Plate-like particle for cathode active material of a lithium secondary battery, a cathode active material film of a lithium secondary battery, and a lithium secondary battery

A lithium secondary battery comprising:

• a positive electrode which contains a plate-like particle having a layered rock salt structure as a cathode active material, wherein a lithium ion gateway plane is oriented in parallel with a plate surface, which is a surface orthogonal to a thickness direction of the particle and thus exposed at the plate surface, a plurality of layers are stacked together in the thickness direction, each of the layers has a plurality of crystallites densely joined together, each crystallite within a given layer has the same crystal axis in the thickness direction but has a different crystal axis in a direction perpendicular to the thickness direction, and each layer in the thickness direction has a dimension of 0.2-5 μm;
• a negative electrode which contains a carbonaceous material or a lithium-occluding material as an anode active material;
• and
• an electrolyte provided so as to intervene between the positive electrode and the negative electrode.