현대 사회로 오면서 가전제품 및 전기자동차를 개발하는 과정에서 에너지를 이용하는 수단인 배터리의 중요성이 더욱 커지고 있으며 이 과정에서 리튬 배터리에 대한 수요가 급증하였다. 초기에는 LiCoO2를 양극 활물질로 이용하였지만 경제적이지 않고 낮은 가역 용량을 가지며 충방전 사이클이 진행되면서 용량이 심하게 감소하였고, 이러한 현상을 해결하기 위하여 성능이 더 좋은 양극 활물질을 개발하려고 노력하였다. 그 결과로 LiNi1-x-yCoxMnyO2를 개발하였는데 이 물질은 초기 양극 활물질인 LiCoO2에 니켈과 ...
현대 사회로 오면서 가전제품 및 전기자동차를 개발하는 과정에서 에너지를 이용하는 수단인 배터리의 중요성이 더욱 커지고 있으며 이 과정에서 리튬 배터리에 대한 수요가 급증하였다. 초기에는 LiCoO2를 양극 활물질로 이용하였지만 경제적이지 않고 낮은 가역 용량을 가지며 충방전 사이클이 진행되면서 용량이 심하게 감소하였고, 이러한 현상을 해결하기 위하여 성능이 더 좋은 양극 활물질을 개발하려고 노력하였다. 그 결과로 LiNi1-x-yCoxMnyO2를 개발하였는데 이 물질은 초기 양극 활물질인 LiCoO2에 니켈과 망간을 치환한 물질이며 치환 물질의 양에 따라서 전기화학적인 특성이 조금씩 달라진다. 이러한 특성은 LiNi0.5Co0.2Mn0.3O2와 LiNi0.6Co0.2Mn0.2O2를 비교실험함으로써 확인할 수 있었다. 결과적으로 니켈의 양이 많은 LiNi0.6Co0.2Mn0.2O2는 LiNi0.5Co0.2Mn0.3O2에 비하여 용량의 감소가 심하였고, 이러한 문제를 해결하기 위하여 전해질 및 양극 활물질과 반응하지 않는 알루미나를 소량 코팅하였다. 코팅함으로써 알루미나가 양극 활물질 표면을 감싸게 하여 리튬 이온의 삽입/탈리 이외의 부반응을 억제해주어 성능이 감소하는 현상을 지연시킬 수 있었다. 본 연구를 통하여 알루미나를 표면에 코팅할 때 온도와 열처리 시간, 알루미나의 코팅 양에 변화를 준 후 전기화학 성능 테스트를 통하여 표면을 코팅할 때 최적의 열처리 조건과 가장 적합한 알루미나의 코팅 양을 알 수 있었으며, 그 조건은 600℃, 4시간, 0.08 wt.%였다.
현대 사회로 오면서 가전제품 및 전기자동차를 개발하는 과정에서 에너지를 이용하는 수단인 배터리의 중요성이 더욱 커지고 있으며 이 과정에서 리튬 배터리에 대한 수요가 급증하였다. 초기에는 LiCoO2를 양극 활물질로 이용하였지만 경제적이지 않고 낮은 가역 용량을 가지며 충방전 사이클이 진행되면서 용량이 심하게 감소하였고, 이러한 현상을 해결하기 위하여 성능이 더 좋은 양극 활물질을 개발하려고 노력하였다. 그 결과로 LiNi1-x-yCoxMnyO2를 개발하였는데 이 물질은 초기 양극 활물질인 LiCoO2에 니켈과 망간을 치환한 물질이며 치환 물질의 양에 따라서 전기화학적인 특성이 조금씩 달라진다. 이러한 특성은 LiNi0.5Co0.2Mn0.3O2와 LiNi0.6Co0.2Mn0.2O2를 비교실험함으로써 확인할 수 있었다. 결과적으로 니켈의 양이 많은 LiNi0.6Co0.2Mn0.2O2는 LiNi0.5Co0.2Mn0.3O2에 비하여 용량의 감소가 심하였고, 이러한 문제를 해결하기 위하여 전해질 및 양극 활물질과 반응하지 않는 알루미나를 소량 코팅하였다. 코팅함으로써 알루미나가 양극 활물질 표면을 감싸게 하여 리튬 이온의 삽입/탈리 이외의 부반응을 억제해주어 성능이 감소하는 현상을 지연시킬 수 있었다. 본 연구를 통하여 알루미나를 표면에 코팅할 때 온도와 열처리 시간, 알루미나의 코팅 양에 변화를 준 후 전기화학 성능 테스트를 통하여 표면을 코팅할 때 최적의 열처리 조건과 가장 적합한 알루미나의 코팅 양을 알 수 있었으며, 그 조건은 600℃, 4시간, 0.08 wt.%였다.
Current lithium-ion battery technology offers the highest energy density among the rechargeable battery technologies, dominating the market for mobile electronic devices for the past several decades. However, alternative forms of transportation, such as electric and plug-in hybrid electric vehicles,...
