Lithium ion secondary battery

1. A lithium ion secondary battery comprising a power generating element, the power generating element including:

at least one positive electrode plate having a shape like a sheet, said positive electrode plate having an area A (cm 2 );

at least one negative electrode plate; and

at least one separator, wherein

a ratio B/A (mΩ cm) of volume resistivity B (mΩ cm 3 ) of the power generating element to the area A (cm 2 ) per one positive electrode plate is 0.488 or more and less than 0.9,

wherein a positive electrode active material layer including a positive electrode active material is disposed on the positive electrode plate,

wherein the positive electrode active material layer has a density of 2.3 or more and 2.9 or less,

wherein the positive electrode active material is a lithium nickel manganese cobalt composite oxide represented by a general formula: Li x Ni y Mn z Co (1-y-z) O 2 , where x is a numeral satisfying 0<x<1.2 and y and z are numerals satisfying y+z<1, and

wherein the lithium nickel manganese cobalt composite oxide has a layer crystal structure.

2. The lithium ion secondary battery according to claim 1 , wherein

a negative electrode active material layer including a negative electrode active material is disposed on the negative electrode plate, and

the negative electrode active material contains graphite particles and amorphous carbon particles.

3. The lithium ion secondary battery according to claim 1 , wherein

the power generating element has a rectangular shape,

one side of the rectangular shape is connected to a positive electrode lead and a negative electrode lead, and

the positive electrode lead and the negative electrode lead are led out of the power generating element.