OER 또는 LiB용 하이니켈 Ni0.9Co0.1O@C과 NCM811의 합성 및 전기화학적 성능

다국어 초록 (Multilingual Abstract)

In Part1. This study aims to design a rational catalyst to secure a large amount of OH−
adsorption sites to obtain excellent OER performance: NiO is selected as the main catalyst,
and a Ni0.9Co0.1O catalyst is prepared with 10% lattice substitution of Co2+ ions. The a
Ni0.9Co0.1O surface was capsulated with amorphous carbon to prevent corrosion by strong
alkaline media. The XPS analysis revealed that Ni2+ ion defects occurred in the a Ni0.9Co0.1O
crystal, and a large amount of highly oxidized Ni3+ ions were mixed to match the stoichiometric
ratio. Electrophilic Ni2O3 in a highly oxidized state favors attack by OH−
ions, a nucleophile,
and easily transforms into a NiOOH intermediate, ultimately leading to rapid OER progressing.
In other words, the strong covalent nature between Ni3+−O2− in the a Ni0.9Co0.1O/CP electrode
promoted charge transfer between the cationic metal surface and the OH− adsorbate, thereby
accelerating OER. Moreover, C−capsulation in a Ni0.9Co0.1O particles played a role in lowering
the band gap due to the electrons filled from C between the Ni 3d and O 2p orbitals. Ultimately,
this improved the conductivity of the electrode, effectively reducing the ohmic potential drop
and energy loss between the catalyst and the current collector. As a result, the overpotential
that this electrode reaches at 10 mA cm−2 was greatly reduced to 332 mV, the Tafel slope was
low at 91.98 mV dec−1. Moreover, this excellent performance remained stable even after 10
days.
In Part 2. In this study, Co2+ doping and phosphate coating formation are achieved at the
same time to more easily remove lithium remaining on the NCM811 surface. Co3(PO4)2 is
separately synthesized and physically mixed with NCM811 by mass ratio, and then easily
coated on the NCM811 surface through firing. The coating of Co3(PO4)2 increases the diffusion
rate of lithium ions in the electrolyte, and Co3(PO4)2 reacts effectively with residual lithium on
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the NCM surface to form excess cathode active material structures such as LiCoPO4 and
LiCoO2 on the NCM surface, which is predicted to improve capacity increase and capacity
retention. In addition, crystal defects are reduced by forming effective CEI on the NCM surface,
thereby suppressing electrochemical side effects between the surface of the cathode active
material and the electrolyte, which has a positive effect on capacity increase. As a result, the
discharge capacity of the battery was significantly increased from 0.1 C to 190 mAh/g to 212
mAh/g, and the capacity retention rate of the battery through 100 cycles of charging and
discharging at 1.0 C increased from 81.3% to 89.5% without coating. In addition, it was
confirmed that the capacity recovery rate was over 90%

목차 (Table of Contents)

• Ⅰ. 서론 1
• 1. 연구배경 및 목표 1
• Ⅱ. 이론 8
• 1. 산소발생반응(OER) 8
• 2. 리튬이온배터리(LIB) 9
• Part 1. 탄소 캡슐화된 Ni0.9Co0.1O@C/CP 전극에서의 OH- 흡착력 향상 및 효과적인 산소 생산 15
• Ⅲ. 실 험 16
• 1. NiO/CP, Ni0.9Co0.1O/CP, and Ni0.9Co0.1O @C/CP 전극 제조 16
• 2. 전극의 물리화학적 특성 평가 방법 19
• 3. 전극의 전기화학적 특성 평가 방법 17
• Ⅳ. 결과 및 토의 21
• 1. NiO, Ni0.9Co0.1O 그리고 Ni0.9Co0.1O@C 전극의 물리화학적 특성 분석 21
• 2. NiO/CP, Ni0.9Co0.1O/CP, Ni0.9Co0.1O@C/CP 전극 OER 성능 평가 34
• 3. NiO/CP, Ni0.9Co0.1O/CP, Ni0.9Co0.1O@C/CP 전극에서의 장기 안정성 42
• 4. Ni0.9Co0.1O@C/CP 전극에서의 향상된 표면 물성 (결함, 전도도, OH-흡착)과 OER 메커니즘 45
• Ⅴ. 결 론 63
• Part 2. Co3(PO4)2 코팅에 의해 잔류 리튬이 제거된 NCM811 양극 활물질에서의 결정 표면 안정성과 개선된 전지 성능 65
• Ⅲ. 실 험 66
• 1. NCM811, Co3(PO4)2, Co3(PO4)2가 표면에 코팅된 NCM811 제조 66
• 2. 양극활물질의 물리화학적 특성 평가 방법 69
• 3. 양극활물질의 전기화학적 특성 평가 방법 70
• Ⅳ. 결과 및 토의 72
• 1. NCM811과 Co3(PO4)2/NCM811의 물리화학적 특성 분석 72
• 2. NCM811, Co3(PO4)2/NCM811 양극활물질의 배터리 성능 평가 88
• Ⅴ. 결 론 96
• ○ Reference 97
• ○ Abstract 115