JP2012243463A5 - - Google Patents

Claims (7)

A positive electrode capable of occluding and releasing lithium and a negative electrode capable of occluding and releasing lithium are non-aqueous electrolyte secondary batteries formed via a separator ,
The positive electrode has a positive electrode mixture containing a positive electrode active material and a conductive additive, and a positive electrode current collector to which the positive electrode mixture is applied,
The positive electrode active material has a first positive electrode active material and a second positive electrode active material which are complex oxides containing Li, Ni, Mn and Co, and the first positive electrode active material has a Ni content of first. 2 is greater than the Ni content of the positive electrode active material, and the average particle size of the first positive electrode active material is larger than the average particle size of the second positive electrode active material,
The non-aqueous electrolyte secondary battery, wherein the conductive auxiliary agent has a first conductive auxiliary agent and a second conductive auxiliary agent having different average particle diameters. The positive electrode active material is
The first positive electrode active material is a composite oxide represented by the chemical formula Li _α Ni _x Mn _(1-xy) Co _y O ₂ (1.05 ≦ α ≦ 1.15, 0.5 ≦ x ≦ 0.6, 0.2 ≦ y ≦ 0.3). The average particle size is 8 μm or more and 15 μm or less,
Composite oxide of the second cathode active material is represented by the chemical formula _{Li β Ni (1-st)} Mn s Co t O 2 ( where, 1.05 ≦ β ≦ 1.10,0.2 ≦ s ≦ 0.4, s + t = 1.0) An average particle diameter of 2 μm or more and 5 μm or less,
The nonaqueous electrolyte secondary battery according to claim 1, wherein a weight ratio of the first positive electrode active material to the second positive electrode active material is in a range of 6: 4 to 8: 2. The positive electrode active material is
The first positive electrode active material has a specific surface area of 0.4 m ² / g or more and 0.6 m ² / g or less,
3. The nonaqueous electrolyte secondary battery according to claim 1, wherein a specific surface area of the second positive electrode active material is 0.8 m ² / g or more and 1.2 m ² / g or less. The conductive aid is
The first conductive assistant is graphite having an average particle size of 4 μm or more and 6 μm or less;
4. The nonaqueous electrolyte secondary battery according to claim 1, wherein the second conductive auxiliary agent is carbon black having an average particle diameter of 0.5 μm to 2 μm.   The non-aqueous electrolyte secondary battery according to claim 4, wherein the carbon black includes ketjen black.   6. The non-aqueous electrolyte secondary battery according to claim 1, wherein a volume ratio of the conductive auxiliary agent to the positive electrode active material is 20% or more and 40% or less. The non-aqueous electrolyte secondary battery according to any one of claims 1 to 6, wherein an electrode density of the positive electrode mixture is 2.82 g / cm ³ or more and 2.88 g / cm ³ or less.