탄소동소체와 니켈을 첨가한 마그네슘 기반의 수소저장재료의 특성 연구

다국어 초록 (Multilingual Abstract)

The most important challenge in modern society is to reduce environmental pollution. The use of energy inevitably leads to environmental pollution, and research on the use and application of pollution-free energy or the emission of very minimal environmental pollutants is in progress. In particular, hydrogen is an energy source that does not emit environmental pollutants at all, and has been spotlighted as an energy source for household or stationary power generation, and is accelerating the development of a storage device accordingly.
Magnesium (Mg) is one of the hydrogen storage materials that can be used in devices that store hydrogen in the form of metal hydrides and use it as an energy medium. Mg has a quite high theoretical storage capacity of 7.6 wt% H, and is of low price due to abundance in the earth’s crust. In contrast, the temperature of hydrogen release is high, which is to be solved.
Consequently, magnesium-based hydrogen storage research is concerned with the development of materials close to the theoretical hydrogen storage capacity and increasing the rate and amount of hydrogen absorption and release.
Reactive mechanical grinding (RMG) refers to milling materials such as magnesium into a finer powder in a hydrogen atmosphere, a reactive gas. RMG is believed to have driven powders to form defects (inducing nucleation), to do surface treatment (increasing the reactivity of magnesium particles), and to micronize particle size (reducing hydrogen diffusion distance), leading to increasing the rate of hydrogenation and dehydrogenation.
This work focuses on the investigation of hydrogen storage properties of Mg alloys prepared by adding carbon allotrope and a transition metal Ni via RMG using Sieverts’ type hydrogenation and dehydrogenation apparatus.
Comparing pure Mg powder samples treated with different reactive mechanical grinding times (12.5 h and 24 h), there was no difference in the amounts of absorbed and released hydrogen for 60 min. Mg (12.5 h) and Mg (24 h) absorbed 7.33 and 6.72 wt% H, respectively, in the first cycle (n=1) under 593 K, 12 bar H2. Mg (12.5 h) and Mg (24 h) released 1.58 and 0.78 wt% H, respectively, in n=1 at 593 K under 1.0 bar H2.
Mg + 5 wt% graphene (M5G), Mg + 2.5 wt% MWCNT (M2.5CNT) and Mg + 2.5 wt% CNF (M2.5CNF) were prepared to examine the effects of carbon allotrope addition. M2.5CNT showed the best absorption and release performance, showing 7.04 wt% H uptake for 60 min under 12 bar H2 at 593 K and 2.24 wt% H release for 60 min under 1.0 bar H2 at 593 K. M2.5CNF absorbed 6.63 wt% H under 12 bar H2 and desorbed 2.15 wt% H under 1.0 bar H2 at 593 K for 60 min. M5G absorbed 5.47 wt% H under 12 bar H2 and desorbed 0.53 wt% H under 1.0 bar H2 at 593 K for 60 min.
In order to increase the initial hydrogenation and dehydrogenation rates as well as the amounts of absorbed and released hydrogen for Mg, Mg + 2.5 wt% graphene + 2.5 wt% Ni (MGN), Mg + 2.5 wt% MWCNT + 2.5 wt% Ni (MTN), and Mg + 2.5 wt% CNF + 2.5 wt% Ni (MFN) was prepared. MFN showed the largest amounts of absorbed and released hydrogen for 60 min in n=3, absorbing 7.11 wt% H under 12 bar H2 and releasing 5.72 wt% H under 1.0 bar H2 at 593 K. However, MTN absorbed 6.85 wt% H at n=1and 6.84 wt% H in n=3 under 12 bar H2 and released 5.44 wt% H in n=1 and 5.64 wt% H in n=3 under 1.0 bar H2 for 60 min at 593 K. MTN showed the best performance in consideration of degradation and the amounts of absorbed and released hydrogen.

목차 (Table of Contents)

• Chapter 1
• 서론 1
• Chapter 2
• 이론적 배경 8
• 2.1. 수소의 특성 8
• 2.2. 수소저장기술 11
• 2.2.1. 고압수소저장 14
• 2.2.2. 액체수소저장 14
• 2.2.3. 화학적 수소화물에 의한 저장 15
• 2.2.4. Metal-Organic Frameworks (MOFs)에 의한 저장 16
• 2.2.5. 나노 구조 탄소동소체를 이용한 저장 16
• 2.2.6. 금속수소화물에 의한 저장 24
• 2.2.7. 마그네슘계 수소저장합금 28
• 2.3. 수소 저장량 측정법 34
• 2.3.1. 수소 저장량 측정 장비 34
• 2.4. 연구 목적 34
• Chapter 3
• 시간을 변수로 반응성 기계적 분쇄법으로 처리한 Magnesium의 수소 저장 특성 평가 38
• 3.1. 배경 설명 38
• 3.2. 실험 방법 39
• 3.2.1. 분말 제조 39
• 3.2.2. 수소 저장특성 측정 39
• 3.2.3. 재료 특성 관찰 42
• 3.3. 결과 및 고찰 43
• 3.4. 결론 56
• Chapter 4
• Graphene을 첨가한 Magnesium 기반의 수소저장재료의 특성 평가 57
• 4.1. 배경 설명 57
• 4.2. 실험 방법 58
• 4.2.1. 분말 제조 58
• 4.2.2. 수소 저장특성 측정 59
• 4.2.3. 재료 특성 관찰 59
• 4.3. 결과 및 고찰 60
• 4.4. 결론 74
• Chapter 5
• CNT (Carbon Nanotube)를 첨가한 Magnesium 기반의 수소저장재료의 특성 평가 79
• 5.1. 배경 설명 79
• 5.2. 실험 방법 80
• 5.2.1. 분말 제조 80
• 5.2.2. 수소 저장특성 측정 81
• 5.2.3. 재료 특성 관찰 82
• 5.3. 결과 및 고찰 83
• 5.4. 결론 96
• Chapter 6
• CNF (Carbon (Graphite) Nanofiber)를 첨가한 Magnesium 기반의 수소저장재료의 특성 평가 101
• 6.1. 배경 설명 101
• 6.2. 실험 방법 102
• 6.2.1. 분말 제조 102
• 6.2.2. 수소 저장특성 측정 103
• 6.2.3. 재료 특성 관찰 104
• 6.3. 결과 및 고찰 105
• 6.4. 결론 119
• Chapter 7
• 수소 분위기에서 반응성 기계적 분쇄법에 의한 탄소 동소체 (Graphene, CNT, CNF)와 Nickel을 첨가한 Magnesium 기반의 수소저장재료의 특성 평가 125
• 7.1. 배경 설명 125
• 7.2. 실험 방법 126
• 7.2.1. 분말 제조 126
• 7.2.2. 수소 저장특성 측정 128
• 7.2.3. 재료 특성 관찰 128
• 7.3. 결과 및 고찰 129
• 7.4. 결론 137
• 7.4.1. Mg-2.5graphene-2.5Ni 결론 137
• 7.4.2. Mg-2.5MWCNT-2.5Ni 결론 146
• 7.4.3. Mg-2.5CNF-2.5Ni 결론 155
• Chapter 8
• 결론 요약 166
• 참고 문헌 189
• Publications 199
• 감사의 글 202