ELECTROCHEMICAL-BEHAVIOR OF CARBON ALLOY CXN PREPARED BY CVD USING A NICKEL-CATALYST

Carbon-nitrogen layered compounds, C14N to C62N have been synthesized by thermal decomposition of acetonitrile at 800-1100 degrees C in the presence of nickel catalyst. The CxN samples prepared with nickel had higher crystallinity and less pyridine-type nitrogens existing at the edge of graphene layers than CxN prepared in the absence of nickel. Wi th an increase in the deposition temperature of CxN, the cycleability for electrochemical intercalation-deintercalation of lithium ions was improved and the profile of the charge-discharge curve approached that of natural graphite powder due to an increase in the crystallinity an d a decrease in the incorporated nitrogens. Surface oxidation of the C xN by nitric acid solutions gave rise to an increase in the surface ox ygens and a slight decrease in nitrogens without any change of crystal linity. The surface modification improved the cycleability for lithium ion intercalation-deintercalation reaction. (C) 1997 Elsevier Science Ltd. All rights reserved.