A sandwich-type sulfur cathode based on multifunctional ceria hollow spheres for high-performance lithium–sulfur batteries

Abstract

Despite prominent research efforts towards developing cathode materials for lithium–sulfur batteries, relatively little emphasis has been placed on constructing functional cathode architectures. Herein, ceria (CeO₂) hollow spheres are prepared to fabricate the inside and outside structures of cathodes. A sandwich-type sulfur cathode, namely, a h-CeO₂/sulfur-x-CNT/h-CeO₂ cathode, is designed and fabricated by a simple layer-by-layer process. Due to its unique structural and compositional features, the h-CeO₂/sulfur-0.8-CNT/h-CeO₂ cathode delivers high specific capacities of 876, 761, and 644 mA h g⁻¹ at 1C, 2C and 5C rates, and the capacity retentions are 85.7%, 87.8%, and 92.4%, respectively. During 100 test cycles, the material displays high coulombic efficiencies (above 99%) after the first cycle. More importantly, the cathode with a sulfur loading of 1.8 mg cm⁻² also exhibits a stable cycling life up to 500 cycles at 1C with a capacity decay as low as 0.073% per cycle.