Polysulfide Electrocatalysis on Framework Porphyrin in High-Capacity and High-Stable Lithium–Sulfur Batteries

Abstract

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, Li 2S nucleation, and dissolution of Li 2S to polysulfides, simultaneously. Consequently, the lithium–sulfur batteries with POF electrocatalysts achieve high capacity of 1611 mAh·g −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 mg·cm −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.