Ti concentration dependence on the microstructure of Ti-doped Al2O3 coatings and electrochemical properties of Ti-doped Al2O3 coated LiCoO2 thin films
- 주제(키워드) LiCoO2 , oxide coating , thin film battery , Li ion batteries , TiAlO coating
- 발행기관 고려대학교 대학원
- 지도교수 이성래
- 발행년도 2008
- 제출일 2008-06-30
- 학위수여년월 2008. 8
- 학위명 석사
- 학과 일반대학원 신소재공학과
- 세부전공 신소재공학전공
- 원문페이지 67 p
- 본문언어 영어
- 제출원본 000045503115
초록/요약
The lithium-ion rechargeable batteries have been widely used in portable electronic devices such as laptop computers, mobile phones, and camcorders. LiCoO2 was one of the most useful cathode materials for lithium-ion batteries due to its good performance. We studied Ti-doped Al2O3 (Ti-Al2O3) coated LiCoO2 thin films with the composition dependence of the microstructure and electrochemical properties of Ti-Al2O3 coating films. The 1.27at.% Ti-Al2O3 were of amorphous structure with better conductivity than pure Al2O3 films by Ti doped. The Ti-Al2O3 coated LiCoO2 films have different electrochemical properties, depending on the Ti concentration. The first discharge capacity 1.27at.% Ti-Al2O3 coated LiCoO2 films was 84.67 μAh/cm2-μm, with a decrease to 78.70 μAh/cm2-μm after 50 cycles. The decrease in discharge capacity of Ti-Al2O3 coated LiCoO2 was investigated by electrochemical impedance spectroscopy (EIS), which showed the suppression of impedance growth. The Ti-Al2O3 coating layer effectively suppressed Co dissolution and the formation of solid electrolyte interface (SEI) films, the latter which contributes to the decrease of Li-conductivity at the interface of LiCoO2 and an electrolyte. At a high voltage (4.5V) of LiCoO2 films, Ti-Al2O3 coating improved the cycling performance and increased the capacity retention to 92.95%. Therefore, Ti-Al2O3 coated LiCoO2 films also showed good cycling behaviors. The Ti-Al2O3 coated LiCoO2 films showed better electrochemical properties than pure Al2O3 coated LiCoO2 films. These results were closely related to the enhanced Li-conductivity and interfacial quality of the Ti-Al2O3 film.
more목차
1. Introduction 9
2. Literature Review 12
2.1. Li-ion secondary batteries 12
2.1.1. Cathode materials 16
2.1.2. Anode materials 19
2.1.3. Electrolyte / Separator 21
2.2. Solid state thin film batteries 22
2.3. LiCoO2 cathode materials 25
2.3.1. Capacity fading mechanisms in LiCoO2 cathode materials 30
2.3.2. Metal-oxide coating on LiCoO2 cathode 34
3. Experimental 39
4. Results and Discussion 45
5. Conclusions 61
6. References 62
