POSITIVE ACTIVE MATERIAL FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, METHOD OF MANUFACTURING THE POSITIVE ACTIVE MATERIAL, ELECTRODE FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY, NONAQUEOUS ELECTROLYTE SECONDARY BATTERY AND METHOD OF MANUFACTURING THE SECONDARY BATTERY

摘要

An object of the present invention is to provide a positive active material for a nonaqueous electrolyte secondary battery which has a large discharge capacity and is superior in charge-discharge cycle performance, initial efficiency and high rate discharge performance, and a nonaqueous electrolyte secondary battery using the positive active material. The present invention pertains to a positive active material for a nonaqueous electrolyte secondary battery containing a lithium transition metal composite oxide which has a crystal structure of an α-NaFeO2 type, is represented by a compositional formula Li1+αMe1−αO2 (Me is a transition metal element including Co, Ni and Mn, α>0), and has a molar ratio Li/Me of Li to the transition metal element Me of 1.2 to 1.6, wherein a molar ratio Co/Me of Co in the transition metal element Me is 0.02 to 0.23, a molar ratio Mn/Me of Mn in the transition metal element Me is 0.62 to 0.72, and the lithium transition metal composite oxide is observed as a single phase attributed to a space group R3-m on an X-ray diffraction chart when it is electrochemically oxidized up to a potential of 5.0 V (vs. Li/Li+).

主权项

1. A positive active material for a nonaqueous electrolyte secondary battery containing a lithium transition metal composite oxide which has a crystal structure of an α-NaFeO2 type, is represented by a compositional formula Li1+αMe1−αO2,
wherein Me is a transition metal element including Co, Ni and Mn, and α>0, a molar ratio Li/Me of Li to the transition metal element Me is 1.2 to 1.6, a molar ratio Co/Me of Co in the transition metal element Me is 0.040 to 0.195, a molar ratio Mn/Me of Mn in the transition metal element Me is 0.625 to 0.707, the lithium transition metal composite oxide is observed as a single phase attributed to a space group R3-m on an X-ray diffraction chart when it is electrochemically oxidized up to a potential of 5.0 V (vs. Li/Li+), and an oxygen position parameter of the lithium transition metal composite oxide, determined by crystal structure analysis by a Rietveld method at the time of using a space group R3-m as a crystal structure model based on an X-ray diffraction pattern in a state of a discharge end, is 0.260 or less.