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–CeO 2– x @N/C, to enhance lean-electrolyte lithium–sulfur battery performance. This catalyst, featuring in situ synthesized Cu clusters, regulates oxygen vacancies in CeO 2 and forms Cu–CeO 2– x heterojunctions, thereby diminishing sulfur conversion barriers and hastening reaction kinetics through the generation of S 3 2– /S 3 *– 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–CeO 2– 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.