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

Abstract

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−1can 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.

Keywords

• transition metal selenide
• catalysis
• electrical conductivity
• lithium sulfur batteries