Nonaqueous electrolyte battery, battery pack and positive electrode active material

A battery pack comprising a plurality of nonaqueous electrolyte batteries, wherein the nonaqueous electrolyte battery comprises:

• a case;
• a positive electrode housed in the case and including a positive electrode active material containing a lithium-nickel composite oxide and at least one of lithium hydroxide and lithium oxide, the sum of lithium hydroxide and lithium oxide falling within not less than 0.1% to not more than 0.5% by weight based on the total amount of the positive electrode active material;
• a negative electrode housed in the case and capable of lithium intercalation-deintercalation;
• and
• a separator sandwiched between the positive electrode and the negative electrode and impregnated with a nonaqueous electrolyte containing γ-butyrolactone.

A positive electrode active material, comprising a lithium-nickel composite oxide and at least one of lithium hydroxide and lithium oxide, wherein:

• the sum of lithium hydroxide and lithium oxide falls within not less than 0.1% to not more than 0.5% by weight based on the total amount of the positive electrode active material;
• the positive electrode active material has a core region and an outer region;
• and
• the sum of lithium hydroxide and lithium oxide in the core region falls within not less than 50% to not more than 200% of the sum of lithium hydroxide and lithium oxide in the outer region.