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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 1s 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 ∼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. © 2000 The Electrochemical Society. All rights reserved.

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The microstructure and electrochemical properties of pristine and boron‐doped mesocarbon microbeads (MCMBs) were comparatively studied by X‐ray diffraction, field‐emission scanning electron microscopy, Raman spectroscopy, and electrochemical measurements. We examined the correlation between the boron‐doping effect and the electrochemical properties of boron‐doped MCMBs prepared at different heat‐treatment temperatures. It was found that boron doping in MCMBs starts above 1800°C, and then the substitution reaction proceeds with increasing heat‐treatment temperature. The effect of boron doping is to accelerate graphitization of MCMBs for heat‐treatment temperatures in the range from 1800 to 2500°C. Electrochemical lithium intercalation takes place at a higher potential in boron‐doped MCMBs than in undoped MCMBs, presumably because the substitutional boron acts as an electron acceptor in the MCMBs. © 2000 The Electrochemical Society. All rights reserved.

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