Electrochemical Restructuring Driven Catalytic Cycle of Bi-Based Heterojunctions for High-Performance Lithium-Sulfur Batteries.

Restructuring is an important phenomenon in catalytic reactions. Conversion-type materials with suitable redox potential may undergo in situ electrochemically driven restructurings and induce highly active catalytic sites in a working lithium-sulfur battery. Herein, driven by the electrochemical conversion reaction of BiVO 4 , a reversible catalytic cycle of Bi/amorphous Li 3 VO 4 (a-Li 3 VO 4 ) and Bi 2 S 3 /a-Li 3 VO 4 heterojunctions is constructed, which targets the oxidation of Li 2 S and the conversion of polysulfide, respectively. The heterostructures and electrochemically driven size confinement provide abundant sites for shuttle restraining and sulfur conversion. Especially, the p-block Bi and Bi 2 S 3 could dramatically reduce the conversion energy barriers of Li 2 S and polysulfide by virtue of the p-p orbital hybridization, promoting bidirectional reactions of the sulfur cathode. As a result, the corresponding sulfur cathode possesses a high reversible capacity of 7.5 mAh cm -2 after 120 cycles under a high sulfur loading of 10.3 mg cm -2 with a current density of 0.38 mA cm -2 . This study furnishes a feasible scheme to obtain highly effective catalysts for bidirectional sulfur redox by utilizing the electrochemically induced restructuring.