Lithium secondary cell and positive electrode active material, positive plate, and method for manufacturing them

Abstract

Using a crystal (lithium cobaltate) having a crystallite size in the direction of (003) plane of not less than 800 angstrom and a coordination number of a cobalt atom to a different cobalt atom of not less than 5.7 as a positive electrode active material, a lithium ion secondary battery is formed. As a result, the rate characteristic, low temperature characteristic, cycle characteristic and the like of the lithium ion secondary battery can be improved. In addition, by combining a preferable embodiment of the positive plate such as (an embodiment wherein not more than 50% of the surface of a positive electrode active material is covered with a conductive material), (an embodiment wherein two kinds of conductive materials having a particle size of not less than 3 μm and a particle size of not more than 2 μm are used, or one kind of a conductive material having a particle size of not more than 10 μm is used and the porosity of the positive electrode coating layer is 0.08 cc/g-0.14 cc/g), (an embodiment wherein a conductive material containing at least carbon black is used and a specific surface area of the positive electrode coating layer is 0.5 m2/g-1.0 m2/g) and the like, and further incorporating a combination of an embodiment of a preferable negative electrode active material and an electrolyte, a more preferable lithium ion secondary battery having sufficient battery capacity, which is superior in cycle characteristic, preservation property, safety, low temperature characteristic and the like is obtained.

Dependencies are inferred from the claim text.