Nonaqueous electrolyte secondary battery, and positive electrode of nonaqueous electrolyte secondary battery

A secondary battery, comprising:

• a positive electrode;
• a negative electrode facing the positive electrode across a separator which is electrically insulative;
• and
• a nonaqueous electrolyte,
• wherein the negative electrode includes an active material comprising at least one titanium compound selected from the group consisting of Li4Ti5O12, H2Ti12O25, and TiO2(B),
• the positive electrode includes an active material comprising a spinel-type lithium manganese oxide and a layered rock-salt compound,
• the spinel-type lithium manganese oxide comprises at least one compound represented by Li1+xAlyMn2-x-yO4 where 0≤x≤0.1, 0≤y≤0.1 or Li1+xMgyMn2-x-yO4 where 0≤x≤0.1, 0≤y≤0.1, and has a number-average particle size of 10 μm to 20 μm and a specific surface area of 0.05 m2/g to 0.4 m2/g,
• the layered rock-salt compound comprises at least one selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt aluminum oxide, and lithium nickel cobalt manganese oxide, and has a number-average particle size of 3 μm to 9 μm and a specific surface area of 0.3 m2/g to 0.6 m2/g, and
• the layered rock-salt compound is included in an amount of 2 to 5 parts by weight per 100 parts by weight of the spinel-type lithium manganese oxide.

A positive electrode, comprising:

• a spinel-type lithium manganese oxide;
• and
• an active material comprising a layered rock-salt compound,
• wherein the spinel-type lithium manganese oxide has a number-average particle size of 10 μm to 20 μm and a specific surface area of 0.05 m2/g to 0.4 m2/g,
• the layered rock-salt compound has a number-average particle size of 3 μm to 9 μm and a specific surface area of 0.3 m2/g to 0.6 m2/g, and
• the layered rock-salt compound is included in an amount of from 2 to 5 parts by weight per 100 parts by weight of the spinel-type lithium manganese oxide.