The invention relates to a
pole piece and a preparation method thereof and an application of the
pole piece in a battery. The
mass content of the conductive agent in the first active material layer iscontrolled to be greater than the
mass content of the conductive agent in the second active material layer; the concentration of the conductive agent in the
pole piece is in longitudinal gradient distribution, so that the content of the conductive agent in the lower active material layer close to the
current collector is high, more conductive paths can be formed due to the high content of the lower conductive agent, the
electron transmission resistance of the pole piece is low, and the rate performance and the
cycling stability of the battery are improved. A double-cavity die head
coating machine is used for
coating two kinds of
slurry at the same time, the problem that the occupied space is large due to the fact that two
coating machines are used for coating at the same time is solved, meanwhile, the double-cavity die head coating
machine can be operated by only one person, and the labor cost is reduced; moreover, two kinds of
slurry are coated at the same time, so that the problem of poor compatibility between
layers caused by separate coating (
drying after bottom layer coating and top layer coating again) in the prior art is solved.