Scalable synthesis of core-shell structured SiOx/nitrogen-doped carbon composite as a high-performance anode material for lithium-ion batteries

• Highly efficient polydopamine coating method was employed to synthesize SiOx/C.
• The SiOx/C has a core-shell structure with uniform nitrogen-doped carbon layer.
• The SiOx/C composite exhibits significantly improved electrochemical performance.
• The versatile and facile polydopamine coating method can be applied widely.

In this work, a novel core-shell structured SiOx/nitrogen-doped carbon composite has been prepared by simply dispersing the SiOx particles, which are synthesized by a thermal evaporation method from an equimolar mixture of Si and SiO2, into the dopamine solution, followed by a carbonization process. The SiOx core is well covered by the conformal and homogeneous nitrogen-doped carbon layer from the pyrolysis of polydopamine. By contrast with the bare SiOx, the electrochemical performance of the as-prepared core-shell structured SiOx/nitrogen-doped carbon composite has been improved significantly. It delivers a reversible capacity of 1514 mA h g−1 after 100 cycles at a current density of 100 mA g−1 and 933 mA h g−1 at 2 A g−1, much higher than those of commercial graphite anodes. The nitrogen-doped carbon layer ensures the excellent electrochemical performance of the SiOx/C composite. In addition, since dopamine can self-polymerize and coat virtually any surface, this versatile, facile and highly efficient coating process may be widely applicable to obtain various composites with uniform nitrogen-doped carbon coating layer.