Accelerating polysulfides conversion by constructing Lewis acidic Mn-N4 single atomic sites for Li-S battery with high sulfur loading
CHEMICAL ENGINEERING JOURNAL(2024)
摘要
The shuttle effects of lithium polysulfides (LiPSs) and the sluggish conversion reaction between LiPSs and Li2S significantly limit the electrochemical performance of Li -S batteries. In this study, a unique structured single atomic Mn anchored on nitrogen -doped carbon black (SAMnN@C) is developed to address above challenges. Physical characterizations confirmed atomically dispersed Mn atoms were anchored on carbon by 4 N atoms forming a typical structure of planar Mn-N-4. Li -S battery assembled by as-prepared SAMnN@C displayed a discharge capacity of 1400 mA h g(-1) at 0.1C, and outstanding stability with a capacity decay rate of 0.052 % per cycle during 1000 cycles at 1C. Moreover, excellent electrochemical performances could be preserved even if the S mass loading increased to 5.7 mg cm (-2) with similar to 5 mu L (mg S)(-1) electrolyte. The mechanism studies revealed that SAMnN@C exhibited a unique Lewis acid -base interaction between Mn-N-4 site and S atom, which significantly lowered the decomposition energy barrier of Li2S2, and eventually accelerated the sluggish solid-state conversion reaction of Li2S2 to Li2S. This study is believed to shed light on the mechanism of SACs for high performance Li -S batteries.
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关键词
Li-S batteries,Single atomic catalyst,In-situ Raman,Lithium polysulfides,Lewis acid-base interaction
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