Alkylamine-tuned MoOx with synergistic manipulation of interlayer spacing and oxygen vacancies toward advanced Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries have been considered a promising next-generation energy storage device. However, the serious polysulfide shuttle effect and slow reaction kinetics hampered their development. Herein, alkylamine-tuned MoOx with synergistic manipulation of interlayer spacing and oxygen vacancies as a bifunctional mediator for separator modification (refer to as MOC/PP) in Li–S batteries is proposed. The increased interlayer spacing provides a rapid and stable pathway for Li+ diffusion, facilitating uniform Li+ deposition on lithium anode. Rich oxygen vacancies serve as active sites for efficient chemisorption and catalysis with polysulfide. As demonstrated by theoretical calculations and experimental results successively, MOC/PP efficiently captures and accelerates the redox reaction of polysulfide. Therefore, LiǁLi symmetric cells with MOC/PP exhibit stable cycling over 1000 h at a current density of 1 mA cm−2. The full cells deliver a notable discharge-specific capacity of 602 mAh g−1 at 5 C (1 C = 1675 mA g−1) and maintain stable cycling for 800 cycles at 1 C, with 0.07% capacity decay per cycle. Even under conditions of lean electrolyte (E/S = 7 μL mgs−1) and high sulfur mass loading (4.3 mg cm−2), the initial capacity exceeds 1200 mAh g−1.