NiSe nanoparticles decorated corn stalk derived 2D carbon nanosheet as separator modifier for high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as the most promising successors of lithium-ion batteries, however, the shuttle effect and sluggish reaction kinetics are the biggest obstacles hindering their commercialization. In this work, a kind of NiSe nanoparticles embedded in corn stalk-derived two-dimensional (2D) porous carbon nanosheet (NiSe@CSC) is constructed as a separator modifier for advanced Li-S batteries. The rich pore structure of the corn stalk-derived carbon nanosheets enables uniform distribution of NiSe and provides more deposition sites for lithium polysulfides (LiPS). Electrochemical analyses show that NiSe increases the affinity for LiPS to suppress the shuttle effect, thereby effectively preventing the corrosion of polysulfide on the lithium anode. NiSe@CSC is found to accelerate the redox conversion of sulfur species in the kinetic study. Consequently, the assembled Li-S cells with NiSe@CSC coating layer exhibit a high-rate performance of 710 mAh g-1 at 3 C and a low capacity attenuation rate of 0.046% per cycle after 800 cycles at 1 C. Furthermore, it can still maintain 2.8 mAh cm-2 at 0.5 C in near-commercial application scenarios of 4.1 mg cm-2 sulfur loading. The NiSe@CSC based Li-Li symmetric cells also demonstrate stability and low overpotential in protecting the lithium anode. This combination of renewable biomass-based carbons and transition metal selenides enriches the exploration of biomass materials in separators and provides new ideas for designing practical Li-S batteries.