Structural and electrochemical properties of pristine and B-doped materials for the anode of Li-ion secondary batteries

The structure and anode performance of Li-ion batteries for three different forms of carbon materials (powder, spheres, fibers) and three boron-doped samples have been studied comparatively. The characterization and properties were obtained by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and electrochemical measurements. The B Is peak of boron-doped graphite I was split into three peaks at 185.6, 187.7, and 189.8 eV, which were assigned to boron in boron carbide, in a boron cluster, or boron bound to incorporated nitrogen atoms, respectively. The electrochemical introduction of Li ions takes place at similar to 40 mV higher potential in boron-doped samples than in undoped samples, presumably because the substitutional boron acts as an electron acceptor in the graphite lattice. Also, it is suggested that the electrochemical properties of boron-doped graphitized materials depend on the structural geometry and chemical composition of the pristine host materials. (C) 2000 The Electrochemical Society. S0013-4651(99)09-071-0. All rights reserved.