Comparative studies on ZnO-coated and uncoated LiCoO2 cycling at various rates and temperatures
- 주제(키워드) Lithium-ion batteries , Zinc oxide coating , Cathode materials , Plasma-enhanced chemical vapor deposition
- 발행기관 고려대학교 대학원
- 지도교수 변동진
- 발행년도 2010
- 학위수여년월 2010. 8
- 학위구분 석사
- 학과 일반대학원 신소재공학과
- 세부전공 전기화학
- 원문페이지 49 p
- 실제URI http://www.dcollection.net/handler/korea/000000022819
- 본문언어 영어
- 제출원본 000045609121
초록/요약
Modification by surface coating of cathode materials is one of the preferred methods to achieve improved electrochemical performance, especially at a high-charge cut-off voltage. In this study, ZnO-coated LiCoO2 powders were prepared by plasma-enhanced chemical vapor deposition (PE-CVD), and examined using field emission-scanning electron microscopy (FE-SEM) and atomic absorption spectroscopy (AAS). In our previous work [1], the roles of ZnO coating in the capacity retention of LiCoO2 during high-voltage cycling in the range of 3.0V-4.5V and the thermal stability of the charged LiCoO2 electrode were investigated as a function of the coating amount. This study confirms the positive effect of ZnO coating on cyclic performances of LiCoO2, in particular at various C-rates and temperatures. In addition, the structural stability of the LiCoO2 materials coated with different amount of ZnO during cycling was investigated using cyclic voltammetry. Although all the ZnO-coated LiCoO2 exhibit a much less degree of phase transition during cycling than does the bare material, 0.38 wt.% ZnO coating resulted in a poor cycleability at all the examined C-rates and temperatures compared with the 0.20 wt.% ZnO coating, which was suggested as an optimum amount from the previous results.
more목차
1. Introduction 9
2. Theoretical background 10
2.1 Lithium ion secondary battery 10
2.1.1 The characteristics of lithium-ion secondary battery 10
2.1.2 The working principle of the lithium ion secondary battery 12
2.1.3 LiCoO2 Cathode materials 14
2.1.4 Anode materials 17
2.1.5 Electrolyte 18
2.1.6 Separators 21
2.2 Deposition method 21
2.2.1 Plasma enhanced chemical vapor deposition (PECVD) 21
3. Experimental 23
3.1 Surface modification of LiCoO2 23
3.1.1 Surface modification of LiCoO2 23
3.1.2 Characterization of active materials 26
3.2 Electrochemical test 26
3.1.1 Fabrication of electrodes and cells 26
3.1.2 Electrochemical performance and structural stability 27
4. Results and discussion 30
4.1 Characterization of surface modified LiCoO2 30
4.2 Electrochemical performance and structural stability 36
4.2.1 Galvanostatic cycling test 36
4.2.1 Cyclic voltammetry and electrochemical impedance spectroscopy 42
5. Conclusions 47
References 48
