Nitrogen-doped hollow carbon boosting the anchoring of sulfur capacity for high-loading lithium–sulfur batteries

Abstract

As one of the best candidates, lithium sulfur battery (Li–S) is extensively explored due to the high theoretical capacity and abundant sources of sulfur. Carbon-based materials take an important role as a host for sulfur in the cathode. In this paper, a nitrogen-doped hollow carbon for sulfur cathode (NHC–S) with high sulfur loading of 92% is studied for Li–S batteries. The structural characterization demonstrates that the N-doping can improve the graphitization of the hollow carbon material, which increases the electrical conductivity. The catalytic and deposition nucleation tests indicate that the N doping can increase the nucleation rate of Li 2 S, which is also illustrated by the larger binding energies of Li 2 S on N-doping substrates than on carbon via density functional theory (DFT) analysis. The initial specific capacity of NHC–S is 864.8 mAh g −1 at the current density of 0.2 C, and 460.8 mAh g −1 after 500 cycles. When the sulfur content loading was up to 2.8 mg cm −2 , the electrode material could achieve 85% capacity retention after 100 reversible cycles. • The sulfur loading of the Li–S batteries achieves 92% in the N-doped sample. • The improved graphitization by N doping accelerates the transportation of electrons. • The N-doped system promotes the redox reaction kinetics in Li–S batteries. • The initial specific capacity of NHC–S achieves 864.8 mAh g −1 at the current density of 0.2 C.