Combination of heterostructure with oxygen vacancies in Co@CoO1-x nanosheets array for high-performance lithium sulfur batteries

[Display omitted] •Free-standing 2D nanosheets array as fabricate high-performance sulfur hosts.•Design core–shell heterostructure in nanosheets with controlled oxygen vacancies.•Highly exposed active sites to realize strong LiPS adsorption ability.•Decrease their negative effect on the electrical conductivity. Shuttle effect of lithium polysulfide (LiPS) and slow sulfur redox kinetics have seriously impeded the commercial application of lithium-sulfur (Li-S) batteries. Here, to solve these issues, a synergistic engineering strategy is proposed to rationally fabricate porous core–shell Co@CoO1-x nanosheets array grown on carbon cloth (CC/Co@CoO1-x) as a sulfur host. The porous two-dimensional (2D) nanosheets array structure endows CoO1-x shells with highly exposed active sites, leading to strong LiPS adsorption ability. Besides, abundant oxygen vacancies (OVs) enhance the electrical conductivities of CoO1-x shells and facilitate the breakage of the S-S bond in adsorbed LiPS. Furthermore, the underneath metallic Co cores with few grain boundaries coupled with CC form integrated and continuous conductive networks, which achieves fast electron transfer from CC to CoO1-x surfaces to accelerate the immobilized LiPS conversion. Due to the synergistic effect of sulfophilic CoO1-x shells and conductive Co cores, the CC/Co@CoO1-x host enables a high-performance Li-S battery with excellent performance even at a high sulfur loading of 5.1 mg cm−2. This work highlights the effectiveness of combination 2D core–shell heterostructure with OVs to inhibit shuttle effect of LiPS and meanwhile boost sulfur conversion, which can guide the future design of high-performance sulfur hosts.