리튬 이차 전지 음극활물질로서 인 도핑 실리콘과 탄소 복합체 제조 및 전기화학적 특성조사
A Study of Synthesis and Electrochemical Characteristics of Phosphorus Doped Silicon and Carbon Composite for the Anode Materials of Lithium Secondary Batteries
- 주제(키워드) 리튬이차전지 , 음극 , 실리콘
- 발행기관 고려대학교 대학원
- 지도교수 이관영
- 발행년도 2009
- 제출일 2009-01-07
- 학위수여년월 2009. 2
- 학위명 석사
- 학과 일반대학원 화공생명공학과
- 원문페이지 91 p
- 실제URI http://www.dcollection.net/handler/korea/000000007976
- 본문언어 한국어
- 제출원본 000045533844
초록/요약
Carbonaceous materials are commercially used for anode materials of lithium-ion batteries. These carbonaceous materials offer good cycling performance due to lithium intercalation-deintercalation mechanism. However, the theoretical maximum capacity of these materials is only 372 mAh/g. Silicon based materials have been studied as alternative anode materials for lithium secondary batteries due to high theoretical capacities(4200 mAh/g) and high energy density. However silicon based materials have several problems as following reasons: i) drastic volume change(>300%) during the alloying-dealloying reaction which lead to remarkably rapid capacity fading of the electrode caused by breakdown of the electrode. ii) low electrical conductivity of silicon itself. Many studies have been done in the past to improve the electrochemical performance and minimize the mechanical stress caused by the large volume change of silicon based materials. In this study, effects of phosphorus doping into silicon particle and carbon composite with doped silicon on electrochemical performance of the anode materials of lithium secondary batteries were investigate, Phosphorus doped Si-C particles were synthesized through a D.C. arc plasma torch. Silane(SiH4) and methane(CH4) were introduced into the reaction chamber as the precursor of silicon and carbon respectively. Phosphine(PH3) was used as a phosphorus dopant gas. Characterization of synthesized particles were carried out scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and bulk resistivity measurement. Half cells were fabricated with the Li metal as a counter electrode to compare electrochemical performance. Electrochemical properties were investigated by galvanostatic method and electrochemical voltage spectroscopy (EVS). In this work, incorporation of carbon into silicon acts as a buffer matrix and phosphorus doping plays an important role to enhance the conductivity of the electrode which leads to improve the cycle performance of the cell.
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제 1 장 서론 ............................................................................................ 1
제 2 장 이론적 배경 ................................................................................ 5
2-1. 리튬 이차 전지의 개요 ................................................................. 5
2-2. 양극 활물질 ................................................................................ 10
2-3. 음극 활물질 ................................................................................. 13
2-3-1. 리튬 금속 음극 재료 .......................................................... 13
2-3-2. 탄소계 음극 재료 ................................................................ 15
2-3-3. 리튬 합금과 금속간 화합물 음극 ........................................ 17
2-3-4. 실리콘계 음극 재료 ............................................................ 19
2-4. 나노입자활물질............................................................................. 22
2-4-1. 나노 입자 양극 활물질 기술개발동향 ................................. 23
2-4-2. 나노 입자 양극 활물질 기술개발동향 ................................. 24
2-4-2. Nano-sized silicon .......................................................... 25
2-5. 전해질 ......................................................................................... 23
2-6. 분리막 ......................................................................................... 27
2-7. D.C. arc plasma process ......................................................... 27
2-7-1. 열플라즈마 .......................................................................... 27
2-7-2. 비이송식 D.C. arc plasma process ................................. 29
2-7-3. 아크 방전 열플라즈마에 의한 나노 분말 제조 .................. 32
2-7-4. 열플라즈마를 이용한 SiH4의 분해 ..................................... 32
2-7-5. 입자의 성장 과정 ................................................................ 33
2-8. n-type doping process ........................................................... 35
제 3 장 실험 방법 ................................................................................. 37
3-1. 열플라즈마법에 의한 실리콘 입자 합성 ..................................... 37
3-1-1. 실리콘 입자의 합성 .............................................................. 37
3-1-2. 인이 도핑된 실리콘 입자의 합성 ....................................... 39
3-1-3. 실리콘/탄소 복합나노입자의 합성 ...................................... 40
3-1-3. 인 도핑된 실리콘/탄소 복합나노입자의 합성 ..................... 41
3-2. 실리콘계 나노입자의 물리적 특성 분석 .................................... 42
3-3. 실리콘계 나노입자를 이용한 반 전지 조립 ................................ 42
3-4. 전기화학적 특성 시험 ................................................................. 43
3-4-1. Galvanostatic Method .................................................... 43
3-4-1. EVS(Electrochemical Voltage Spectroscopy) ............ 46
제 4 장 실험 결과 및 고찰 .................................................................... 38
4-1. 실리콘계 나노 입자의 물리적 특성 분석 .................................... 47
4-1-1. XRD ................................................................................... 47
4-1-2. SEM ................................................................................... 50
4-1-3. XPS ................................................................................... 50
4-1-4. 전기 전도도 ........................................................................ 54
4-2. 전기화학적 특성 분석................................................................... 55
4-2-1. Cycle Test ......................................................................... 55
4-2-1-1. 실리콘/탄소 복합체의 Cycle Test................................ 55
4-2-1-2. 1% 인 도핑된 실리콘의 Cycle Test ........................... 57
4-2-1-3. 1% 인 도핑된 실리콘/탄소 복합체의 Cycle Test ...... 60
4-2-2. Charge-Discharge Characteristics................................... 63
4-2-3. EVS .................................................................................. 67
4-2-4. 전기화학반응 전후의 전극 표면 특성 비교.......................... 69
제 5 장 결 론.......................................................................................... 73
참고 문헌 ................................................................................................ 75
