Redox shuttles for lithium-ion batteries at concentrations up to 1 M using an electroactive ionic liquid based on 2,5-di-tert-butyl-1,4-dimethoxybenzene

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DOIResolve DOI: http://doi.org/10.1149/2.0131508jes
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TypeArticle
Journal titleJournal of the Electrochemical Society
ISSN0013-4651
Volume162
Issue8
PagesA1432A1438
SubjectCharging (batteries); Cyclic voltammetry; Electric batteries; Electric discharges; Electrolytes; Ethylene; Ionic liquids; Ions; Lithium; Lithium alloys; Lithium compounds; Negative ions; Salts; Secondary batteries; Diethyl carbonates; Discharge capacities; Electrochemical cycling; Ethylene carbonate; Hexafluorophosphates; Imidazolium salt; Overcharge protection; Lithium-ion batteries
AbstractIn this work, we designed two redox shuttles with high solubility (up to 1 M) in conventional carbonate-based lithium-ion battery (LIB) electrolytes. At this high concentration, redox shuttles ensure improved overcharge protection than lower concentrations. We developed electroactive imidazolium salts by modifying imidazolium with 2,5-di-tert-butyl-1,4-dimethoxybenzene. Two salts with the cation 1-(3-(2,5-di-tert-butyl-1,4-methoxyphenoxy)propyl)-3-methyl-1H-imidazol-3-ium (EMIm) were synthesized using either hexafluorophosphate (DDB-EMIm-PF<inf>6</inf>) or bis(trifluromethanesulfonyl)amide (DDB-EMIm-TFSI)) anions. The electrochemical properties of DDB-EMIm-PF<inf>6</inf> and DDB-EMIm-TFSI dissolved in ethylene carbonate: diethyl carbonate (EC:DEC), in the presence of either LiPF<inf>6</inf> or LiTFSI, were evaluated. Cyclic voltammetry showed a compatible potential (∼3.85 V vs. Li/Li+) for use in LIBs using LiFePO4 as cathodes. Electrolytes using 0.1 M of DDB-EMIm-PF<inf>6</inf> or 0.3, 0.7 and 1 M of DDB-EMIm-TFSI were prepared and evaluated in Li/LiFePO<inf>4</inf> (LFP) test cells to demonstrate overcharge protection. Electrochemical cycling at C/10 showed an overcharge protection for all concentrations of the redox ionic salts under 100% overcharge conditions. Among these salts, DDBEMIm-TFSI, at a concentration of 0.7 M, was effective in shuttling excess current for over 200 cycles, representing over 6000 operating hours, while maintaining nominal values for the discharge capacity of LiFePO<inf>4</inf>.
Publication date
PublisherThe Electrochemical Society
LanguageEnglish
AffiliationNational Research Council Canada; Energy, Mining and Environment
Peer reviewedYes
NPARC number21275621
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Record identifierd04c1612-70cc-499c-82a2-072a3a841970
Record created2015-07-14
Record modified2016-05-09
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