Nitrogen-doped graphitized porous carbon with embedded NiFe alloy nanoparticles to enhance electrochemical performance for lithium-sulfur batteries

Abstract In this work, we prepared the nitrogen-doped graphitized porous carbon with embedded nickel-iron alloy nanoparticles (NiFe@NC) as a sulfur host for lithium-sulfur (Li-S) batteries via a stepwise coating-calcining process of metal-organic framework (MOF) precursors. In the composite, the nitrogen-doped graphitized porous carbon possesses good electronic conductivity and physical adsorption capability for soluble lithium polysulfides (LiPSs). Furthermore, the polar NiFe alloy provides the active sites to anchor the LiPSs and effectively promote the redox conversion kinetics of these intermediates. To confirm this, the density functional theory (DFT) calculations were applied to demonstrate that there is sufficient binding energy between the NiFe alloy and LiPSs. Owing to the above-mentioned benefits, the batteries with the S/NiFe@NC cathode deliver a high initial reversible capacity (1224 mA h g−1 at 0.2 C) along with a stable cycling ability (565 mA h g−1 at 1 C after 500 cycles). Our findings provide insights towards building the novel sulfur-host materials for advanced Li-S batteries.