Positive electrode active material and a lithium ion battery for a lithium ion battery

Investigate the cause that affects the voltage drop, it is possible to obtain a high output, and to provide a voltage less lithium ion battery of drop under storage charge state and high temperature, iron contained in the positive electrode active material element the content of (ICP measured by emission spectrometer) is not less 10ppm or more and a lithium ion, characterized in that does not include a magnetically attached having a 0.70 times or more the size of the layer thickness of the separator layer substantially to propose a battery.