A novel raspberry-like yolk-shell structured Si/C micro/nano-spheres as high-performance anode materials for lithium-ion batteries

Abstract Seeking a silicon/carbon (Si/C) composite with a reasonable structure and high electrochemical performance fabricated by a new method to simultaneously satisfy low-cost and large-scale production is a common goal in the field of anode materials of lithium ion batteries. The preparation of Si/C composite microspheres by spray drying using common pitch as a carbon coating has not been reported, although it can greatly reduce the production cost. Through technological innovation, we prepared pitch-doped composite microspheres by spray drying. Furthermore, a novel type of raspberry-like yolk-shell structured (R–YS) Si/C micro/nano-spheres was successfully designed and prepared using low-cost pitch as the carbon shell precursor and commercial silicon nanoparticles as the Si yolk. Through systematic microstructural and electrochemical analysis, it is found that the R–YS Si/C micro/nano-spheres exhibit a better structural and cyclic stability than those of common YS Si/C nanospheres. Electrochemical test results show that reversible capacity of R–YS Si/C micro/nano-spheres is 1064 mA h/g at 200 mA/g. Along with structural adjustment during the cycling process, reversible capacity decreases at the beginning, but recovered to 981 mA h/g after 250 cycles, with a high capacity retention rate of 92%. This research provides a new strategy to fabricate Si/C composites as anode materials with a low-cost, facile preparation method and high performance simultaneously, which is beneficial to promote the practical application of Si/C anode materials.