A Novel Synthesizing Strategy of 3D Cose2 Porous Hollow Flowers for High Performance Lithium-Sulfur Batteries

Redox kinetics of lithium polysulfides (LiPSs) conversion and poor electrical conductivity of sulfur during the charge-discharge process greatly inhibit the commercialization of high-performance lithium-sulfur (Li-S) batteries. Herein, we synthesized CoSe2 porous hollow flowers (CoSe2-PHF) by etching and further selenizing layered double hydroxide, which combined the high catalytic activity of transition metal compound and high electrical conductivity of selenium. The obtained CoSe2-PHF can efficiently accelerate the catalytic conversion of LiPSs, expedite the electron transport, and improve utilization of active sulfur during the charge-discharge process. As a result, with CoSe2-PHF/S-based cathodes, the Li-S batteries exhibited a reversible specific capacity of 955.8 mAh g(-1) at 0.1 C and 766.0 mAh g(-1) at 0.5 C, along with a relatively small capacity decay rate of 0.070% per cycle within 400 cycles at 1 C. Even at the high rate of 3 C, the specific capacity of 542.9 mAh g(-1)can be maintained. This work enriches the way to prepare porous composites with high catalytic activity and electrical conductivity as sulfur hosts for high-rate, long-cycle rechargeable Li-S batteries.