Synergistic structural integrity and remarkable structural stability of NC@Si anodes for lithium-ion batteries

Abstract

The silicon-based anode has attracted wide attention because of its high theoretical specific capacity, which is expected to greatly improve the batteries’ energy density. However, during the charge-discharge cycles, the great volume expansion of the anode active silicon seriously restricts its electrochemical stability. Herein, N-doping carbon-coated silicon microsphere was prepared for lithium-ion batteries. Benefit from the core-shell structure formed from silicon carbon, the volume change of silicon anode during the cycle is well coordinated. What's more, N-doping carbon reduces the reaction energy barrier between silicon and lithium and accelerates the electrochemical reaction, which improves the cycling performance of the battery. The specific capacity of the prepared button battery is as high as 2913.13 mAh g⁻¹ at the current density of 0.21 mA g⁻¹, and the average coulomb efficiency is higher than 99.84 % during the cycling. And the capacity of NC@SiO₂ anode gradually stabilizes after 500 cycles.