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

Abstract

The present invention provides a positive electrode active material which is capable of suppressing an increase in the direct-current resistance caused by repeated charging and discharging. This positive electrode active material, which is contained in nonaqueous electrolyte secondary batteries, contains a lithium-containing composite oxide that has a layered rock salt structure and a sulfonic acid compound that is present on the surface of the lithium-containing composite oxide; the lithium-containing composite oxide contains 25% by mole to 75% by mole of Ni, 15% by mole to 40% by mole of Co and 5% by mole to 50% by mole of Mn relative to the total number of moles of metal elements other than Li; and the sulfonic acid compound is represented by general formula I. (In the formula, A represents a group I element or a group 2 element; R represents a hydrocarbon group; and n is 1 or 2.)

Dependencies are inferred from the claim text.