电解质
介电谱
电化学
石墨
锂(药物)
化学
无机化学
碳酸乙烯酯
化学工程
电极
有机化学
物理化学
医学
工程类
内分泌学
作者
Saad Azam,Quinton Meisner,C. P. Aiken,Wentao Song,Qian Liu,Dong-Joo Yoo,A. Eldesoky,Zhengcheng Zhang,J. R. Dahn
出处
期刊:Journal of The Electrochemical Society
[The Electrochemical Society]
日期:2022-10-20
卷期号:169 (10): 100552-100552
标识
DOI:10.1149/1945-7111/ac9c36
摘要
In search for new classes of additives for high voltage NMC/graphite lithium-ion cells, the precursor additive bis(trimethylsilyl) malonate (bTMSM) is shown to be activated via a spontaneous reaction with LiPF 6 and LiBF 4 salts in carbonate-based electrolyte to form lithium tetrafluoro(malonato)phosphate (LiTFMP), and lithium difluoro(malonato)borate (LiDFMB), respectively. The reaction schemes and rates were studied via NMR spectroscopy and GCMS. The effects of LiTFMP and LiDFMB on high voltage electrochemical performance were then examined up to 4.5 V in Li[Ni 0.4 Mn 0.4 Co 0.16 ]O 2 (NMC442)/graphite and Li[Ni 0.6 Mn 0.4 Co 0.0 ]O 2 (NMC/640)/graphite pouch cells using aggressive voltage-hold cycling, long-term charge/discharge cycling, storage experiments, electrochemical impedance spectroscopy, and gas evolution measurements. While in situ converted additives suffer from gassing issues due to the presence of trimethylfluorosilane (TMSF) gas, a side product of the in situ reaction of bTMSM with LiPF 6 , the cycling and storage capability for the activated additives under study shows competitive performance and controlled impedance when compared to other well-known high voltage additives. Micro X-ray fluorescence spectroscopy ( μ XRF) confirmed that LiTFMP successfully minimizes the rate of transition metal deposition on the surface of graphite apparently by forming a protective agent at the cathode surface, hence allowing for improved cycling performance at high voltages.
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