N, P-co-doped three-dimensional porous carbon nanocomposites for lithium–sulfur batteries

Porous carbon materials have been widely used in lithium–sulfur batteries due to the excellent electrical conductivity, high porosity, and efficient adsorption of polysulfides. In this work, N, P co-doped three-dimensional porous carbon nanocomposites (FeNi/FeNiP@NP-C) were successfully prepared by the pyrolysis method using phytic acid (PA) and melamine as phosphorus and nitrogen sources as sulfur-loaded substrates. It can be found that the FeNi/FeNiP@NP-C material with the three-dimensional porous carbon framework has good conductive performance, which can not only adsorb soluble polysulfides, but also can promote electron transfer to improve reaction kinetics. The results show that the S@FeNi/FeNiP@NP-C cathode has good electrochemical performance and cycle stability. The reversible initial capacity of the S@FeNi/FeNiP@NP-C cathode reaches 1035.8 mAh g⁻¹ under the sulfur loading of 1.0 mg cm⁻² and current density of 0.1 C. Moreover, under the high sulfur loadings (4.3 mg cm⁻²), it still can maintain the specific discharge capacity of 435.5 mAh g⁻¹ after 100 cycles at 0.1 C.