Multi-functional double carbon shells coated boron-doped porous Si as anode materials for high-performance lithium-ion batteries

Various strategies have been devised to relieve the volume expansion and enhance the electronic conductivity of Si-based anode materials in LIBs. Herein, we have synthesized a novel double carbon shells coated boron-doped porous Si (B-PSi@double C) composite using low-cost industrial ferrosilicon alloys as raw materials through a modified ball milling combined with self-polymerization of dopamine hydrochloride and chemical vapor deposition process with acetylene. In this work, the boron-modified porous Si structure facilitates improved electron and Li+ kinetics. The inner flexible carbon can regulate the volume variation of Si during lithiation and enhance the particles' electrical connectivity. Moreover, the outer rigid carbon promotes stable SEI formation and maintains structural integrity. This unique rigid-flexible double carbon structure, combined with the highly -capacity modified porous Si particles, render the composite to display outstanding electrochemical properties regarding both lithium storage capacity and cycling stability. As a result, the B-PSi@double C electrode displays a reversible capacity of 1105.8 mAh g-1 at 0.5 A g-1 over 300 cycles and excellent cyclic stability. This study provides a novel idea for producing low-cost and high-energy Si-based anode materials for LIBs.