Positive active material for nonaqueous electrolyte secondary battery, method of producing positive active material for nonaqueous electrolyte secondary battery, positive electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

A positive active material for a nonaqueous electrolyte secondary battery containing a lithium transition metal composite oxide,

• wherein
• the lithium transition metal composite oxide has an α-NaFeO2 structure,
• a molar ratio Li/Me of Li and a transition metal (Me) of 1.05≤Li/Me≤1.4,
• a porosity of 5 to 15%,
• the lithium transition metal composite oxide contains Ni and Mn or Ni, Co, and Mn as the transition metal (Me),
• a molar ratio Mn/Me of Mn to the transition metal element Me is 0.35 or more and less than 0.6, and
• the lithium transition metal composite oxide is made by
• coprecipitating a compound containing Ni and Mn, or Ni, Co, and Mn in a solution of pH of 9.8 to 10.2 to make a transition metal hydroxide precursor, wherein the transition metal hydroxide precursor is a mixture of αMe(OH)2 and βMe(OH)2, and
• firing a mixture of a lithium compound and the transition metal hydroxide precursor at 750 to 1000° C.