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The structural characteristics of litchi shell-derived carbon are conducive to regulation and modification. Using biomass waste litchi shells as carbon source and nano-silicon particles to prepare silicon-carbon composite materials to relieve the volume effect of silicon in the charge and discharge process, litchi shell-derived activated carbon (LAC) with high specific surface area (1011.115 m2 g−1) and high porosity was obtained from litchi shell as silicon buffer matrix by simple high-temperature calcination and activation of ZnCl2. A silicon-carbon composite material (3D LAC@Si) with an embedded cladding structure was prepared with a high-energy ball milling process. In the electrochemical performance test, 3D LAC@Si as the negative electrode of a lithium-ion battery showed a high lithium storage capacity of 834.4 mAh g−1 and a high coulombic efficiency of 98.34% after cycling 100 cycles at a current density of 0.2A g−1. [ABSTRACT FROM AUTHOR]

• The facile and cost-effective preparation process of yolk-shell Si/C composites and modification methods with high scalability. • The designed pore channel structures endowing the optimal lithium storage capacity and volume change tolerance. • The high crystallinity ensures the outstanding electronic conductivity and robust carbon shell. • The optimal Si/C composite with a well matching microstructure of carbon shell exhibits excellent cycling performance and rate capacity (55% retention at 300th cycle, 743 mAh g−1 at 2 A g−1). • Correlation between microstructural feature (crystallinity and pores) of the carbon shell and the electrochemical behaviors of the Si/C electrodes is established. Silicon-carbon composites have proved to be effective in addressing the issues of silicon anodes, however, few works focus on understanding the effect of the microstructure of the carbon component on their electrochemical performance. Herein, we prepare a series of yolk-shell structured silicon-carbon nanocomposites with adequate voids through a facile and scalable process. By deliberately selecting the pitch species and delicately adjusting the heat treatment temperature, the microcrystal texture and pore structure of the soft carbon can be easily tuned. Finally, a well matching of the crystalline and pore structure ensure the rapid charge transport and the good structural robustness, further endowing the optimal lithium storage, cycle performance and rate capability of the electrodes. The Si/C composite with an optimized carbon shell delivers a reliable cycle stability with a capacity retention ratio of 55% after 300 cycles at 0.2 A g−1 and a remained capacity of 743 mAh g−1 at a high current density of 2.0 A g−1. Importantly, the correlation between the lithium storage of the Si/C composites and the microstructure features (crystallinity and pores) of the carbon shell has been established, which may provide an effective guidance for optimizing the microstructure design of the promising Si/C anode materials. We established the relationship between designed microstructural feature (crystallinity and pores) of the carbon shell and corresponding electrochemical performance of the Si/C anodes. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Silicon can be used in a variety of applications. Particularly, silicon particles are attracting increased attention as energy storage materials for lithium-ion batteries. However, silicon has a limited cycling performance owing to its peeling from the current collector and the volume expansion that occurs during alloying with lithium in the charging process. Significant contributors to this problem are the even distribution of silicon nanoparticles within the carbon matrix and their deep placement in the internal structure. In this study, we synthesized silicon nanoparticles and carbon materials via a bottom-up approach using a new method called plasma in solution. Silicon nanoparticles and the carbon matrix were synthesized in a structure similar to carbon black. It was confirmed that the silicon particles were evenly distributed in the carbon matrix. In addition, the evaluation of the electrochemical performance of the silicon–carbon matrix (Si–C) composite material showed that it exhibited stable cycling performance with high reversible capacity. [ABSTRACT FROM AUTHOR]