Sanyo Electric Co., Ltd.

Yuu Takanashi

Atsushi Fukui

Kazuhiro Hasegawa

Sho Tsuruta

Masao Inoue

Toyoki Fujihara

Fumiharu Niina

Kentaro Takahashi

Takahiro Isono

Ken Kaneko

This nonaqueous electrolyte secondary battery has a non-aqueous electrolyte and an electrode assembly formed by layering a positive electrode and a negative electrode layered via a separator. The positive electrode has a positive electrode core and a positive electrode mix layer containing a positive electrode active substance. The median diameter (D) of the positive electrode active substance in terms of volume is 5.0 to 7.0 μm, the BET specific surface area of the positive electrode active substance is 2.00 to 3.00 m/g, the TAP density of the positive electrode active substance is 1.30 to 1.70 g/cm, and the density of the positive electrode mix layer is 2.3 to 2.5 g/cm.

Nonaqueous electrolyte secondary battery

A nonaqueous electrolyte secondary battery includes an electrode assembly including a negative plate and a positive plate including a positive electrode active material mix layer, a nonaqueous electrolyte, a battery case that houses the electrode assembly and the nonaqueous electrolyte, and a pressure-sensitive safety system that operates when the pressure in the battery case reaches a value greater than or equal to a predetermined value. The positive electrode active material mix layer contains lithium carbonate and lithium phosphate. The average particle size of lithium carbonate contained in the positive electrode active material mix layer is greater than the average particle size of lithium phosphate contained in the positive electrode active material mix layer. The number of particles of lithium carbonate contained in the positive electrode active material mix layer is less than the number of particles of lithium phosphate contained in the positive electrode active material mix layer.

A non-aqueous electrolyte secondary battery positive electrode capable of suppressing a decomposition reaction of an electrolyte solution in an overcharged state is provided. A non-aqueous electrolyte secondary battery positive electrode according to this embodiment includes a positive electrode active material layer which includes a positive electrode active material () containing a lithium transition metal oxide, a tungsten compound (), a phosphoric acid compound () not in contact with the positive electrode active material (), and an electrically conductive agent () in contact with the tungsten compound () and the phosphoric acid compound ().

Non-aqueous electrolyte secondary battery positive electrode and non-aqueous electrolyte secondary battery

Provided is a nonaqueous electrolyte secondary battery in which the structural change of a positive electrode active material is suppressed at high voltage and which can achieve high capacity and long life. The nonaqueous electrolyte secondary battery includes a positive electrode containing a positive electrode active material storing and releasing lithium ions, a negative electrode containing a negative electrode active material storing and releasing lithium ions, and a nonaqueous electrolyte. The positive electrode active material is a cobalt composite oxide which has a layered rock salt structure and which includes a lithium layer containing magnesium, magnesium is present in the lithium layer after charge is performed at a potential of 4.53 V or more versus lithium, and 4.5 mole percent to 10 mole percent of a magnesium-containing compound is present on the negative electrode with respect to magnesium in the positive electrode.

A nonaqueous electrolyte secondary battery which can suppress the change in structure of a positive electrode active material at a high voltage is provided. The nonaqueous electrolyte secondary battery has a positive electrode including a positive electrode active material which absorbs and releases lithium ions; a negative electrode including a negative electrode active material which absorbs and releases lithium ions; and a nonaqueous electrolyte. The positive electrode active material has a surface to which a rare earth compound is adhered and includes a lithium cobalt composite oxide containing at least one type selected from the group consisting of Ni, Mn, Ca, Cu, Zn, Sr, Ge, Sn, Si, P, Nb, Mo, S, and W, and charge is performed so that the potential of the positive electrode is 4.53 V or more with reference to lithium.

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Hyogo, Japan

Yuu Takanashi