1. Electron delocalization-enhanced sulfur reduction kinetics on an MXene-derived heterostructured electrocatalyst.
- Author
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Li, Yunmeng, Zuo, Yinze, Li, Xiang, Zhang, Yongzheng, Ma, Cheng, Cheng, Xiaomin, Wang, Jian, Wang, Jitong, Lin, Hongzhen, and Ling, Licheng
- Abstract
Lithium-sulfur (Li-S) batteries mainly rely on the reversible electrochemical reaction of between lithium ions (Li
+ ) and sulfur species to achieve energy storage and conversion, therefore, increasing the number of free Li+ and improving the Li+ diffusion kinetics will effectively enhance the cell performance. Here, Mo-based MXene heterostructure (MoS2 @Mo2 C) was developed by partial vulcanization of Mo2 C MXene, in which the introduction of similar valence S into Mo-based MXene (Mo2 C) can create an electron delocalization effect. Through theoretical simulations and electrochemical characterisation, it is demonstrated that the MoS2 @Mo2 C heterojunction can effectively promote ion desolvation, increase the amount of free Li+ , and accelerate Li+ transport for more efficient polysulfide conversion. In addition, the MoS2 @Mo2 C material is also capable of accelerating the oxidation and reduction of polysulfides through its sufficient defects and vacancies to further enhance the catalytic efficiency. Consequently, the Li-S battery with the designed MoS2 @Mo2 C electrocatalyst performed for 500 cycles at 1 C and still maintained the ideal capacity (664.7 mAh·g−1 ), and excellent rate performance (567.6 mAh·g−1 at 5 C). Under the extreme conditions of high loading, the cell maintained an excellent capacity of 775.6 mAh·g−1 after 100 cycles. It also retained 838.4 mAh·g−1 for 70 cycles at a low temperature of 0 °C, and demonstrated a low decay rate (0.063%). These results indicate that the delocalized electrons effectively accelerate the catalytic conversion of lithium polysulfide, which is more practical for enhancing the behaviour of Li-S batteries. [ABSTRACT FROM AUTHOR]- Published
- 2024
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