Positive electrode for lithium-ion secondary batteries and lithium-ion secondary batteries

Abstract

The purpose of the present invention is to provide a positive electrode which can achieve both high energy density and long service life for a lithium ion secondary battery. A lithium ion secondary battery positive electrode according to the present invention comprises a positive electrode current collector and a positive electrode active material layer laminated on the positive electrode current collector. The positive electrode active material layer includes a first positive electrode active material layer laminated on the positive electrode current collector and a second positive electrode active material layer laminated on the first positive electrode active material layer. The first positive electrode active material layer contains a first positive electrode active material containing, as a main component, a lithium-containing composite oxide containing Li and Ni. The second positive electrode active material layer contains a second positive electrode active material containing, as a main component, a lithium-containing composite oxide containing Li and Ni. The mole fraction of Ni in the second positive electrode active material of the second positive electrode active material layer is less than the mole fraction of Ni in the first positive electrode active material of the first positive electrode active material layer.

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