Enhanced sulfur redox kinetics and polysulfide regulations with petal-like nickel hydroxide nanosheets/rGO modified separators in Li-S batteries

Highlights: • A petal-like nickel hydroxide nanosheets/rGO used for modified separators in Li-S Batteries. • NHN plays a key role in promoting the redox reaction kinetics of Li-S batteries. • The high conductivity of rGO helps to enhance the electrochemical function of NHN. • The modified separators significantly improve the specific capacity and cycling stability. Li-S batteries have been regarded as one of the most prospective energy-storage systems because of its high-energy-density. To suppress the shuttling effect of dissolved lithium polysulfides, different mass ratios petal-like nickel hydroxide nanosheets (NHN) decorated reduced graphene oxide (rGO) materials are synthesized in this study using a one-step hydrothermal method and applied modified separators in Li-S batteries. With up to 73.5 wt% of sulfur content in the cathode, the optimized sample (the mass ratio of graphene oxide to nickel nitrate is 1:9) enables discharge capacities up to 1579 mAh g⁻¹ at 0.2 C (the areal sulfur loading is 5 mg cm⁻²). The cell also exhibits a retention of 840 mAh g⁻¹ in specific capacity after 200 cycles, exhibiting higher utilizations and better cycling stabilities for Li-S batteries. Electrochemical measurements and density functional theory (DFT) calculations prove that NHN plays a critical role in promoting the redox reaction kinetics of Li-S batteries, and the high conductivity of rGO enhances the electrochemical function of NHN. This study provides a low cost approach for the developments of modified separators in future practical Li-S batteries.