A cathode includes a cathode current collector; and a cathode active material layer disposed on a surface of the cathode current collector. The cathode active material layer includes a first particle and a second particle, the first particle including a secondary particle composed of a third particle, the third particle being a primary particle, the first particle having an average particle size of 5 μm to 20 μm, the third particle having an average particle size of 200 nm to 700 nm, the second particle including a fourth particle and/or a secondary particle composed of the fourth particle, the fourth particle being a primary particle, the second particle having an average particle size of 3 μm to 5 μm, the fourth particle having an average particle size of 800 nm to 5 μm.