MOF-derived hierarchical CoP nanoflakes anchored on vertically erected graphene scaffolds as self-supported and flexible hosts for lithium–sulfur batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-01, Vol.8 (6), p.3027-3034
• Main Authors: Jin, Jia, Cai, Wenlong, Cai, Jingsheng, Shao, Yuanlong, Song, Yingze, Xia, Zhou, Zhang, Qiang, Sun, Jingyu
• Format: Article
• Language: English
• Subjects: Batteries; Cathodes; Cloth; Cycles; Decay rate; Electrochemical analysis; Electrochemistry; Energy storage; Graphene; Lithium; Lithium sulfur batteries; Robustness; Sulfur
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/C9TA13046B

Lithium–sulfur (Li–S) batteries have garnered a lot of attention in the realm of electrochemical energy storage owing to their high energy and low cost. However, the serious polysulfide shuttle effect of the sulfur cathode poses a critical challenge for the development of Li–S batteries with elevated sulfur loadings. In addition, the poor robustness of traditional blade-casting cathodes greatly impedes the practical applications of flexible Li–S cells that display high areal capacity. To address these concerns, we report herein a freestanding hybrid sulfur host via in situ crafting of flexible carbon cloth (CC), vertically grown graphene nanoflakes over CC (G/CC) and metal–organic-framework derived CoP anchored on vertical graphene (CoP@G/CC). The thus-derived sulfur cathodes (CoP@G/CC-S) with a typical sulfur loading of 2 mg cm −2 exhibit outstanding electrochemical performances, including excellent rate capability (930.1 mA h g −1 at 3.0C) and impressive cycling stability (0.03% capacity decay per cycle after 500 cycles at 2.0C). A high areal capacity of 8.81 mA h cm −2 at 0.05C can also be obtained even at an elevated sulfur loading of 10.83 mg cm −2 . Furthermore, flexible pouch cells based on the self-supported CoP@G/CC-S showcase favorable rate and cycling performances with high mechanical robustness.