Design of hierarchical buffer structure for silicon/carbon composite as a high-performance Li-ion batteries anode

Silicon-based materials are used as anode material for lithium-ion batteries, due to ultra-high theoretical specific capacity. However, large volume changes, continuous formation of unstable solid electrolyte interface film and low conductivity greatly restricted its large-scale development and application. In this case, a composite with hierarchical buffer structure coated Si nanoparticles (Si@RF@MP) was designed and manufactured by the surfactant template and emulsification method in this study. The resorcinol–formaldehyde resin acts as the structural buffer and the conductive layer to accommodate the volume change of silicon and provide fast channels for electron transfer and lithium-ion diffusion. The unique turbostratic structure of mesophase pitch can effectively improve the integral conductivity and the structural stability of the electrode. As a result, the Si@RF@MP composite exhibited an excellent reversible discharge capacity of 389 mA h g^?1 after 200 cycles at 200 mA g^?1, and retained a discharge capacity of 345 mA h g^?1 after 300 cycles at a high current density of 1000 mA g^?1. In addition, the Si@RF@MP composite delivered reversible capacities of about 546 mA h g^?1, 495 mA h g^?1, and 437 mA h g^?1 in current densities of 500 mA g^?1, 1000 mA g^?1, and 2000 mA g^?1, respectively, indicating good rate performance. Hence, this strategy provides a new method and idea for the further development of silicon/carbon composites and a strategy to achieve high value and green utilization of pitch.