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

Abstract

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.