Breaking Barriers to High-Practical Li-S Batteries with Isotropic Binary Sulfiphilic Electrocatalyst: Creating a Virtuous Cycle for Favorable Polysulfides Redox Environments.

Investigations into lithium-sulfur batteries (LSBs) has focused primarily on the initial conversion of lithium polysulfides (LiPSs) to Li 2 S 2 . However, the subsequent solid-solid reaction from Li 2 S 2 to Li 2 S and the Li 2 S decomposition process should be equally prioritized. Creating a virtuous cycle by balancing all three chemical reaction processes is crucial for realizing practical LSBs. Herein, amorphous Ni 3 B in synergy with carbon nanotubes (aNi 3 B@CNTs) is proposed to implement the consecutive catalysis of S 8(solid) → LiPSs (liquid) → Li 2 S (solid) →LiPSs (liquid) . Systematic theoretical simulations and experimental analyses reveal that aNi 3 B@CNTs with an isotropic structure and abundant active sites can ensure rapid LiPSs adsorption-catalysis as well as uniform Li 2 S precipitation. The uniform Li 2 S deposition in synergy with catalysis of aNi 3 B enables instant/complete oxidation of Li 2 S to LiPSs. The produced LiPSs are again rapidly and uniformly adsorbed for the next sulfur evolution process, thus creating a virtuous cycle for sulfur species conversion. Accordingly, the aNi 3 B@CNTs-based cell presents remarkable rate capability, long-term cycle life, and superior cyclic stability, even under high sulfur loading and extreme temperature environments. This study proposes the significance of creating a virtuous cycle for sulfur species conversion to realize practical LSBs.