차세대 나트륨-이온 전지 응용을 위한 그래핀 기반 탄산인산나트륨 음극 소재 연구 = A Study on the Graphene Supported Sodium Carbonophosphate Anode for Next Generation Sodium-ion Battery Application

다국어 초록 (Multilingual Abstract)

Sodium-ion batteries (SIBs) are emerging as a promising alternative to lithium-ion batteries (LIBs), owing to the natural abundance of sodium and their lower material cost. Nevertheless, their commercial deployment remains challenging due to limited energy density and stability. In this study, we explored polyanionic carbonophosphate-based compounds, Na3M(PO4)(CO3) (where M is Ni or Co), as conversion-type anodes for SIBs. Although conversion-type electrodes offer higher capacities than intercalation materials, their practical performance is often limited by poor conductivity and structural degradation during cycling. To overcome these drawbacks, reduced graphene oxide (rGO) was incorporated to form composite anodes. Electrochemical evaluation revealed that pristine Ni-CP ( Na3Ni(PO4)(CO3)), Co-CP (Na3Co(PO4)(CO3)), NiCo-CP (Na3Ni0.5Co0.5(PO4)(CO3)) exhibited specific capacities of 203.08 mAh∙g−1, 151.38 mAh∙g−1, and 114.18 mAh∙g−1, respectively. Upon introducing 10 wt% rGO, the capacities were significantly enhanced to 361.87 mAh∙g−1 for the Ni-based, 160.60 mAh∙g−1 for the Co-based, and 240.95 mAh∙g−1 for the mixed-metal electrode. Notably, the 20 wt.% rGO+Ni-CP composite exhibited the best overall electrochemical performance, while the 20 wt.% rGO+NiCo-CP composite showed the second-best performance due to the synergistic combination of high capacity of the Ni-based system and the superior stability of the Co-based counterpart. These results highlight the potential of Na3M(PO4)(CO3)/rGO composites as promising anode materials and provide new insights into the rational design of high-performance sodium-ion batteries.

목차 (Table of Contents)

• LIST OF FIGURES iv
• LIST OF TABLES ix
• LIST OF ABBREVIATIONS x
• ABSTRACT xii
• 제 1 장 서론 １
• 1.1 연구배경 １
• 1.2 연구목적 및 범위 ３
• 제 2 장 이론적 고찰 ８
• 2.1 나트륨이온전지의 개요 및 구동 원리 ８
• 2.2 탄산인산 나트륨 (Sodium carbonophosphate) 11
• 제 3 장 실험 재료 및 방법 14
• 3.1 시약 및 재료 14
• 3.1.1 Sodium Carbonophosphate 합성을 위한 시약 및 재료 14
• 3.1.2 Sodium Carbonophosphate/rGO 합성을 위한 시약 및 재료 14
• 3.1.3 셀제작을 위한 시약 및 재료 15
• 3.2 실험 방법 16
• 3.2.1 Na3Ni(PO4)(CO3) 합성 16
• 3.2.2 Na3Co(PO4)(CO3) 합성 16
• 3.2.3 Na3Ni0.5Co0.5(PO4)(CO3) 합성 17
• 3.2.4 Na3M(PO4)(CO3) (M= Ni, Co)/rGO 합성 17
• 3.2.5 전해질 제조 18
• 3.3 특성 평가 21
• 3.3.1 물리적 특성 평가 21
• 3.3.2 전기 화학적 특성 평가 22
• 제 4 장 결과 및 고찰 24
• 4.1 형태 및 구조적 특성 연구 24
• 4.1.1 라만 분광 분석(Raman Spectroscopy) 24
• 4.1.2 주사 전자 현미경 분석(FE-SEM) 26
• 4.1.3 투과 전자 현미경 분석(TEM) 29
• 4.1.4 X-ray 회절 분석(XRD) 32
• 4.1.5 X-ray 광전자 분광법 분석(XPS) 40
• 4.1.6 X-ray 흡수 분광법 분석(XAS) 44
• 4.2 전기화학적 특성연구 47
• 4.2.1 순환 전압전류법(CV) 47
• 4.2.2 코인셀 충ㆍ방전 분석(GCD) 57
• 4.2.3 전기화학 임피던스 분광법(EIS) 73
• 제 5 장 결론 77
• 참고문헌 79
• 감사의 말 90