Yolk-double shell structured bread-like Si@Z-700N@void@C nanocomposites as high stability anodes for lithium-ion batteries

Abstract

Although silicon is a promising anode material for lithium-ion batteries, efficient and controllable synthesis of silicon anodes with good cyclability and low electrode swelling remains a major challenge. Here, we have synthesized a novel bread-like Si/C composite with a yolk-double shell structure through sol–gel and self-template methods. In this design, the zeolite imidazolate framework-derived nitrogen-doped porous carbon skeleton is applied to enhance the electrical conductivity of silicon, and the adequate space inside the yolk-double shell structure can effectively mitigate the volume change of silicon. Additionally, porous structures are not only conducive to the rapid diffusion of the electrolyte but also shorten the migration channel of lithium ions and electrons. The stable bread-like double carbon layer structure helps in the formation of stable solid electrolyte interphase films. As expected, the composite demonstrates exceptional electrochemical properties, including outstanding reversible capacity (868.1 mA h g⁻¹ after 500 extended cycles at 1 A g⁻¹) and remarkable rate capability (408.1 mA h g⁻¹ at a high current density of 5 A g⁻¹). Moreover, the anode has a low electrode expansion rate of 31% after cycling. This study provides a new idea for designing high-stability silicon-based anode materials.