The present application relates to the field of battery, in particular to a positive electrode piece, an electrochemical device and an apparatus. The positive electrode piece of the present application includes a current collector and an electrode active material layer arranged on at least one surface of the current collector, where the current collector includes a support layer and a conductive layer arranged on at least one surface of the support layer. The thickness D2 of one side of the conductive layer D2 satisfies 30 nm≤D2≤3 μm, the material of the conductive layer is aluminum or aluminum alloy, and the density of the conductive layer is 2.5 g/cm3 to 2.8 g/cm3, and a primer layer containing a conductive material and a binder is also arranged between the current collector and the electrode active material layer.