| 摘要 |
Provided are a positive electrode active material, which is improved in a volumetric density, discharge capacity, heat stability, and high rate discharge capacity as compared with conventional positive electrode active materials, and a preparation thereof. The composite positive electrode active material comprises at least one large-diameter active material selected from the group consisting of the compounds represented by the following formulae 1 and 2, and at least one small-diameter active material selected from the group consisting of compounds represented by the following formulae 2, 3, and 4 and carbonaceous materials. The ratio of the average diameter(D50) of the small-diameter active material to the large-diameter active material is 6:1 to 20:1. The weight ratio of the large-diameter active material and the small-diameter active material is (60/M_(w1):40/M_(w2)) to (90/M_(w1):10/M_(w2)), wherein M_(w1) is a molecular weight of a large-diameter active material, M_(w2) is a molecular weight of a small-diameter active material, W1 and W2 each is an integer except for 0. The large-diameter active material has an electric capacity larger than the small-diameter active material. The small-diameter active material has heat stability or conductivity higher than the large-diameter active material. |
