A novel positive electrode sheet, a secondary battery, a battery module, a battery pack and an electrical apparatus are described. The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer with a single-layer structure or a multi-layer structure. When the positive electrode film layer is a single-layer structure, at least one of the positive electrode film layers comprises a first positive electrode active material and a second positive electrode active material; and/or, when the positive electrode film layer is a multi-layer structure, at least one layer of at least one of the positive electrode film layers comprises a first positive electrode active material and a second positive electrode active materials. The first positive electrode active material includes an inner core, a first cladding layer comprising crystalline pyrophosphates, a second cladding layer comprising crystalline phosphate, and a third cladding layer.