Electrochemical behaviors of carbon alloy BC{sub}x and of BC{sub}x-coated graphite prepared by chemical vapor deposition

摘要

Boron-substituted carbons (C/B=3.8-18.8) have been synthesized by chemical vapor deposition (CVD) using benzene, boron trichloride and hydrogen at 800-1000℃ in the presence of a nickel catalyst under atmospheric pressure. BCN prepared with thenickel catalyst had a higher crystallinity than that prepared in the absence of nickel. BCx samples prepared by short duration deposition showed relatively higher charge capacities and better cycleability due to a smaller amount of the less organizedregion. A longer duration of the reaction, however, yielded a larger amount of less crystallized regions within BCx. BCx compounds have also been coated by CVD using cyclohexane as a carbon source on two kinds of graphite: natural graphite powder andgraphite treated with 94% HNO{sub}3. XPS and Raman spectroscopy indicated that these materials were not mixtures of BCx and graphite, but BCx-coated graphites. The BCx-coating modified the charge-discharge profiles of natural graphite. The potential ofthe electrode was low and flat and gradually increased during the last stage of lithium ion deintercalation reaction.