An integrated cathode with bi-functional catalytic effect for excellent-performance lithium-sulfur batteries

Abstract

The high energy density of lithium-sulfur batteries (LSBs) is mainly based on the complex redox reactions and phase conversions. The sluggish redox kinetics and the large accumulation of soluble polysulfides in the electrolyte leads to low sulfur utilization and serious shuttle effect. Herein, an integrated sulfur cathode is constructed through a facile and large-scale method. It is composed of sulfur-N, S doped bamboo like CNTs@Co3S4 (CNTs@Co3S4) composites on polypropylene separator. The immobilized polysulfides on the CNTs@Co3S4 surface are further reduced/oxidized during the discharge/charge process via the efficient bi-functional catalytic effect of CNTs@Co3S4, resulting in the rapid conversion of LiPSs. Consequently, the integrated sulfur cathode delivers a high initial reversible capacity of 1,473.6 mAh·g−1 at 0.2 C and a high specific capacity of 979 mAh·g−1 at 1 C after 500 cycles as well as excellent cycling stability for 1,000 cycles with a high specific capacity of 362.5 mAh·g−1 at 5 C, which are superior to reported similar host materials.