A positive current collector, a secondary battery, and an electrical device are provided. In some embodiments, the positive current collector includes: a support layer; and a conductive layer located on at least one surface of the support layer, where the conductive layer includes a first metal portion configured to connect to a tab, where, along a thickness direction of the conductive layer, the first metal portion includes at least three sublayers, and melting points of the at least three sublayers rise stepwise in ascending order of distance from the support layer. In the embodiments of this application, the first metal portion includes at least three sublayers, and the melting points of the at least three sublayers rise stepwise in ascending order of distance from the support layer, thereby helping increase a bonding force between the conductive layer and the support layer and reducing the probability of peel-off and delamination between the layers.