Selenide in 3D structure of polyhedra branching out nanotubes for collaborative facilitated conversion and capturing of polysulfide in Li–S batteries

Lithium–sulfur batteries (LSBs) are considered as the promising solution to replace conventional lithium–ion batteries due to satisfactory energy density. In recent times, the LSBs field has been found to face some difficulties in exploring practical applications in which cycling stability and cycle life are awful owing to the shuttling effect of lithium polysulfides (LiPSs) and low sulfur utilization. In this work, by synthesizing Co₃Se₄ nanoparticles onto N-doped carbon (NC) polyhedra interconnected with carbon nanotubes (CNTs), NC@Co₃Se₄/CNTs is proposed as a multifunctional sulfur carrier. The Co₃Se₄ nanoparticles fleetly catalyze the conversion of LiPSs and availably immobilize LiPSs. Meanwhile, the NC polyhedral skeleton enhances the electronic conductivity of active sulfur, while the CNTs facilitate Li⁺ diffusion and supply a mass of conductive channels. Density-functional theory (DFT) calculations demonstrate the relevant mechanisms. That is to say, the NC@Co₃Se₄/CNTs benefit from the synergistic effect of Co₃Se₄ nanoparticles (highly catalytic ability and strong adsorbability for LiPSs) and the special carbonaceous structure, rapidly converting LiPSs and inhibiting the shuttle of LiPSs. Therefore, lithium–sulfur battery assembled with S/NC@Co₃Se₄/CNTs cathode as well as nitrogen and sulfur co-doped carbon-coated polypropylene (N,S-C/PP) separator possesses a high initial discharge capacity of 1413 mAh·g⁻¹ at 0.12C and persistently circulates for 1000 cycles at 1C with a capacity attenuation rate per cycle of 0.034%. This work provides a realistic idea for the use of transition metal selenide in the field of high-performance LSBs.

Graphical Abstract