Nonaqueous electrolyte secondary battery

A nonaqueous electrolyte secondary battery comprising:

• a pressure-operated current interrupt device;
• a nonaqueous electrolytic solution containing a gas producing agent;
• and
• an electrode group in which a positive electrode and a negative electrode are arranged to face each other with a separator interposed between the positive electrode and the negative electrode, wherein
• the positive electrode includes a positive electrode current collector and a positive electrode mixture layer that has a main surface and is formed on the positive electrode current collector,
• the positive electrode mixture layer includes a first layer that includes the main surface and a second layer that is formed closer to the positive electrode current collector side than the first layer,
• a ratio of a volume of the first layer to a volume of the positive electrode mixture layer is 20 vol % to 75 vol %,
• the first layer contains lithium iron phosphate and lithium nickel cobalt manganese composite oxide,
• a ratio of a mass of the lithium iron phosphate to a total mass of the lithium iron phosphate and the lithium nickel cobalt manganese composite oxide in the first layer is more than 0 mass % and 80 mass % or less,
• the second layer contains lithium nickel cobalt manganese composite oxide,
• a ratio of the mass of the lithium iron phosphate to a total mass of a positive electrode active material in the positive electrode mixture layer is 7.5 mass % to 20 mass %, and
• a maximum pore size of the first layer is 0.50 μm to 0.70 μm.