Carbon nitride “patching” Fe-CoHNC catalysts for accelerating conversion kinetics in wide-temperature lithium-sulfur batteries

Abstract

Metal-nitrogen-carbon (M‒N‒C) catalysts have been widely studied in lithium-sulfur (Li-S) batteries due to high atomic utilization and well-defined structure. However, these catalysts often exhibit a substantial number of macropores on the surface of carbon matrix, with uneven distribution of pore structures, which limits their ability to effectively inhibit the shuttle effect. Herein, we combine oxidized two-dimensional carbon nitride (Ox-C₃N₄) with Fe and Co-contained three-dimensional carbon nanocages (Fe-CoHNC) to enhance the electrochemical performance of Li-S batteries (denoted as Fe-CoHNC@OCN). Ox-C₃N₄, with its large specific surface area and unique layered architecture, is selected for its strong ability to “patch” the pore structure of the Fe-CoHNC catalysts. The “patching” regulation not only reduces the quantity of macropores, improving the physical blocking efficiency, but also introduces additional chemical trapping sites to anchor and convert polysulfides, which is demonstrated by in-situ Raman test. Impressively, the Fe-CoHNC@OCN modified cell demonstrates remarkable cycling stability, achieving a decay rate of 0.064 % per cycle over 800 cycles at 1.0 C, and decent capacity tolerance at extreme temperatures (–10 °C and 60 °C).