| Summary: | 碩士 === 元智大學 === 化學工程與材料科學學系 === 105 === A lithium rich phase 0.4Li2MnO3·0.6LiMn1/3Co1/3Ni1/3O2, is a promising cathode material for Li-ion batteries due to its very high theoretical capacity. This experiment was divided into three parts, the first part is to find the optimal processing parameters by Taguchi method. The second part is to confirm the influences of reaction temperature in the range of 60℃-100℃ on the electrochemical performance of 0.4Li2MnO3·0.6LiMn1/3Co1/3Ni1/3O2 cathode materials. The final part is to investige the effect of reaction temperature above 100℃on the 0.4Li2MnO3·0.6LiMn1/3Co1/3Ni1/3O2 cathode material in different solvent.
Layered Li-rich 0.4Li2MnO3·0.6LiMn1/3Co1/3Ni1/3O2 materials was prepared by microwave co-precipitation method and used as cathode material for lithium-ion batteries. The cathode powders were well-indexed to the expected layered 0.4Li2MnO3·0.6LiMn1/3Co1/3Ni1/3O2 solid solution, which has no second phases. The particle size of powders decreases with the temperature increases. The morphology and size of particles are very important to enhance the electrochemical properties of cathode materials. The electrochemical properties were investigated by galvanostatic cycling in the voltage range of 2.0–4.8V at room temperature as well as at 25 ◦C. The 0.4Li2MnO3.0.6LiMn1/3Co1/3Ni1/3O2 electrode has discharge capacity of 190 mAhg-1 at 0.1 C. The morphology of 0.4Li2MnO3.0.6LiMn1/3Co1/3Ni1/3O2 which systhesied in ethylene glycol (EG) is different comparing to that prepared in water. The particle of powder prepared in EG is more spherical and rough. The capacity of 0.4Li2MnO3.0.6LiMn1/3Co1/3Ni1/3O2 increases with temperature increases. When the synthesized temperature aboved 130 ℃, it show the better electochemical performance. In addition, the powders which calcined two time is benefit to form impurity phase. The 0.4Li2MnO3.0.6LiMn1/3Co1/3Ni1/3O2 has discharge capacities of 149 mAhg-1 at 0.1 C. In summary, the microwave co-precipitation method is a potem excellent method to prepare high electrochemical properties of 0.4Li2MnO3.0.6LiMn1/3Co1/3Ni1/3O2.
|
|---|
