New Insight on the Role of Electrolyte Additives in Rechargeable Lithium Ion Batteries

J.M.J. Ming, Z. Cao, Y. Wu, W. Wahyudi, W. Wang, X. Guo, L. Cavallo, J.-Y. Hwang, A. Shamim, L.-J. Li, Y.-K. Sun, H.N. Alshareef
ACS Energy Letters, (2019)

New Insight on the Role of Electrolyte Additives in Rechargeable Lithium Ion Batteries

Keywords

Electrolyte Additives, Lithium Ion Batteries

Abstract

​Solid electrolyte interphase (SEI)-forming agents such as vinylene carbonate, sulfone, and cyclic sulfate are commonly believed to be film-forming additives in lithium-ion batteries that help to enhance graphite anode stability. However, we find that the film-forming effect and the resultant SEI may not be the only reasons for the enhanced graphite stability. This is because the as-formed SEI cannot inhibit Li+–solvent co-intercalation once the additive is removed from the electrolyte. Instead, we show that the Li+ solvation structure, which is modified by these additives, plays a critical role in achieving reversible Li+ (de)intercalation within graphite. This discovery is confirmed in both carbonate and ether-based electrolytes. We show that the problem of graphite exfoliation caused by Li+–solvent co-intercalation can be mitigated by adding ethene sulfate to tune the Li+ coordination structure. This work brings new insight into the role of additives in electrolytes, expanding the prevailing thinking over the past 2 decades. In addition, this finding can guide the design of more versatile electrolytes for advanced rechargeable metal-ion batteries.

Code

DOI: 10.1021/acsenergylett.9b01441

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