Bilayer functional interlayer coupling defect and Li-ion channel for high-performance Li-S batteries

• Defect design of Se doping synchronously improves the electronic conductivity and polysulfide adsorption–catalysis capability of MoS 2 . • rGO/MoSSe functional layer serves as an auxiliary cathode and upper current collector accelerates the electron transport and redox kinetics of polysulfide. • The carbon nanofiber layer providing channels for the rapid transmission of Li + improves the reversible capacity at high current densities. • The designed Li–S batteries exhibit enhanced capacities and cyclic stabilities. Lithium-sulfur (Li-S) batteries have been demonstrated as one of the promising candidates for next-generation energy-storage devices. However, low utilization of active materials, detrimental shuttle effect of lithium polysulfides, and sluggish redox kinetics hamper the commercial applications of Li-S batteries. Herein, we design a bilayer functional interlayer composed of reduced graphene oxide/Se-doped MoS 2 (rGO/MoSSe) layer and carbon nanofiber (CNF) layer (rGO/MoSSe@CNF) for high-performance Li-S batteries. The defective structure of Se-doped MoS 2 significantly improves the polysulfide adsorption–catalytic ability due to the exposure of more active sites and the adjustment of local electronic structure. Accordingly, the rGO/MoSSe functional layer effectively improves the electrochemical reaction kinetics and cyclic stability. In addition, the CNF layer effectively reduces the transport resistance of Li + , and improves the reversible capacity at high current densities. The Li-S coin cell with rGO/MoSSe@CNF interlayer delivers a remarkable reversible specific capacity of 922.4 mAh g −1 after 140 cycles at 0.2 C and a slow capacity decay rate of 0.057% per cycle over 1000 cycles at 1 C. Moreover, the Li-S pouch cell with rGO/MoSSe@CNF interlayer at sulfur loading of 3 mg cm −2 can maintain a reversible specific capacity of 706.2 mAh g −1 after the rate test and 175 cycles at 0.2 C. A bilayer functional interlayer composed of reduced graphene oxide/Se-doped MoS 2 (rGO/MoSSe) layer and carbon nanofiber (CNF) layer is designed for Li-S batteries . Defect design of Se doping improves the polysulfide (LPSs) adsorption–catalytic ability of MoS 2 . The rGO/MoSSe functional layer serves as an auxiliary cathode and upper current collector, improving LPSs redox kinetics and cyclic stability. The CNF layer providing channels for the rapid transmission of Li + improves the reversible capacity at high current densities.