POSITIVE ELECTRODE ACTIVE MATERIAL AND NONAQUEOUS ELECTROLYTE SECONDARY CELL COMPRISING THE SAME

A positive active material capable of giving a non-aqueous electrolyte secondary battery excellent in high-rate charge/discharge performance and charge/discharge cycle performance and having a high energy density is provided. Also provided is a non-aqueous electrolyte secondary battery excellent in high-rate charge/discharge performance and charge/discharge cycle performance and having a high energy density. The positive active material comprises an Li-Mn-Ni composite oxide as the main component, and is characterized in that the Li-Mn-Ni composite oxide has a specific surface area as measured by the BET method of from 0.3 m/g to 1.5 m/g. The non-aqueous electrolyte secondary battery employs this active material.