Investigation of porous multi-carbon layers constructed on submicron silicon flakes for high-performance Li-ion batteries anode

Low initial coulombic efficiency (ICE) of crystal silicon anode is fatal for lithium-ion batteries, leading to impossibility for commercial application. In this study, the submicron flaky silicon particles recycled from Si waste in photovoltaic industry clustered and formed into new structure through liquid-phase pyrolysis of amorphous carbon. After covered by amorphous carbon layer, the silicon flakes are surrounded by carbon skeleton of mesh-porous to be a Nitrogen-doped submicron silicon/multi-carbon material (SCN). The initial coulombic efficiency of SCN reaches 88.55 % at high discharge/charge capacities of 960.4/850.5 mAh g⁻¹, which owe to the appropriate amorphous carbon on surface of Si for reducing the initial irreversible capacity loss due to solid electrolyte interface layer. The capacity retention of SCN keeps to a high stage up to 74.8 % after 100 cycles. It is realized that the Nitrogen-doped reticulated porous carbon not only improves the transport of particles, but also mitigates the volume expansion of silicon during charging and discharging and improves the cycling stability of the electrode. The stable performance of large-size silicon particles in the anode provides a good guarantee for the future development of lithium-ion batteries.