Current lithium-ion battery technology offers the highest energy density among the rechargeable battery technologies, dominating the market for mobile electronic devices for the past several decades. However, alternative forms of transportation, such as electric and plug-in hybrid electric vehicles, require significant improvements in energy density, safety, durability, cost, etc. The key to the successful development of novel and advanced rechargeable batteries is the materials. Since Sony commercialized the lithium-ion secondary battery (C/LiCoO2 cell) in 1991, various cathode (positive electrode) materials, which account for approximately 30% of materials in the lithium-ion battery, have been studied by many investigators. LiCoO2 has been the dominating cathode material for commercial lithium-ion batteries owing to its high capacity, stable cycling, and easy production. However, cobalt is a rare metal, expensive, and toxic, therefore alternative cathode materials such as ternary Li(Ni1-x-yCoxMny)O2 compounds with layered structures have been intensively investigated as a possible replacement for LiCoO2. Nickel-rich (Ni-rich) layered compounds (1 – x – y ≥ 0.5), such as Li(Ni0.6Co0.2Mn0.2)O2 are the most promising because high Ni and low Co content contributes to the improvement of specific capacity and the reduction of cost. However, as the content of Ni in Li(Ni1-x-yCoxMny)O2 increases, its thermal, structural, and chemical stabilities decrease. Accordingly, the cathode materials with high capacity and good thermal stability, simultaneously, are necessary. This could be achieved by improving the degradation of the electrochemical properties and thermal stability in lithium-ion batteries caused by the interface reaction between the cathode material and the electrolyte solution. This problem could be solved by coating the surface of the cathode material with a different material. Among the coating processes, wet chemical processes such as sol-gel and precipitation are widely applied, which typically require 0.3–5 wt.% of coating material respect to the cathode material and resulted in substantially inhomogeneous coating. Herein, we demonstrate the use of simple surface modification in water media to improve the electrochemical properties, especially high capacity and stable cycling, of the Li(Ni0.6Co0.2Mn0.2)O2 cathode. The Al2O3-coated Li(Ni0.6Co0.2Mn0.2)O2 cathode materials were prepared by mixing cathode powder with Al2O3 precursor in water, drying the mixed slurry, and then annealing at various temperatures and hours. The effects of the Al2O3 coating on the structural and electrochemical properties of the Li(Ni0.6Co0.2Mn0.2)O2 cathode material were investigated. Measurement of electrochemical properties in this research showed that Li(Ni0.6Co0.2Mn0.2)O2 coated with Al2O3 of 0.08 wt.% had a high initial discharge capacity of 206.9 mAh/g at a rate of 0.05 C over 3.0–4.5 V and high capacity retention of 94.5% at 0.5 C after 30 cycles (uncoated sample: 206.1 mAh/g and 90.8%, respectively). The rate capability of this material was also improved.
Key words: Lithium-ion secondary battery, Cathode active materials, LiNi0.6Co0.2Mn0.2O2
Current lithium-ion battery technology offers the highest energy density among the rechargeable battery technologies, dominating the market for mobile electronic devices for the past several decades. However, alternative forms of transportation, such as electric and plug-in hybrid electric vehicles, require significant improvements in energy density, safety, durability, cost, etc. The key to the successful development of novel and advanced rechargeable batteries is the materials. Since Sony commercialized the lithium-ion secondary battery (C/LiCoO2 cell) in 1991, various cathode (positive electrode) materials, which account for approximately 30% of materials in the lithium-ion battery, have been studied by many investigators. LiCoO2 has been the dominating cathode material for commercial lithium-ion batteries owing to its high capacity, stable cycling, and easy production. However, cobalt is a rare metal, expensive, and toxic, therefore alternative cathode materials such as ternary Li(Ni1-x-yCoxMny)O2 compounds with layered structures have been intensively investigated as a possible replacement for LiCoO2. Nickel-rich (Ni-rich) layered compounds (1 – x – y ≥ 0.5), such as Li(Ni0.6Co0.2Mn0.2)O2 are the most promising because high Ni and low Co content contributes to the improvement of specific capacity and the reduction of cost. However, as the content of Ni in Li(Ni1-x-yCoxMny)O2 increases, its thermal, structural, and chemical stabilities decrease. Accordingly, the cathode materials with high capacity and good thermal stability, simultaneously, are necessary. This could be achieved by improving the degradation of the electrochemical properties and thermal stability in lithium-ion batteries caused by the interface reaction between the cathode material and the electrolyte solution. This problem could be solved by coating the surface of the cathode material with a different material. Among the coating processes, wet chemical processes such as sol-gel and precipitation are widely applied, which typically require 0.3–5 wt.% of coating material respect to the cathode material and resulted in substantially inhomogeneous coating. Herein, we demonstrate the use of simple surface modification in water media to improve the electrochemical properties, especially high capacity and stable cycling, of the Li(Ni0.6Co0.2Mn0.2)O2 cathode. The Al2O3-coated Li(Ni0.6Co0.2Mn0.2)O2 cathode materials were prepared by mixing cathode powder with Al2O3 precursor in water, drying the mixed slurry, and then annealing at various temperatures and hours. The effects of the Al2O3 coating on the structural and electrochemical properties of the Li(Ni0.6Co0.2Mn0.2)O2 cathode material were investigated. Measurement of electrochemical properties in this research showed that Li(Ni0.6Co0.2Mn0.2)O2 coated with Al2O3 of 0.08 wt.% had a high initial discharge capacity of 206.9 mAh/g at a rate of 0.05 C over 3.0–4.5 V and high capacity retention of 94.5% at 0.5 C after 30 cycles (uncoated sample: 206.1 mAh/g and 90.8%, respectively). The rate capability of this material was also improved.
Key words: Lithium-ion secondary battery, Cathode active materials, LiNi0.6Co0.2Mn0.2O2
AI-Helper
※ AI-Helper는 부적절한 답변을 할 수 있습니다.