Carbon black, slurry and lithium ion secondary battery

Carbon black in which, when aggregates are divided into first primary aggregates having an X value of more than 1.7 determined by the following Formula (X),

• second primary aggregates having an X value of 1.7 or less and a Y value of 1.2 or less determined by the following Formula (Y),
• third primary aggregates having an X value of 1.7 or less, a Y value of more than 1.2, and a Z value of 2.0 or less determined by the following Formula (Z), and
• fourth primary aggregates having an X value of 1.7 or less, a Y value of more than 1.2 and a Z value of more than 2.0,
• a number percentage of a total number of the second primary aggregates and the third primary aggregates with respect to a total number of the first primary aggregates, the second primary aggregates, the third primary aggregates and the fourth primary aggregates is 23% or more:
• X
• =
• L
• /
• W
• (
• X
• )
• Y
• =
• P
• 2
• /
• 4
• ⁢
• π
• ⁢
• A
• (
• Y
• )
• Z
• =
• (
• L
• ×
• W
• )
• /
• A
• (
• Z
• )
• [in the formula, in a two-dimensional projection image of a primary aggregate under a transmission electron microscope, the Feret's diameter of the primary aggregate in the minor axis direction is W (μm), the Feret's diameter of the primary aggregate in the major axis direction is L (μm), the perimeter of the primary aggregate is P (μm), and the projected area of the primary aggregate is A (μm2)].