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 CeO₂ and forms Cu-CeO_2-x heterojunctions, thereby diminishing sulfur conversion barriers and hastening reaction kinetics through the generation of S₃^2-/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-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.