Improved rate capability of Si–C composite anodes by boron doping for lithium-ion batteries

• The effects of boron doping on the rate capability of Si–C composite are studied
• Boron doping lowers the charge transfer resistance of the composite
• Boron-doped Si–C composite shows much improved rate capability than the undoped one
• Boron-doped Si–C composite can deliver a high capacity of 575 mAh/g at 6.4 A/g without any external carbon additive

We report a novel strategy to enhance the rate capability of Si–C composite by facile boron doping. Boron doping was confirmed by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The boron-doped Si–C composite shows much improved rate capability, delivering a capacity of 575 mAh/g at 6.4 A/g without any external carbon additive, 80% higher than that of undoped composite. Electrochemical impedance spectroscopy (EIS) measurement shows that boron-doped Si–C composite has lower charge transfer resistance, which helps improve its rate capability.