Polysulfide electrocatalysis on framework porphyrin in high-capacity and high-stable lithium-sulfur batteries

Lithium-sulfur batteries with an ultrahigh theoretical energy density of 2600 Wh kg-1 are highly considered as desirable next-generation energy storage devices that will meet the growing demand of energy consumption worldwide. However, complicated sulfur redox reactions and polysulfide shuttling significantly postpone the applications of lithium-sulfur batteries with rapid capacity decay and low Coulombic efficiency. Herein, a unique strategy of polysulfide electrocatalysis is proposed to improve the kinetics of the sulfur species and inhibit polysulfide shuttling in working lithium-sulfur batteries. Inspired by a natural biocatalyst and congener oxygen electrocatalysis, porphyrin was selected as the electrocatalytic active site, and framework porphyrin (POF) electrocatalysts were rationally designed, precisely fabricated, and demonstrated superior full-scheme electrocatalytic performance with regard to improving the kinetics for polysulfide conversion, Li2S nucleation, and dissolution of Li2S to polysulfides, simultaneously. Consequently, the lithium-sulfur batteries with POF electrocatalysts achieve high capacity of 1611 mAhg-1 at 0.1 C; outstanding stability with the capacity decay rate of 0.071% in 400 cycles, and satisfied performance with a high sulfur loading up to 4.3 mgcm-2. The strategy of polysulfide electrocatalysis develops our chemical understanding of sulfur species in energy-related applications and inspires the electrocatalysis concept for extended energy conversion and storage systems based on multielectron redox reactions.