Pole piece and preparation method thereof, battery and electric equipment

The invention relates to a pole piece and a preparation method thereof, a battery and electric equipment, and belongs to the technical field of secondary batteries. The pole piece comprises a current collector and an active material layer arranged on at least one side of the current collector, and the porosity of the active material layer is increased in the first direction from the position close to the current collector to the position away from the current collector; the active material layer includes an active material. At least part of the pole pieces in the thickness direction meet the condition that any (10 +/-1) mu m * (10 +/-1) mu m * (10 +/-1) mu m block of the active material layer is taken in the thickness direction, the particle size of the active material in the block is detected through a laser particle analyzer with the model of Mastersized 3000 to obtain a particle size distribution diagram, the particle size distribution diagram comprises a first peak with the abscissa being D1 and a second peak with the abscissa being D2, and D1 is smaller than D2. According to the battery formed by the pole piece, the electrolyte permeability is relatively good, and meanwhile, the energy density, the rate capability and the cycle capacity retention ratio of the battery can be improved.