Understanding the Curvature Effect of FeCo Nanoalloy Encapsulated by Nitrogen‐Doped Carbon Nanotubes for High‐Performance Lithium–Sulfur Batteries

Well-designed structures of the electrocatalyst provide excellent catalytic activity and high structural stability during the sulfur reduction reaction of Lithium-sulfur batteries (LSBs). In this study, a novel and efficient structure is developed to encapsulate bimetallic FeCo nanoalloy catalysts within N-doped carbon nanotube (NCNT) on carbon nanofibers (FeCo@NCNT/CNFs) using a combination of electrospinning and rapid-cooling techniques. The NCNT matrix with abundant sites not only serves as a high pathway for electron transport during the reaction, but its encapsulation structure also acts as armor to protect the FeCo nanoalloy. Further, the curvature effect of the FeCo@NCNT structure facilitates greater electron transfer from the FeCo nanoalloy to the NCNT, and lowering the reaction barrier for the liquid-solid conversion process. As a result, the S/FeCo@NCNT/CNFs cathode can achieve exceptional cycle performance of 500 cycles at 5 C, with an ultra-low capacity fade rate of 0.031% per cycle. Moreover, even under extreme temperature conditions of -20 and 80 °C, the battery still delivers a specific capacity of 827.16 and 697.46 mAh g^-1 at 1 C. This work shows an effective insight into enhancing the LiPS conversion kinetics over a wide temperature range in Li-S batteries.