A positive electrode sheet may comprise a positive electrode current collector and a positive electrode film layer having a single-layer structure or a multi-layer structure provided on at least one surface thereof; when the positive electrode film layer is of a single-layer structure, at least one positive electrode film layer may comprise both a first positive electrode active material and a second positive electrode active material; and/or, when the positive electrode film layer is of a multi-layer structure, at least one layer of the at least one positive electrode film layer may comprise both a first positive electrode active material and a second positive electrode active material; the first positive electrode active material may comprises an inner core containing Li1+xMn1-yAyP1-zRzO4, a first coating layer containing pyrophosphate MP2O7 and phosphate XPO4 and covering the inner core, and a second coating layer containing carbon element and covering the first coating layer.