리튬이차전지용 Al(OH)3 코팅된 Li[Ni0.88Co0.10Al0.02]O2 양극 소재의 수명특성에 관한 연구

Abstract

리튬이차전지용 Li[Ni0.88Co0.10Al0.02]O2 양극 활물질 수명성능향상을 위하여, 볼밀 건식 코팅법으로 Al(OH)3 를 코팅하였다. 코팅 방법은 양극 활물질과 Al(OH)3 를 무게비로 혼합한 후에 400℃ 에서 5시간동안 산소 분위기에서 진행하였다. Al(OH)3 코팅된 Li[Ni0.88Co0.10Al0.02]O2 양극 활물질은 SEM과 TEM으로 분석하였다. 상온 30℃에서 Pristine은 213.5 mAh g-1 용량과 100cycle후 59.1%의 성능 대비 Al(OH)3 코팅된 Li[Ni0.88Co0.10Al0.02]O2 양극 활물질은 204.8 mAh g-1 용량과 100cycle후 78.7%의 성능을 보였고, 고온 55℃에서 Pristine은 225.9 mAh g-1 용량과 100cycle후 57.8% 대비 Al(OH)3 코팅된 Li[Ni0.88Co0.10Al0.02]O2 양극 활물질은 219.8 mAh g-1 용량과 100cycle후 71.2% 성능을 보였다. 이는 Al(OH)3 코팅된 Li[Ni0.88Co0.10Al0.02]O2 양극 활물질이 Pristine보다 HF에 의한 metal용출문제와 고온성능에 더 나은 성능을 나타내는 것으로 보였다. 그리고 Al(OH)3 코팅이 cycle 중의 표면 film 저항과 charge transfer 저항이 감소하는 걸로 보였다. 그래서 Al(OH)3 코팅이 고온환경에서 양극 활물질의 용출을 보호하는 역할을 하는 것으로 보인다.|To improve cycle performance of the Al(OH)3 coated Li[Ni0.88Co0.10Al0.02]O2 cathode for lithium ion batteries, we make Li[Ni0.88Co0.10Al0.02]O2 coated easily by Al(OH)3 layer via dry coating method ball mill coating. The ball-mill coating process is easy and basic coating method in lithium ion battery. The Al(OH)3 coated cathode was obtain from firing of the mixture consisting of Al(OH)3 particles and the cathode powder with a various weight ratio at 400℃ for 5hr in O2 condition. The morphology of the Al(OH)3-coated Li[Ni0.88Co0.10Al0.02]O2 was seen using SEM and TEM analysis. At high temperature, the Al(OH)3 coated Li[Ni0.88Co0.10Al0.02]O2 electrode delivered discharge capacity of 221.2mAh g-1 while the pristine delivered discharge capacity of 225.9mAh g-1 and provided a high capacity retention of 71.2% after 100cycles, compared of 57.8% for pristine. Furthermore, the Al(OH)3 Coated Li[Ni0.88Co0.10Al0.02]O2 had good thermal stability than pristine. The improved electro chemical properties started from the Al(OH)3 coating on cathode surface which may have retarded the transition metal dissolution from HF attack. And, the Al(OH)3 Coating reduced the resistance for both surface film (Rsf) and charge transfer (Rct) during cycling. Furthermore, Al(OH)3 Coating prevent metal dissolution in the electrolyte at high temperature.; To improve cycle performance of the Al(OH)3 coated Li[Ni0.88Co0.10Al0.02]O2 cathode for lithium ion batteries, we make Li[Ni0.88Co0.10Al0.02]O2 coated easily by Al(OH)3 layer via dry coating method ball mill coating. The ball-mill coating process is easy and basic coating method in lithium ion battery. The Al(OH)3 coated cathode was obtain from firing of the mixture consisting of Al(OH)3 particles and the cathode powder with a various weight ratio at 400℃ for 5hr in O2 condition. The morphology of the Al(OH)3-coated Li[Ni0.88Co0.10Al0.02]O2 was seen using SEM and TEM analysis. At high temperature, the Al(OH)3 coated Li[Ni0.88Co0.10Al0.02]O2 electrode delivered discharge capacity of 221.2mAh g-1 while the pristine delivered discharge capacity of 225.9mAh g-1 and provided a high capacity retention of 71.2% after 100cycles, compared of 57.8% for pristine. Furthermore, the Al(OH)3 Coated Li[Ni0.88Co0.10Al0.02]O2 had good thermal stability than pristine. The improved electro chemical properties started from the Al(OH)3 coating on cathode surface which may have retarded the transition metal dissolution from HF attack. And, the Al(OH)3 Coating reduced the resistance for both surface film (Rsf) and charge transfer (Rct) during cycling. Furthermore, Al(OH)3 Coating prevent metal dissolution in the electrolyte at high temperature.