410082, P.R.China)
Abstract: A needle coke was graphitized at different heat treatment temperature ( 2000℃ to 3000℃ ). The electrochemical intercalation mechanism of Li into the graphitized coke has been studied in Li｜1mol·L-1 LiClO4+ ethylene carbonate/diethylene carbonate｜graphite cells, using an in-situ X-ray diffraction (XRD) technique. The study of Li-C intercalation processes of the graphitized coke reveals that there are three major types of intercalation behavior. The first is uniformly intercalated at all Li-C compounds in graphitized coke heated at 2250℃; the second is obviously staging phenomenon during intercalating for the graphitized coke heated at 2750℃; the third is cointercalation of solvated Li-ion at high potential (＞0.3V ) and then lithium electrochemical intercalation at lower potential for that heated at 3000℃, resulting in the decrease of capacity and efficiency of graphite negative electrode for lithium-ion secondary battery.
Key words: needle coke; graphitized; intercalation