Yolk-shell structure MnO2@Hollow carbon nanospheres as sulfur host with synergistic encapsulation of polysulfides for improved Li–S batteries

• Published in: Journal of alloys and compounds Vol. 842; p. 155790
• Main Authors: Shao, Qinjun, Guo, Decai, Wang, Chong, Chen, Jian
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.11.2020; Elsevier BV
• Subjects: Architecture; Barriers; Carbon; Decay rate; Encapsulation; Lithium sulfur batteries; Manganese dioxide; Metal compounds; MnO2 nanoflakes; Nanospheres; Polysulfides; Rechargeable batteries; Redox reactions; Shells (structural forms); Shuttle effect; Synergistic encapsulation; Thiosulfates; Yolk-shell structure; Lithium-sulfur batteries; Synergistic encapsulation; Yolk-shell structure; MnO2 nanoflakes; Shuttle effect
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.155790

Increasing the sluggish redox reactions of soluble lithium polysulfides (LiPSs) and suppressing their shuttle effect are the key challenges for lithium-sulfur (Li–S) batteries with long-term cyclic stability. Herein, an integrated design of hollow carbon nanospheres filled by polar manganese oxide (δ-MnO2) nanoflakes (MnO2@HCS) as a sulfur host is proposed, in which the physical confinement and chemical interaction for LiPSs are successfully achieved simultaneously. In this architecture, the outer porous carbon shell can support the fast electron/ion transfer and serve as a physical barrier to confine the soluble LiPSs. Besides, the hollow architecture can accommodate the active sulfur and buffer its volume variation during cycling. Moreover, the inner polar MnO2 nanoflakes can trap and boost the redox reactions of LiPSs through thiosulfate-polythionate conversion leading to inhibited shuttle effect. Due to the unique synergistic encapsulations, the MnO2@HCS-S cathode achieves a high initial specific discharge capacity of 1250 mAh g−1, and exhibits a stable cyclic property maintaining 705 mAh g−1 after 500 cycles at 1.0C corresponding to an ultralow capacity decay of 0.078% per cycle. As a result, this proposed strategy will guide a new direction for the development of polar metal compounds with special architectures for advanced Li–S batteries. [Display omitted] •Yolk-shell structure MnO2@HCS nanospheres were firstly designed as sulfur host.•Thiosulfate-polythionate conversion of MnO2 is confirmed to propel the redox reactions.•The shuttle effect was effectively restrained by synergistic encapsulations.•The MnO2@HCS-S materials exhibited excellent electrochemical performance.