Journal
SMALL METHODS
Volume 5, Issue 8, Pages -Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/smtd.202100441
Keywords
electrolytes; lithium anodes; solid electrolyte interphase; solvation sheath structures; theoretical calculations
Funding
- National Natural Science Foundation of China [11675051, 21905086, U20A20248]
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The study used quantum chemical calculations and molecular dynamics to reveal the mechanisms of SEI formation with carbonate-based electrolyte additives at the atomic level, confirming that Li-coordinated carbonate species are the main participants in SEI formation. High reduction potential Li-coordinated additives can dominate SEI formation by excluding other substances, leading to improved cycling performance in batteries.
Solid electrolyte interphase (SEI), determined by the components of electrolytes, can endow batteries with the ability to repress the growth of Li dendrites. Nevertheless, the mechanism of commercial carbonates on in situ-generated SEI and the consequential effect on cycling performance is not well understood yet, although some carbonates are well used in electrolytes. In this work, quantum chemical calculations and molecular dynamics are used to reveal the formation mechanisms of SEI with carbonate-based electrolyte additives on the atomic level. It is confirmed that the Li-coordinated carbonate species are the leading participant of SEI formation and their impact on battery performance is clarified. Fluoroethylene carbonate (FEC) exhibits a completely different behavior from vinyl ethylene carbonate (VEC), ethylene carbonate (EC), and vinylene carbonate (VC). High reduction potential Li+-coordinated additives, e.g. FEC and VEC can dominate the formation of SEI by excluding propylene carbonate (PC) and LiPF6 from the decomposition, and the corresponding Li||Li symmetric cells show enhanced long-term performance compared with those with pure PC electrolyte, while the low reduction priority additives (e.g., EC and VC) cannot form a uniform SEI by winning the competitive reaction.
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