Abstract
Molybdenum disulfide is considered one of the most promising anodes for lithium-ion batteries due to its high specific capacity; however, it suffers from an unstable solid electrolyte interphase. Understanding its structural evolution and reaction mechanism upon charging/discharging is crucial for further improvements in battery performance. Herein, the interfacial processes of solid electrolyte interphase film formation and lithiation/delithiation on ultra-flat monolayer molybdenum disulfide are monitored by in situ atomic force microscopy. The live formation of ultra-thin and dense films can be induced by the use of fluoroethylene carbonate as an additive to effectively protect the anode electrodes. The evolution of the fluoroethylene carbonate-derived solid electrolyte interphase film upon cycling is quantitatively analysed. Furthermore, the formation of wrinkle-structure networks upon lithiation process is distinguished in detailed steps, and accordingly, structure-reactivity correlations are proposed. These quantitative results provide an in-depth understanding of the interfacial mechanism in molybdenum disulfide-based lithium-ion batteries.
Highlights
Molybdenum disulfide is considered one of the most promising anodes for lithium-ion batteries due to its high specific capacity; it suffers from an unstable solid electrolyte interphase
To capture the initial nucleation processes of solid electrolyte interphase (SEI) formation and lithiation/delithiation, a large-area ultra-flat monolayer MoS2 electrode prepared by the chemical vapour deposition (CVD) method was employed in the present work
These results provide a fundamental comprehension of the quantitative live formation of ultra-thin SEIs derived from film-forming additives and direct insights into the structural evolution and reaction mechanism of the MoS2/electrolyte interface upon charging/discharging processes
Summary
Molybdenum disulfide is considered one of the most promising anodes for lithium-ion batteries due to its high specific capacity; it suffers from an unstable solid electrolyte interphase. The formation of wrinkle-structure networks upon lithiation process is distinguished in detailed steps, and structure-reactivity correlations are proposed These quantitative results provide an in-depth understanding of the interfacial mechanism in molybdenum disulfide-based lithium-ion batteries. Two key fundamental issues at electrode/electrolyte interfaces in MoS2-based LIBs still demand prompt solution to further establish structure–reactivity correlations: first, in situ and quantitative investigation on the initial nucleation and subsequent growth of SEI film and the surface effect of a filmforming electrolyte additive on the electrochemical performance, and second, the nanoscale structural evolution and reaction mechanism of lithiation/delithiation of the MoS2 anode upon charging/discharging. A significant step will advance to the understanding of the dynamic development of ultra-thin and high-quality SEI films and the interfacial engineering and prospective optimization of MoS2-based LIBs
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