Positive electrode and nonaqueous electrolyte secondary battery using the same
Provided is a positive electrode that can provide a nonaqueous electrolyte secondary battery with high gas generation suppressing performance during storage and high cycle characteristics. The positive electrode disclosed here includes a positive electrode current collector and a positive electrode active material layer supported by the positive electrode current collector. The positive electrode active material layer includes monoparticulate first Ni-containing lithium composite oxide particles and secondary particulate second Ni-containing lithium composite oxide particles. The first Ni-containing lithium composite oxide particles and the second Ni-containing lithium composite oxide particles have layered crystal structures. The first Ni-containing lithium composite oxide particles have an average particle size (D50) of 2 μm to 6 μm. The second Ni-containing lithium composite oxide particles have an average primary particle size of 1.2 μm to 2.0 μm. The second Ni-containing lithium composite oxide particles have an average particle size (D50) of 12 μm to 20 μm.
1 . A positive electrode, comprising:
a positive electrode current collector; and
a positive electrode active material layer supported by the positive electrode current collector, wherein
the positive electrode active material layer includes
monoparticulate first Ni-containing lithium composite oxide particles, and
secondary particulate second Ni-containing lithium composite oxide particles,
the first Ni-containing lithium composite oxide particles and the second Ni-containing lithium composite oxide particles have layered crystal structures,
the first Ni-containing lithium composite oxide particles have an average particle size (D50) of 2 μm to 6 μm,
the second Ni-containing lithium composite oxide particles have an average primary particle size of 1.2 μm to 2.0 μm,
the second Ni-containing lithium composite oxide particles have an average particle size (D50) of 12 μm to 20 μm, and
the second Ni-containing lithium composite oxide particles have a BET specific surface area of 0.41 m 2 /g or more and 0.48 m 2 /g or less when the second Ni-containing lithium composite oxide particles are press-molded for 30 seconds under a load of 70 kN into a cylinder shape of Φ 19 mm×4.0 mm to 4.5 mm and then disintegrated.
2 . The positive electrode according to claim 1 , wherein
the positive electrode active material layer has a density of 3.00 g/cm 3 to 4.00 g/cm 3 .
3 . The positive electrode according to claim 1 , wherein
each of the first Ni-containing lithium composite oxide particles and the second Ni-containing lithium composite oxide particles is particles of a lithium nickel cobalt manganese composite oxide.
4 . The positive electrode according to claim 3 , wherein
a content of nickel in all metal elements except for lithium in the lithium nickel cobalt manganese composite oxide is 50 mol % or more.
5 . A nonaqueous electrolyte secondary battery, comprising:
a positive electrode including
a positive electrode current collector, and
a positive electrode active material layer supported by the positive electrode current collector;
a negative electrode; and
a nonaqueous electrolyte, wherein
the positive electrode active material layer includes monoparticulate first Ni-containing lithium composite oxide particles and secondary particulate second Ni-containing lithium composite oxide particles,
the first Ni-containing lithium composite oxide particles and the second Ni-containing lithium composite oxide particles have layered crystal structures,
the first Ni-containing lithium composite oxide particles have an average particle size (D50) of 2 μm to 6 μm,
the second Ni-containing lithium composite oxide particles have an average primary particle size of 1.2 μm to 2.0 μm,
the second Ni-containing lithium composite oxide particles have an average particle size (D50) of 12 μm to 20 μm, and
the second Ni-containing lithium composite oxide particles have a BET specific surface area of 0.41 m 2 /g or more and 0.48 m 2 /g or less when the second Ni-containing lithium composite oxide particles are press-molded for 30 seconds under a load of 70 kN into a cylinder shape of Φ 19 mm×4.0 mm to 4.5 mm and then disintegrated.
6 . The positive electrode according to claim 1 , wherein
one or more of the second Ni-containing lithium composite oxide particles having the BET specific surface area of 0.41 m 2 /g or more and 0.48 m 2 /g or less are cracked.
7 . The nonaqueous electrolyte secondary battery according to claim 5 , wherein
one or more of the second Ni-containing lithium composite oxide particles having the BET specific surface area of 0.41 m 2 /g or more and 0.48 m 2 /g or less are cracked.