Nonaqueous electrolyte secondary battery positive electrode and nonaqueous electrolyte secondary battery
The positive electrode mixture layer of this nonaqueous electrolyte secondary battery positive electrode, which is one exemplary embodiment, contains a first lithium-transition-metal composite oxide represented by general formula Li x Ni 1-y-z Co y M z O 2 (in the formula. 0.8≤x≤1.2, 0≤y≤0.2, 0<z≤0.5, and M is at least one metal element excluding Li, Ni, and Co), a second lithium-transition-metal composite oxide represented by general formula Li a Ni 2-a-b Me b O 2 (in the formula, 0<a≤0.5, 0≤b≤0.5, and Me is at least one metal element excluding Li and Ni), and a carbon nanotube.
1 . A positive electrode for a non-aqueous electrolyte secondary battery, having a positive electrode mixture layer, wherein
the positive electrode mixture layer includes:
a first lithium-transition metal composite oxide represented by the general formula Li x Ni 1-y-z Co y M 2 O 2 , wherein 0.8≤x≤1.2, 0≤y≤0.2, 0<z≤0.5, and M represents at least one metal element excluding Li, Ni, and Co;
a second lithium-transition metal composite oxide represented by the general formula Li a Ni 2-a-b Me b O 2 , wherein 0<a≤0.5, 0≤b≤0.5, and Me represents at least one metal element excluding Li and Ni; and
a carbon nanotube.
2 . The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 , wherein a content of the second lithium-transition metal composite oxide is greater than or equal to 0.1 mass % and less than or equal to 10 mass % relative to a total mass of the positive electrode mixture layer.
3 . The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the second lithium-transition metal composite oxide is a composite oxide having at least one diffraction peak having a peak top at a diffraction angle (2θ) of greater than or equal to 21.40° and less than or equal to 21.65° in a radiation X-ray diffraction at a radiation energy of 16 KeV.
4 . The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 , wherein a content of the carbon nanotube is greater than or equal to 0.01 mass % and less than or equal to 5 mass % relative to a total mass of the positive electrode mixture layer.
5 . The positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the carbon nanotube has an average diameter of less than or equal to 20 nm and an average fiber length of greater than or equal to 1 μm.
6 . A non-aqueous electrolyte secondary battery, comprising:
the positive electrode for a non-aqueous electrolyte secondary battery according to claim 1 ;
a negative electrode; and
a non-aqueous electrolyte.
7 . The non-aqueous electrolyte secondary battery according to claim 6 , wherein
the negative electrode includes, as a negative electrode active material, a carbon-based active material, and a second active material that is:
one or more of a metal element M3 selected from the group consisting of Si, Sn, Sb, Mg, and Ge, or
a compound containing the metal element M3, or
both; and
a content of the second active material is greater than or equal to 1 mass % and less than or equal to 15 mass % relative to a total mass of the negative electrode active material.