Synthesis of spinel LiMn2O4/MWCNT/rGO composites via hydrothermal method as cathode for lithium ion batteries
- 주제(키워드) Lithium ion batteries , Cathode , Spinel LiMn2O4 , Reduced graphene oxide , MWCNTs , Electrochemical properties
- 발행기관 고려대학교 대학원
- 지도교수 윤호규
- 발행년도 2013
- 학위수여년월 2013. 8
- 학위구분 석사
- 학과 일반대학원 신소재공학과
- 원문페이지 56 p
- 실제URI http://www.dcollection.net/handler/korea/000000045315
- 본문언어 영어
- 제출원본 000045764531
초록/요약
The purpose of this study is to confirm electrochemical properties of the spinel LiMn2O4/Multi walled carbon nanotubes (MWCNT)/reduced Graphene oxide (rGO) composites as cathode for lithium-ion batteries. The obtained composites show good electrochemical properties, which is due to the outstanding electronic conductivity of the MWCNTs and large surface of rGO and the short lithium ion diffusion path provided by well-crystallized spinel LiMn2O4 nanoparticles. The LiMn2O4/MWCNT/rGO composites were successfully synthesized via two-step hydrothermal method. First, the functionalized MWCNTs and rGO networks were decorated with MnO2 thin layer generated by redox reactions. And then MnO2/MWCNT/rGO composites were converted to LiMn2O4/MWCNT/rGO composites using hydrothermal method via LiOH aqueous solution as conversion agent. The results of specific capacity and cycle performance for the LiMn2O4/MWCNT/rGO composites was higher than that the pristine LiMn2O4, LiMn2O4/MWCNT composites and LiMn2O4/rGO composites. The initial charge and discharge capacities of electrode were 142.7 mAh/g and 134.7 mAh/g at 0.1 C rate, respectively, with an coulombic efficiency nearly to 94.4 %. The LiMn2O4/MWCNT/rGO composites showed excellent initial capacity and stable coulombic efficiency for lithium-ion batteries.
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ABSTRACT i
LIST OF TABLES iv
LIST OF FIGURES iv
1. INTRODUCTION 1
2. EXPERIMENTAL 5
2-1. Raw Materials 5
2-2. Sample preparation 7
2-2-1. Acid-treated MWCNTs 7
2-2-2. Synthesis of microwave reduction of Graphene oxide (mRGO) 8
2-2-3. Synthesis of the LiMn2O4 nanoparticles 10
2-2-4. Synthesis of the LiMn2O4/MWCNT composites 11
2-2-5. Synthesis of the LiMn2O4/rGO composites 12
2-2-6. Synthesis of the LiMn2O4/MWCNT/rGO composites 13
2-3. Measurement 16
2-3-1. Characterization 16
2-3-2. Morphology 18
2-3-3. Electrochemical measurement 19
3. RESULTS AND DISCUSSION 21
3-1. Characteristic of the LiMn2O4/MWCNT/rGO composites 21
3-2. Morphology of the LiMn2O4/MWCNT/rGO composites 31
3-3. Electrochemical Properties 36
4. CONCLUSIONS 43
REFERENCES 44
