Accelerated redox kinetics and suppressed shuttle effect via B–N–P tri-doped MWCNT/S cathode coupled with a prelithiated Si/rGO anode

Lithium–sulfur (Li–S) batteries are promising next-generation energy storage systems due to their high theoretical energy density; however, their practical application is hindered by sluggish redox kinetics, severe polysulfide shuttle effect, and poor electrode stability. Herein, a B–N–P tri-doped multi-walled carbon nanotube (MWCNT) sulfur cathode coupled with a pre-lithiated Si/reduced graphene oxide (Si/RGO) anode is designed to simultaneously address these challenges. The tri-doped MWCNT framework provides a conductive and defect-rich architecture that enhances polysulfide confinement and accelerates redox conversion. Density functional theory (DFT) calculations reveal significantly strengthened adsorption of Li₂S on the tri-doped surface compared to pristine carbon, arising from electronic redistribution induced by heteroatom incorporation. Electrochemical analyses, including cyclic voltammetry, electrochemical impedance spectroscopy, and rate capability tests, demonstrate improved charge-transfer kinetics, reduced polarization, and superior lithium-ion diffusion. The tri-doped cathode delivers high reversible capacity, excellent cycling stability over extended cycles, and remarkable rate performance compared to pristine MWCNT-based electrodes. Furthermore, symmetric cell CV and UV–vis adsorption tests confirm accelerated Li₂S₆ redox kinetics and strong polysulfide trapping ability, effectively suppressing shuttle behavior. Post-cycling morphological analysis verifies the structural robustness and long-term stability of the tri-doped architecture. The synergistic B–N–P tri-doping strategy provides an efficient pathway to regulate electronic structure, enhance catalytic activity, and stabilize sulfur species, offering a promising route toward high-performance Li–S energy storage systems.