The effect of boron doping on lithium intercalation performance of boron-doped carbon materials

Boron-doped carbons were prepared by pyrolysis of phenolic resin and of pitch with boric acid. The charge-discharge performance of those carbons as an anode electrode material of lithium-ion batteries is here reported. Results showed that the reversible capacity of carbon from pyrolysis of boron-doped phenolic resin was 176.6 mA h g(-1) and its charge-discharge efficiency during the first cycle did not change apparently, while that of carbon from pitch was 258.5 mA h g(-1), and its charge-discharge efficiency during the first cycle was 92.2%. XRD analysis for the present boron-doped materials showed that the distance between carbon layers was lowered by a proper amount of doped boron. XPS analysis with Ar bombardment showed that boron mainly stays on the surface of carbon from pitch, and the increase of surface content of oxygen and nitrogen was also observed. The influence of boron doping on the graphitization of pitch coke and the behavior of lithium intercalation was regarded as surface effect, thus elucidating the increases of graphitization degree and lithium intercalation capacity, and the decrease of irreversible capacity by boron doping. (C) 2002 Elsevier Science B.V. All rights reserved.