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Application and Characterization of Pyrrolinium-based Ionic liquids as Electrolytes for Lithium Ion Batteries

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dc.contributor.advisor김영규-
dc.contributor.author김형태-
dc.date.accessioned2017-10-27T16:46:20Z-
dc.date.available2017-10-27T16:46:20Z-
dc.date.issued2017-08-
dc.identifier.other000000145807-
dc.identifier.urihttps://hdl.handle.net/10371/136855-
dc.description학위논문 (박사)-- 서울대학교 대학원 공과대학 화학생물공학부, 2017. 8. 김영규.-
dc.description.abstractLithium ion batteries (LIBs) have been used as a battery of portable electronic device and concerned as a one of the most promising energy conversion/storage systems for large-scale devices such as electric vehicles (EVs) and energy storage systems (ESSs). However, the need for the high energy density of current LIBs have been increased, which results that many research have been focus on the advanced electrode materials for high working voltage, a large specific capacity to enhance overall energy density of the lithium ion cells. In other words, the relatively low safety of current organic electrolyte should be overcome to catch up with the enhancement of the energy density for reaching the high level of LIBs. For increasing the safety performance of the conventional electrolyte, many attempts have been studied to apply ionic liquids as alternative electrolyte or additive.
Ionic liquids are ionic species that remain in liquid phase at room temperature even if they are composed of ionic species, cations and anions. Due to ionic interaction, they have unique properties such as high ionic conductivity, non-volatility, and non-flammability as well as a wide liquid range and wide electrochemical stability window. In spite of these advantages, the ILs are not useful as electrolytes for LIBs owing to somewhat defect such as decomposition or high viscosity. As already reported, the well-known ILs such as imidazolium-based ILs have been investigated to allow them apply the LIBs, which is not carried on its acidic proton of C-2 position in imidazolium structure. To exclude the active proton, pyrrolidnium and piperidinium-based ILs have been researched
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dc.description.abstracthowever, their relatively high viscosity is the obstacle to facilitate in LIBs. To enhance both the mobility of Li+ and the safety performance of LIBs, we suggest the pyrrolinium-based ILs with multifunctional groups such as a planar sp2 carbon of C=N double bond, a C-O ether linkage, and no unstable C-H bond, which would be beneficial to improve the physical properties as well as electrochemical performances. Among the prepared pyrrolinium-based ILs, the N-ethyl-2-methoxypyrrolinium bis(fluorosulfonyl)imide (E(OMe)Pyrl-FSI) exhibit the highest value of ionic conductivity, and the N-allyl-2-methoxypyrrolinium bis(fluorosulfonyl)imide (A(OMe)Pyrl-FSI) shows the best electrochemically performance and lithium ion mobility.
To obtain the synergetic effect of pyrrolinium-based ILs and carbonate solution, we prepared the binary electrolytes systems composed of two type electrolytes. Among the prepared pyrrolinium-based ILs, the E(OMe)Pyrl-FSI is chosen as the one of the binary electrolytes systems due to its highest value of ionic conductivity. In ionic conductivity of these binary electrolytes, the optimum compositions are 40 wt% and 60 wt% of pyrrolinium-based ILs. Additionally, when the 60 wt% of E(OMe)Pyrl-FSI (E60) is in binary system, the SET (self extinguish time, s g-1) is outstandingly reduced. In electrochemical performance, all of the binary electrolytes exhibit the similar results that of the conventional carbonate. It should be noted that the E 60 binary system is the best synergetic effect on both the electrochemical performance and fire-retarding characteristic.
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dc.description.tableofcontentsIntroduction.. 1
1. 1. Lithium Ion Batteries.. 1
1.1. Introduction of lithium ion batteries 1
1.2. Safety issue of LIBs . 2
2. Ionic Liquids . 6
2.1. Introduction of ionic liquids.. 6
2.2. Species of ionic liquids.. 7
2.3 Application of ionic liquids 10
2.3.1 Reaction solvent in organic synthesis . 10
2.3.2 Lubricants. 14
2.3.3 Electrolytes for LIBs 15
Results and discussion .. 19
1. Synthesis and Properties of N-alkyl-2-methoxypyrrolinium bis(fluorosulfonyl)imide .. 19
1.1. Strategy . 19
1.2. Preparation. 24
1.3. Thermal behaviors. 26
1.4. Physical properties. 29
1.5. Electrochemical stability . 31
1.6. Electrochemical performance .. 34
1.7. Summary ... 42
2. Preparation and Properties of Binary Electrolytes . 44
2.1. Strategy . 44
2.2. Preparation . 46
2.3. Flammability test 47
2.4. Physical properties . 51
2.5. Electrochemical stability 54
2.6. Electrochemical performance . 57
2.7. Summary . 63
Conclusions.. 66
Experimental Details. 69
1. General... 69
2. General Procedure for the Preparation of the Pyrrolinium-based Ionic Liquids .. 72
2.1. General procedure for the preparation of N-alkyl-2-pyrrolidinone 72
2.2. General procedure for the preparation of N-alkyl-2-methoxypyrrolinium methyl sulfates . 73
2.3. General procedure for the anion metathesis - Preparation of N-alkyl-2-methoxypyrrolinium bis(fluorosulfonyl)imides . 75
2.4. Preparation of the binary electrolytes of E(OMe)Pyrl-FSI. 77
3. Electrochemical Performance.. 77
3.1. Preparation of electrode and cell fabrication 77
3.2. Electrochemical characterization 78
REFERENCES.. 80
APPENDICES. 84
ABSTRACT IN KOREAN 105
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dc.formatapplication/pdf-
dc.format.extent3445964 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoko-
dc.publisher서울대학교 대학원-
dc.subjectLithium ion battery-
dc.subjectpyrrolinium-based ionic liquids-
dc.subjectFSI anion-
dc.subjectthermal stability-
dc.subjectbinary electrolytes-
dc.subject.ddc660.6-
dc.titleApplication and Characterization of Pyrrolinium-based Ionic liquids as Electrolytes for Lithium Ion Batteries-
dc.typeThesis-
dc.description.degreeDoctor-
dc.contributor.affiliation공과대학 화학생물공학부-
dc.date.awarded2017-08-
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Chemical and Biological Engineering (화학생물공학부)Theses (Ph.D. / Sc.D._화학생물공학부)
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