Facile synthesis of silicon/carbon nanospheres composite anode materials for lithium-ion batteries

• The amorphous carbon shell function as conducting framework.
• The carbon spheres accommodate large volume expansion of silicon.
• The composite exhibited stable cycling properties and excellent rate capability.

Silicon/carbon nanospheres composite has been prepared by a facile chemical method followed by heat treatment. The Si particles are coated by an amorphous carbon layer that supresses agglomeration of pristine Si. Carbon spheres accommodate large volume expansion of silicon during cycling. The unique carbon frameworks enhance transmission capability of the composite by offering a large surface area and a short diffusion distance. By electrochemical characterizations, the silicon/carbon nanospheres composite exhibits initial reversible specific capacity of 888.6 mAh g−1 at current density of 200 mA g−1. After cycling up to 50 cycles, the electrode still delivers charge capacities of 610.7 mAh g−1. Notably enhanced rate capability is attained, with a reversible specific capacity of 811.4, 747.3, 395.5, 289.9 mAh g−1 at the current density of 0.5, 1, 3 and 5 A g-1, respectively.