A self-sacrifice template strategy to synthesize silicon@carbon with interior void space for boosting lithium storage performance

A sufficient internal void space is highly desirable for relieving the volume expansion of silicon anode materials upon repeated insertion/extraction. Herein, Si/graphene@carbon (Si/G@C) composites with internal voids are prepared via ultrasonic spraying under vacuum, in which void spaces come into being by low-temperature calcinating acid citric (CA) as self-sacrifice template. Benefiting from the appropriate amount of void space in composites, Si/G@C-1gCA exhibits best electrochemical performances among the as-prepared composites, delivering a long-term cycle life (1048.8 mAhg−1 after 150 cycles at 2 Ag−1) and superior rate capability (660.6 mAhg−1 at 10 Ag−1). In contrast, excessive void spaces in composites would expectantly reduce the mechanical strength of carbon framework in composites, induce more electrolyte permeation into composites, lead to excessive decomposition of the electrolyte, and consequently result in unstable SEI-film evolution. The obtained investigation further reveals that appropriate amount of void spaces in Si/G@C composites is beneficial for the improved performances of anode materials in terms of stable SEI-film evolution and structural integrity.Graphical abstractThis work offers a eco-friendly self-sacrifice template strategy for fabricating high-performance Si/graphene@carbon anodes with appropriate internal void.