Strategically Engineered Metal Cluster–Rare Earth Oxide Heterojunction Catalyst for High-Performance Lean Electrolyte Lithium–Sulfur Batteries

Developing high-energy-density lithium–sulfur batteries faces serious polysulfide shuttle effects and sluggish conversion kinetics, often necessitating the excessive use of electrolytes, which in turn adversely affects battery performance. Our study introduces a meticulously designed electrocatalyst, Cu–CeO2–x@N/C, to enhance lean-electrolyte lithium–sulfur battery performance. This catalyst, featuring in situ synthesized Cu clusters, regulates oxygen vacancies in CeO2 and forms Cu–CeO2–x heterojunctions, thereby diminishing sulfur conversion barriers and hastening reaction kinetics through the generation of S32–/S3*– intermediates. Besides, the three-dimensional conductive networks, composed of Cu and nitrogen-doped carbon matrices with high electrolyte affinity, effectively confine sparse electrolytes proximal to the catalyst locations, thereby facilitating rapid transport of Li+/electron to the active sites. As a result, the 1% Cu–CeO2–x@N/C cell demonstrated robust performance, achieving an initial discharge capacity of 793.2 mAh/g at 5 C over 500 cycles and maintaining a capacity of 719.9 mAh/g at 0.3 C with an electrolyte-to-sulfur ratio of 5 μL mg–1 and a high sulfur loading of 5.4 mg cm–2 after 60 cycles. These findings highlight the catalyst design for high-performance lean-electrolyte lithium–sulfur batteries, further paving the way for their commercialization.