다중벽 탄소나노튜브(MWCNT) 도전재가 첨가된 실리콘-흑연 복합 음극 개발 = Development of a Silicon-Graphite Composite Anode with Multi-Walled Carbon Nanotube (MWCNT) Conductive Additive

다국어 초록 (Multilingual Abstract)

The electrochemical properties of Si-Gr composite anodes were investigated with the addition of multi-walled carbon nanotube (MWCNT) materials. To determine whether the addition of CNT alleviates the mechanical degradation caused by the volume expansion of silicon, the performance differences between non-CNT-added and CNT-added electrodes were examined using different ratios of active materials, GrSi6 and GrSi30. The GrSi6 with CNT electrode demonstrated higher capacity retention compared to the GrSi6 non-CNT-added electrode, even over long cycling periods. Similarly, the GrSi30 with CNT electrode also retained its capacity better than its non-CNT-added counterpart.
To evaluate fast charge and discharge performance, the GrSi6 with CNT electrode was subjected to repeated charging and discharging at high current densities, followed by a return to low current densities. The electrode effectively recovered to its initial capacity, indicating that CNT reduces structural damage, thereby preserving capacity under repetitive charge-discharge conditions. Even at a high current density of 6C, the CNT-added electrodes showed higher overall average capacity compared to the non-CNT-added electrodes.
Electrochemical impedance spectroscopy (EIS) results revealed that the addition of CNT enhances electrochemical conductivity by reducing charge transfer resistance and increasing ionic diffusivity. This suggests that the low electrical conductivity of silicon can be compensated by CNT addition, and mechanical degradation caused by volume expansion can be mitigated. Moreover, the capacity was well-maintained even at high current densities, which contributes to the overall capacity improvement.
Further research on CNT materials as a solution to address capacity degradation due to silicon volume expansion is expected to facilitate the development of high-capacity, fast-charging batteries.

목차 (Table of Contents)

• 1. 서론 1
• 1.1 연구 배경 및 목적 2
• 2. 이론과 배경 3
• 2.1 리튬 이온 배터리 3
• 2.1.1 양극 활물질 5
• 2.1.2 음극 활물질 7
• 2.1.3 분리막 9
• 2.1.4 전해질 10
• 2.2 도전재. 11
• 2.2.1 카본 블랙 12
• 2.2.2 탄소나노튜브 13
• 2.3 실리콘-흑연 복합 음극 15
• 3. 실험 방법 17
• 3.1 전지 재료와 구성 17
• 3.2 전극 제작 19
• 3.3 반쪽 전지 제작 20
• 3.4 전지 활성화 21
• 3.5 사이클 특성 실험 22
• 3.6 전지 평가와 분석 23
• 3.6.1 임피던스 측정 23
• 3.6.2 DCA 분석 23
• 3.6.3 순환 전압 전류법 24
• 4. 결과 25
• 4.1 GrSi6 의 CNT 첨가 여부에 따른 전극 성능 24
• 4.1.1 사이클 진행에 따른 전압-용량, dQ/dV 분석 26
• 4.1.2 전기화학적 특성 33
• 4.2 GrSi30 의 CNT 첨가 여부에 따른 전극 성능 41
• 4.2.1 사이클 진행에 따른 전압-용량, dQ/dV 분석 41
• 4.2.2 전기화학적 특성 50
• 5. 결론 57
• 6. 참고문헌 58