电解质
石墨
酰亚胺
材料科学
锂(药物)
无机化学
化学工程
化学
电极
高分子化学
复合材料
物理化学
医学
工程类
内分泌学
作者
Eric Logan,Ahmed Eldesoky,Ethan Eastwood,Helena Hebecker,Connor Aiken,Michael Metzger,J. R. Dahn
出处
期刊:Journal of The Electrochemical Society
[The Electrochemical Society]
日期:2022-04-01
卷期号:169 (4): 040560-040560
被引量:14
标识
DOI:10.1149/1945-7111/ac67f9
摘要
The use of LiPF 6 in Li-ion battery electrolytes provides sufficient stability, conductivity, and cost in most applications. However, LiPF 6 has also been known to cause degradation in Li-ion cells, primarily from its thermal decomposition or hydrolysis to form acidic species. This work considers the use of imide salts lithium bis(fluorosulfonyl)imide (LiFSI) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as an alternative to LiPF 6 in LiFePO 4 /Graphite cells. The use of LiFSI or LiTFSI over LiPF 6 improved cycling performance both in control electrolyte (no additives) and electrolyte containing 2% vinylene carbonate (VC). However, while metrics from ultra high precision coulometry, isothermal microcalorimetry, and storage experiments all agreed with long-term cycling results for cells with control electrolyte, the opposite was seen with 2VC electrolyte. Pouch bag experiments elucidated information about the origin of parasitic reactions in LFP/Graphite cells, showing that most parasitic reactions originate at the negative electrode. Additionally, pouch bag experiments reveal a more passivating graphite solid electrolyte interphase (SEI) for LiFSI + 2VC electrolyte, agreeing with long term cycling experiments. It is concluded that in control electrolyte, the use of LiFSI limits redox shuttles, Fe dissolution, and SEI decomposition, while in 2VC electrolyte, LiFSI introduces a minor self-discharge reaction that does not impact long-term cycling.
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