ACTIVE MATERIAL FOR NON-AQUEOUS ELECTROLYTE SECONDARY CELL, METHOD FOR MANUFACTURING ACTIVE MATERIAL, ELECTRODE FOR NON-AQUEOUS ELECTROLYTE SECONDARY CELL, AND NON-AQUEOUS ELECTROLYTE SECONDARY CELL

摘要

An object of the present invention is to provide an active material for a nonaqueous electrolyte secondary battery, which has a high discharge capacity and excellent power performance in a low SOC region. The active material for a nonaqueous electrolyte secondary battery includes a lithium transition metal composite oxide which has an ±-NaFeO 2 -type crystal structure, is represented by the compositional formula Li+ ± Me 1-± O 2 (Me is a transition metal element containing Mn, Ni and Co; and 0 < ± < 1) and satisfies the requirement of 1.250 ‰¤ (1+±)/(1-±) ‰¤ 1.425. The half-width of a diffraction peak at 2¸ = 18.6° ± 1° is 0.20° to 0.27° and/or the half-width of a diffraction peak at 2¸ = 44.1° ± 1° is 0.26° to 0.39° in X-ray diffraction measurement using a CuK± radiation. The lithium transition metal composite oxide is observed as a single phase indexed a hexagonal crystal (space group R3-m) on the X-ray diffraction patterns when electrochemically oxidized to a potential of 5.0 V (vs. Li/Li + ).