수열합성법을 이용한 리튬-공기전지용 IrO2/MnO2 촉매 합성 및 전기화학 특성 평가 = Hydrothermal synthesis and electrochemical characterization of IrO2/MnO2 bifunctional catalysts for lithium air battery

다국어 초록 (Multilingual Abstract)

Li-Air batteries are the most promising secondary battery system. They have 10 times more energy density (3500 Wh/kg) than lithium-ion battery. However, Li-Air batteries have some problems such as are low cycle life and energy efficiency. Many research groups have solved these problems using catalysts that could easily decompose Li2O2 which is the discharge product of Li-Air batteries.
In this study, we have synthesized IrO2/MnO2 bi-functional catalysts by a low temperature hydrothermal technique, to improve the formation and decomposition of Li2O2 during discharge and charge processes of Li-Air battery.
Various experiments were conducted for optimization of IrO2/MnO2 catalysts. It was found that the sulfuric acid is a crucial factor to make uniformly shaped IrO2/MnO2 catalyst. The electrocatalytic activity and cyclic performance of as synthesized catalysts were characterized using various analytic techniques. It was found that the uniform catalysts have better catalytic activity and cycle performance. To know the decomposition potential of Li2O2, various electrodes with Li2O2 of different particle sizes were made. Li2O2 was also ball-milled for different time period and utilized in this work. Electrochemical experiments such as Linear sweep voltammetry and cyclic voltammetry were performed. The 5 hours ball-milled electrodes showed equal and low decomposition potential of Li2O2. It could be resolved that the smaller particle size of Li2O2 is decomposed at low potential because of the nonconductive property of Li2O2. As a result we synthesized IrO2/MnO2 as bi-functional catalysts and confirmed their better catalytic activity. Various electrochemical evaluation were performed to understand its catalytic activity.

목차 (Table of Contents)

• 1. 서 론 1
• 2. 이론적 배경 3
• 2.1. 리튬-공기전지 3
• 2.2. 망간산화물 4
• 2.3. 이리듐산화물 5
• 2.4. 전기화학 측정 방법 5
• 2.5 IrO2/MnO2 혼합촉매 5
• 3. 실 험 7
• 3.1. IrO2/MnO2촉매합성 7
• 3.2. IrO2합성 8
• 3.3. 구조 특성 분석 10
• 3.4. 전기화학 측정 10
• 3.5. 공기전극 제조 및 전지 측정 11
• 3.6. Li2O2파우더를 포함한 전극제작 및 전지 제작 13
• 3.7 Li2O2파우더를 포함한 전지 측정 14
• 4. 결과 및 고찰 15
• 4.1. 촉매의 물리적 특성 분석 15
• 4.2. 전기화학 특성 분석 35
• 4.3. 전지측정 49
• 4.4. Li2O2파우더를 포함한 전극 전기화학 측정 55
• 5. 결론 61
• 참고자료 및 문헌 63