Insight into the Catalytic Role of Defect-Enriched Vanadium Sulfide for Regulating the Adsorption–Catalytic Conversion Behavior of Polysulfides in Li–S Batteries
2022
Zeng, Peng | Zhou, Ziyi | Li, Bin | Yu, Hao | Zhou, Xi | Chen, Gairong | Chang, Baobao | Chen, Manfang | Shu, Hongbo | Su, Jincang | Wang, Xianyou
The performance promotion of Li–S batteries relies primarily on inhibition of the shuttle effect and improvement of the catalytic-conversion reaction kinetics of polysulfides. Herein, we prepare defect-enriched VS₂ nanosheets (VS₂–ₓ) as catalysts for Li–S batteries and further study the catalytic mechanism of VS₂–ₓ via ex situ X-ray diffraction and in situ UV–vis spectroscopy. A multifunctional S cathode was also obtained by assembling VS₂–ₓ on a C cloth to achieve high S loading for Li–S batteries. It was found that VS₂–ₓ catalysts undergo a lithiation process in the work voltage of Li–S batteries, and the triggered LiyVS₂–ₓ intermediates reciprocate VS₂–ₓ with a high catalytic activity so as to enhance the performance of Li–S batteries by promoting the dissociation process of S₆²– to S₃•–. Consequently, Li–S batteries with a C/VS₂–ₓ/S cathode deliver a high reversible capacity (1471 mAh g–¹ at 0.1 C) and good cycling performance (low fading rate of 0.064% per cycle after 400 cycles). Meanwhile, the CC@VS₂–ₓ/S cathode with a high S areal loading of 5.6 mg cm–² can render a satisfactory areal capacity of 4.22 mAh cm–² at 0.2 C and a cycle stability of over 100 cycles. Therefore, the study on the catalysis of LiyVS₂–ₓ intermediates provides a scientific view for revealing the catalysis mechanism of a sulfide-based electrocatalyst and boosting the development of an electrocatalyst for Li–S batteries.
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