Enhanced electroactivity and diffusion by cobalt atomic clusters impregnated in biomass-derived porous carbon for...

Room temperature (RT) Na-S batteries are promising for widespread applications offering a compelling combination of high energy density and low-cost raw materials. Nevertheless, poor electrochemical activity of the sulfur cathode and shuttle effect of sodium polysulfides (NaPSs) severely hinder the commercialization of RT Na-S batteries. Herein, cobalt atomic clusters-loaded biomass-derived porous carbon (PC-Co_ac) was used to fabricate a cathode overcome the shortcomings, of which the N-Co₃-N₄ species offers high catalytic activity and excellent charge transport ability while PC possessing optimized porosity for rapid mass diffusion. The assembled RT Na-S batteries deliver excellent performance in ester-based electrolytes, exhibiting a high initial Coulombic efficiency (76.5 %), a notable rate capability of 628 mAh g^-1 at 8 A g^-1, and a reversible capacity of 528 mAh g^-1 after 400 cycles at 4 A g^-1. The synergy between the porous carbon and cobalt atomic clusters enhances the reaction kinetics of sulfur, mitigates the polysulfide shuttle effect, and improves sulfur utilization, leading to superior battery performance. Electrochemical analysis reveals that the synthesized material facilitates sodium-ion diffusion, reduces interfacial charge-transfer resistance, and mitigates stress from volume expansion. This work demonstrates a great potential of metal atomic clusters and offers valuable insights into the design of biomass-derived porous carbon for high-performance RT Na-S batteries.