Secondary battery having improved high-temperature properties

A secondary battery comprising:

• a positive electrode current collector;
• a first positive electrode mixture layer disposed on the positive electrode current collector and including a first positive electrode active material and a binder;
• and
• a second positive electrode mixture layer disposed on the first positive electrode mixture layer and including a second positive electrode active material and a binder,
• wherein the first positive electrode active material is a lithium transition metal oxide comprising nickel, manganese and cobalt, and contains 42% by weight or more of nickel,
• wherein the second positive electrode active material is a lithium transition metal oxide comprising nickel, manganese and cobalt, and contains 37% by weight or less of nickel,
• wherein a nickel content of the second positive electrode active material is 62.9% by weight or less of a nickel content of the first positive electrode active material,
• wherein the amount of the second positive electrode active material in the second positive electrode mixture layer is 50% by weight or less of the amount of the first positive electrode active material in the first positive electrode mixture layer, and
• wherein an average nickel content of the first positive electrode active material in the first positive electrode mixture layer and the second positive electrode active material in the second positive electrode mixture layer is 44% by weight or less.