Design Multifunctional Catalytic Interface: Toward Regulation of Polysulfide and Li2 S Redox Conversion in Li-S Batteries.

The polysulfide shuttle effect and sluggish reaction kinetics hamper the practical applications of lithium-sulfur (Li-S) batteries. Incorporating a functional interlayer to trapping and binding polysulfides has been found effective to block polysulfide migration. Furthermore, surface chemistry at soluble polysulfides/electrolyte interface is a crucial step for Li-S battery in which stable cycling depends on adsorption and reutilization of blocked polysulfides in the electrolyte. A multifunctional catalytic interface composed of niobium nitride/N-doped graphene (NbN/NG) along the soluble polysulfides/electrolyte is designed and constructed to regulate corresponding interface chemical reaction, which can afford long-range electron transfer surfaces, numerous strong chemisorption, and catalytic sites in a working lithium-sulfur battery. Both experimental and theoretical calculation results suggest that a new catalytic interface enabled by metal-like NbN with superb electrocatalysis anchored on NG is highly effective in regulating the blocked polysulfide redox reaction and tailoring the Li2 S nucleation-growth-decomposition process. Therefore, the Li-S batteries with multifunctional NbN/NG barrier exhibit excellent rate performance (621.2 mAh g-1 at 3 C) and high stable cycling life (81.5% capacity retention after 400 cycles). This work provides new insights to promote Li-S batteries via multifunctional catalytic interface engineering.