Mechanistic insight into the role of N-doped carbon matrix in electrospun binder-free Si@C composite anode for lithium-ion batteries

Abstract

To improve the long cyclic stability and rate capability of Si-based anode, we demonstrate a core-shell structural Si@NC composite decorates with N-doped carbon network using a low-cost, a simple process of electrospinning and low-temperature pyrolysis. Si@PVP/Urea fabric composite spun on the copper foil was directly carbonized and then was cut into wafers used as the electrode plates without extra conductive agent and binder. The enhanced rate capability and cyclic stability of special structural Si@NC is mainly ascribable to N-doped carbon matrix providing numerous active sites, which attract Li to those points in an efficient way, and the core-shell structures supply high mechanical strength for Si@NC composite. Importantly, almost 3-fold improvement in the capacity retention rate of the Si@NC has been observed at high current densities of 1.6 and 3.2 A g−1. Meanwhile, DFT calculations confirm that Li will be easily adsorbed by N-active sites in N-doped carbon model to strengthen chemical absorption ability, which could have more chance to grab the quickly moving Li in a brief period. It is significant for theoretical guidance of subsequent studies. The findings should make an important contribution providing a great possibility for the mass production and application to the field of lithium-ion battery.