Abstract

Micro/nano-Si flakes were obtained by a facile approach of reaction ball milling self-assembly, and then, a Si@C anode material with a carbon content of 17.7wt% was synthesized by combining the Si flakes with phenol formaldehyde resin. It was revealed that the micro/nano-Si flakes inherited the advantages of both nano-Si and bulk Si, showing not only a considerable surface area of 65.6 m² g⁻¹ but also a high tap density of 0.66 g cm⁻³. The Si@C anode showed outstanding electrochemical performance, particularly its high volumetric capacity, due to the formation of dual-layer SiO_x/C film on the micro/nano-Si. The Si@C anode delivered a gravimetric/volumetric capacity as high as 1721.9 mAh g⁻¹/1239.8 mAh cm⁻³ at 0.05 A g⁻¹ and preserved a large gravimetric/volumetric capacity of 1028.7 mAh g⁻¹/740.7 mAh cm⁻³ at 2.0 A g⁻¹. It retained 92.0% of its initial capacity after 200 cycles at 0.5 A g⁻¹.