Positive-electrode active material for lithium secondary cell

• Main Authors: Yoshimi Hata, Daisuke Washida, Hideaki Matsushima, Shinya Kagei, Daisuke Inoue, Hitohiko Ide, Toshikazu Matsuyama, Tetsuya Mitsumoto
• Format: Patent
• Language: English
• Published: 21.12.2016
• Subjects: BASIC ELECTRIC ELEMENTS; CHEMISTRY; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; ELECTRICITY; INORGANIC CHEMISTRY; METALLURGY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

The present invention pertains to a positive-electrode active material containing a lithium metal composite oxide having a laminar crystal structure, and provides a novel positive-electrode active material for a lithium secondary cell with which it is possible to suppress reactions with a liquid electrolyte and increase the service life characteristics of the cell, while also improving the output characteristics of the cell. The present invention proposes a positive-electrode active material for a lithium secondary cell, the active material containing active particles provided with a surface portion in which one or more elements from the group consisting of Al, Ti, and Zr ("surface element A") is present on the surface of particles comprising a lithium metal composite oxide having a laminar crystal structure, the lithium metal composite oxide being represented by the general formula Li1+xM1-xO2 (in the formula, M represents one or more elements from the group consisting of Mn, Co, Ni, transition elements present from group 3 elements to group 11 elements of the periodic table, and main-group elements up to period 3 of the periodic table ("structural element M")), wherein the positive-electrode active material for a lithium secondary cell is characterized in that the ratio (CA/CM) of the concentration CA of surface element A to the concentration CM of structural element M, as measured by XPS, is 0 to 0.8 exclusive; the amount of surface lithium impurities is less than 0.40% by weight; and the ratio (003)/(104) of the integral intensity of the peak attributed to the (003) plane to the integral intensity of the peak attributed to the (104) plane in an X-ray diffraction pattern measured by XRD is greater than 1.15.